Diastolic Dysfunction - MD Anaesthesiology Exam Notes

1. Definition and Basic Physiology

Four Phases of Diastole

2. Causes of Diastolic Dysfunction

1. Primary myocardial disease - hypertrophic cardiomyopathy, infiltrative disease (amyloid, sarcoid), myocarditis
2. Secondary LV hypertrophy - systemic hypertension (most common), aortic stenosis
3. Coronary artery disease - ischaemia impairs active relaxation (ATP-dependent process)
4. Extrinsic constraint - pericardial disease, constrictive pericarditis, tamponade

• Systemic hypertension
• Coronary artery disease
• Diabetes mellitus
• Advanced age (the single greatest risk factor)
• Aortic stenosis
• Cardiomyopathies

Key point (Morgan & Mikhail): Older adult patients undergoing echocardiographic evaluation for surgery have a significantly increased incidence of diastolic dysfunction compared with younger patients. Marked diastolic dysfunction may be seen with hypertension, CAD, cardiomyopathies, and valvular disease - all more common in the elderly.

3. Pathophysiology

Active vs. Passive Components

• Active relaxation (early diastole): energy-dependent (requires ATP); calcium reuptake into sarcoplasmic reticulum via SERCA2a; impaired in ischaemia, hypertrophy, tachycardia
• Passive compliance (late diastole): determined by wall stiffness; impaired by fibrosis, hypertrophy, infiltration

Pressure-Volume Relationship (Barash)

• In diastolic dysfunction: EDPVR shifts upward and to the left - the LV cannot fill without elevated LV end-diastolic pressure
• This is the hallmark of HFpEF (heart failure with preserved ejection fraction)
• LVEDP rises → LA pressure rises → pulmonary venous hypertension → pulmonary oedema without systolic dysfunction
• EF may be normal (>50%) yet the patient is in frank heart failure

The HFpEF Concept

• Diastolic dysfunction is the primary mechanism in HFpEF
• A diagnosis of diastolic heart failure is an independent predictor of mortality
• Not uncommon in patients with normal systolic function presenting for surgery (Cios et al. 2023)

4. Grading / Classification by Echocardiography

Doppler Parameters Used

• E wave = peak early diastolic mitral inflow velocity
• A wave = peak atrial (late diastolic) inflow velocity
• DT = deceleration time of E wave
• IVRT = isovolumic relaxation time
• e' (tissue Doppler) = early diastolic myocardial annular velocity; < 8-10 cm/s = impaired
• E/e' ratio > 15 = elevated LVEDP; < 8 = normal filling pressure

Grades of Diastolic Dysfunction

Tip: E/e' > 15 reliably predicts elevated LVEDP regardless of the transmitral pattern.

5. Anaesthetic Significance and Perioperative Risk

Why Diastolic Dysfunction Matters to the Anaesthesiologist

1. Prevalence is high and underdiagnosed - Many patients presenting for surgery have unrecognised diastolic dysfunction. Preoperative evaluation often focuses on EF but overlooks diastolic function.
2. Independent predictor of adverse outcomes - Associated with increased perioperative morbidity and mortality, even with a normal EF.
3. Exaggerated haemodynamic instability on induction - Diminished cardiac reserve leads to exaggerated decreases in blood pressure during induction of general anaesthesia (Morgan & Mikhail).
4. Intolerance of tachycardia - Shorter diastolic filling time worsens filling and raises LVEDP; any tachycardia is extremely poorly tolerated.
5. Intolerance of fluid shifts - The stiff ventricle sits on a steep part of the pressure-volume curve: small volume increases cause large pressure rises → acute pulmonary oedema.
6. Intolerance of fluid restriction - Conversely, they are also preload-dependent; hypovolaemia and vasodilation cause precipitous falls in CO.
7. Loss of atrial kick is catastrophic - Atrial contraction contributes 20-40% of CO in dysfunction (vs ~20% normally). New-onset AF in these patients causes acute decompensation.

6. Perioperative Management Principles

Preoperative

• Identify diastolic dysfunction from history (hypertension, DM, elderly, aortic stenosis) and any available echo data
• Review E/e' ratio, e' velocity, BNP/NT-proBNP - elevated levels indicate raised filling pressure
• Optimise BP, heart rate, and fluid status preoperatively
• Continue beta-blockers (heart rate control), ACE inhibitors, ARBs, diuretics up to morning of surgery
• Preoperative echocardiography is warranted in symptomatic patients or those with poor functional capacity (Cios et al. 2023)

Intraoperative - Key Goals

Neuraxial Anaesthesia Considerations (Morgan & Mikhail)

• Spinal anaesthesia can cause both hypotension and bradycardia - dual threat in diastolic dysfunction
• Administration of large IV volumes to treat spinal hypotension risks acute pulmonary oedema (fluid overload), especially once sympathetic block resolves postoperatively
• Use vasopressors (phenylephrine) preferentially over large fluid boluses to manage spinal hypotension in these patients

Intraoperative Monitoring

• TOE/TEE is the gold standard for real-time assessment of diastolic function and filling pressures intraoperatively
• Mitral inflow E/A, E/e', pulmonary venous flow patterns on TEE guide fluid management
• Invasive arterial monitoring is advisable in moderate-severe dysfunction
• Central venous pressure is unreliable as a measure of LV filling in diastolic dysfunction

Postoperative

• Fluid overload is common postoperatively as mobilised intravenous fluids return to the circulation
• Careful diuresis if pulmonary oedema develops
• Continue heart rate control
• High vigilance for new-onset AF

7. Effects of Anaesthetic Agents on Diastolic Function

8. Diastolic Dysfunction in Specific Anaesthetic Contexts

Cardiac Surgery

• Diastolic dysfunction is near-universal in patients undergoing cardiac surgery (hypertension, CAD, valve disease)
• Cardioplegia and cardiopulmonary bypass worsen diastolic function acutely
• Post-bypass diastolic dysfunction (low output syndrome with preserved EF) requires volume and rhythm management, not inotropes

Elderly Patients

• Aging normally causes myocardial fibrosis, reduced arterial elasticity, and LV hypertrophy - all increase diastolic stiffness
• Even healthy octogenarians have grade I diastolic dysfunction by echocardiographic criteria
• Decreased baroreceptor reflex + diastolic dysfunction = magnified haemodynamic instability under anaesthesia

Sepsis and ICU

• Sepsis-induced cardiomyopathy frequently includes diastolic dysfunction
• Vasopressors used in sepsis can worsen LV afterload and filling pressures in pre-existing diastolic dysfunction
• TEE-guided fluid management is invaluable

Obstetric Anaesthesia

• Pre-eclampsia causes diastolic dysfunction via hypertension-induced LV hypertrophy
• Peripartum cardiomyopathy can manifest with diastolic features
• Fluid management in these patients requires careful titration

9. Quick Recall Summary

DIASTOLIC DYSFUNCTION - ANAESTHETIC PEARLS

PHYSIOLOGY:   Impaired relaxation (↓ SERCA) + ↓ compliance → ↑ LVEDP
DIAGNOSIS:    TEE/Echo: E/A ratio, e' velocity, E/e' ratio (>15 = ↑ LVEDP)
GRADING:      I (Impaired relax) → II (Pseudonormal) → III/IV (Restrictive)
KEY TRAP:     Normal EF does NOT exclude haemodynamically significant disease

INTRAOP GOALS:
  HR:     50-80 bpm (atrial kick critical; tachycardia lethal)
  RHYTHM: Sinus at all costs - AF = acute decompensation
  FLUID:  Titrate carefully; avoid both overload and hypovolaemia
  MAP:    Maintain; vasopressors > fluid boluses for hypotension
  TEE:    Monitor E/e', pulmonary veins, LV filling in real time

AGENTS TO USE WITH CAUTION:
  - High-dose volatiles (↓ compliance)
  - Ketamine (tachycardia)
  - Large spinal anaesthesia volumes (post-sympathectomy overload)
  - Tachycardia-inducing drugs (atropine, pancuronium, desflurane at high doses)

1. Physiology - the four phases of diastole with the physiological basis for dysfunction
2. Causes - the four basic mechanisms with clinically relevant associations
3. Pathophysiology - active vs. passive components, the P-V relationship, and the HFpEF concept (a common exam question)
4. Echo grading - all four grades including the classic pseudonormal trap with E/A, DT, IVRT, e', and E/e' ratios in a table
5. Anaesthetic significance - seven reasons why this matters perioperatively
6. Perioperative management - pre/intra/postoperative goals in a table format
7. Drug effects - each agent's impact on diastolic function
8. Special contexts - cardiac surgery, elderly, sepsis, obstetrics
9. Quick recall box - for last-minute revision before the exam

• E/e' > 15 = elevated LVEDP (regardless of E/A appearance)
• Pseudonormal pattern (Grade II) has normal E/A but low e' - tissue Doppler is the key to unmask it
• Atrial contraction contributes 20-40% of CO in dysfunction - loss of sinus rhythm is catastrophic
• Vasopressors > fluid boluses when managing hypotension in these patients
• Normal EF does not exclude haemodynamically significant diastolic heart failure