RISK FACTORS : INCREASING AGE, MALE SEX, HYPERTENSION & DISEASES OF AORTIC ROOT ( MARFAN DISEASE, CYSTIC MEDIAL NECROSIS, SYPHILIS, CONNECTIVE TISSUE DISORDERS )
Medical Care:
Medical vs Surgical Treatment: Medical therapy is appropriate for many patients with mild to moderate chronic AR. The appropriate use of vasodilators, as described below, is associated with improvement in symptoms and is thought to slow the development of LV enlargement and dysfunction and the need for surgery. That said, physicians treating patients with chronic AR must be attentive to any changes that suggest worsening LV function and the need for surgery. Subjective reporting of exercise tolerance by patients is often unreliable. In patients with borderline AR, formal exercise testing on an annual basis may be useful. Annual echocardiography to assess LV size and function is also useful. As with mitral valve regurgitation, patients should be referred for surgical evaluation before irreversible LF dysfunction has occurred.
Patients with acute, significant AR represent an entirely different group. Surgical treatment is almost always indicated and medical therapy (typically using intravenous medications titrated to blood pressure, as described below) is recommended only as an interim measure.
Medical Care: Vasodilator therapy is designed to optimize LV loading conditions and achieve a favorable remodeling process through systolic unloading and reduction in regurgitant volume. Treat asymptomatic patients with chronic severe AR and dilated but normal LV systolic function medically, and monitor their cases for development of indications for AVR. Patients with mild AR and normal LV size require no therapy other than endocarditis prophylaxis.
" Earlier studies revealed that long-term vasodilator therapy with nifedipine reduces or delays the need for AVR in asymptomatic patients with severe AR and normal LV function. Nifedipine was also shown to reduce LV size and mass significantly. However, use of nifedipine in patients with LV dysfunction should be cautioned because calcium channel blockers generally are contraindicated in patients with CHF.
" Enalapril therapy achieves significant LV mass regression, LV end-diastolic and end-systolic volume index reduction, and renin-angiotensin system suppression. Enalapril may have favorable influence on the natural history of chronic AR by delaying the need for AVR.
" Digoxin and diuretics can be used to relieve symptoms of congestion.
" Recent publications have yielded conflicting results on the use of vasodilators in this group. One recent follow-up study confirmed the positive effects of using nifedipine in severe asymptomatic AR. This study showed that nifedipine delayed the onset of LV dysfunction and prolonged survival and protected the myocardium after AVR, even if stopped at surgery. Patients in this study had moderate to severe hypertension at entry into the study. A separate study comparing the use of nifedipine, enalapril, and placebo was unable to show a benefit to vasodilator therapy in a cohort of normotensive patients. In this study, vasodilator therapy with nifedipine or enalapril did not delay the need for AVR or improve parameters such as regurgitant volume, LV size, or LV systolic function.
" The main goal of medical therapy is to significantly reduce the systolic hypertension associated with chronic severe AR.
" Antibiotic prophylaxis for endocarditis is discussed as follows:
o AR leads to damaged endothelial lining of the valve and predisposes the valve to platelet and fibrin deposition.
o In the presence of bacteremia, colonization of platelets and/or fibrin deposition can lead to bacterial endocarditis; thus, antibiotic prophylaxis is important for preventing this serious complication.
" Acute AR usually is severe and rapidly leads to LV decompensation, failure, and cardiogenic shock. The treatment of choice for acute AR is AVR. Medical therapy can be used as a bridge to surgery but should not replace it.
o Dobutamine reduces afterload and assists with forward outflow. It also has a positive inotropic effect.
o Vasodilators achieve significant LV mass regression, LV end-diastolic and end-systolic volume index reduction, and renin-angiotensin system suppression.
o Intra-aortic balloon pump is contraindicated in AR.
" Percutaneous transcatheter implantation of a heart valve prosthesis may be available in the future, but these techniques are investigational at this time.
Surgical Care: Surgical treatment of AR almost always requires replacement of the diseased valve with a prosthetic valve. The surgical mortality rate for AVR probably is 3%, although the mortality rate may be higher if patients also need coronary artery bypass grafts. In addition, the long-term complications of prosthetic valves need to be considered.
" AVR is indicated in patients with normal systolic function (defined as EF >0.50 at rest) who have New York Heart Association (NYHA) functional class III or IV symptoms. Also consider patients with Canadian Heart Association functional class II-IV angina pectoris for surgery. In many patients with NYHA functional class II dyspnea, the etiology of symptoms often is unclear and clinical judgment is required.
" Patients with NYHA functional class II, III, or IV symptoms and with mild-to-moderate LV systolic dysfunction (EF 0.25-0.49) should undergo AVR. Patients with functional class IV symptoms have worse postoperative survival rates and a lower likelihood of recovery of systolic function when compared to patients with less severe symptoms, but AVR improves ventricular loading conditions and expedites subsequent management of LV dysfunction.
" Symptomatic patients with severe LV dysfunction (EF <0.25) pose difficult management issues. Most patients develop irreversible myocardial damage and may not show improved LV function or NYHA functional class after AVR; however, some patients may gain meaningful recovery of LV function. Surgery carries an operative mortality rate of approximately 10%, but medical therapy alone carries a mortality rate of higher than 20% per year; thus, high-risk AVR may be a viable option when compared to the even worse prognosis associated with medical therapy alone.
" Asymptomatic patients with evidence of LV systolic dysfunction (EF <0.50) should undergo AVR. The postoperative recovery of LV function and survival is strongly associated with preoperative LV function; thus, do not delay AVR for patients with evidence of LV dysfunction.
" Asymptomatic patients with severe AR and normal LV function but with severe LV dilatation (end-diastolic dimension >75 mm or end-systolic dimension >55 mm) should undergo AVR. These patients tend to progress to symptomatic or LV dysfunction rapidly. Postoperative survival and reduction of LV dimension in this subgroup of patients are excellent.
" Preoperative predictors of poor postoperative survival and LV function include the following:
o LVESD greater than 55 mm
o LVEF less than 0.50
o NYHA CHF class III, IV
o Duration of CHF symptoms longer than 12 months
Diet: Place patients on a low-sodium diet with fluid restriction when CHF symptoms appear.
Activity: Asymptomatic patients with normal LV systolic function may participate in all forms of normal daily physical activity, including mild forms of exercise and, in some cases, competitive athletics; however, isometric exercise (eg, weight lifting) should be avoided. Patients with evidence of LV dysfunction or low cardiac reserve should not engage in vigorous sports or heavy exertion.
DRUG TREATMENT :
1. ACE INHIBITORS
2. CALCIUM CHANNEL BLOCKERS
3. CARDIAC GLYCOSIDES
4. DIURETICS
5. DIRECT ACTING ADRENERGIC AGONISTS - DOBUTAMINE IN CHF