#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
HKMLE Module 1D Study Note Builder
Valvular + Pericardial + Cardiomyopathies + Infective Endocarditis
Renders a mini-markup CONTENT string into a formatted PDF using reportlab.
"""
import re
from reportlab.lib.pagesizes import A4
from reportlab.lib.units import cm
from reportlab.lib import colors
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.platypus import (SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle,
                                 PageBreak, ListFlowable, ListItem, HRFlowable, KeepTogether,
                                 Frame, NextPageTemplate, PageTemplate)
from reportlab.platypus.doctemplate import BaseDocTemplate
from reportlab.pdfbase.pdfmetrics import stringWidth

# ---------------------------------------------------------------- STYLES ---
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def esc(t):
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def inline(t):
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def P(text, style='Body'):
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                             leftMargin=1.4*cm, rightMargin=1.4*cm,
                             title="HKMLE Module 1D: Valvular, Pericardial, Cardiomyopathy and Endocarditis")
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    doc.build(story, onFirstPage=footer, onLaterPages=footer)

if __name__ == '__main__':
    from content import CONTENT
    build(CONTENT, '/tmp/workspace/module1d/HKMLE_Module1D_Valvular_Pericardial_Cardiomyopathy_IE.pdf')
    print("DONE")

# -*- coding: utf-8 -*-
CONTENT = r"""
# HKMLE Module 1D
# Valvular Heart Disease, Pericardial Disease,
# Cardiomyopathies and Infective Endocarditis
# High-Yield Ace-Level Study Note for HKMLE Paper 1 and Paper 2

HR

BOX|SUMMARY|How to use this note
- Each condition follows the same skeleton: Definition, Classification, Aetiology, Pathophysiology, Risk Factors, Symptoms, Signs, Investigations, Management, Complications, Prognosis.
- Boxes flag exam traps, Hong Kong Hospital Authority (HA) pathways, CHP notification status, local epidemiology, investigation interpretation, legal/ethical issues, red flags and exam questions.
- End-of-note tables consolidate drug traps, trials, mnemonics and cross-links to other modules.
ENDBOX

PAGEBREAK

## 1. AORTIC STENOSIS (AS)

### Definition
Progressive narrowing of the aortic valve orifice causing obstruction to left ventricular (LV) outflow during systole. The commonest primary valve lesion requiring surgery in the developed world and in Hong Kong's ageing population.

### Classification
TABLE
Severity | Aortic Jet Velocity | Mean Gradient | Valve Area
Mild | 2.6-2.9 m/s | less than 20 mmHg | greater than 1.5 cm2
Moderate | 3.0-3.9 m/s | 20-39 mmHg | 1.0-1.5 cm2
Severe | 4.0 m/s or more | 40 mmHg or more | less than 1.0 cm2 (indexed less than 0.6 cm2/m2)
Critical/Very Severe | 5.0 m/s or more | 60 mmHg or more | less than 0.6 cm2
ENDTABLE
Special subtype: **low-flow low-gradient severe AS** (valve area less than 1.0 cm2 but mean gradient less than 40 mmHg due to reduced LV stroke volume) - needs dobutamine stress echo or CT calcium scoring to confirm true severity.

### Aetiology / Causes
> Mnemonic: "CRAB" causes of AS -- Calcific (senile, most common overall), Rheumatic (commonest cause in young adults / developing world), Anomalous bicuspid valve (commonest cause under age 65 in developed countries), Bicuspid congenital valve accelerates calcification.
- **Senile calcific degeneration** - commonest overall cause, age greater than 65, related to atherosclerosis-like process (lipid deposition, inflammation, calcification) -- shares risk factors with coronary artery disease.
- **Congenital bicuspid aortic valve** - commonest cause in patients under 65; accelerated wear leads to calcification one to two decades earlier than tricuspid valves; associated with aortopathy/dissection risk.
- **Rheumatic heart disease** - fusion of commissures plus cusp fibrosis; almost always coexists with mitral valve disease; important cause in older Hong Kong Chinese and mainland-born patients.
- Rare: radiation-induced valve disease, Paget's disease of bone, chronic kidney disease/dialysis-related calcification, familial hypercholesterolaemia.

BOX|TRAP|Bicuspid vs calcific age trap
Many candidates automatically write "rheumatic" as the top cause of AS because that is the classic UK teaching for MS. In HKMLE, senile calcific degeneration is the overall commonest cause of AS; bicuspid valve is the commonest cause in a patient presenting before age 65. Match the age in the vignette to the correct answer.
ENDBOX

### Pathophysiology (step by step)
1. Valve orifice narrows -> fixed outflow obstruction -> LV must generate higher systolic pressure to maintain cardiac output (pressure overload).
2. Chronic pressure overload triggers **concentric LV hypertrophy** (sarcomeres added in parallel) to normalise wall stress (Laplace's law).
3. Hypertrophied, stiff LV has impaired diastolic relaxation -> raised LV end-diastolic pressure -> reduced coronary perfusion pressure gradient, especially subendocardially.
4. Increased myocardial oxygen demand (thicker muscle) plus reduced supply (compressed coronary microcirculation, diastolic filling time shortened) -> **angina even without coronary artery disease**.
5. Fixed obstruction means cardiac output cannot rise with exercise -> exertional syncope/pre-syncope (inadequate cerebral perfusion) and dyspnoea.
6. Eventually LV systolic function decompensates -> dilatation, reduced ejection fraction, symptoms of heart failure -- this marks a very poor prognostic turning point.

### Risk Factors
> Mnemonic: "OLD CALCIUM" -- Old age, Lipid abnormalities/dyslipidaemia, Diabetes mellitus, Chronic kidney disease, Atherosclerosis, LDL elevation, Congenital bicuspid valve, Inflammation (rheumatic fever history), Uraemia/dialysis, Male sex.
- Age over 65, male sex, smoking, hypertension, diabetes mellitus, dyslipidaemia (same profile as atherosclerosis).
- Congenital bicuspid aortic valve, chronic kidney disease/dialysis, prior chest radiotherapy, history of rheumatic fever.

### Symptoms
> Mnemonic: **SAD** -- Syncope (exertional), Angina, Dyspnoea (exertional, progressing to orthopnoea/PND as LV fails).
- Classic triad: exertional dyspnoea (earliest and commonest), angina, syncope/presyncope.
- Late: symptoms of congestive heart failure, sudden death (rare, usually in previously symptomatic severe AS).

BOX|REDFLAG|Red flags in AS
- Syncope or angina in a patient with known AS = urgent cardiology referral, avoid vasodilators.
- Onset of ANY symptom in severe AS is an indication for valve intervention regardless of LV function.
- Sudden death can be the first presentation of previously undiagnosed severe AS -- always auscultate for murmurs in unexplained syncope.
ENDBOX

### Signs
> Mnemonic: **SPADE** -- Slow-rising (anacrotic) carotid pulse, Pulse pressure narrow, A2 soft or absent/single S2, Displaced, sustained apex beat (heaving, non-displaced until late), Ejection systolic murmur crescendo-decrescendo at right upper sternal border radiating to carotids.
- Slow-rising "plateau" carotid pulse (pulsus parvus et tardus), narrow pulse pressure.
- Ejection systolic murmur, harsh, crescendo-decrescendo, loudest at right 2nd intercostal space, radiates to carotids, softer with Valsalva, louder on expiration leaning forward.
- Soft or absent A2 (calcified immobile valve); paradoxical splitting of S2 in severe AS; S4 gallop (forceful atrial contraction against stiff LV).
- Sustained, heaving, non-displaced apex beat; palpable systolic thrill at base/carotids.

BOX|TRAP|Loudness of murmur is NOT severity
A common HKMLE distractor: "murmur is very loud, therefore AS is severe." In fact, as AS becomes critical and cardiac output falls, the murmur may become SOFTER. Signs that DO correlate with true severity: slow-rising pulse, narrow pulse pressure, soft/absent S2, late-peaking murmur, LV failure signs -- not murmur intensity alone.
ENDBOX

### Investigations
> Mnemonic: "ECHO-CATH-CT-EX" -- Echocardiography first, Catheterisation if discordant, CT calcium score for low-flow low-gradient, Exercise testing avoided if symptomatic.
#### Bedside -> Labs -> Imaging algorithm
- **Bedside**: pulse character, blood pressure (narrow pulse pressure), auscultation, 12-lead ECG (LV hypertrophy with strain pattern, left axis deviation).
- **Labs**: BNP/NT-proBNP (rises with decompensation, useful prognostic marker in asymptomatic severe AS), routine bloods for surgical fitness (renal function, FBC, group and save, coagulation).
- **Imaging (definitive)**: Transthoracic echocardiogram (TTE) is first-line and diagnostic -- measures valve area, mean gradient, jet velocity, LV size/EF, associated aortic root disease.
- **Further work-up**: Cardiac catheterisation / coronary angiography before surgery (assess concomitant coronary disease, especially in men over 40 or women over 50 with risk factors); Dobutamine stress echo for low-flow low-gradient AS; Cardiac CT for valve calcium scoring and pre-TAVI annulus sizing; CT aortogram if bicuspid valve (aortopathy screening).

BOX|INVEST|Classic echo report and interpretation
Raw data: "Aortic valve: heavily calcified, restricted leaflet motion. Peak velocity 4.6 m/s, mean gradient 52 mmHg, calculated valve area 0.7 cm2. LVEF 55%. Mild LVH."
Interpretation: this meets ALL three criteria for severe aortic stenosis with preserved LV systolic function -- if the patient has ANY of syncope, angina or dyspnoea, this is an indication for aortic valve intervention (TAVI or SAVR) regardless of normal EF.
ENDBOX

### Management
> Mnemonic: "No medical cure -- Symptoms or LV dysfunction = INTERVENE" (there is NO effective drug therapy that halts progression of AS).
#### Chronic / definitive management
- **Aortic valve replacement (surgical, SAVR) or transcatheter aortic valve implantation (TAVI)** is the only effective treatment -- valve area cannot be improved by drugs.
- Indications for intervention (ESC/ACC 2021 guidelines): (1) Severe AS with symptoms; (2) Severe AS + LVEF less than 50% even if asymptomatic; (3) Severe AS undergoing other cardiac surgery (e.g. CABG); (4) Very severe AS (velocity 5 m/s or more) even if asymptomatic in low-risk patients; (5) Abnormal exercise test response (fall in BP, symptoms) in asymptomatic severe AS.
- **TAVI vs SAVR decision**: driven by surgical risk score (STS/EuroSCORE II), age, frailty, valve anatomy and vascular access.
  - Younger, low surgical risk, good anatomy -> SAVR traditionally preferred (durability, especially if concomitant CABG/aortopathy needed).
  - Elderly (75 or more) or intermediate-high surgical risk, or prohibitive surgical risk -> TAVI preferred (PARTNER and NOTION trial evidence of non-inferiority/superiority even in lower risk groups now).
  - Bicuspid valve, small annulus, need for concomitant aortic root surgery -> favours SAVR.
- Medical therapy: treat coexisting hypertension cautiously (avoid aggressive vasodilation causing hypotension), statins do NOT halt progression (proven in trials), diuretics for congestion but avoid over-diuresis (preload dependent).
#### Acute presentation (decompensated severe AS / cardiogenic shock)
Verbal orders in an unstable patient with severe AS and pulmonary oedema:
- "Sit the patient up, give high-flow oxygen via non-rebreathe mask, target saturation above 94%."
- "Attach cardiac monitor and 12-lead ECG, obtain IV access x2, send troponin, BNP, U&E, FBC, coagulation and group and save."
- "Give IV furosemide 40 mg slow bolus if fluid overloaded -- titrate cautiously, these patients are preload-dependent and can drop cardiac output with over-diuresis or vasodilators."
- "AVOID nitrates and other vasodilators as first-line -- they can precipitate profound hypotension in fixed-obstruction AS."
- "Call cardiology urgently for consideration of emergency balloon aortic valvuloplasty as a bridge, or urgent TAVI/SAVR work-up."
- "If in cardiogenic shock, consider inotropic support and intra-aortic balloon pump as a bridge to definitive valve intervention -- discuss with ICU and cardiothoracic team."

BOX|HA|HA Clinical Pathway - Aortic Valve Disease
- Public hospital patients with symptomatic severe AS are referred from general medicine/cardiology clinics to a Cardiac Centre (e.g. Queen Mary Hospital, Grantham Hospital, Princess Margaret Hospital) for a joint cardiology-cardiothoracic Heart Team decision (mirrors international Heart Team model).
- TAVI in HA hospitals is offered mainly to patients at high or prohibitive surgical risk, or those over 80, subject to case-by-case funding/resource assessment; SAVR remains first-line for lower risk, younger patients given resource constraints and durability data.
- Waiting time for elective SAVR in HA can be many months to over a year for stable outpatients -- any red-flag symptom (syncope, decompensated heart failure) should prompt urgent/priority booking, not routine queueing.
- Self-financed items list applies to certain TAVI valve devices and surgical prosthetic valves -- know that patients may be counselled about the Samaritan Fund / Community Care Fund for subsidy of high-cost items.
ENDBOX

### Complications
> Mnemonic: "SHAFT" -- Sudden death, Heart failure, Arrhythmia (AF, complete heart block if calcification extends to conduction system), Failure (LV), Thromboembolism/infective endocarditis.
- Heart failure, atrial fibrillation, complete heart block (calcium extension into conduction tissue near non-coronary cusp), infective endocarditis, sudden cardiac death, post-TAVI: paravalvular leak, conduction block requiring pacemaker, stroke.

### Prognosis
> Mnemonic: "Once symptomatic, the clock is ticking" -- untreated severe symptomatic AS carries roughly 50 percent 2-year mortality; asymptomatic severe AS has good prognosis until symptoms/LV dysfunction develop, then mortality rises sharply.
- Asymptomatic severe AS: relatively good short-term prognosis but risk of sudden symptom onset; average rate of progression is an increase in jet velocity of about 0.3 m/s per year.
- Symptomatic severe AS without intervention: very poor prognosis (average survival roughly 2-3 years after symptom onset, worse with heart failure or syncope).
- After successful TAVI/SAVR: prognosis approaches age-matched population if no major peri-procedural complication.

BOX|EXAMQ|Common Exam Question
"A 78-year-old man presents with exertional syncope. On examination there is a slow-rising pulse, narrow pulse pressure and an ejection systolic murmur radiating to the carotids. What is the single most useful next investigation, and what is the definitive management if severe?"
Answer: Transthoracic echocardiogram to confirm severity (valve area, gradient, jet velocity); definitive management is aortic valve replacement (TAVI or SAVR depending on surgical risk) -- symptomatic severe AS is an indication for intervention regardless of EF.
ENDBOX

PAGEBREAK

## 2. AORTIC REGURGITATION (AR)

### Definition
Incompetence of the aortic valve allowing retrograde flow of blood from the aorta into the LV during diastole, due to disease of the valve cusps and/or the aortic root.

### Classification
TABLE
Type | Onset | Typical Cause | Key Feature
Chronic AR | Gradual, years | Bicuspid valve, rheumatic, degenerative, aortic root dilatation | LV dilates and hypertrophies (eccentric), compensated for years
Acute AR | Sudden, hours-days | Infective endocarditis, aortic dissection, chest trauma | LV cannot dilate acutely -- rapid rise in LVEDP -- acute pulmonary oedema and cardiogenic shock, often a surgical EMERGENCY
ENDTABLE

### Aetiology / Causes
> Mnemonic: "RIBS MAD" -- Rheumatic fever, Infective endocarditis, Bicuspid aortic valve, Syphilis (tertiary, aortitis), Marfan syndrome / connective tissue disease, Aortic dissection, Dilated aortic root (hypertension, ankylosing spondylitis, Ehlers-Danlos).
- **Valve leaflet disease**: rheumatic heart disease (leaflet thickening/retraction), bicuspid aortic valve, infective endocarditis (leaflet destruction/perforation - can cause acute severe AR), degenerative calcific disease.
- **Aortic root/annular disease**: aortic dissection (Type A - regurgitation from annular dilatation or cusp prolapse - surgical emergency), Marfan syndrome, ankylosing spondylitis, syphilitic aortitis (now rare), hypertensive aortic root dilatation, Ehlers-Danlos syndrome.

BOX|TRAP|Acute AR is a different disease, not just "severe AR"
Do not manage acute AR (e.g. post-endocarditis valve perforation or aortic dissection) the same way as chronic AR. Acute AR is a surgical EMERGENCY because the non-compliant, non-dilated LV cannot accommodate the sudden regurgitant volume -- LVEDP rises steeply causing pulmonary oedema and cardiogenic shock with a soft, easily missed murmur. Waiting for "optimisation" before surgery in acute severe AR from endocarditis or dissection can be fatal.
ENDBOX

### Pathophysiology (step by step)
1. Incompetent valve allows diastolic backflow from aorta into LV -> LV receives both the normal preload from the left atrium AND the regurgitant volume -> **combined volume and (in chronic disease) pressure load**.
2. Chronic AR: LV compensates over years by **eccentric hypertrophy** (dilatation with sarcomeres added in series) -- allows the LV to eject a large total stroke volume while keeping wall stress normal (Laplace's law: larger radius offset by proportionally thicker wall).
3. Because a large stroke volume is ejected rapidly into a low-resistance, "leaky" aorta, systolic BP rises and diastolic BP falls -> **wide pulse pressure** and the peripheral signs (collapsing pulse, Corrigan sign, Quincke sign, De Musset sign, Traube's "pistol shot" sound, Duroziez's sign).
4. Eventually LV dilatation becomes decompensated, contractility falls, LVEDP rises -> symptoms of heart failure develop; by the time symptoms appear, myocardial damage may already be present -- hence surgery is often timed BEFORE symptoms using LV size/EF thresholds.
5. Acute AR: no time for eccentric hypertrophy -> normal-sized, stiff LV subjected to a sudden huge regurgitant volume -> LVEDP rises immediately -> acute pulmonary oedema/cardiogenic shock, often with a soft, short diastolic murmur that is easy to miss.

### Risk Factors
> Mnemonic: "MARCH" -- Marfan/connective tissue disease, Ankylosing spondylitis, Rheumatic fever history, Congenital bicuspid valve, Hypertension (root dilatation) / History of IV drug use (endocarditis risk).
- Bicuspid aortic valve, rheumatic fever history, Marfan syndrome, ankylosing spondylitis and other seronegative spondyloarthropathies, IV drug use (endocarditis), uncontrolled hypertension, prior aortic dissection, tertiary syphilis (rare now).

### Symptoms
> Mnemonic: "DEEP" -- Dyspnoea (exertional, progressive), Exercise intolerance/fatigue, Episodes of palpitation (forceful heartbeat awareness), Pounding sensation in the chest/neck (due to large stroke volume).
- Chronic: long asymptomatic phase (years), then exertional dyspnoea, fatigue, palpitations, awareness of forceful heartbeat especially when lying on left side (Duroziez awareness), angina (uncommon, due to reduced coronary diastolic filling pressure despite large stroke volume).
- Acute: sudden severe dyspnoea, pulmonary oedema, may present as cardiogenic shock.

### Signs
> Mnemonic: "CQ WIDE" -- Corrigan's sign (visible carotid pulsation), Quincke's sign (capillary pulsation in nail beds), Wide pulse pressure, water hammer/collapsing pulse, Diastolic murmur (early, decrescendo, left sternal edge), de Musset's sign (head nodding with each heartbeat), also Austin Flint murmur, Duroziez's sign, Traube's sign, Pistol-shot femorals.
- **Collapsing ("water-hammer") pulse**, wide pulse pressure (e.g. BP 160/40).
- **Early diastolic murmur**, high-pitched, decrescendo, best heard at left sternal edge 3rd/4th intercostal space, louder on expiration leaning forward -- radiates to apex if severe/root dilated (right sternal edge if root cause), louder along right sternal border if aortic root dilation is the cause.
- **Austin Flint murmur**: soft mid-diastolic rumble at the apex caused by the regurgitant jet hitting the anterior mitral leaflet, functionally "pseudo-mitral stenosis" -- do not confuse with true MS.
- Eponymous peripheral signs: Corrigan's sign, Quincke's sign (capillary pulsations), De Musset's sign (head bobbing), Duroziez's sign (to-and-fro femoral bruit with light compression), Traube's sign ("pistol-shot" femoral sounds), Muller's sign (uvula pulsation).
- Displaced, hyperdynamic apex beat (volume-overloaded, dilated LV).

BOX|TRAP|Austin Flint vs true mitral stenosis
HKMLE loves this distractor: a patient with known AR has a mid-diastolic rumble at the apex. Candidates jump to "mitral stenosis." Check for an opening snap and loud S1 (favour true MS) versus signs of AR (collapsing pulse, wide pulse pressure, early diastolic murmur) with NO opening snap (favours Austin Flint, a functional flow murmur from the AR jet, not organic MS). Echocardiography differentiates definitively.
ENDBOX

### Investigations
Bedside -> Labs -> Imaging, same overall structure as AS:
- **Bedside**: pulse character and pulse pressure, full auscultation for both diastolic murmur and Austin Flint, ECG (LV hypertrophy, may show volume-overload pattern).
- **Labs**: BNP, blood cultures x3 if endocarditis suspected, syphilis serology if clinically indicated, HLA-B27/inflammatory markers if spondyloarthropathy suspected.
- **Imaging**: TTE first line -- LV size/volumes, EF, regurgitant jet width/vena contracta, aortic root and ascending aorta diameter; Cardiac MRI for accurate regurgitant volume/fraction quantification when echo equivocal; CT aortogram if root/dissection suspected; cardiac catheterisation pre-operatively for coronary assessment.

### Management
> Mnemonic: "SEVERE = Size, EF, Exertional symptoms, Root diameter, Endocarditis/dissection = operate."
#### Chronic AR
- Serial echo surveillance if asymptomatic with normal LV size/function.
- Surgical indications (aortic valve replacement/repair): (1) symptomatic severe AR regardless of LV function; (2) asymptomatic severe AR with LVEF 50 percent or less; (3) asymptomatic severe AR with severe LV dilatation (LV end-systolic diameter greater than 50 mm or indexed greater than 25 mm/m2, or LV end-diastolic diameter greater than 65-70 mm); (4) any AR with ascending aorta greater than 55 mm (greater than 45-50 mm if Marfan/bicuspid with risk factors) undergoing valve/root surgery together.
- Medical therapy: vasodilators (ACE inhibitors/ARBs, dihydropyridine calcium channel blockers) may be used for symptom control or in patients with hypertension/not yet meeting surgical criteria, or those unfit for surgery -- NOT proven to delay surgery in normotensive asymptomatic patients per trial data, so should not be used simply to "buy time" if surgical criteria are met.
- Beta-blockers used cautiously (may prolong diastole and worsen regurgitant time) except when needed for associated aortic disease (e.g. Marfan root protection) or arrhythmia control.
#### Acute severe AR (endocarditis, dissection) -- surgical emergency, verbal orders
- "Call cardiothoracic surgery immediately -- this is a surgical emergency, do not delay for medical optimisation."
- "High-flow oxygen, sit up, IV access, urgent bloods including blood cultures x3 before antibiotics if endocarditis suspected."
- "Start empirical IV antibiotics per local protocol once cultures taken if endocarditis is likely cause."
- "Avoid intra-aortic balloon pump -- it is CONTRAINDICATED in AR (worsens regurgitation)."
- "Urgent CT aortogram if dissection suspected; urgent echocardiogram to confirm severity and mechanism."
- "Cautious afterload reduction (nitroprusside) and inotropic support may be used as a bridge only, definitive treatment is emergency surgery."

BOX|HA|HA Clinical Pathway
Suspected acute Type A aortic dissection with AR triggers the HA's cardiothoracic on-call emergency pathway -- direct transfer/bypass to a designated cardiothoracic centre (e.g. Queen Mary Hospital / Grantham Hospital on Hong Kong Island, Prince of Wales Hospital in NT) is arranged via the on-call cardiothoracic surgeon, analogous to a "code" pathway for STEMI.
ENDBOX

### Complications
- Heart failure, arrhythmia (AF, ventricular arrhythmia from LV dilatation), infective endocarditis, aortic dissection/rupture (if root disease is the aetiology), sudden death (rare, usually in advanced disease).

### Prognosis
- Chronic compensated AR: good prognosis for years, but once LV dysfunction or symptoms develop, prognosis worsens rapidly if surgery delayed -- irreversible LV damage may occur even after "successful" late surgery.
- Acute severe AR: high mortality without emergency surgery.

PAGEBREAK

## 3. MITRAL STENOSIS (MS)

### Definition
Narrowing of the mitral valve orifice obstructing flow from left atrium (LA) to LV during diastole.

### Classification
TABLE
Severity | Valve Area | Mean Gradient
Mild | greater than 1.5 cm2 | less than 5 mmHg
Moderate | 1.0-1.5 cm2 | 5-10 mmHg
Severe | less than 1.0 cm2 | greater than 10 mmHg
ENDTABLE
**Wilkins score** (0-16, scores leaflet mobility, thickness, calcification, subvalvular thickening each 0-4): score of 8 or less predicts good outcome from percutaneous balloon mitral valvotomy; higher scores favour surgery.

### Aetiology / Causes
> Mnemonic: "Rheumatic Rules MS" -- over 95 percent of MS worldwide is rheumatic in origin.
- **Rheumatic heart disease -- by far the commonest cause** (chronic valvulitis causes commissural fusion, leaflet thickening, chordal shortening -- "fish mouth" or "buttonhole" valve).
- Rare: mitral annular calcification (elderly, causes functional MS), congenital MS, carcinoid syndrome, systemic lupus erythematosus (Libman-Sacks), infective endocarditis with large vegetation obstructing orifice, radiation valvulopathy.

BOX|EPI|Local Epidemiology - Rheumatic MS in Hong Kong
Rheumatic fever/RHD is now rare in Hong Kong-BORN children due to improved living standards, antibiotic access and reduced overcrowding, but rheumatic MS remains an important cause of valve disease in ELDERLY Hong Kong Chinese (exposed decades ago) and in migrants/domestic helpers from regions with ongoing high RHD prevalence (mainland China rural areas, Philippines, Indonesia, South Asia). Always consider RHD in an older patient or a migrant worker presenting with a diastolic murmur.
ENDBOX

### Pathophysiology (step by step)
1. Fused, thickened, calcified valve creates a fixed obstruction to LA emptying in diastole -> pressure gradient develops between LA and LV.
2. Chronically elevated LA pressure -> LA dilatation -> predisposes to **atrial fibrillation** (loss of atrial kick further reduces cardiac output and worsens symptoms suddenly) and **LA thrombus formation** (stasis, especially in LA appendage) -> risk of systemic embolism/stroke.
3. Elevated LA pressure transmits backward to pulmonary veins and capillaries -> pulmonary venous congestion -> exertional dyspnoea, orthopnoea, and can cause pulmonary capillary rupture -> **haemoptysis**.
4. Chronic pulmonary venous hypertension -> reactive pulmonary arterial hypertension -> right ventricular pressure overload -> RV hypertrophy/failure -> peripheral oedema, hepatomegaly, ascites (right heart failure signs).
5. A markedly enlarged LA can compress the left recurrent laryngeal nerve against the aortic arch/pulmonary artery -> hoarseness (**Ortner's syndrome**), or compress the oesophagus -> dysphagia.
6. Because the mitral valve is a fixed narrow orifice, cardiac output cannot increase with exertion or tachycardia (shortened diastolic filling time in tachycardia/AF worsens the gradient acutely) -- this is why new-onset AF can precipitate acute decompensation ("MS + fast AF = pulmonary oedema emergency").

### Risk Factors
- History of rheumatic fever/sore throats in childhood, growing up in overcrowded/low-resource settings, female sex (MS is more common in women than men), age (long latency of 20-40 years between acute rheumatic fever and symptomatic MS).

### Symptoms
> Mnemonic: **"DHH + Palpitations"** -- Dyspnoea (progressive exertional), Haemoptysis, Hoarseness (Ortner's syndrome), plus Palpitations (AF) and fatigue.
- Progressive exertional dyspnoea (earliest symptom), orthopnoea, paroxysmal nocturnal dyspnoea.
- Haemoptysis (pulmonary venous hypertension, or pink frothy sputum in acute pulmonary oedema).
- Hoarseness of voice (Ortner's syndrome - rare but classic exam fact), dysphagia (oesophageal compression - rare).
- Palpitations from atrial fibrillation, fatigue, symptoms of systemic embolism (stroke, limb ischaemia) as a presenting feature.

### Signs
> Mnemonic: **"MOM Tap"** -- Malar flush, Opening snap, Mid-diastolic murmur with presystolic accentuation, Tapping (palpable) apex beat.
- **Malar flush** ("mitral facies") - due to chronic hypoxia/low cardiac output causing cutaneous vasodilation.
- **Tapping, non-displaced apex beat** (palpable S1, not true LV heave - LV is usually normal size in pure MS).
- **Loud S1**, **opening snap** shortly after S2 (the closer the opening snap to S2, the more severe/higher the LA pressure).
- **Mid-diastolic rumbling murmur**, low-pitched, best heard at the apex with the bell in the left lateral position, with presystolic accentuation if in sinus rhythm (lost if AF present).
- Signs of pulmonary hypertension/right heart failure in advanced disease (raised JVP, parasternal heave, loud P2, peripheral oedema).
- Irregularly irregular pulse if in atrial fibrillation.

### Investigations
> Mnemonic: "ECHO is King" for valve disease -- Bedside ECG/CXR -> Labs -> Echo definitive.
- **Bedside**: pulse for AF, auscultation, 12-lead ECG (P mitrale - broad notched P wave in lead II from LA enlargement; AF is common).
- **CXR**: LA enlargement (double right heart border, splaying of carina, enlarged LA appendage as a third bulge on left heart border), pulmonary venous congestion/Kerley B lines, and in longstanding cases mitral valve calcification.
- **Labs**: BNP if diagnostic uncertainty for dyspnoea, INR if on warfarin for AF/mechanical valve, blood cultures if endocarditis suspected.
- **Imaging (definitive)**: TTE - measures valve area (planimetry, pressure half-time), mean gradient, Wilkins score for valve morphology, LA size, pulmonary artery pressure estimate, presence of LA thrombus (though TOE better for this), assess for coexisting MR.
- **Trans-oesophageal echo (TOE)**: superior for LA appendage thrombus exclusion before balloon valvotomy/cardioversion, and for detailed valve morphology.
- Cardiac catheterisation reserved for discordant clinical-echo findings or pre-op coronary assessment.

BOX|INVEST|Classic CXR description and interpretation
Raw data: "PA chest film shows a double right heart border, straightening of the left heart border, and prominent upper lobe pulmonary vessels with Kerley B lines."
Interpretation: consistent with left atrial enlargement (double density sign) and pulmonary venous congestion from mitral stenosis -- go straight to echocardiography to confirm and grade severity.
ENDBOX

### Management
> Mnemonic: "Rate, Rhythm, Rheumatic prophylaxis, Relieve obstruction" (4 R's of MS management).
#### Chronic management
- Rate control for AF (beta-blockers or rate-limiting calcium channel blockers, or digoxin if hypotensive/heart failure) -- controlling ventricular rate is crucial because tachycardia shortens diastolic filling time and worsens the transmitral gradient.
- Anticoagulation with **warfarin** (target INR 2-3) mandatory if AF present, prior embolism, or large LA/spontaneous echo contrast, even in sinus rhythm with very large LA -- **DOACs are NOT recommended in valvular AF due to mitral stenosis** (excluded from major DOAC trials, and specifically contraindicated in rheumatic MS with AF per guidelines).
- Secondary rheumatic fever prophylaxis (benzathine penicillin) continued as appropriate (see RHD section).
- Diuretics for pulmonary congestion symptoms.
- **Definitive relief of obstruction**:
  - **Percutaneous balloon mitral valvotomy (PBMV)** - first-line if valve morphology favourable (low Wilkins score, no significant MR, no LA thrombus, no severe calcification/commissural calcification) - Class I indication for symptomatic severe MS with suitable anatomy.
  - **Surgical mitral valve replacement or open commissurotomy** - if unfavourable anatomy for PBMV, presence of LA thrombus, coexisting significant MR, or failed PBMV.
- Asymptomatic severe MS: consider intervention if new AF, pulmonary hypertension (PASP greater than 50 mmHg), or need for other cardiac/non-cardiac surgery requiring anticoagulation interruption.
#### Acute decompensation (e.g. new fast AF causing pulmonary oedema) -- verbal orders
- "Sit the patient up, give high-flow oxygen, attach cardiac monitor and obtain 12-lead ECG."
- "IV access, send U&E, troponin, TFT (if new AF, check thyroid function), coagulation, and INR if on warfarin."
- "Give IV furosemide for pulmonary oedema."
- "Control ventricular rate -- IV beta-blocker (e.g. metoprolol) or IV digoxin if hypotensive -- the goal is to slow the rate to improve diastolic filling time, this is different from most AF where rhythm may not need urgent control."
- "If haemodynamically unstable with fast AF causing pulmonary oedema/hypotension refractory to rate control, call for urgent synchronised cardioversion after discussion regarding thrombus risk -- ideally after TOE to exclude LA thrombus unless truly life-threatening."
- "Involve cardiology early for consideration of urgent balloon valvotomy if this is decompensation of previously undiagnosed or under-treated MS."

BOX|TRAP|DOACs and mitral stenosis
A very common HKMLE trap: candidates reflexively choose a DOAC (e.g. rivaroxaban, apixaban) for AF anticoagulation because DOACs are now first-line for most non-valvular AF. In RHEUMATIC MITRAL STENOSIS with AF, warfarin remains the required anticoagulant -- DOACs are contraindicated in this specific valvular AF population (excluded from pivotal trials, confirmed inferior in the INVICTUS trial of rivaroxaban in rheumatic AF).
ENDBOX

BOX|HA|HA Clinical Pathway
Percutaneous balloon mitral valvotomy and mitral valve surgery in HA hospitals are performed in designated cardiac catheterisation/cardiothoracic centres following Heart Team review; patients on warfarin for rheumatic MS with AF are typically followed in HA anticoagulation clinics with regular INR monitoring (point-of-care INR clinics are widely available in HA General Out-patient Clinics).
ENDBOX

### Complications
> Mnemonic: "SPHERE" -- Stroke/systemic embolism, Pulmonary hypertension, Haemoptysis, Endocarditis, Right heart failure, atrial (a)Fibrillation.
- Atrial fibrillation, systemic thromboembolism/stroke, pulmonary hypertension, right heart failure, infective endocarditis (lower risk than regurgitant lesions but still possible), pulmonary oedema precipitated by tachyarrhythmia or pregnancy (increased cardiac output/heart rate).

### Prognosis
- Slowly progressive disease over decades from initial rheumatic insult to symptomatic MS; once symptomatic (NYHA class II or more), 10-year survival without treatment is poor; pulmonary hypertension and AF are markers of worse prognosis. Good outcomes achievable with timely balloon valvotomy or surgery.

PAGEBREAK

## 4. MITRAL REGURGITATION (MR)

### Definition
Incompetent mitral valve allowing retrograde flow of blood from LV to LA during systole.

### Classification
TABLE
Type | Timeline | Examples | Physiology
Primary (organic) MR | Chronic, gradual | Myxomatous degeneration/prolapse, rheumatic, degenerative annular calcification, endocarditis | Intrinsic leaflet/chordal abnormality
Secondary (functional) MR | Chronic | Ischaemic cardiomyopathy, dilated cardiomyopathy | Normal leaflets, annular dilatation/papillary muscle displacement from LV remodelling
Acute MR | Sudden | Papillary muscle rupture post-MI, chordal rupture, endocarditis with leaflet perforation | No time for LA/LV compensation -- acute pulmonary oedema
ENDTABLE

### Aetiology / Causes
> Mnemonic: "MIRROR" -- Myxomatous degeneration (mitral valve prolapse, commonest cause in developed countries), Ischaemic/papillary muscle dysfunction or rupture, Rheumatic heart disease, Rupture of chordae tendineae, Others (connective tissue disease, congenital), Radiation/drug-induced, endocarditis.
- **Myxomatous degeneration (mitral valve prolapse)** - commonest cause in high-income settings, associated with Marfan/Ehlers-Danlos, can cause chordal rupture ("flail leaflet").
- **Ischaemic MR** - papillary muscle dysfunction (chronic, from LV remodelling/dilated annulus) or papillary muscle rupture (acute, classically postero-medial papillary muscle after inferior MI - catastrophic acute severe MR).
- **Rheumatic heart disease** - often coexists with MS ("mixed mitral valve disease").
- **Infective endocarditis** - leaflet destruction/perforation, chordal rupture.
- Others: annular calcification (elderly), dilated cardiomyopathy (functional/secondary MR from LV dilation), hypertrophic cardiomyopathy (systolic anterior motion), connective tissue disease.

### Pathophysiology - ACUTE vs CHRONIC (critical exam distinction)
#### Chronic MR
1. Regurgitant volume returns to a LA that has TIME to dilate and become compliant -> LA pressure rises only modestly initially -> patient may be asymptomatic for years.
2. LV receives increased preload (regurgitant volume returns from LA in next diastole) -> **eccentric hypertrophy and LV dilatation** compensate, maintaining forward stroke volume for a long time (this is a volume overload lesion, similar concept to AR).
3. Ejection fraction may appear falsely "normal" or even high early on because the LV ejects into a low-pressure LA as well as the aorta -- a "normal" EF of 55-60 percent in severe chronic MR may actually indicate early LV dysfunction (true contractility is reduced). **This is why surgery is triggered at an EF threshold of 60 percent or less in MR (higher cut-off than other valve lesions).**
4. Eventually LV decompensates -> reduced forward output, symptoms of heart failure, pulmonary hypertension.
#### Acute MR
1. Sudden regurgitant volume enters a normal-sized, non-compliant LA -> LA pressure rises steeply and immediately -> acute pulmonary oedema.
2. LV has not had time to dilate -> forward stroke volume falls acutely -> **cardiogenic shock** can occur rapidly, classically after acute MI with papillary muscle rupture.
3. Murmur may be SHORT and SOFT (because LA and LV pressures equalise rapidly) - easily missed, another classic HKMLE trap.

BOX|TRAP|"Normal EF" in MR does not mean normal LV function
Because the LV can eject blood into the low-pressure LA as well as the aorta, EF is artificially preserved in MR until LV disease is quite advanced. An EF of 55 percent that would be reassuring in AS or in a normal heart may indicate significant LV dysfunction in severe MR -- the surgical EF threshold for intervention in MR (60 percent or less) is HIGHER than for AS or AR, precisely because of this physiology.
ENDBOX

### Risk Factors
- Mitral valve prolapse (young, often female, associated with connective tissue disorders), prior MI (papillary muscle dysfunction/rupture), rheumatic fever history, infective endocarditis risk factors, age-related annular calcification, dilated/ischaemic cardiomyopathy.

### Symptoms
> Mnemonic: same **"DEF"** framework as other volume-overload lesions -- Dyspnoea (exertional, progressive), Exercise intolerance/fatigue, Fluid overload symptoms (orthopnoea, PND, oedema) in decompensation; ACUTE MR presents with sudden severe dyspnoea/pulmonary oedema or shock.
- Chronic: long asymptomatic period, then exertional dyspnoea, fatigue, palpitations (AF common as LA dilates).
- Acute (e.g. post-MI papillary rupture): sudden severe breathlessness, pink frothy sputum, hypotension/shock -- medical emergency.

### Signs
> Mnemonic: **"PSA"** -- Pansystolic murmur at the apex radiating to the axilla, Soft S1 (poor leaflet coaptation), Apex beat displaced and hyperdynamic (volume overload).
- **Pansystolic (holosystolic) murmur**, blowing quality, loudest at the apex, classically radiating to the axilla (posterior leaflet lesions radiate anteriorly/to the base, an exam pearl for identifying which leaflet is affected).
- Soft S1, widely split S2 (early aortic valve closure due to shortened LV ejection), S3 gallop (rapid LV filling in early diastole from large volume returning from LA).
- Displaced, hyperdynamic (thrusting) apex beat.
- Signs of pulmonary hypertension/right heart failure in advanced disease; signs of the underlying cause (e.g. midsystolic click of MVP, signs of Marfan syndrome).
- Acute severe MR: murmur may be soft/absent, patient in florid pulmonary oedema/cardiogenic shock -- clinical picture dominated by haemodynamic collapse, not the murmur.

### Investigations
- **Bedside**: auscultation (identify murmur radiation to localise leaflet), ECG (may show LA enlargement/P mitrale, AF, evidence of prior MI if ischaemic MR).
- **Labs**: BNP, troponin if acute MI-related, blood cultures if endocarditis suspected.
- **Imaging**: TTE first line - mechanism (prolapse/flail/functional/rheumatic), severity (vena contracta, regurgitant volume/fraction, effective regurgitant orifice area), LV size and EF, LA size, pulmonary artery pressure; TOE for pre-operative planning and better mechanism/severity assessment, especially for repair feasibility; cardiac catheterisation/coronary angiography if ischaemic aetiology suspected or pre-operative in older patients.

### Management
> Mnemonic: "Repair over Replace, EF60 is the trigger" for chronic primary MR.
#### Chronic primary (organic) MR
- Surgical indications: (1) symptomatic severe MR; (2) asymptomatic severe MR with LVEF 60 percent or less or LV end-systolic diameter 40 mm or more; (3) asymptomatic severe MR with new AF or pulmonary hypertension (PASP greater than 50 mmHg); (4) asymptomatic severe MR with normal LV function but high likelihood of durable repair at an experienced centre (early surgery favoured, "watchful waiting" is increasingly discouraged when repair is highly likely to succeed).
- **Mitral valve repair strongly preferred over replacement** wherever anatomically feasible (better survival, preserved LV geometry/chordal support, no long-term anticoagulation needed) -- especially for degenerative/prolapse disease.
- Transcatheter edge-to-edge repair (e.g. MitraClip) for high surgical risk patients with suitable anatomy.
#### Secondary (functional) MR
- Optimise guideline-directed medical therapy for underlying heart failure/cardiomyopathy first (ACE inhibitor/ARB/ARNI, beta-blocker, mineralocorticoid receptor antagonist, SGLT2 inhibitor, cardiac resynchronisation therapy if indicated) -- MR often improves with treatment of the underlying LV disease.
- Transcatheter edge-to-edge repair may be considered in selected patients with persistent severe secondary MR despite optimal medical therapy (COAPT trial showed benefit in a specific population; MITRA-FR trial was neutral -- patient selection matters).
#### Acute severe MR (e.g. papillary muscle rupture post-MI) -- surgical emergency, verbal orders
- "This is a cardiac surgical emergency -- call cardiothoracic surgery and cardiology immediately."
- "High-flow oxygen, sit the patient up, IV access, continuous cardiac monitoring."
- "Start IV diuretics and vasodilators (e.g. nitroprusside) to reduce afterload and improve forward flow if blood pressure allows."
- "If hypotensive/in cardiogenic shock, start inotropic support and insert an intra-aortic balloon pump as a bridge to surgery -- IABP IS indicated in acute MR (unlike in AR) because it reduces afterload and augments coronary perfusion."
- "Urgent bedside echocardiogram to confirm diagnosis and mechanism."
- "Arrange emergency mitral valve surgery -- do not delay for prolonged medical stabilisation in papillary muscle rupture, mortality is extremely high without surgery."

BOX|HA|HA Clinical Pathway
Acute papillary muscle rupture post-MI is a cardiac surgical emergency requiring immediate transfer to a cardiothoracic centre; in HA, this triggers direct liaison between the admitting cardiology team and the on-call cardiothoracic surgeon, often with IABP support arranged at the percutaneous coronary intervention centre before transfer.
ENDBOX

### Complications
- Atrial fibrillation, pulmonary hypertension, right heart failure, infective endocarditis, acute pulmonary oedema/cardiogenic shock (acute MR), sudden death (rare, MVP with certain high-risk features).

### Prognosis
- Chronic compensated primary MR with repair: excellent long-term prognosis, especially with successful early repair at experienced centres.
- Secondary MR: prognosis dominated by the underlying cardiomyopathy/ischaemic heart disease, not the valve lesion itself.
- Acute severe MR (papillary rupture): very high mortality without emergency surgery.

PAGEBREAK

## 5. RHEUMATIC HEART DISEASE (RHD)

### Definition
Chronic valvular damage that follows one or more episodes of acute rheumatic fever (ARF), an autoimmune multisystem inflammatory disease triggered by pharyngeal infection with group A beta-haemolytic Streptococcus (Streptococcus pyogenes).

### Aetiology / Pathophysiology (step by step)
> Basic science mnemonic: "Molecular Mimicry Makes Myocarditis" -- the M protein of group A Streptococcus resembles cardiac tissue antigens.
1. Group A Streptococcus (GAS) pharyngitis (NOT skin infection -- important distinction from post-streptococcal glomerulonephritis, which can follow either throat OR skin infection).
2. The bacterial **M protein** shares structural epitopes with human cardiac myosin, tropomyosin and valvular endothelium -- "**molecular mimicry**."
3. In a genetically susceptible host (HLA associations), the antibody and T-cell response against GAS cross-reacts with cardiac tissue -> **autoimmune valvulitis, myocarditis and pericarditis (pancarditis)**.
4. Acute valvulitis causes verrucous nodules on valve leaflets (classically the mitral valve, most commonly, then aortic) -- can heal with fibrosis, causing commissural fusion, leaflet thickening and chordal shortening -- the anatomical basis of chronic RHD (typically MS +/- MR, +/- AR).
5. Repeated episodes of ARF (from recurrent untreated GAS pharyngitis) cause progressive, cumulative valvular scarring -- this is why **secondary prophylaxis to prevent recurrent ARF** is the single most important preventive strategy once a diagnosis is made.

### Diagnosis - Revised Jones Criteria (for FIRST episode of ARF)
Diagnosis requires: evidence of preceding GAS infection PLUS (2 major criteria) OR (1 major + 2 minor criteria).
TABLE
Category | Criteria
Major | Carditis (clinical or subclinical on echo), Polyarthritis (migratory, large joints) / polyarthralgia in high-risk populations, Chorea (Sydenham chorea), Erythema marginatum, Subcutaneous nodules
Minor | Fever, Polyarthralgia (monoarthralgia in high-risk populations), Raised ESR/CRP, Prolonged PR interval on ECG
Evidence of preceding GAS infection | Positive throat culture or rapid antigen test, OR rising/elevated anti-streptolysin O (ASO) or anti-DNase B titre
ENDTABLE
> Mnemonic for major criteria: **"J O N E S"** -- Joints (migratory polyarthritis), O (carditis, think of the heart shape), Nodules (subcutaneous), Erythema marginatum, Sydenham chorea.
Note: for RECURRENT ARF in a patient with known RHD, only 2 minor criteria plus evidence of GAS infection are needed (major criteria not required again) -- an important exam nuance.

### Symptoms and Signs of Acute Rheumatic Fever
- Fever, migratory polyarthritis (large joints - knees, ankles, elbows, wrists - exquisitely tender, responds dramatically to aspirin/NSAIDs), new murmur (carditis), Sydenham chorea (involuntary, purposeless movements, often delayed onset weeks after the sore throat, can occur in isolation), erythema marginatum (transient pink rash with pale centre, trunk/proximal limbs), subcutaneous nodules (firm, painless, over extensor surfaces/bony prominences).

### Investigations
- Throat swab/culture, rapid antigen test, ASO and anti-DNase B titres (evidence of preceding GAS infection), ESR/CRP, ECG (prolonged PR interval, arrhythmia), echocardiogram (valvulitis - even subclinical carditis detectable on echo per revised criteria; important because clinical carditis may be silent), blood cultures if endocarditis is a differential.

### Management
#### Acute rheumatic fever
- Eradicate the streptococcal infection: a single dose of intramuscular benzathine penicillin G, or oral penicillin V for 10 days (erythromycin/macrolide if penicillin-allergic).
- Anti-inflammatory treatment: aspirin or NSAIDs for arthritis/fever (dramatic response to aspirin is itself almost diagnostic); corticosteroids for severe carditis/pancarditis with heart failure.
- Bed rest during the acute illness, treat heart failure supportively if carditis is severe.
- Treat chorea supportively (usually self-limiting; carbamazepine or valproate if severe).
#### Secondary prophylaxis (the KEY preventive intervention)
> Mnemonic: **"Penicillin for Years, not just Days"**
- **Intramuscular benzathine penicillin G**, standard dose 1.2 million units (600,000 units if 27 kg or less) every 4 weeks -- may be given every 3 weeks (or even every 2 weeks) in very high-risk settings/patients with breakthrough ARF, as this improves efficacy at the cost of more injections.
- Alternative if penicillin-allergic: oral erythromycin or a macrolide.
- **Duration** of secondary prophylaxis depends on severity and time since last episode: at minimum 5 years or until age 21 (whichever is longer) for ARF without carditis; longer (10 years or until age 21, whichever is longer) with mild carditis/healed carditis; lifelong for severe valvular disease or after valve surgery.

BOX|TRAP|Duration of prophylaxis is age- and severity-dependent, not a fixed number
HKMLE examiners often test whether you know prophylaxis duration is NOT a flat "5 years for everyone." The rule of thumb is: no carditis = 5 years or until age 21 (longer of the two); carditis but resolved/mild residual disease = 10 years or until age 21 (longer of the two) or up to age 25 in some protocols; severe RHD/prosthetic valve = lifelong.
ENDBOX

BOX|CHP|Statutory Notification status
Acute rheumatic fever and rheumatic heart disease themselves are NOT on the list of statutory notifiable infectious diseases in Hong Kong under the Prevention and Control of Disease Ordinance (Cap. 599). However, if the underlying infection is diagnosed as SCARLET FEVER (caused by the same organism, group A Streptococcus, with its characteristic rash), scarlet fever IS a statutory notifiable disease and must be reported to the Centre for Health Protection. Do not confuse "notifiable organism-related presentation" with "notifiable diagnosis" -- ARF/RHD as such require no CHP notification.
ENDBOX

BOX|EPI|Local Epidemiology - Hong Kong relevance
Rheumatic fever incidence in Hong Kong has fallen dramatically since the mid-20th century due to improved socioeconomic conditions, antibiotic availability and reduced household crowding -- it is now UNCOMMON in Hong Kong-born children. However, RHD remains clinically important because: (1) many ELDERLY Hong Kong Chinese patients acquired RHD decades ago and now present with longstanding valve disease (especially MS) requiring intervention; (2) Hong Kong's large population of foreign domestic helpers and new migrants from areas with ongoing high ARF/RHD incidence (parts of mainland China, Philippines, Indonesia, South Asia, sub-Saharan Africa) means clinicians must keep RHD on the differential for younger patients with valve disease too.
ENDBOX

### Complications
- Chronic valvular heart disease (MS most common, MR, AR, mixed lesions), heart failure, atrial fibrillation, infective endocarditis (damaged valves are a major risk factor), recurrent ARF causing progressively worse valve damage, Sydenham chorea sequelae.

### Prognosis
- Depends heavily on adherence to secondary prophylaxis -- consistent penicillin prophylaxis dramatically reduces recurrence and progression of valvular damage. Without prophylaxis, recurrent ARF episodes cause cumulative, progressive valve destruction ultimately requiring valve replacement.

BOX|SUMMARY|Quick Summary - Valvular Disease Block
- AS: fixed outflow obstruction, SAD symptoms, slow-rising pulse, ejection systolic murmur, no effective drug -- TAVI/SAVR is definitive treatment triggered by symptoms or LV dysfunction.
- AR: volume + pressure overload, wide pulse pressure/collapsing pulse, early diastolic murmur, surgery triggered by symptoms, LV size/EF thresholds, or root diameter; ACUTE AR (endocarditis/dissection) is a surgical emergency.
- MS: almost always rheumatic, malar flush/tapping apex/opening snap/mid-diastolic murmur, warfarin (NOT DOAC) for AF, balloon valvotomy if favourable anatomy else surgery.
- MR: volume overload, "normal" EF is falsely reassuring, pansystolic murmur radiating to axilla, repair preferred over replacement, EF 60 percent is the surgical trigger; ACUTE MR (papillary rupture) is a surgical emergency needing IABP as a bridge.
- RHD: molecular mimicry after GAS pharyngitis, Jones criteria for diagnosis, benzathine penicillin secondary prophylaxis is the single most important preventive measure.
ENDBOX

PAGEBREAK

## 6. INFECTIVE ENDOCARDITIS (IE)

### Definition
Infection of the endocardial surface of the heart, typically involving native or prosthetic heart valves, characterised by formation of vegetations composed of platelets, fibrin, microorganisms and inflammatory cells.

### Classification
TABLE
Category | Subtype | Typical Organism(s)
By valve | Native valve endocarditis (NVE) | Strep viridans, Staph aureus, Enterococcus
By valve | Prosthetic valve endocarditis (PVE) - early (less than 1 year post-op) | Staph epidermidis (coagulase-negative staph), Staph aureus
By valve | Prosthetic valve endocarditis - late (1 year or more post-op) | Similar organisms to NVE, plus coagulase-negative staph
By tempo | Acute IE | Staph aureus - rapid, destructive, high fever, embolic phenomena
By tempo | Subacute IE | Strep viridans - indolent, weeks-months, low-grade fever, immune phenomena
By risk group | IV drug users | Staph aureus (often right-sided, tricuspid valve)
By culture status | Culture-negative IE | HACEK organisms (fastidious), Coxiella, Bartonella, Q fever, prior antibiotics
ENDTABLE

### Aetiology / Causative Organisms
> Mnemonic: **"SHE Cured Bugs"** for the common groups -- Strep viridans (dental/native valve), HACEK (culture negative), Enterococcus (GU/GI procedures), Staph aureus (Coagulase positive - acute, IVDU, prosthetic), Bugs (coagulase-negative staph in early prosthetic valve).
- **Streptococcus viridans group** - commonest cause of subacute native valve IE, classically follows dental procedures/poor dental hygiene, colonises previously damaged/abnormal valves.
- **Staphylococcus aureus** - commonest cause of ACUTE IE overall, associated with IV drug use (often right-sided/tricuspid), skin infections, indwelling lines, healthcare-associated infection, and can affect previously NORMAL valves (unlike Strep viridans which usually needs an abnormal valve).
- **Enterococcus species** - associated with genitourinary or gastrointestinal procedures/manipulation, older patients.
- **Coagulase-negative staphylococci (e.g. Staph epidermidis)** - commonest cause of EARLY prosthetic valve endocarditis (biofilm formation on prosthetic material).
- **HACEK organisms** (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella) - fastidious Gram-negative organisms, classic cause of "culture-negative" endocarditis requiring prolonged culture incubation.
- Fungal (Candida) - IV drug users, immunosuppressed, prosthetic valves - large vegetations, poor prognosis.
- Streptococcus bovis (now called S. gallolyticus) endocarditis - classic association with colorectal malignancy, warrants colonoscopy.

BOX|TRAP|Strep bovis / Streptococcus gallolyticus and colon cancer
A classic HKMLE association question: endocarditis caused by Streptococcus bovis (S. gallolyticus) should prompt investigation for underlying colorectal malignancy/polyps with colonoscopy -- do not miss this cross-link between cardiology and gastroenterology/oncology.
ENDBOX

### Pathophysiology (step by step)
1. Endothelial damage (from turbulent flow across an abnormal valve, congenital defect, or prosthetic material) exposes subendothelial collagen/tissue factor -> deposition of platelets and fibrin -> forms a sterile **"nonbacterial thrombotic endocarditis" (NBTE)** nidus.
2. Transient bacteraemia (from dental work, skin breach in IVDU, GI/GU instrumentation, or even normal daily activities like chewing/brushing teeth) seeds the NBTE nidus.
3. Bacteria adhere via surface adhesins, proliferate, and become enmeshed in fibrin/platelets -> forms a mature **vegetation**, which shields the organisms from host immune defences and antibiotics (hence the need for prolonged, high-dose, often bactericidal IV antibiotic therapy).
4. Local destructive effects: valve leaflet perforation/erosion causing new or worsening regurgitation, abscess formation (especially aortic root - can cause heart block if it extends to the conduction system, or fistula formation), chordal rupture.
5. Embolic effects: fragments of vegetation break off and embolise systemically (stroke, splenic infarct, renal infarct, digital emboli causing Janeway lesions/splinter haemorrhages) -- right-sided IE embolises to the LUNGS (septic pulmonary emboli), classic in IVDU tricuspid endocarditis.
6. Immune complex-mediated phenomena from prolonged antigenaemia: glomerulonephritis, Osler's nodes, Roth spots (immune complex deposition, NOT direct embolic phenomena -- an important distinction).

### Risk Factors
> Mnemonic: **"VALVE DIP"** -- previous Valve disease (native abnormal valve e.g. bicuspid, MVP, rheumatic), Artificial/prosthetic valve, IV drug use, congenital heart Disease, Immunosuppression, Poor dental hygiene/recent dental procedure; also previous IE, indwelling lines/haemodialysis, degenerative valve disease in elderly.
- Structural heart disease (rheumatic valve disease, MVP with regurgitation, bicuspid aortic valve, congenital heart disease), prosthetic heart valves, prior IE, IV drug use, intracardiac devices (pacemakers/ICDs), haemodialysis, immunosuppression, poor dental hygiene, recent invasive dental/GI/GU procedures.

### Symptoms
> Mnemonic: **"FROM Janeway"** -- Fever (persistent, often low-grade in subacute disease), Rigors/night sweats, Osler-related joint/muscle aches (arthralgia, myalgia), Malaise/weight loss, plus symptoms of embolic/immune complications.
- Fever (most common symptom, may be low-grade and prolonged in subacute Strep viridans IE), malaise, weight loss, night sweats, arthralgia/myalgia, symptoms of new/worsening heart failure (new regurgitant murmur), symptoms from embolic events (stroke symptoms, flank pain from renal infarct, abdominal pain from splenic infarct).

### Signs
> Mnemonic: **"FROM JANE"** -- Fever, Roth spots, Osler's nodes, Murmur (new or changing), Janeway lesions, Anaemia (normocytic, chronic disease), Nail-bed splinter haemorrhages, Emboli (splenomegaly, clubbing in longstanding disease).
- New or changing cardiac murmur (most important sign - suggests valve destruction).
- **Osler's nodes** - tender, purplish nodules on finger/toe pads (immune complex-mediated, PAINFUL - "Osler's = Ouch").
- **Janeway lesions** - non-tender, erythematous/haemorrhagic macules on palms/soles (embolic phenomenon - painless).
- **Roth spots** - retinal haemorrhages with pale centres (immune complex-mediated).
- Splinter haemorrhages under nails, clubbing (chronic disease), splenomegaly, petechiae (conjunctivae, palate), microscopic haematuria (immune complex glomerulonephritis).

BOX|TRAP|Osler's nodes vs Janeway lesions - do not swap them
Extremely common HKMLE distractor. Osler's nodes are PAINFUL, on finger/toe PADS, immune-complex mediated (subacute IE). Janeway lesions are PAINLESS, on PALMS/SOLES, embolic (acute IE, classically Staph aureus). Remember: "Osler = Ouch (painful), Janeway = no pain."
ENDBOX

### Investigations - Modified Duke Criteria
Diagnosis of definite IE: 2 major criteria, OR 1 major + 3 minor, OR 5 minor criteria.
TABLE
Category | Criteria
Major | Positive blood culture: typical organism from 2 separate cultures (Strep viridans, Strep gallolyticus, HACEK, Staph aureus, or community-acquired enterococci without a primary focus), OR persistently positive cultures; Evidence of endocardial involvement: positive echocardiogram (vegetation, abscess, new partial dehiscence of prosthetic valve) OR new valvular regurgitation
Minor | Predisposing heart condition or IV drug use; Fever 38 degrees C or more; Vascular phenomena (arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial haemorrhage, Janeway lesions); Immunologic phenomena (glomerulonephritis, Osler's nodes, Roth spots, rheumatoid factor); Microbiological evidence not meeting major criteria (positive culture not meeting major criteria, or serological evidence of active infection)
ENDTABLE

#### Bedside -> Labs -> Imaging algorithm
- **Bedside**: full cardiac and peripheral examination (murmur, Osler/Janeway/Roth/splinters), fundoscopy, urinalysis for haematuria, temperature charting.
- **Labs**: **blood cultures - THREE separate sets from different venepuncture sites BEFORE starting antibiotics** (the single most important investigation), FBC (normocytic anaemia, raised WCC), raised ESR/CRP, renal function (glomerulonephritis, renal emboli), urinalysis (microscopic haematuria), rheumatoid factor.
- **Imaging**: **Transthoracic echocardiogram (TTE)** first line to look for vegetations/abscess/new regurgitation; **Trans-oesophageal echo (TOE)** if TTE inconclusive, prosthetic valve, suspected abscess, or high clinical suspicion with negative TTE (TOE has higher sensitivity, especially for posterior structures/prosthetic valves); CT/MRI brain if embolic stroke suspected; CT chest/abdomen if septic emboli suspected; PET-CT increasingly used for prosthetic valve endocarditis diagnosis (detects perivalvular inflammation).

BOX|INVEST|Classic blood culture and echo scenario
Raw data: "Three sets of blood cultures taken 1 hour apart all grow Streptococcus viridans. TOE shows a 12 mm vegetation on the mitral valve with moderate new mitral regurgitation. Patient has fever 38.5 degrees C."
Interpretation: this meets 2 major Duke criteria (typical organism from separate cultures + echocardiographic evidence of endocardial involvement) -- diagnosis of definite infective endocarditis, start IV antibiotics per organism-directed regimen and involve the endocarditis multidisciplinary team.
ENDBOX

### Management
> Mnemonic: **"BLOOD FIRST"** -- take Blood cultures x3 before starting antibiotics, then treat -- never give empirical antibiotics before cultures except in genuinely septic/unstable patients.
#### Acute management - verbal orders for suspected IE
- "Take three sets of blood cultures from different sites, at least one hour apart if possible, BEFORE starting any antibiotics."
- "Send FBC, U&E, CRP, ESR, urinalysis."
- "Arrange an urgent transthoracic echocardiogram."
- "If the patient is septic/haemodynamically unstable, do NOT delay antibiotics for more than a short window -- give empirical broad-spectrum IV antibiotics immediately after cultures are drawn per local microbiology protocol, then de-escalate once organism/sensitivities known."
- "Involve the Endocarditis Team (cardiology, microbiology/infectious diseases, cardiothoracic surgery) early -- this is a multidisciplinary team disease."
#### Organism-directed antibiotic therapy (standard international regimens)
- Streptococcus viridans (penicillin-sensitive): IV benzylpenicillin or ceftriaxone for 4 weeks (2 weeks if combined with gentamicin in low-risk uncomplicated cases).
- Staphylococcus aureus (native valve, methicillin-sensitive): IV flucloxacillin (or cloxacillin) for 4-6 weeks; if MRSA, IV vancomycin (or daptomycin).
- Enterococcus: IV amoxicillin/ampicillin plus gentamicin (synergistic), or vancomycin plus gentamicin if penicillin-allergic/resistant, typically for 4-6 weeks.
- Prosthetic valve endocarditis (Staph, especially coagulase-negative): combination therapy typically vancomycin plus rifampicin plus gentamicin for prolonged courses (6 weeks or more) - reflects biofilm formation on prosthetic material.
- HACEK organisms: ceftriaxone typically for 4 weeks.
- Duration is typically LONGER (4-6 weeks, sometimes longer for prosthetic valve disease) than most infections because vegetations are relatively avascular and organisms are protected within biofilm/fibrin matrix.
#### Indications for surgery in IE
- Heart failure due to severe valve dysfunction, uncontrolled infection (persistent bacteraemia/fever despite appropriate antibiotics, perivalvular abscess, fistula, new heart block), fungal endocarditis, large vegetations (greater than 10 mm) with high embolic risk especially after a systemic embolic event, prosthetic valve dehiscence, relapsing PVE.
#### Antibiotic prophylaxis for at-risk procedures - an evolving and contested area
- Modern guidelines (AHA 2007 revision, ESC, NICE) have progressively NARROWED prophylaxis indications because evidence for benefit is weak and antibiotic use carries its own risks.
- **AHA/ESC**: antibiotic prophylaxis before HIGH-RISK dental procedures is reserved for HIGHEST-RISK cardiac conditions only: prosthetic valves/prosthetic material used for valve repair, previous infective endocarditis, unrepaired cyanotic congenital heart disease (or repaired with residual defects/prosthetic material within 6 months), cardiac transplant recipients with valvulopathy.
- **NICE (UK)** historically recommended AGAINST routine antibiotic prophylaxis for dental procedures altogether (though updated slightly to align closer with AHA in recent revisions) - a well-known international guideline discrepancy.
- Standard regimen when indicated: single dose amoxicillin 2 g orally (or IV ampicillin) 30-60 minutes before the procedure; clindamycin if penicillin-allergic.

BOX|TRAP|NICE vs AHA prophylaxis - know which one HKMLE expects
Because Hong Kong's medical education and guidelines are heavily influenced by BOTH UK and US traditions, this is a genuine grey area. For HKMLE purposes, the safest answer is to follow the AHA/ESC-style highest-risk-only approach (prosthetic valve, previous IE, unrepaired cyanotic congenital heart disease, cardiac transplant with valvulopathy) rather than blanket NICE "no prophylaxis" -- but always read the vignette carefully, as some HKMLE questions are written from a UK/NICE framework. If the question explicitly references NICE, answer that no prophylaxis is routinely recommended for dental procedures.
ENDBOX

BOX|HA|HA Clinical Pathway - empirical therapy and referral
- HA hospitals follow local Infection Control Branch / hospital antimicrobial guidelines for empirical IE therapy, typically a combination covering Streptococcus, Staphylococcus (including MRSA coverage in appropriate risk patients) and Enterococcus while awaiting culture results (e.g. IV vancomycin plus gentamicin plus ampicillin-type combinations, adjusted per local protocol and microbiology advice) - always confirm with the hospital's own antimicrobial guideline/microbiologist rather than assuming a fixed regimen.
- Suspected IE cases in HA are managed by a multidisciplinary Endocarditis Team involving Cardiology, Microbiology/Infectious Disease, and Cardiothoracic Surgery, often with case discussion at a joint meeting, mirroring the international Endocarditis Team model recommended by ESC guidelines.
- IV drug use-associated tricuspid IE (Staph aureus) is an important local presentation seen in HA hospitals, particularly through Substance Abuse clinics/Correctional Services referrals - always screen for HIV/Hepatitis B and C co-infection in this population.
ENDBOX

### Complications
> Mnemonic: **"HEART FAILS"** -- Heart failure (valve destruction), Emboli (systemic, septic pulmonary), Abscess (perivalvular), Renal (glomerulonephritis, immune complex or septic emboli), Torsion of rhythm (heart block from conduction system abscess), Fistula, AV block, Immune complex disease, Longstanding relapse, Splenic infarct/abscess.
- Heart failure, perivalvular abscess, heart block (aortic root abscess near conduction system), systemic and septic emboli (stroke, mycotic aneurysm, splenic/renal infarct, septic pulmonary emboli in right-sided IE), immune complex glomerulonephritis, relapse/treatment failure.

### Prognosis
- In-hospital mortality for IE remains significant (roughly 15-20 percent depending on organism and complications) despite modern antibiotics; Staph aureus IE and fungal IE carry worse prognosis than Strep viridans subacute disease; prosthetic valve endocarditis and heart failure/abscess complications significantly worsen outcome.

PAGEBREAK

## 7. PERICARDIAL DISEASE

### 7A. Acute Pericarditis

#### Definition
Inflammation of the pericardium, typically presenting with characteristic sharp chest pain, a pericardial friction rub, and diffuse ECG changes.

#### Aetiology / Causes
> Mnemonic: **"CARDIAC RIND"** -- Collagen vascular disease (SLE, RA), Aortic dissection, Radiation, Drugs (e.g. hydralazine, procainamide - lupus-like), Infection (viral - commonest overall; TB - important in HK/Asia; bacterial/purulent), Acute MI (early peri-infarction OR Dressler syndrome weeks later), Cancer (malignant pericardial disease), RENAL failure (uraemic pericarditis), Idiopathic (very common), Neoplasm, Dressler syndrome.
- **Viral/idiopathic - by far the commonest cause overall** in immunocompetent patients (Coxsackievirus, echovirus, adenovirus, or presumed viral even if not confirmed).
- **Tuberculous pericarditis - important cause in Hong Kong/Asia and in HIV-positive patients** - can progress to constrictive pericarditis if untreated.
- Uraemic pericarditis (chronic kidney disease/dialysis patients).
- Post-MI: early peri-infarction pericarditis (days) vs **Dressler syndrome** (autoimmune, weeks to months post-MI, associated fever/pleuritis/pericarditis).
- Autoimmune/connective tissue disease (SLE, RA), malignancy (metastatic, especially lung/breast/lymphoma), radiation therapy, drug-induced, purulent bacterial pericarditis (rare, very sick patients), post-cardiac surgery/post-pericardiotomy syndrome.

#### Pathophysiology
1. Inflammatory insult (infective, autoimmune, uraemic toxins, malignant infiltration, radiation) causes inflammation of the visceral and parietal pericardial layers.
2. Inflamed pericardial surfaces rub against each other with each heartbeat -> the characteristic **pericardial friction rub** and sharp, pleuritic chest pain (worse lying flat, relieved sitting forward, because this reduces contact between inflamed surfaces).
3. Diffuse subepicardial inflammation (not localised to a coronary territory, unlike MI) produces widespread, concordant ECG changes rather than territorial changes.
4. Exudation of inflammatory fluid into the pericardial space can accumulate as a **pericardial effusion** -- if it accumulates faster than the pericardium can stretch, intrapericardial pressure rises and can progress to **cardiac tamponade** (see below).
5. Chronic/recurrent inflammation (especially TB, purulent, or radiation-induced) can lead to pericardial fibrosis and calcification -> **constrictive pericarditis**.

#### Symptoms
> Mnemonic: **"SAD PPP"** (adapted) -- Sharp, pleuritic chest pain, worse lying flat/lying on left side, relieved sitting forward and leaning; radiates to trapezius ridge (a fairly specific pericardial pain feature); Associated fever/malaise if infective; Preceding viral prodrome common; Positional variation is the hallmark.
- Sharp retrosternal chest pain, pleuritic (worse with inspiration/coughing), positional (worse lying supine, better sitting forward), may radiate to the trapezius ridge (highly specific for pericardial pain, due to shared phrenic nerve innervation), preceded by fever/viral prodrome in infective cases.

#### Signs
- **Pericardial friction rub** - a superficial, scratchy, triphasic (or biphasic) sound heard best with the diaphragm at the left sternal border, patient leaning forward in expiration -- pathognomonic when present but often intermittent.
- Fever, tachycardia; signs of the underlying cause (uraemic fetor, malignancy, connective tissue disease stigmata).
- If effusion develops: muffled heart sounds, and if tamponade develops, Beck's triad (see below).

#### Investigations
BOX|INVEST|Classic ECG description and interpretation
Raw data: "12-lead ECG shows widespread saddle-shaped (concave-up) ST elevation in leads I, II, aVL, V2-V6, with PR segment depression, and reciprocal ST depression with PR elevation in aVR."
Interpretation: this pattern (diffuse, non-territorial ST elevation with PR depression) is classic for acute pericarditis, NOT STEMI -- STEMI produces territorial ST elevation with reciprocal changes limited to specific leads, not this diffuse concordant pattern.
ENDBOX
- **Bedside**: ECG (diffuse saddle-shaped ST elevation with PR depression - stage 1; normalisation - stage 2/3; T wave inversion - stage 4), auscultation for friction rub, temperature.
- **Labs**: FBC, ESR/CRP (elevated), troponin (may be mildly elevated if myopericarditis present - check for concurrent myocarditis), U&E (uraemia), autoimmune screen if indicated, blood cultures if bacterial suspected, TB workup (sputum/pericardial fluid AFB smear, culture, GeneXpert, adenosine deaminase level) if TB suspected.
- **Imaging**: Chest X-ray (may show enlarged "water bottle" cardiac silhouette if significant effusion, otherwise often normal in pure pericarditis without effusion), Echocardiogram to look for associated pericardial effusion/tamponade physiology, Cardiac MRI if diagnosis uncertain or myopericarditis suspected.

#### Management
> Mnemonic: **"NSAID + Colchicine, Avoid steroids first-line"**
- First-line: high-dose **NSAIDs** (e.g. ibuprofen or aspirin, especially aspirin if post-MI pericarditis since NSAIDs may interfere with infarct healing) PLUS **colchicine** (reduces recurrence risk significantly, per the landmark COPE and ICAP trials) for typically 3 months.
- Avoid corticosteroids as first-line therapy in viral/idiopathic pericarditis - associated with higher recurrence rates; reserve for NSAID/colchicine-refractory cases, autoimmune aetiology, or pregnancy (where NSAIDs are contraindicated in later pregnancy).
- Treat the underlying cause specifically: anti-tuberculous therapy for TB pericarditis (quadruple therapy, HA follows CHP/WHO regimens - see TB module), dialysis intensification for uraemic pericarditis, treat underlying malignancy/autoimmune disease.
- Avoid strenuous exercise until symptoms resolve and inflammatory markers normalise (typically 3 months) - relevant for athlete-clearance questions.
- Recurrent pericarditis (multiple relapses despite colchicine): consider IL-1 blockade (e.g. anakinra, rilonacept - newer evidence-based option) or, rarely, pericardiectomy for refractory cases.

### 7B. Pericardial Effusion and Cardiac Tamponade

#### Definition
Pericardial effusion = abnormal accumulation of fluid in the pericardial sac. Cardiac tamponade = haemodynamically significant compression of the heart by pericardial fluid (or blood/pus/air) under pressure, impairing diastolic filling and reducing cardiac output - a medical EMERGENCY.

#### Pathophysiology (step by step)
1. Fluid accumulates in the pericardial sac; the rate of accumulation matters far more than the absolute volume -- a SLOW accumulation (e.g. malignant effusion over weeks) allows the pericardium to stretch and accommodate large volumes (over a litre) without tamponade, while a RAPID accumulation (e.g. haemopericardium from aortic dissection or ventricular free wall rupture) can cause tamponade with as little as 100-200 mL.
2. Rising intrapericardial pressure eventually exceeds and equalises with intracardiac diastolic pressures -> impaired ventricular filling in diastole (all chambers compressed equally -> "equalisation of pressures" across chambers, a haemodynamic hallmark).
3. Reduced diastolic filling -> reduced stroke volume -> reduced cardiac output -> compensatory tachycardia and peripheral vasoconstriction to maintain blood pressure (hence, hypotension is often a LATE sign).
4. **Ventricular interdependence and pulsus paradoxus**: during inspiration, intrathoracic pressure falls, increasing venous return to the RV -- in tamponade, the fixed total pericardial volume means the RV can only expand into the fixed space by encroaching on LV filling (interventricular septum shifts left) -> LV stroke volume and systolic BP fall further during inspiration than normal -> **pulsus paradoxus** (an exaggeration of the normal, defined as an inspiratory fall in systolic blood pressure of more than 10 mmHg).
5. If untreated, progresses to obstructive cardiogenic shock and pulseless electrical activity/cardiac arrest.

#### Symptoms and Signs
> Mnemonic: **Beck's Triad** -- Hypotension, raised JVP (distended neck veins), muffled/distant heart sounds; PLUS Pulsus paradoxus.
- Symptoms: dyspnoea (often the earliest and most sensitive symptom), chest discomfort/fullness, dizziness/presyncope, anxiety/restlessness.
- Signs: Beck's triad (hypotension, raised JVP, muffled heart sounds) - classically seen in ACUTE tamponade (e.g. trauma, aortic dissection rupture) but often incomplete/absent in slower-onset tamponade; tachycardia; pulsus paradoxus (inspiratory fall in systolic BP greater than 10 mmHg); Kussmaul's sign may be seen in some cases (though classically more associated with constrictive pericarditis); cool peripheries, narrow pulse pressure.

BOX|REDFLAG|Red Flags for Tamponade
- Any patient with known pericardial effusion who develops new hypotension, tachycardia, or worsening dyspnoea needs urgent echo -- do not wait for full Beck's triad, which is often incomplete.
- Post-cardiac catheterisation/pacemaker insertion chest pain plus hypotension = suspect iatrogenic cardiac perforation and tamponade until proven otherwise.
- Penetrating chest trauma with hypotension unresponsive to fluids = suspect traumatic tamponade, prepare for emergency thoracotomy/pericardiocentesis.
ENDBOX

#### Investigations
BOX|INVEST|Classic echo description and interpretation
Raw data: "Echocardiogram shows a large circumferential pericardial effusion with diastolic collapse of the right ventricular free wall and right atrial collapse, with greater than 25 percent respiratory variation in mitral inflow velocity."
Interpretation: right ventricular diastolic collapse and exaggerated respiratory variation in transmitral flow are echocardiographic hallmarks of cardiac tamponade physiology -- this patient needs urgent pericardiocentesis, not conservative monitoring.
ENDBOX
- **Bedside**: vital signs (hypotension, tachycardia), JVP assessment, pulsus paradoxus measurement by manual sphygmomanometry, ECG (low-voltage QRS, electrical alternans - beat-to-beat variation in QRS amplitude/axis from the heart swinging within a large effusion).
- **Imaging**: **Echocardiogram is the key diagnostic test** - effusion size, RV diastolic collapse, RA systolic collapse, IVC plethora (dilated, non-collapsing IVC), respiratory variation in valve inflow velocities; Chest X-ray (enlarged "water bottle" silhouette if effusion is large and chronic; may be normal in acute tamponade with only a small rapidly-accumulated volume - another key exam trap).
- Pericardiocentesis is both diagnostic (fluid analysis - cytology, culture, AFB/TB studies, protein/LDH for exudate/transudate classification) and therapeutic.

BOX|TRAP|Normal CXR does NOT exclude tamponade
A classic HKMLE trap: candidates assume a normal-sized cardiac silhouette on CXR excludes tamponade. In ACUTE tamponade (e.g. haemopericardium from trauma or aortic dissection), as little as 100-200 mL of rapidly accumulated fluid can cause life-threatening tam