AS occurs as a congenital lesion but more commonly as an acquired disease. Stenosis can develop on a previously normal AV following rheumatic fever or from progressive calcification. Congenitally bicuspid AVs are also prone to calcification with eventual stenosis. Calcification of the AV leaflets can result in incomplete closure of the valve with associated insufficiency.

AI is usually an acquired disease. The most common causes include bacterial endocarditis and rheumatic heart disease (RHD). Annular dilation with resultant AI can result from connective tissue diseases, proximal aortic aneurysms or aortic dissection.

MS is almost always caused by RHD. Although rare in high-income countries, RHD remains the leading cause of primary valvular heart disease worldwide. The inflammatory process of RHD results in thickening of the leaflets and fusion of the commissures. Other rare causes of MS include congenital stenosis and systemic diseases such as systemic lupus erythematosus and carcinoid. Pathophysiology similar to that seen with valvular MS can occur with obstructing left atrial tumors and cor triatriatum.

MR can result from defects in the leaflets, the annular ring, or the supporting chords or papillary muscles (PM) or any combination of these. Primary leaflet dysfunction occurs with RHD (ultimately leading to calcification and MS) but can also follow bacterial endocarditis, connective tissue disorders, myxomatous degeneration, and congenital malformations. Annular dilation can follow left ventricular dysfunction and dilation. MV prolapse and rupture of PM result in incomplete leaflet closure or coaptation with resultant MR. Left ventricular ischemia can affect PM contraction and lead to functional MR.

References

• Coffey S, Roberts-Thomson R, Brown A, et al. Global epidemiology of valvular heart disease. Nat Rev Cardiol. 2021;18:853-864.
• Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA guideline for the management of patients with valvular heart disease: executive summary: a report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2021;143:e35-e71.
• Pandian NG, Kim JK, Arias-Godinez JA, et al. Recommendations for the use of echocardiography in the evaluation of rheumatic heart disease: a report from the American Society of Echocardiography. J Am Soc Echocardiogr. 2023;36:3-28.