Cardiomegaly

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Cardiomegaly

Definition

Cardiomegaly refers to an enlarged heart, most commonly identified on chest radiography (CXR) as an increased cardiac silhouette. In adults, cardiomegaly is defined by a cardiothoracic (CT) ratio ≥ 0.5, measured by dividing the maximum transverse cardiac diameter by the maximum internal thoracic diameter on a PA CXR. A CT ratio > 0.6 generally indicates significant enlargement and carries prognostic weight (e.g., in Ebstein anomaly, CTR > 0.6 correlates with worse outcomes and higher risk of reoperation).

Important caveat: An enlarged cardiac silhouette on CXR does not always equal true cardiomegaly - pericardial effusion can mimic it and must be excluded.

Frameworks for Internal Medicine

Pathophysiology: How the Heart Enlarges

The heart enlarges through two main mechanisms:

1. Eccentric Hypertrophy (Volume Overload)

Chamber dilation with relative thinning of the ventricular wall
Results in an increased chamber size - the "big and floppy" heart
Seen in dilated cardiomyopathy, chronic volume overload (AR, MR), heart failure with reduced ejection fraction
This is the pattern that produces cardiomegaly visible on CXR

2. Concentric Hypertrophy (Pressure Overload)

Wall thickens disproportionately, chamber size decreases
Typical of hypertension, aortic stenosis
May NOT cause cardiomegaly on CXR despite significant hypertrophy
Frameworks for Internal Medicine

Causes of Cardiomegaly

Category	Examples
Myocardial	Dilated cardiomyopathy (ischemic, non-ischemic), previous MI with LV remodeling
Ischemic	Post-MI LV dilation, chronic ischemic heart disease
Hypertensive	Long-standing hypertension causing LV dilation
Valvular	Aortic regurgitation (chronic - gross cardiomegaly), mitral regurgitation, aortic stenosis (later stages)
Pericardial	Pericardial effusion (can mimic cardiomegaly)
High-output states	Hyperthyroidism, severe anemia, beriberi, arteriovenous shunts
Congenital	Ebstein anomaly (massive cardiomegaly), ASD (with right heart enlargement), coarctation of the aorta
Toxic/Metabolic	Alcoholic cardiomyopathy (~20-30% of nonischemic dilated CMP), tachycardia-mediated CMP
Rheumatologic	Myocarditis (in SLE, rheumatoid, other connective tissue disease)

Goldman-Cecil Medicine, Katzung Pharmacology, Fuster & Hurst's The Heart, Braunwald's Heart Disease

Radiographic Appearances

Acute vs. Chronic Heart Failure

Acute left-sided HF: Normal heart size + alveolar pulmonary edema (butterfly pattern). Cardiomegaly is typically absent because there is no time for cardiac remodeling.
Chronic left-sided HF: Gross cardiomegaly + striking cephalization of pulmonary vasculature + Kerley B lines + interstitial pulmonary edema or fibrosis.
Chronic right-sided HF: Cardiomegaly with right-sided chamber enlargement; pulmonary vascular changes depend on etiology.
Fuster & Hurst's The Heart, 15th Edition

Disease-Specific Patterns (from CXR)

Condition	CXR Findings
Aortic stenosis	Mild cardiomegaly or LV prominence; aortic calcification
Aortic regurgitation (chronic)	Gross cardiomegaly; pulmonary edema, widened mediastinum
Ebstein anomaly	Massive globular cardiomegaly (CTR often >0.6); "box-shaped" heart; bulging right heart border
ASD	Cardiomegaly + increased vascular markings (right heart enlargement)
Coarctation of aorta	Cardiomegaly + pulmonary edema (neonates); rib notching (older children/adults)

Washington Manual of Medical Therapeutics, Fuster & Hurst's The Heart, Tintinalli's Emergency Medicine

Below: ECGs and CXRs in Ebstein anomaly showing the spectrum from mild (C, CTR 0.49) to massive cardiomegaly (D, CTR 0.78):

ECGs and chest radiographs in Ebstein anomaly showing spectrum of cardiomegaly

Signs and Symptoms

Cardiomegaly itself is a radiographic/imaging finding, not a symptom, but the underlying cause typically produces:

Symptoms: Dyspnea (exertional, then at rest), orthopnea, PND, fatigue, decreased exercise tolerance, peripheral edema
Signs: Tachycardia, displaced apex beat (toward the axilla), S3 gallop (specific for systolic dysfunction), S4, murmurs of valvular disease, raised JVP, hepatomegaly, peripheral edema
ECG changes: LVH, LAE, LBBB, ST-T changes depending on the cause

Primary signs and symptoms of heart failure include tachycardia, decreased exercise tolerance, shortness of breath, and cardiomegaly. - Katzung's Basic and Clinical Pharmacology, 16th Edition

Diagnostic Workup

Chest X-ray - initial identification; CT ratio ≥ 0.5 = cardiomegaly
ECG - LVH, conduction defects, arrhythmias, prior MI evidence
Echocardiography - gold standard for assessing chamber size, wall motion, EF, valvular disease, pericardial effusion; differentiates dilated vs. hypertrophic vs. restrictive patterns
BNP / NT-proBNP - elevated in heart failure, guides severity assessment
Troponin - rules out acute ischemic cause
Thyroid function, CBC, iron studies - screen for reversible/high-output causes
Cardiac MRI - tissue characterization (fibrosis, infiltration, myocarditis), laminopathy evaluation
Coronary angiography - if ischemic etiology suspected

Tintinalli's Emergency Medicine, Goldman-Cecil Medicine

Management Principles

Management targets the underlying cause:

Cause	Treatment
Systolic HF (HFrEF)	ACE inhibitors/ARBs, beta-blockers, MRAs, SGLT2 inhibitors, diuretics
Hypertension	Antihypertensive therapy
Valvular disease	Surgical/transcatheter repair or replacement
Alcoholic CMP	Abstinence (may be partially reversible)
Thyroid disease	Treat hyperthyroidism
Severe anemia	Treat underlying cause, transfusion if needed
Pericardial effusion	Pericardiocentesis
Congenital defects	Surgical/catheter-based repair

"High-output" heart failure (hyperthyroidism, beriberi, AV shunts, severe anemia) responds poorly to conventional heart failure drugs and must be treated by correcting the underlying cause. - Katzung's Basic and Clinical Pharmacology, 16th Edition

Key Differentials for an Enlarged Cardiac Silhouette on CXR

True cardiomegaly (from any cause above)
Pericardial effusion - globular "water bottle" heart; no pulmonary vascular changes
Pericardial fat pad - pseudo-enlargement
AP film artifact - portable AP CXRs magnify the cardiac shadow; always compare with PA erect films
Ebstein anomaly - massive RA/RV enlargement mimicking pericardial effusion globular shape

Summary

Cardiomegaly is a final common radiographic manifestation of many cardiac conditions. The most common causes are dilated cardiomyopathy (ischemic or non-ischemic), chronic valvular disease, and long-standing hypertension. Echocardiography is the key next step after CXR to define the structural cause. Management is directed at the specific etiology, with heart failure therapies forming the backbone when systolic dysfunction is present.

Congestive heart' failure

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Congestive Heart Failure (CHF)

Definition

Heart failure occurs when the heart is unable to provide adequate perfusion to meet the metabolic requirements of peripheral tissues. Inadequate cardiac output is usually accompanied by increased congestion of the venous circulation - hence the term "congestive" heart failure. Normal cardiac output is approximately 5 L/min/70 kg body weight.

Robbins, Cotran & Kumar Pathologic Basis of Disease; Katzung's Basic and Clinical Pharmacology, 16th Edition

Etiology and Causes

Category	Examples
Ischemic heart disease	MI (most common cause globally), chronic ischemic CMP
Hypertension	Long-standing systemic hypertension (pressure overload)
Valvular disease	Aortic stenosis/regurgitation, mitral regurgitation/stenosis
Primary myocardial disease	Dilated cardiomyopathy (idiopathic, alcoholic, viral, familial)
Tachyarrhythmia	Atrial fibrillation with rapid rate (tachycardia-mediated CMP)
High-output states	Hyperthyroidism, severe anemia, beriberi, AV shunts
Infiltrative	Amyloidosis, sarcoidosis, hemochromatosis
Toxic	Alcohol, anthracyclines, cobalt, cocaine
Congenital	Large shunts (ASD, VSD), Ebstein anomaly
Pericardial disease	Constrictive pericarditis (mimics CHF)

Pathophysiology

The Core Problem

Increased mechanical work on either ventricle (from pressure or volume overload) triggers a cascade:

Causes and consequences of cardiac hypertrophy - from hypertension, valvular disease, and MI leading through wall stress, hypertrophy/dilation, to cardiac dysfunction

Pressure overload (e.g., hypertension, aortic stenosis): new sarcomeres assemble in parallel → concentric hypertrophy → wall thickens, chamber shrinks
Volume overload (e.g., aortic/mitral regurgitation): new sarcomeres assemble in series → eccentric hypertrophy → chamber dilates, wall may thin
Patients with hypertension, IHD, aortic stenosis, MR, or dilated CMP frequently have heart weights double or triple the average.
Robbins, Cotran & Kumar Pathologic Basis of Disease

Molecular Changes in the Failing Heart

Initially beneficial hypertrophy becomes harmful over time:

Immediate-early genes (FOS, JUN, MYC) are induced
Fetal gene program is re-expressed (fetal myosin isoforms, natriuretic peptides, collagen)
Capillary density does NOT increase proportionally to muscle mass → relative ischemia
Mitochondrial dysfunction → impaired energy production
Calcium handling is disrupted (SERCA impaired, RyR channels leak Ca²⁺ → arrhythmias)
Accelerated myocyte apoptosis → progressive loss of contractile mass
The result: cardiac remodeling - progressive dilation, fibrosis, and dysfunction
Katzung's Basic and Clinical Pharmacology, 16th Edition; Robbins Pathology

Neurohumoral Compensation (the Vicious Cycle)

Neurohumoral compensatory responses in CHF - reduced CO activates SNS and RAAS, increasing preload, afterload, and remodeling

Low cardiac output triggers two major compensatory axes:

Sympathetic nervous system: Baroreceptors are reset; sympathetic outflow increases → tachycardia, increased contractility, vasoconstriction. Chronically, norepinephrine promotes myocyte hypertrophy and apoptosis.
RAAS: Reduced renal perfusion → renin release → angiotensin II → aldosterone → sodium and water retention → increased preload and afterload. Angiotensin II also promotes remodeling and vasoconstriction.

Both mechanisms initially compensate but ultimately worsen cardiac function through increased afterload and remodeling - creating the classic vicious cycle of progressive heart failure.

Katzung's Basic and Clinical Pharmacology, 16th Edition

Types of CHF

1. HFrEF (Heart Failure with Reduced Ejection Fraction)

EF < 40-45%; also called "systolic failure" or "pump failure"
The heart is big and floppy (eccentric hypertrophy/dilation)
Responds to positive inotropes, neurohormonal blockers
Most common after MI, in dilated CMP

2. HFpEF (Heart Failure with Preserved Ejection Fraction)

EF ≥ 50%; also called "diastolic failure"
LV is stiff and cannot relax - filling is impaired
Any increase in filling pressure is immediately transmitted back to the lungs → pulmonary edema
Most common in elderly, hypertensives, diabetics, obese patients
Does NOT respond well to positive inotropes
Also associated with myocardial fibrosis (IHD, cardiomyopathies) and infiltrative disease (amyloidosis)

3. Left-Sided vs. Right-Sided vs. Biventricular

Left-sided failure → back-pressure into pulmonary circulation:

Pulmonary congestion, edema, dyspnea, orthopnea, PND
"Heart failure cells" (hemosiderin-laden macrophages) in alveoli - a pathological hallmark
Pulmonary rales, S3/S4, displaced apex, cardiomegaly

Right-sided failure → back-pressure into systemic circulation:

Peripheral edema (feet, ankles, presacral)
Hepatomegaly ("nutmeg liver" - centrilobular congestion), congestive splenomegaly
Ascites, pleural effusions
Raised JVP, with or without pulsatile liver
In severe/chronic cases: cardiac cirrhosis

Biventricular / Global CHF: Most chronic CHF patients develop this; left-sided failure commonly causes right-sided failure by increasing pulmonary pressure, increasing RV afterload.

Robbins, Cotran & Kumar Pathologic Basis of Disease

4. High-Output Failure

Cardiac output is increased (>8-10 L/min), yet still insufficient for the body's demands
Causes: hyperthyroidism, severe anemia, beriberi, AV shunts
Responds poorly to standard HF drugs; treat the underlying cause

Clinical Features

Symptoms

Left Heart Failure	Right Heart Failure
Dyspnea on exertion (earliest)	Peripheral edema
Orthopnea	Abdominal distension (ascites)
Paroxysmal nocturnal dyspnea (PND)	Right upper quadrant discomfort (hepatomegaly)
Cough (frothy, sometimes pink)	Anorexia, nausea (gut edema)
Fatigue, reduced exercise tolerance	Weight gain (fluid retention)

In advanced CHF:

Prerenal azotemia (reduced renal perfusion)
Cerebral hypoperfusion: confusion, irritability, stupor, coma
Cardiac cachexia (chronic severe CHF)

Signs

Tachycardia - earliest compensatory sign
S3 gallop - early diastolic sound; indicates volume overload and systolic dysfunction (high specificity)
S4 gallop - increased myocardial stiffness (diastolic dysfunction)
Displaced apex beat toward the axilla (eccentric hypertrophy)
Cardiomegaly on CXR
Bilateral basal crepitations/rales - alveolar fluid
Raised JVP
Pitting edema (dependent)
Hepatojugular reflux
Mitral regurgitation murmur (functional - from papillary muscle displacement due to LV dilation)
Pleural effusion (particularly right-sided)
Robbins, Cotran & Kumar Pathologic Basis of Disease

NYHA Functional Classification

Class	Description
I	No symptoms with ordinary activity
II	Slight limitation; comfortable at rest, symptoms with moderate exertion
III	Marked limitation; comfortable at rest, symptoms with minimal exertion
IV	Symptoms at rest or with any activity

ACC/AHA Staging (A-D)

Stage	Description
A	High risk, no structural disease, no symptoms
B	Structural disease, no symptoms
C	Structural disease with current or prior symptoms
D	Refractory heart failure requiring advanced interventions

Investigations

Test	Findings / Purpose
CXR	Cardiomegaly (CTR ≥0.5), cephalization, Kerley B lines, pulmonary edema, pleural effusion
ECG	LVH, LBBB, Q waves, arrhythmias (AF is present in 10-50% depending on NYHA class)
Echocardiogram	EF, chamber dimensions, wall motion, valve function, pericardial effusion; KEY investigation
BNP / NT-proBNP	Elevated with ventricular wall stress; high negative predictive value when low
Troponin	Rules out acute ischemic cause; mildly elevated in decompensated CHF
U&E, creatinine	Baseline renal function; monitor for cardiorenal syndrome
FBC	Anemia (aggravates CHF)
TFTs	Hypo-/hyperthyroidism as cause or aggravator
Iron studies	Hemochromatosis; iron deficiency (treat even without anemia in CHF)
Cardiac MRI	Tissue characterization, fibrosis mapping, myocarditis, infiltrative disease

Management

General Principles

Treatment first corrects any reversible underlying cause (valvular disease, ischemia, arrhythmia, thyroid disease), then targets the neurohumoral dysregulation driving progression.

Non-Pharmacological

Salt restriction (evidence supports modest restriction in chronic CHF; recent meta-analysis 2024 - PMID 37389661)
Fluid restriction in hyponatremia or severe CHF
Daily weight monitoring (alert if >2 kg in 2 days)
Aerobic exercise rehabilitation (improves symptoms and quality of life)
Smoking cessation, alcohol abstinence (alcoholic CMP may partially reverse)
Treat sleep apnea (CPAP reduces symptoms)
Vaccination (influenza, pneumococcal)

Pharmacotherapy for HFrEF - the "Fantastic Four"

Current guidelines recommend four pillars of disease-modifying therapy for HFrEF (EF <40%):

Drug Class	Examples	Key Benefits
ARNI (preferred) or ACE inhibitor / ARB	Sacubitril/valsartan (ARNI); enalapril, ramipril (ACE-i); losartan, candesartan (ARB)	Reduces afterload, blocks angiotensin II, prevents remodeling, ↓ mortality
Beta-blocker	Carvedilol, bisoprolol, metoprolol succinate	↓ HR, ↓ catecholamine toxicity, ↑ EF, ↓ mortality by ~27-34% in sinus rhythm
Mineralocorticoid receptor antagonist (MRA)	Spironolactone, eplerenone	Blocks aldosterone → ↓ Na/water retention, ↓ fibrosis, ↓ mortality
SGLT2 inhibitor	Dapagliflozin, empagliflozin	Osmotic diuresis, metabolic effects, cardioprotection; ↓ hospitalizations and mortality

The combination of a beta-blocker with an ARNI (or ACE inhibitor/ARB) is a cornerstone of treatment of symptomatic heart failure. Treatment should be started at low dose ("start low, go slow") and up-titrated toward trial-proven target doses.

Goldman-Cecil Medicine

Diuretics (not disease-modifying but essential for symptom relief):

Loop diuretics (furosemide, torasemide) for most patients
Thiazides can be added in combination for diuretic resistance (sequential nephron blockade)
IV diuretics if oral absorption impaired by gut edema

Digoxin: Reduces hospitalizations, rate control in AF with HFrEF, does not reduce mortality

Device Therapy

Device	Indication
ICD (Implantable Cardioverter-Defibrillator)	EF ≤35% on optimal medical therapy (primary prevention of sudden cardiac death)
CRT (Cardiac Resynchronization Therapy)	EF ≤35% + LBBB + QRS ≥130 ms + NYHA II-IV symptoms; improves EF and symptoms
CRT-D	When EF ≤30-35% and unlikely to recover; provides both CRT and ICD benefit
LVAD (Left Ventricular Assist Device)	Bridge to transplant or destination therapy in stage D HF

Atrial fibrillation management in CHF:

Rate control: beta-blockers preferred in HFrEF; non-dihydropyridine CCBs in HFpEF
Rhythm control: amiodarone and dofetilide are the only antiarrhythmics safe in HF
AF catheter ablation in HF patients: associated with greater improvement in LVEF, quality of life, and reduced mortality (CASTLE-AF trial)
AV node ablation + biventricular pacing when rate cannot be controlled
Braunwald's Heart Disease, 2 Vol Set

Advanced/End-Stage HF (Stage D)

Cardiac transplantation (gold standard for eligible patients)
LVAD as destination therapy
Ultrafiltration for refractory volume overload
Palliative care

Key Pathological Findings

Location	Finding in CHF
Lungs	Pulmonary edema, "heart failure cells" (hemosiderin-laden macrophages)
Liver	"Nutmeg liver" (centrilobular congestion), cardiac cirrhosis (chronic)
Spleen	Congestive splenomegaly with platelet sequestration
Kidneys	Increased congestion in right HF; prerenal azotemia
Periphery	Pitting edema, sacral edema in bedridden patients, anasarca (severe)
Pleura/Peritoneum	Transudative pleural effusions, ascites

Robbins, Cotran & Kumar Pathologic Basis of Disease

Prognosis

CHF remains a serious cause of morbidity and mortality despite modern therapy. The annual mortality in severe (NYHA class IV) heart failure exceeds 50%. Key prognostic factors include:

LVEF
NYHA functional class
BNP/NT-proBNP levels
Serum sodium (hyponatremia = poor prognosis)
Heart rate in sinus rhythm (higher HR = worse outcome)
Comorbidities (renal dysfunction, diabetes, COPD)

Summary

CHF is the common final pathway of most cardiac diseases. It is driven by a self-amplifying neurohumoral spiral (SNS + RAAS activation) that initially compensates but ultimately accelerates myocardial deterioration through remodeling, apoptosis, and arrhythmogenesis. Modern treatment - combining ARNI/ACE-i, beta-blocker, MRA, and SGLT2 inhibitor - targets each arm of this spiral and has dramatically improved outcomes over the past three decades.

Dv t

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Deep Vein Thrombosis (DVT)

Definition

Deep vein thrombosis is the formation of a thrombus within the deep venous system, most commonly in the lower extremity. It is part of the spectrum of venous thromboembolism (VTE), which also includes pulmonary embolism (PE) - the most feared complication, which may be fatal. VTE causes more than 50,000 deaths per year in the United States, with ~25% occurring in the perioperative period.

Sabiston Textbook of Surgery

Relevant Anatomy

The deep venous system of the lower extremity (the usual site of DVT):

Diagram of leg vein anatomy relevant to DVT diagnosis, showing deep veins from IVC to peroneal veins

Key veins involved (proximal to distal): common femoral → femoral → popliteal → posterior tibial / peroneal / anterior tibial → calf (gastrocnemius, soleus)

Proximal DVT: involves popliteal vein or above - higher risk of PE
Distal DVT: isolated calf vein involvement - lower PE risk; may propagate proximally if untreated
Iliac/pelvic DVT: requires CT venography or MRI to diagnose (not seen on standard duplex US)

Note: DVT occurs with slightly higher frequency on the left leg because the left iliac vein is vulnerable to compression by the left iliac artery - May-Thurner syndrome.

Rosen's Emergency Medicine

Pathophysiology - Virchow's Triad

Rudolf Virchow (1856) described three factors that predispose to venous thrombosis - collectively known as Virchow's Triad:

Component	Mechanism	Examples
1. Venous stasis	Reduced flow creates hypoxia; downregulates antithrombotic proteins (thrombomodulin, endothelial protein C receptor); allows clotting factors to accumulate	Immobility, long-haul travel, paralysis, CHF, obesity, pregnancy (uterine compression)
2. Endothelial injury	Exposes subendothelial tissue factor (TF); activates coagulation cascade; hypoxia + cytokines induce TF expression and P-selectin on intact endothelium	Surgery, trauma, IV catheters, vasculitis
3. Hypercoagulability	Hereditary or acquired procoagulant state; impaired fibrinolysis	Factor V Leiden, antiphospholipid syndrome, malignancy, OCP use, pregnancy

The molecular cascade once initiated: TF:FVIIa → thrombin generation → platelet activation → polyphosphate release + neutrophil extracellular traps (NETs) → intrinsic pathway activation via FXI → propagating procoagulant environment.

Sabiston Textbook of Surgery; Gray's Anatomy for Students

Risk Factors

Acquired Risk Factors

Immobility: prolonged bed rest (≥3 days), long-haul travel, plaster cast, paralysis
Surgery: particularly high-risk - pelvic surgery, total hip/knee replacement, major abdominal surgery
Malignancy: especially pancreatic, lung, ovarian, GI cancers (Trousseau's syndrome)
Pregnancy & postpartum: compression of iliac veins by gravid uterus + hypercoagulable state
Combined oral contraceptive pill / HRT
Prior DVT / PE
Obesity
Age > 60
Heart failure, nephrotic syndrome, dehydration
Indwelling venous catheters (>90% of upper extremity DVTs occur in the presence of a catheter/device)
Antiphospholipid antibody syndrome

Inherited Thrombophilias

Thrombophilia	Mechanism	Notes
Factor V Leiden	Arg506Gln mutation → resistance to activated Protein C	Most common inherited thrombophilia in White populations (heterozygote prevalence ~4.7%); RR 6-8x
Prothrombin gene mutation (G20210A)	Gly→Ala at position 20210 → increased thrombin synthesis	Second most common
Protein C deficiency	Reduced natural anticoagulant; cannot inactivate FVa and FVIIIa	Autosomal dominant
Protein S deficiency	Cofactor for Protein C; disrupted interaction with APC and TFPI	Levels lower in females, pregnancy, OCP use
Antithrombin deficiency	Cannot clear thrombin and FXa	SERPINA1 mutation

Sabiston Textbook of Surgery

Surgical Risk Stratification

Risk Level	Procedures
Low	Maxillofacial, neurosurgery, cardiothoracic surgery
Medium	Inguinal hernia repair, abdominal, gynaecological, urological surgery
High	Pelvic surgery (elective and trauma), total hip and knee replacement

Bailey and Love's Short Practice of Surgery

Clinical Features

Symptoms

Unilateral leg swelling (hallmark)
Calf pain or aching - may be only mild cramping or a "sense of fullness"
Redness and warmth of the affected limb
Engorged superficial (collateral) veins
Rarely: a palpable venous cord

Key point: Most DVTs show NO physical signs. Clinical examination alone is unreliable.

Signs

Pitting edema of the affected limb
Erythema and warmth
Tenderness along the course of the deep venous system
Homans' sign (calf pain on dorsiflexion of the foot) - historically described but neither sensitive nor specific; do not rely on it

Special Scenarios

Upper extremity DVT: Arm pain/swelling ipsilateral to an IV catheter or pacemaker wire. In young athletes without a device: Paget-Schroetter syndrome (effort-induced thrombosis from thoracic outlet compression, dominant arm)
Bilateral DVT: Less than 10% of ED-diagnosed DVT cases
Pregnancy: Left leg more commonly affected (gravid uterus compresses left external iliac vein)
Rosen's Emergency Medicine; Bailey and Love's Surgery

Differential Diagnosis

Diagnosis	Distinguishing Feature
Cellulitis	Fever, no deep tenderness; DVT concurrent in only ~3%
Ruptured Baker cyst	Often has prior knee effusion; sudden onset calf swelling
Gastrocnemius muscle tear / Achilles injury	History of exertion/trauma
Superficial thrombophlebitis	Palpable, tender, indurated superficial cord; overlying skin erythema
Venous insufficiency	Bilateral, chronic; varicosities
Asymmetric edema from CHF, liver disease	Bilateral in most cases; no deep tenderness
Hematoma (spontaneous calf)	Coagulopathy history, no systemic features

Diagnosis

Step 1 - Pretest Probability: Wells DVT Score

Clinical Feature	Score
Active cancer (treatment in last 6 months or palliative)	+1
Paralysis, paresis, or recent plaster immobilization of lower limbs	+1
Bedridden ≥3 days or major surgery within 12 weeks (general/regional anesthesia)	+1
Localized tenderness along the deep venous system	+1
Entire leg swollen	+1
Calf swelling ≥3 cm larger than asymptomatic side (measured 10 cm below tibial tuberosity)	+1
Pitting edema confined to symptomatic leg	+1
Collateral superficial veins (non-varicose)	+1
Previously documented DVT	+1
Alternative diagnosis at least as likely as DVT	-2

Score < 2 = Low PTP | Score ≥ 2 = High PTP

Step 2 - Diagnostic Algorithm

D-Dimer

Measures enzymatic breakdown of cross-linked fibrin from any intravascular thrombus
Standard cutoff: >500 ng/mL = positive
Age-adjusted cutoff: Age × 10 ng/mL (e.g., for an 80-year-old, cutoff = 800 ng/mL) - safely increases percentage of patients who can avoid US
Sensitivity ~92%, Specificity ~45% for DVT in low PTP patients
False positives in: pregnancy, malignancy, recent surgery, trauma, infection, inflammation, liver disease, renal failure
Note: warfarin use is associated with false-negative D-dimer results

Venous Ultrasound (Duplex)

Gold standard investigation; non-invasive, no radiation
Criteria for DVT on US: non-compressibility of the vein, absence of flow, absent respiratory variation, no augmentation on calf compression
Whole-leg US (criterion standard): images all deep and superficial veins; 3-month VTE event rate 0.5% after negative result
Three-point (compression) US: common femoral, femoral, popliteal veins; sensitivity 95%, specificity 95% for proximal DVT
POCUS (bedside): 90-95% accurate in trained hands for proximal veins

Imaging Limitations

US cannot evaluate iliac veins or IVC - CT venography or MRI required for suspected pelvic/iliac DVT
MRI preferred in pregnant patients (no ionizing radiation)
Rosen's Emergency Medicine

Complications

Pulmonary Embolism (PE)

The most serious complication. Thrombus dislodges from the leading edge of the DVT, passes through the right heart, and lodges in the pulmonary arterial tree. Symptoms range from pleuritic chest pain (small emboli) to haemodynamic collapse and death (massive PE).

Post-Thrombotic Syndrome (PTS)

Chronic venous insufficiency, persistent leg swelling, pain, skin changes, venous ulceration
Occurs in 20-50% of DVT patients over time
Caused by valvular incompetence from thrombus damage

Phlegmasia Cerulea Dolens

Massive iliofemoral DVT causing complete venous outflow obstruction
Limb becomes cyanotic, intensely swollen, and extremely painful
Risk of venous gangrene without urgent intervention

Treatment

Anticoagulation Options

Anticoagulant	Initial Dose	Key Restriction
Unfractionated heparin (UFH)	70-80 U/kg IV bolus then 17-18 U/kg/h	HIT; use when rapid reversibility needed
Enoxaparin (LMWH)	1 mg/kg q12h or 1.5 mg/kg q24h SC	CrCl < 30 mL/min
Dalteparin (LMWH)	200 U/kg daily SC	CrCl < 30 mL/min
Fondaparinux	5-10 mg SC daily	CrCl < 30 mL/min; use in HIT
Rivaroxaban (DOAC)	15 mg BD × 21 days, then 20 mg OD	CrCl < 30; no bridging needed
Apixaban (DOAC)	10 mg BD × 7 days, then 5 mg BD	CrCl < 30; no bridging needed
Dabigatran (DOAC)	After 5-10 days of LMWH	Requires initial parenteral lead-in
Warfarin	Bridged with LMWH until INR 2-3 for 2 consecutive days	Interactions, INR monitoring; less favoured now

DOACs (rivaroxaban, apixaban) are now first-choice for most patients with DVT - equally effective as warfarin for preventing recurrent VTE, with fewer major bleeding events, and no need for INR monitoring or bridging with LMWH.

DOAC contraindications/cautions: pregnancy, severe renal failure (CrCl < 30), liver failure, antiphospholipid antibody syndrome, high-risk PE.

Cancer-associated thrombosis: LMWH traditionally preferred for lower VTE recurrence risk, but recent evidence suggests DOACs are also safe and effective - meta-analysis 2025, PMID 40578592.

Isolated distal (calf) DVT: Whether to anticoagulate remains controversial. A recent 2025 meta-analysis (PMID 40400471) evaluated anticoagulant treatment for isolated distal DVT; serial surveillance US is an acceptable alternative in low-risk patients without symptoms or propagation risk.

Duration of Anticoagulation

Scenario	Duration
First DVT, provoked (reversible risk factor)	3 months minimum
First DVT, unprovoked	3-6 months; consider indefinite if low bleed risk
Recurrent DVT	Indefinite anticoagulation
Active cancer	Indefinite (or until cancer resolved)
Antiphospholipid syndrome	Indefinite

Reversal Agents

Drug	Reversal Agent
Heparin / LMWH	Protamine sulfate
Warfarin	FFP, 4-factor PCC, Vitamin K
Dabigatran	Idarucizumab
Rivaroxaban / Apixaban	Andexanet alfa

IVC Filter

For patients who cannot be safely anticoagulated (e.g., active bleeding, recent intracranial surgery)
Temporary/retrievable filters preferred
Reduces PE risk but does NOT treat DVT; retrieve when anticoagulation becomes safe

Endovascular Intervention (Catheter-Directed Thrombolysis / Thrombectomy)

Increasingly used in acute iliofemoral DVT (proximal, large-burden thrombosis)
Goals: restore patency, reduce post-thrombotic syndrome risk
Techniques: pharmacomechanical thrombolysis, aspiration thrombectomy, venous stenting
Best evidence in selected patients with acute proximal iliofemoral DVT and low bleed risk
Bailey and Love's Short Practice of Surgery; Rosen's Emergency Medicine

Prophylaxis

All hospitalised patients must be risk-assessed within 24 hours of admission for VTE risk.

Method	Notes
Graduated compression stockings	Avoid in: PAD, neuropathy, severe leg oedema, skin breakdown, leg deformity, allergy
Intermittent pneumatic compression (calf pumps)	For patients at high DVT risk who cannot have anticoagulation
LMWH (e.g., enoxaparin 40 mg SC OD)	Mainstay of pharmacological prophylaxis in surgical/medical patients
Unfractionated heparin	Alternative if renal impairment
Fondaparinux	Option in HIT; good for orthopaedic prophylaxis

Risk should be reviewed if the patient's clinical condition changes.

Bailey and Love's Short Practice of Surgery

Summary

DVT is a common, potentially life-threatening condition driven by Virchow's triad (stasis, endothelial injury, hypercoagulability). Diagnosis requires systematic pretest probability assessment (Wells score), followed by D-dimer and/or venous duplex ultrasound. DOACs (rivaroxaban, apixaban) are now first-line treatment, offering equal efficacy to warfarin with a better safety profile and simpler dosing. Duration depends on provoked vs unprovoked DVT, with unprovoked and recurrent DVT warranting longer or indefinite anticoagulation. Prevention through VTE risk assessment and prophylaxis in all surgical and hospitalised patients remains the most effective strategy.

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