7.3 Valvular Heart Disease & Murmur Interpretation

Valvular heart disease and infective endocarditis are core pillars of cardiovascular examination and therapeutics in MRCP(UK) Part 1. Candidates must recognize classic hemodynamic profiles, eponymous physical examination signs, echocardiographic grading thresholds, diagnostic criteria, and indications for surgical intervention.

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1. Aortic Stenosis (AS)

Pathophysiology & Aetiology

Aortic stenosis is the most prevalent primary valvular lesion in the UK and Western nations. The primary aetiologies include:

1. Calcific Degeneration: Age-related dystrophic calcification and progressive fibrocalcific remodelling of a trileaflet aortic valve, typically manifesting in patients >70 years.
2. Congenital Bicuspid Aortic Valve (BAV): Affects 1–2% of the population. Accelerated shear stress causes valve calcification and stenosis manifesting significantly earlier (40–60 years). Strongly associated with ascending aortic aneurysm, aortic coarctation, and aortic dissection.
3. Rheumatic Heart Disease: Characterized by commissural fusion, leaflet thickening, and concurrent mitral valve involvement; now rare in the UK but prevalent in developing nations.

Progressive outflow obstruction causes compensatory concentric left ventricular hypertrophy (LVH) to normalize wall stress (Laplace's law: stress = pressure x radius / 2 x wall thickness). Over time, diastolic dysfunction develops, followed by subendocardial ischaemia, myocyte apoptosis, left ventricular dilatation, and systolic heart failure.

Clinical Presentation & Cardinal Symptoms

Asymptomatic AS carries a relatively low risk of sudden cardiac death (<1% per year). However, the onset of cardinal symptoms marks a dramatic transition in prognosis:

• Angina Pectoris (Average survival ~5 years without valve replacement): Driven by increased myocardial oxygen demand (hypertrophied LV and high systolic wall stress) alongside decreased oxygen supply (compression of subendocardial coronary arterioles and reduced coronary perfusion pressure).
• Syncope / Presyncope (Average survival ~3 years): Typically exertional. Caused by an inability to augment cardiac output across the fixed, stenotic orifice during exercise, combined with peripheral vasodilation and exercise-induced ventricular mechanoreceptor reflexes (Bezold-Jarisch reflex) triggering sudden bradycardia and vasodepression.
• Dyspnoea / Heart Failure (Average survival ~2 years): Reflects elevated left ventricular end-diastolic pressure transmitting retrogradely into pulmonary capillaries.

Physical Examination Signs

• Arterial Pulse: Pulsus parvus et tardus (slow-rising, low-amplitude carotid pulse with a delayed peak). Narrow pulse pressure (e.g., 105/85 mmHg).
• Precordial Palpation: Heaving, sustained, non-displaced apex beat (concentric LVH). Palpable systolic thrill over the second right intercostal space.
• Auscultation:
  • Murmur: Harsh, crescendo-decrescendo ejection systolic murmur, loudest at the second right intercostal space, radiating characteristically to both carotid arteries. Murmur intensity peaks later in systole as stenosis worsens.
  • Second Heart Sound (S2): Soft or inaudible aortic closure sound (A2) due to rigid, calcified leaflets. Paradoxical (reversed) splitting of S2 occurs because prolonged LV ejection delays A2 until after pulmonic valve closure (P2); consequently, splitting narrows during inspiration and widens during expiration.
  • Fourth Heart Sound (S4): Frequently present, reflecting vigorous left atrial contraction into a non-compliant, stiff hypertrophied LV.

Echocardiographic Severity Criteria & Management

Transthoracic echocardiography is the gold standard diagnostic investigation:

• Indications for Valve Intervention:
  1. All symptomatic patients with severe AS.
  2. Asymptomatic patients with severe AS who have:
     • Impaired left ventricular systolic function (LVEF <50%) without other identifiable cause.
     • Symptoms unmasked on supervised exercise testing (or an abnormal fall in blood pressure >10 mmHg during exercise).
     • Very severe AS defined by peak velocity >5.0 m/s or mean gradient >60 mmHg.
• Intervention Modality (Heart Team Decision):
  • Surgical Aortic Valve Replacement (SAVR): Preferred in patients <75 years of age with low surgical risk (STS/EuroSCORE II <4%) or those undergoing concurrent CABG/aortic root surgery. Mechanical valves are favored in patients <60 years (require lifelong warfarin with INR target 2.0–3.0 depending on risk factors); bioprosthetic valves are used in older patients (do not require lifelong anticoagulation, but degenerate over 10–15 years).
  • Transcatheter Aortic Valve Implantation (TAVI): Preferred in patients >=75 years, those with high or prohibitive surgical risk, severe frailty, or a porcelain aorta.

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2. Aortic Regurgitation (AR)

Pathophysiology & Aetiology

Aortic regurgitation results from leaflet incompetence or aortic root dilatation:

• Valvular Causes: Infective endocarditis, congenital bicuspid valve, rheumatic heart disease, trauma.
• Aortic Root Causes: Ascending aortic aneurysm, Stanford Type A aortic dissection, connective tissue disorders (Marfan syndrome, Loeys-Dietz, Ehlers-Danlos), systemic hypertension, syphilitic aortitis, and seronegative spondyloarthropathies (ankylosing spondylitis).

In chronic AR, diastolic regurgitation into the left ventricle induces combined volume and pressure overload, triggering eccentric left ventricular hypertrophy and massive ventricular dilatation ("cor bovinum").

Physical Examination & Eponymous Signs

• Pulse & Hemodynamics: Collapsing pulse ("water-hammer" or Corrigan's pulse)—rapid distension with abrupt collapse. Wide pulse pressure (e.g., 170/45 mmHg) resulting from elevated systolic stroke volume and rapid diastolic run-off into both the peripheral circulation and back into the left ventricle.
• Apex Beat: Displaced inferolaterally, hyperdynamic, and thrusting.
• Auscultation:
  • High-pitched, blowing early diastolic decrescendo murmur, best appreciated at the left lower sternal border (3rd/4th intercostal space) with the patient sitting forward, in held end-expiration.
  • Systolic flow murmur across the aortic valve due to massive forward stroke volume.
  • Austin Flint Murmur: Low-pitched, rumbling mid-diastolic apical murmur caused by the regurgitant aortic jet striking and vibrating the anterior mitral valve leaflet, creating functional mitral stenosis.
• Classic Eponymous Peripheral Signs:
  • Quincke's Sign: Capillary pulsations visible in the nail beds upon gentle compression.
  • de Musset's Sign: Rhythmic nodding of the head in synchrony with cardiac systole.
  • Duroziez's Sign: Double murmur auscultated over the femoral artery (systolic murmur with proximal compression, diastolic murmur with distal compression).
  • Traube's Sign: Booming "pistol shot" sounds heard over the femoral arteries during systole.
  • Müller's Sign: Systolic pulsation of the uvula.

Management

Surgical aortic valve replacement is indicated in all symptomatic severe AR patients, and in asymptomatic patients with resting LVEF <=50% or progressive left ventricular dilatation (LV end-systolic diameter >50 mm or >25 mm/m² BSA).

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3. Mitral Valve Disease

Mitral Stenosis (MS)

• Aetiology: Rheumatic fever accounts for >95% of cases worldwide. Fibrotic leaflet thickening, commissural fusion, and chordal shortening produce a "fish-mouth" or "funnel-shaped" orifice.
• Hemodynamics: Fixed mechanical obstruction to left ventricular filling elevates left atrial pressure, causing left atrial enlargement, pulmonary venous hypertension, reactive pulmonary arteriolar vasoconstriction, and secondary right-sided heart failure.
• Physical Signs:
  • Malar Flush: Plum-coloured purplish patch over the malar prominences, secondary to cutaneous vasodilation and chronic low cardiac output.
  • Apex Beat: Tapping apex beat (representing a palpable, loud first heart sound without cardiomegaly; the apex beat is not displaced).
  • Auscultation: Loud S1 (pliable leaflets snap shut under elevated LA pressure); Opening Snap (OS) (high-frequency early diastolic sound caused by sudden arrest of doming stenotic leaflets). The interval between A2 and the opening snap inversely correlates with severity (narrow A2–OS interval denotes more severe stenosis). Followed by a low-pitched, rumbling mid-diastolic murmur best heard with the stethoscope bell at the apex in the left lateral decubitus position, terminating with presystolic accentuation (lost when atrial fibrillation supervenes).
• Complications: Thromboembolism (stroke in 20%), hemoptysis (rupture of bronchial veins/pulmonary apoplexy), and Ortner's syndrome (hoarseness caused by compression of the left recurrent laryngeal nerve between the enlarged left atrium and the pulmonary artery).
• Intervention: Percutaneous Mitral Balloon Commissurotomy (PMBC) is the procedure of choice if the valve morphology is pliable and free of heavy calcification (Wilkins echocardiographic score <=8) without left atrial thrombus or moderate-to-severe MR.

Mitral Regurgitation (MR)

• Aetiology: Degenerative/Myxomatous (mitral valve prolapse—presents with a mid-systolic click and late systolic murmur), ischaemic (papillary muscle dysfunction or acute rupture, classically the posteromedial papillary muscle following RCA inferior MI), functional (LV dilatation in cardiomyopathy), infective endocarditis, or rheumatic.
• Physical Signs: Hyperdynamic, laterally displaced apex beat; blowing pansystolic (holosystolic) murmur loudest at the apex, radiating into the left axilla; soft S1; prominent third heart sound (S3) reflecting high-volume, rapid diastolic filling of the left ventricle.

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4. Physical Examination & Murmur Summary Table

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