Overview of Cardiac Valvular Disorders
Any heart valve can become stenotic or insufficient (also termed incompetent), causing hemodynamic changes long before symptoms. Most often, valvular stenosis or insufficiency occurs in isolation in individual valves, but multiple valvular disorders may coexist, and a single valve may be both stenosed and insufficient.
Heart valve disorders include
Aortic regurgitation: Insufficiency of the aortic valve causing backflow of blood from the aorta into the left ventricle during diastole
Aortic stenosis: Narrowing of the aortic valve, obstructing blood flow from the left ventricle to the ascending aorta during systole
Mitral regurgitation: Insufficiency of the mitral valve causing flow of blood from the left ventricle (LV) into the left atrium during ventricular systole.
Mitral stenosis: Narrowing of the mitral orifice that impedes blood flow from the left atrium to the left ventricle
Mitral valve prolapse: Billowing of mitral valve leaflets into the left atrium during systole
Pulmonic regurgitation: Insufficiency of the pulmonic valve causing blood flow from the pulmonary artery into the right ventricle during diastole
Pulmonic stenosis: Narrowing of the pulmonary outflow tract causing obstruction of blood flow from the right ventricle to the pulmonary artery during systole
Tricuspid regurgitation: Insufficiency of the tricuspid valve causing blood flow from the right ventricle to the right atrium during systole
Tricuspid stenosis: Narrowing of the tricuspid orifice that obstructs blood flow from the right atrium to the right ventricle
Historically, diagnosis of valvular disorders by observation, palpation, and auscultation was a tough test for aspiring clinicians (1). Today, with the physical examination supplemented by cardiac ultrasonography, diagnosis is comparatively straightforward. Standard 2-dimensional studies show the anatomy. Doppler echocardiographyevaluates pressure gradients and blood flow. Evaluation also includes ECG (to detect heart rhythm and chamber alterations) and chest x-ray (to detect chamber alterations, pulmonary congestion, and other lung pathology).
Management of a valvular lesion commonly requires only periodic observation, with no active treatment for many years. In general, neither lifestyle measures nor drugs alter the natural history of valvular lesions. Intervention is usually indicated only when a moderate or severe valvular lesion causes symptoms or cardiac dysfunction. Because patients may not recognize symptoms due to their slow onset, many clinicians now use exercise testing to help monitor patients.
The intervention may involve valvuloplasty, valve repair, or valve replacement, all of which may be done percutaneously or surgically. Valvular disorders are currently subject to intensive research to develop percutaneous valve replacement. In addition, randomized, controlled trials of different valvular interventions are being done. The result for patients is an increasing number of therapeutic options and better evidence on how to choose one. For clinicians, the increase in complexity now requires a multidisciplinary heart valve team composed of surgeons, cardiologists, and other specialists to help decide which intervention is best for a given patient.
If coronary artery bypass surgery is being done, it is usual to surgically treat (during the same operation) any moderate or severe valve lesions, even if asymptomatic.
Endocarditis prophylaxis is indicated when there is a history of endocarditis and for patients with prosthetic heart valves.
For replacement, two kinds of valve prosthesis are used:
Traditionally, a mechanical valve has been used in patients < 65 and in older patients with a long life expectancy because bioprosthetic valves deteriorate over 10 to 12 yr (more rapidly in younger patients).
Lifelong anticoagulation with warfarin is required in patients with a mechanical valve to prevent thromboembolism. Newer novel oral anticoagulants (NOAC) are ineffective and should not be used.
An aortic bioprosthetic valve, which does not require anticoagulation beyond the immediate postoperative period, has been used in patients > 65, younger patients with a life expectancy < 10 yr, and those with some right-sided lesions. However, newer bioprosthetic valves may be more durable than 1st-generation valves; thus, patient preference regarding valve type can now be considered.
Women of childbearing age who require valve replacement and plan to become pregnant must balance the teratogenic risk due to warfarin when mechanical valves are used against the risk of accelerated valve deterioration when bioprosthetic valves are used. Teratogenic risks can be reduced by use of heparin instead of warfarin in the first 12 wk and last 2 wk of the pregnancy, but management is difficult and careful discussion is required before surgery.