heart author" faq


This is a condition in which the aortic valve has become disfigured to such an extent that its leaflets no longer are able to completely oppose each other during diastole (see figures 48a, 48b, 48c, 48d).

This condition allows blood to flow back into the left ventricle from the ascending aorta during diastole (figures 48i, 48j, 48k). Normally, there is no leakage of blood from the ascending aorta back into the left ventricle after systole.

Aortic valve regurgitation can be caused by infection of the aortic valve due to syphilis via unprotected coitus, (figure 205 immediately below) and bacteria, which have gained access to the blood stream and the aortic valve through the use of illicit drugs intravenously.

Figure 205

Examination of a 74-year-old man with a one-year history of mild, stable angina revealed a murmur consistent with the presence of aortic regurgitation. Echocardiography demonstrated severe aortic regurgitation as a result of marked dilatation of the aortic root (diameter, 5.4 cm in the proximal ascending aorta). Gadolinium-enhanced magnetic resonance
angiography (Panel A) revealed saccular dilatation of the aorta from its root to beyond the distal arch (short arrows), with involvement of the innominate artery (long arrow). T1-weighted images also revealed evidence of mural thrombus in the superior aspect of the aneurysm, beyond the left subclavian artery (arrow in Panel B). Serologic immunofluorescence studies revealed the presence of Treponema pallidum antigen, confirming the clinical suspicion of syphilitic aortitis and aneurysm. The patient received 10 days of intramuscular penicillin G procaine with oral probenecid without complications, and he continues to receive medical therapy under close surveillance.
The cardiovascular complications of syphilis predominantly involve the aorta, leading to the formation of aneurysms and aortic-valve incompetence. Angina may result from coronary ostial stenosis or associated atherosclerosis. The incidence of tertiary syphilis has declined in recent decades owing to the early recognition of the disease and the sensitivity of the pathogen to antibiotics. However, the reemergence of syphilis in the developing world, particularly among drug abusers and the sexually promiscuous, may mean that the delayed cardiovascular and neurologic complications of late syphilis will be seen with increasing frequency.

Pugh,P.J.andGrech,E.D.,N Engl.Med,Vol.346,No.9,P.676,Feg.28,2002.

These infections may also be caused by bacteria gaining access to the blood stream from dental procedures.

Certain congenital abnormalities such as bicuspid aortic valve (see figure 23b) and disorders of connective tissue as well as rheumatic heart disease (see figure 48b, 111), inflammation of the aorta (Takayasu), high blood pressure, arteriosclerosis, infective endocarditis (see figure 48c, 48e, 48f), following prosthetic valve surgery including fungus infection (see above figure 48g), cystic medial necrosis of aorta are some of the causes of aortic regurgitation.

Myxomatous Aortic Valve Prolapse

The aortic valve has three cusps (right and left coronary ones and a noncoronary one). In the case of myxomatous cusps ,there is the finding histologically of a marked increase in the delicate myxomatous connective tissue between the aortic surface (thick layer of collagen and elastic tissue forming the the aortic aspect of the cusp) and the fibrosa or ventricularis, which is composed of dense layers of collagen and forms the basic support of the cusp.This myxomatous proliferation of the acid mucopolysaccharide-containing spongiosa tissue causes focal interruption of the fibrosa. Secondary effects include fibrosis(scarring) of the surfaces of the cusps, and ventricular friction lesions.The valves become redundant and scalloped.

Aortic valve prolapse occurs in 2 % of patients with mitral valve prolapse(MVP).The primary form of MVP may occur in families,where it appears to be inherited as an autosomal dominant trait with varying penetrance. It can also occur in isolated cases.MVP has been found with incresing frequency in patients with Marfan syndrome.

MVP is commonly associated with thoracic skeletal abnormalities such as the straight spine and pectus excavatum.

Some have postulated that MVP results from fetal exposure to toxic substances during the early part of pregnancy.

Management of Aortic Insufficiency

All patients with AR need antibiotic prophylaxis to prevent infective endocarditis. Patients with AR of a rheumatic origin need antibiotic prophylaxis to prevent recurrences of rheumatic carditis. Patients with syphilitic AR need a course of antibiotics to treat syphilis.
Patients with mild AR need no specific therapy ( Table 1 ). They do not need to restrict their activities and can lead a normal life. Patients with moderate AR also usually need no specific therapy. These patients, however, should avoid heavy physical exertion, competitive sports, and isometric exercise.
The value of long-term vasodilators to produce an improvement in LV size and function has been evaluated in two placebo-controlled randomized trials. In the hydralazine trial, 36 percent of the patients were in NYHA functional class II, and patients had moderate to severe AR. Hydralazine produced modest reduction of LV end-diastolic volume and a small increase in ejection fraction at the end of 2 years; however, because of side effects, long-term compliance was poor, which probably accounted for the extremely modest beneficial effects. In asymptomatic patients with severe AR, a calcium channel blocking agent, long-acting nifedipine, produced significant reductions in blood pressure and LV end-diastolic volume and mass and major increases in LV ejection fraction at the end of 1 year. Almost all patients completed the trial. Recently, a prospective randomized trial in asymptomatic patients with normal LV systolic function showed that at the end of 6 years, 34 ± 6 percent of patients treated with digoxin developed LV systolic dysfunction and/or symptoms and thus needed valve replacement, compared to 15 ± 3 percent of patients treated with long-acting nifedipine (p < .001) ( Fig. 48l ); 90 percent (23 of 26) of those who needed valve replacement had developed LV systolic dysfunction with or without symptoms; only 3 had become symptomatic without developing LV systolic dysfunction. Accordingly, all asymptomatic patients with severe AR and normal LV systolic function should be treated with a vasodilator (calcium antagonists long-acting nifedipine) unless there is a contraindication to its use.
The role of nifedipine in patients with moderate AR has not been studied. In view of its beneficial effects in severe AR, long-acting nifedipine could be used in selected patients with moderate AR if there are no contraindications to its use. An acute study showed that nifedipine was superior to an ACE inhibitor, and a 6-month trial showed that the results with captopril were similar to placebo. One study with quinapril involved 10 patients, many of whom had moderate AR.In another study with enalapril, most patients had mild to moderate AR and many had severe systemic hypertension.Moreover, there are no published data to show that ACE inhibitor therapy reduces the need for valve surgery. In brief, ACE inhibitors are not of proven benefit in asymptomatic patients with AR and with normal LV systolic function.
Symptomatic patients with severe AR need medical and surgical treatment. Medical treatment ( Table 1 below ) consists of the administration of digitalis, diuretics, and vasodilators. Digitalis acts by increasing myocardial contractility, often reducing LV end-diastolic volume while increasing the LV ejection fraction and also the cardiac output if it is reduced in the resting state. Digitalis is clearly indicated in patients with symptoms.

TABLE 1 Medical Treatment of Patients with Aortic Regurgitation

SOURCE: Copyright © by S. H. Rahimtoola, M.B., F.R.C.P., M.A.C.P., MA.C.C. See Ref. 93.

The need for and benefits of this therapy in asymptomatic patients have not been well documented. Diuretics are of value when the left atrial pressure is elevated and in the presence of heart failure.
Vasodilators are either arterial, venous, or both. Vasodilators act by reducing the peripheral arterial resistance, which favors forward cardiac output and reduces regurgitant volume; initially, the total LV stroke volume remains unchanged. If the left atrial pressure is elevated and LV ejection fraction reduced, vasodilators frequently result in an improvement in both.
Long-term hydralazine therapy in symptomatic patients resuits in significant benefit in only 20 to 35 percent of patients.Those who are likely to benefit cannot be predicted. Vasodilators are indicated in patients who refuse surgery or are not operative candidates for any reason.
Vasodilators are also indicated for short-term therapy in patients awaiting valve replacement to optimize their hemodynamics (reduce filling pressures and increase cardiac output) and thus reduce their operative risks. If LV systolic function is normal, they can be given long-acting nifedipine. if they have abnormal LV systolic function, they should be treated with digitalis and ACE inhibitors; diuretics and hydralazine, with or without nitrates, can be used if needed. Small doses of hydralazine (50 mg) are without therapeutic effect in AR, and larger doses (approximately 100 mg) need to be given only twice daily; the twice-daily regimen reduces the incidence of side effects. Hydralazine should be started in small doses and gradually increased, depending on patient tolerance of the drug.
Vasodilators are of considerable short-term benefit in patients in functional classes III and IV or heart failure. All such patients need digitalis, diuretics, and ACE inhibitors. In patients in functional class IV with heart failure, vasodilators should ideally be started after the institution of beside henmodynamic monitoring-that is measuring of pulmonary artery wedge pressure and cardiac output with the use of ballon flotation catheters. Hemodynamic monitoring accurately identifies patients who need the therapy, since clinical judgments can be wrong. It establishes whether arterial dilators alone will suffice or whether additional venodilators are needed. Finally, it provides information on the optimum dosage of vasodilator therapy. After the initial hemodynamic measurements are made, arterial dilators are given in progressively increasing dosage until an optimum effect on cardiac output has been obtained. If cardiac output does not show any further increase but left atrial pressure is still very high, additional venodilator therapy should be given. If the patient is very ill or the hemodynamic abnormalities are marked, intravenous therapy (e.g., sodium nitroprusside) is the vasodilator of first choice. In this situation, intravenous vasodilator therapy should be used only with bedside hemodynamic monitoring. Inotropic agents, such as dobutamine, may be needed to improve LV function and increase cardiac output. Low-dose dopamine may be of value to increase urinary output.

Patients with severe chronic AR need valve surgery. The correct timing of surgical therapy is now better defined but is not fully clarified. Valve replacement should be performed before irreversible LV dysfunction occurs. The major problem, however, is identifying the precise point at which LV dysfunction will occur. Here, two major difficulties are encountered:
(1) patients may already have impaired LV systolic pump function at rest when they firstpresent or at the time of the first symptom and
(2) patients with severe symptoms may have normal LV systolic pump function.
Patients may be in NYHA functional class III (symptoms with less than ordinary activity), with a normal LV ejection fraction, or they may be in functional class I (asymptomatic), with a reduced LV ejection fraction. A reduced LV ejection fraction demonstrated by two-dimensional echocardiography and/or radionuclide ventriculography is the best noninvasive indicator of depressed LV systolic function.

Decisions about surgery in AR should be based on the clinical functional class and on the LV ejection fraction at rest ( Table 2 ) Patients with chronic severe AR who are symptomatic (NYHA functional classes II to IV) need valve replacement. Although there may be some disagreement about recommending valve replacement to patients with normal ejection fraction who are in functional class II, we currently would do so. The benefit from valve replacement has been demonstrated even when the LV ejection fraction is 0.25 or less. As opposed to AS, in which there is no lower level of ejection fraction that indicates inoperability, it is likely that some patients with AR and a very low ejection fraction become inoperable. This level has not been precisely defined but may be about 0.15 or less. There is a need to individualize the need for valve replacement in those with very severe LV systolic dysfunction at rest, in those with very severe LV dilatation (LV end-diastolic volume index approximately 300 mL/m2),’ and in those with a small regurgitant volume, with a ratio of regurgitant volume to end-diastolic volume of 0.14 ( Table 2 ). Recent data indicate that patients with severe AR, LV end-diastolic dimension on echocardiography of approximately 80 mm, and mild to moderate reduction of LV ejection fraction (mean 0.43) can obtain benefit from valve replacement. Postoperatively, they are symptomatically improved, LV ejection fraction increases, and LV size is reduced; the 5-and 10-year survivals are 87 and 71 nercent. respectivelv.

Although.the issue is controversial in some countries,we believe that patients who are in NYHA functional class 1 (asymptomatc) and have a reduced ejection fraction at rest should be offered aortic valve replacement. If the ejection fraction is normal at rest, one should consider valve replacement in NYHA functional class I patients if they have severe obstructive CAD and/or need surgery for other valve disease ( Table 2 ). It is suggested that patients undergo an exercise test during right heart catheterization if the left ventricle is large (LV end-diastolic volume approximately 150 mL/m2, LV internal dimension on M-mode echocardiography of approximately 70 mm at end diastole and approximately 50 mm at end systole) and/or the LV ejection fraction shows a new, persistent reduction to 0.54 to 0.60; if the patients have reduced exercise capacity on treadmill testing; or if ambulatory ECG monitoring demonstrates ventricular tachyarrhythmias. Valve replacement is recommended if the pulmonary artery wedge pressure during exercise approximately 20 to 24 mmHg. Patients with associated significant CAD should have coronary bypass surgery performed at the time of valvular surgery .
Aortic valve replacement, with or without associated coronary bypass surgery for obstructive CAD, can be performed at many surgical centers with an operative mortality of 5 percent or less. In those without associated CAD or reduced LV systolic function, the operative mortality may be in the range of 1 to 2 percent. If aortic valve replacement is successful and uncomplicated, LV volume and hypertrophy regress but do not return to normal; the beneficial effects on LV size, volume, and mass continue to be seen up to 5 years after surgery. Impaired LV systolic pump function improves postoperatively in 50 percent or more of patients; this improvement is more likely to occur if LV dysfunction has been present preoperatively for 12 months or less, and in this subgroup LV ejection fraction usually normalizes. Even if LV systolic pump function does not improve, there is a reduction in end-diastolic volume and hypertrophy; from a cardiac point of view, this is advantageous to the patient. The 5-year survival of patients undergoing aortic valve replacement in severe AR is 85 percent (this figure includes operative and late cardiac deaths). The 5-year survival of patients with LV ejection fraction _0.45 is 87 percent, versus 54 percent in patients with an ejection fraction <O.4S.1TM Late survival after valve replacement for chronic severe AR is best predicted by variables indicative of LV systolic pump function. Both the operative mortality and late survival are dependent on cardiac and LV function and associated noncardiac comorbid factors .

Indeed, in general, the major factors influencing outcome in patients with valvular heart disease are: LV dysfunction and its magnitude, duration of LV dysfunction, degree of LV dilatation, greater NYHA functional class, older age, associated CAD, and comorbid conditions.
New techniques of aortic valve repair are being developed and evaluated, and early results are encouraging in selected subgroups. It is possible that selected patients may eventually need to have valve repair rather than valve replacement for AR.
The recommendations of the ACC/AHA Practice Guidelines are shown in Table 3 Guidelines are not and should not be the Law. Application of such guidelines to clinical practice should be based on the following principles:
(1) classes I and III applies to all patients in these classes unless there is a specific clinical circumstance not to do so;
(2) class II applies to patients in this class depending on the clinical conditions of the patients and the skill and experience at the individual medical center.

Rahimtoola,S.H.,Aortic Valve Disease,Hurst's The Heart,10th Edition,Pages 1667-1692