VALVULAR HEART DISEASE
As discussed by Dr. Gary C. Burke, D.O.
The development of antibiotics over the last 50 years and the resultant decrease in the incidence of rheumatic fever has had a significant impact on the pathophysiology of valvular heart disease (VHD), according to Dr. Gary C. Burke of Associated Cardiovascular Consultants.
Dr. Burke explained that the focus has shifted from rheumatic valvular heart disease to degenerative VHD in the elderly, the more common manifestations of which are mitral regurgitation and aortic stenosis. Mitral stenosis is not seen much anymore in the United States.
Other factors are also changing the landscape. "With improved surgical techniques and cardiac anesthetics, operative risks have declined, leading to earlier operations to avoid the potential manifestations of illness," Dr. Burke said. Improvements in surgical techniques, he continued, have led to the repair rather than the replacement of many valves. "In the training of the 1980s, replacing of valves was a trade off of one disease for another. Now, better surgical techniques with improved anesthesia and better valves have made surgery safer in an older population."
The timing of heart valve surgery, however, is the most difficult challenge facing physicians because of the long asymptomatic standpoint for VHD. "If you wait for symptoms, you may have waited too long," Dr. Burke said.
Dr. Burke described early reports indicating that the monitoring of brain natriuretic peptide (BNP) levels from heart tissue may be of help as a marker for the timing of valve surgery. "Cardiopulmonary stress testing may also be of help," he said, along with MRI and electron-beam CT as tools to follow patients with VHD. But echocardiography remains the principal noninvasive means of assessing the significance of cardiac murmurs and valvular heart disease.
Abnormal valvular morphology or motion may be detected using two-dimensional echocardiography, but the severity of valvular disease is more readily detected with Doppler echocardiography. Despite the importance of these tests, however, they are not indicated for all patients with cardiac murmurs. Accordingly, the American College of Cardiology has formulated guidelines for the management of patients with VHD, including recommendations for echocardiography in both asymptomatic and symptomatic patients with cardiac murmurs. These are available in detail at the American College of Cardiology website (www.acc.org) and have been published in both the Journal of the American College of Cardiology (Vol. 32, Nov 5, 1998) and in Circulation (Nov. 3, 1998).
The guidelines are summarized here:
Echocardiogarphy is useful and effective for asymptomatic patients with:
- Diastolic or continuous murmurs
- Holosystolic or late systolic murmurs
- Grade 3 or midsystolic murmurs
The weight of evidence/opinion favors echocardiography for asymptomatic patients with murmurs associated with abnormal physical findings or with an abnormal ECG or chest x-ray.
Echocardiography is not useful and may be harmful in some cases for asymptomatic patients with Grade 2 or softer midsystolic murmur identified as innocent or functional by an experienced observer or to detect "silent" aortic or mitral regurgitation in patients without murmurs, for whom endocarditis prophylaxis is recommended.
Echocardiogarphy is useful and effective for symptomatic patients with:
- Symptoms or signs of congestive heart failure, myocardial ischemia, or syncope
- Symptoms consistent with infective endocarditis or thromboembolism
Echocardiography is also indicated for patients with symptoms or signs likely due to noncardiac disease when cardiac disease has not been ruled out by standard cardiovascular evaluations.
Echocardiography is not indicated for patients with symptoms of noncardiac disease with an isolated midsystolic "innocent" murmur.
- With the decline of rheumatic heart disease, the focus of treatment has shifted to degenerative valvular heart disease in the elderly, often manifesting as aortic stenosis or mitral regurgitation.
- Earlier operations to avoid the manifestations of illness are now possible because of reduced operative risks.
- Echocardiography is the principal noninvasive means of assessing the significance of cardiac murmurs.
A take-home message about... Valvular heart disease
- The timing of heart valve surgery is the most difficult challenge facing physicians because of the long asymptomatic standpoint for valvular heart disease.
- Better operations and better valves make surgery possible in an older population.
- The American College of Cardiology's guidelines provide a framework for evaluating the need for echocardiography in both symptomatic and asymptomatic patients.
Dr. Gary C. Burke
received his medical degree from the Philadelphia College of Osteopathic Medicine. After his residency in internal medicine at the Hospital of the Philadelphia College of Osteopathic Medicine, he completed a fellowship in cardiac medicine at Deborah Heart and Lung Center in Browns Mills, N.J. A fellow of the American College of Cardiology, Dr. Burke is board certified in internal medicine and in cardiology. He is a member of the American Society of Echocardiography, the American Osteopathic Association, the New Jersey Osteopathic Association and a fellow of the American College of Osteopathic Internists.