Valvular Heart Disease

Valvular heart disease refers to structural or functional abnormality of one or more of the four cardiac valves, causing either stenosis (obstruction to forward flow) or regurgitation (backward leakage of blood), or a combination of both.

Aortic stenosis, most commonly degenerative and calcific in older adults (though congenital bicuspid aortic valve predisposes to earlier onset stenosis) or rheumatic in origin in endemic settings, is the most common valve lesion requiring intervention in high income countries.

Mitral regurgitation arises from primary valve pathology (degenerative mitral valve prolapse, rheumatic disease, infective endocarditis) or secondary functional regurgitation from left ventricular dilation distorting the normal valve geometry.

Aortic regurgitation results from either primary valve leaflet disease (bicuspid valve, rheumatic disease, endocarditis) or aortic root dilation (hypertension, aortopathy, connective tissue disease such as Marfan syndrome).

Mitral stenosis is overwhelmingly rheumatic in origin, remaining an important cause of valve disease in regions with ongoing rheumatic fever burden (see Rheumatic Fever entry).

Aortic stenosis classically causes the triad of exertional angina, syncope (particularly exertional), and heart failure symptoms, with a harsh ejection systolic murmur radiating to the carotids and a slow rising carotid pulse (pulsus parvus et tardus) on examination. Once symptomatic, severe aortic stenosis carries a poor prognosis without intervention, which is why the onset of symptoms is such a critical trigger for referral.

Mitral regurgitation presents with exertional dyspnea and fatigue as the ventricle progressively dilates, with a pansystolic murmur radiating to the axilla. Acute severe mitral regurgitation, for example from papillary muscle rupture post myocardial infarction or acute endocarditis, presents dramatically with sudden pulmonary edema and hemodynamic compromise, in contrast to the gradual, often well tolerated course of chronic regurgitation.

Aortic regurgitation causes exertional dyspnea as the disease progresses, with a collapsing (water hammer) pulse and wide pulse pressure on examination, and a decrescendo early diastolic murmur heard best at the left sternal edge with the patient leaning forward in expiration. Acute severe aortic regurgitation, from endocarditis or aortic dissection, is a hemodynamic emergency with sudden pulmonary edema and shock, poorly tolerated given the lack of time for compensatory ventricular dilation.

Mitral stenosis classically causes exertional dyspnea, and, given the associated left atrial enlargement, a significantly increased risk of atrial fibrillation and consequent thromboembolic stroke. A mid diastolic rumbling murmur with an opening snap is heard at the apex.

Echocardiography is the definitive investigation for all valvular heart disease, quantifying the severity of stenosis or regurgitation, assessing ventricular size and function, and estimating pulmonary artery pressure. Severity grading (mild, moderate, severe) combines multiple echocardiographic parameters rather than a single measurement, and forms the basis for intervention timing decisions.

ECG may show left ventricular hypertrophy (aortic stenosis, aortic regurgitation), left atrial enlargement, or atrial fibrillation (particularly mitral stenosis). CXR can show cardiac chamber enlargement, pulmonary congestion, or valve calcification.

Cardiac catheterization is occasionally needed when echocardiographic findings are discordant with clinical presentation, or to assess coronary anatomy before planned valve surgery.

CT is used for pre-procedural planning, particularly before transcatheter aortic valve implantation, to assess annular sizing and vascular access.

Differentials for the murmur itself include innocent flow murmurs (common, particularly in younger patients or high output states, generally soft and without associated symptoms or radiation), hypertrophic cardiomyopathy (dynamic outflow murmur), and ventricular septal defect.

Asymptomatic mild to moderate valvular disease is managed with regular clinical and echocardiographic surveillance, at intervals guided by severity, since the timing of intervention depends heavily on the development of symptoms or objective evidence of ventricular decompensation.

Symptomatic severe aortic stenosis is an indication for valve replacement, either surgical aortic valve replacement or transcatheter aortic valve implantation (TAVI), with the choice guided by surgical risk, patient age, valve anatomy, and patient preference, following a heart team multidisciplinary assessment. Medical therapy has no role in altering the natural history of aortic stenosis itself, though standard heart failure and blood pressure management is used to control symptoms while awaiting intervention.

Mitral regurgitation management depends on whether it is primary or secondary.

Symptomatic severe primary mitral regurgitation, or asymptomatic severe disease with evidence of ventricular decompensation, is treated with surgical repair where feasible (preferred over replacement given better long term outcomes) or valve replacement.

Secondary functional mitral regurgitation is managed primarily by optimizing the underlying heart failure therapy, with transcatheter edge to edge repair considered in selected patients who remain symptomatic despite optimal medical therapy.

Aortic regurgitation is managed with vasodilator therapy (ACE inhibitors, or dihydropyridine calcium channel blockers) to reduce afterload in symptomatic patients not yet undergoing surgery. Surgical valve replacement is indicated for symptomatic severe disease or asymptomatic severe disease with evidence of ventricular dilation or declining ejection fraction.

Mitral stenosis is managed with:

• Rate control for associated atrial fibrillation
• Anticoagulation given the high thromboembolic risk (particularly with atrial fibrillation, though anticoagulation is also considered in severe mitral stenosis with an enlarged left atrium even in sinus rhythm)
• Either percutaneous balloon mitral valvotomy (preferred where valve morphology is suitable) or surgical valve repair or replacement for symptomatic severe disease

Anticoagulation with warfarin, rather than a direct oral anticoagulant, remains the standard of care for patients with a mechanical prosthetic valve or moderate to severe mitral stenosis with atrial fibrillation, given the lack of adequate efficacy data for direct oral anticoagulants in these specific populations.

Referral: cardiology for all confirmed valvular disease, for surveillance and to determine intervention timing; cardiothoracic surgery or structural intervention cardiology once an indication for intervention is met.