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Overview of Cardiac Valvular Disorders
Any heart valve can become stenotic or insufficient, 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.
Diagnosis involves clinical evaluation and echocardiography. Standard 2-dimensional studies show the anatomy. Doppler echocardiography evaluates 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 or valve repair or replacement and may be carried out either percutaneously or surgically. Some institutions now use 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.
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). Patients with a mechanical valve or bioprosthetic mitral valve require lifelong anticoagulation (to prevent thromboembolism) and antibiotics before some medical or dental procedures (to prevent endocarditis). 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.
Endocarditis prophylaxis is indicated when there is a history of endocarditis and for patients with prosthetic heart valves.
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