Nitroglycerin-induced improvement in exercise tolerance and hemodynamics in patients with chronic rheumatic heart valve disease

Drug Therapy for Heart Valve Diseases

Valvular heart diseases (VHDs) are progressive. When not caused by acute comorbidities they are generally characterized by long asymptomatic phases during which hemodynamic severity may progress leading to morbidity and mortality. Treatment depends on VHD type and severity but when severe and symptomatic, usually involves mechanical intervention. Asymptomatic patients, and those who lack objective descriptors associated with high risk, are closely observed clinically with optimization of associated cardiovascular risk factors until surgical indications develop. Though often prescribed based on theory, no rigorous evidence supports pharmacological therapy in most chronic situations though drugs may be appropriate in acute valvular diseases, or as a bridge to surgery in severely decompensated patients. Herein, we examine evidence supporting drug use for chronic VHDs.

Mitral regurgitation: relationship of noninvasive descriptors of right and left ventricular performance to clinical and hemodynamic findings and to prognosis in medically and surgically treated patients

To determine objective predictors of survival, 53 patients with chronic, hemodynamically severe mitral regurgitation underwent rest and exercise radionuclide cineangiography, echocardiography, treadmill exercise testing, and ambulatory electrocardiographic monitoring before prospective (average 30 month) follow-up. At entry, symptom status correlated best with radionuclide-based right ventricular ejection fraction (RVEF) and left atrial size, while treadmill exercise tolerance correlated best with RVEF during exercise (r = .48, p less than .005). Correspondingly, in 23 patients who underwent cardiac catheterization, pulmonary arterial systolic and wedge pressures were significantly inversely related to RVEF. On the 24 hr ambulatory electrocardiogram, nonsustained ventricular tachycardia was present in 29% of patients, most frequently when both RVEF and left ventricular ejection fraction (LVEF) were subnormal (p = .03 vs other patients). Since entry, 35 patients have been managed without surgery for 9 to 57 months (average 28); three of these who subsequently underwent operation also are among the 21 patients who have undergone mitral valve replacement (MVR). During the average 28 months of observation under medical treatment five of 35 nonoperated patients have died; all five were among the six nonoperated patients with RVEFs of 30% or less at entry, a descriptor that significantly identified those at high mortality risk (p less than .0001 vs patients with RVEFs greater than 30%). All five also were among the eight nonoperated patients with LVEFs of 45% or less (lower limit of normal), a descriptor that also significantly predicted mortality. Three of the 21 patients who underwent surgery have died, all late after MVR. Among operated patients, only age was a predictor of postoperative survival. A trend toward improved survival was found in the patients with depressed right or left ventricular ejection fraction who underwent surgery compared with those who did not.

Assessment of left ventricular function in coronary artery disease with the nuclear probe during intervention studies

The nuclear probe was used for measuring left ventricular function in 11 normal subjects and the results compared with those using a digital gammacamera. The probe was then used to measure left ventricular function in patients with coronary artery disease during dynamic exercise and stress atrial pacing. The ability of the probe to detect changes induced by glyceryl trinitrate was also evaluated in separate parallel studies. In the 11 normal subjects there was a good correlation between the left ventricular ejection fraction measured by the gammacamera and the nuclear probe both at rest and during exercise. Exercise increased this value by at least 5% in all normal subjects during measurements with both the gammacamera and the nuclear probe. The mean (SD) difference was -0.3% (2.60) at rest and 2.3% (5.02) at peak exercise. Both exercise and pacing produced angina in the patient group and the mean (SEM) value fell from 52% (3.5) to 28% (2.6) and from 46% (5.1) to 34% (3.2) respectively. Glyceryl trinitrate prolonged the exercise and pacing times, and the corresponding falls in ejection fraction were significantly reduced. The non-imaging nuclear probe is a cheap and portable instrument capable of assessing left ventricular function in patients with cardiac disease. It is designed for high count rate acquisition over a short period of time and can thus provide both beat to beat and summated left ventricular time activity curves suitable for quantitative analysis. It therefore has important advantages in the clinical setting and during controlled interventions compared with the gammacameras.

Acute and chronic effects of sustained action buccal nitroglycerin in severe congestive heart failure

Vasodilators, such as nitroglycerin, have been widely used in the treatment of acute and chronic heart failure for therapeutic manipulation of the venous and arterial circulations to improve left ventricular function. We have tested the efficacy of a new formulation for sustained release buccal delivery of nitroglycerin (biological life 5-6 hr) in 21 patients with severe congestive heart failure due to ischaemic cardiomyopathy using maximal treadmill exercise testing and radionuclide angiography. A single-blind placebo-controlled acute and an open chronic phase (4 weeks) of treatment were employed. The mean dose was 23.4 mg daily, and clinical assessment suggested significant improvement in 15 patients. The mean ejection fraction (placebo) of 14.1% +/- 1.6 SEM increased to 19.1% +/- 1.7 (acute) and to 21.6% +/- 1.7 (chronic treatment) (P less than 0.001; n = 16). The mean exercise time increased from 3.02 +/- 0.4 min (basal) to 5.95 +/- 0.6 min (chronic) (P less than 0.001). Segmental wall motion abnormality was shown to improve after treatment for 4 weeks. There were no major side effects. Nine patients were reassessed after 24 weeks on the same regimen; exercise time and left ventricular ejection fraction were similar to the 4-week period, thus demonstrating a sustained improvement in cardiac function and functional capacity. A worthwhile functional and objective haemodynamic improvement was demonstrated in these patients with severe chronic congestive heart failure. This mode of treatment may have useful therapeutic value in the management of patients with a wide range of ischaemic heart failure.

Effects of nitroglycerin on supine and upright exercise in mitral stenosis

Resting, supine, and upright exercise hemodynamics were studied in 11 patients with pure or predominant mitral stenosis before and after 0.4 mg sublingual nitroglycerin. Resting mean pulmonary wedge pressure was reduced from 27 +/- 1.6 to 21 +/- 1.6 mm Hg (p less than 0.001), while mean cardiac index (2.98 +/- 0.40 vs 2.68 +/- 0.30 cc/min/m2; NS) and mean heart rate (82 +/- 4.4 vs 87 +/- 6.7 bpm; NS) were unchanged after nitroglycerin. Resting mean left ventricular end-diastolic pressure dropped from 11 +/- 1.7 to 8 +/- 1.1 mm Hg (p less than 0.02) after nitroglycerin, while stroke index (37 +/- 5.1 vs 32 +/- 3.8 mm Hg; NS) was unchanged. Left ventricular systolic pressure fell from 122 +/- 6.0 to 111 +/- 3.1 mm HG (p less than 0.001) after nitroglycerin. At peak supine exercise similar qualitative changes were observed. Mean pulmonary wedge pressure was lower after nitroglycerin (43 +/- 2.3 vs 36 +/- 2.1 mm Hg; p less than 0.02), while cardiac index (3.62 +/- 0.39 vs 3.4 +/- 0.26 cc/min/m2; NS) and heart rate (116 +/- 7.1 vs 113 +/- 4.6 bpm; NS) were not different. Left ventricular end-diastolic pressure (13 +/- 1.4 vs 10 +/- 1.3; NS) was slightly but not significantly reduced by nitroglycerin. Left ventricular stroke index (34 +/- 3.4 vs 31 +/- 2.2 mm Hg; NS) was unchanged by nitroglycerin. Left ventricular systolic pressure (137 +/- 7.3 vs 127 +/- 6.1 mm Hg; p less than 0.02) was reduced 10 mm Hg at peak supine exercise after nitroglycerin. During upright exercise, peak heart rate (160 +/- 8.1 vs 160 +/- 8.0 bpm; NS) and peak systolic blood pressure (117 +/- 5.7 vs 112 +/- 2.8 mm Hg; NS) were not changed with nitroglycerin. Exercise duration was improved after nitroglycerin (5.02 +/- 0.62 vs 5.66 +/- 0.65 minutes; p less than 0.02). Thus sublingual nitroglycerin lowers mean pulmonary wedge pressure to reduce pulmonary congestive symptoms, improves supine exercise hemodynamics, and may enhance treadmill exercise duration in some patients with pure or predominant mitral stenosis.

Mitral annular calcification: a cause of systolic murmur in the elderly

Mitral annular calcification is predominantly a disease of females, typically above 65 years of age. The diagnosis should be considered in patients with a systolic murmur which is mitral in origin. This murmur is caused by mitral regurgitation due to loss of the sphincter action of the mitral annulus. Diagnosis is made by one- or two-dimensional echocardiography. Calcification in the mitral ring may be seen on chest x-ray films or fluoroscopy. Management includes antibiotic prophylaxis to avoid infective endocarditis and observation for the development of congestive heart failure. Conventional management with digitalis and diuretics is supplemented with use of vasodilators in severe cases.

Diagnostic quantification of CASS (coronary artery surgery study) clinical and exercise test results in determining presence and extent of coronary artery disease. A multivariate approach

Multivariate linear discriminant function analysis on maximal exercise treadmill and angiographic data from 500 men with definite angina, 584 men with probable angina and 267 men with nonspecific chest pain identified independent predictors of presence and extent of coronary disease. We used the discriminant function to develop a clinical risk index and a clinical and exercise risk index for each patient subset. Probability curves were generated to predict the presence and extent of coronary disease. In definite angina cases, exercise testing provided more diagnostic information than clinical data alone. However, in the 10% of cases with the smallest risk indexes, half of the patients had coronary disease and one-quarter had multivessel disease. In men with probable angina, exercise testing added substantially more diagnostic information than clinical data. The probability of multivessel disease was reduced to less than 10% for 30% of patients with probable angina, an important diagnostic contribution. Exercise testing in men with nonspecific chest pain was of limited value because disease prevalence was already low.

Long-term vasodilator therapy with trimazosin in chronic cardiac failure

Patients with cardiac failure have a generalized sympathetic vasoconstriction that may impair cardiac function and exercise tolerance. The ability of long-term alpha-receptor blockade and vasodilation with trimazosin (TMZ) to improve exercise capacity was studied in patients with chronic, stable heart failure of varying severity (functional exercise classes B to D). Exercise performance was monitored by respiratory gas exchange and air flow before and after patients were randomized to placebo (13 patients) or TMZ were then followed on treatment for up to 52 weeks. Significant (P less than 0.05) and sustained increases in exercise capacity, oxygen uptake, and oxygen pulse were observed with TMZ treatment in each Class B or C patient and in six of nine Class D patients, and were not observed during treatment with placebo.

Influence of short-term oral hydralazine therapy on exercise hemodynamics in patients with severe chronic heart failure

Changes in left ventricular performance were evaluated in 14 patients with functional New York Heart Association class III or IV chronic heart failure before and after the addition of oral hydralazine to conventional therapy. With conventional therapy, cardiac output increased from 3.4 +/- 0.8 (mean +/- 1 standard deviation) at rest to 4.7 +/- 1.4 liters/min during exercise. This increase in cardiac output on exercise during conventional therapy was mainly due to an increase in heart rate. After the addition of hydralazine, cardiac output at rest increased to 5.0 +/- 1.4 liters/min. The increase in cardiac output was essentially due to an increase in stroke volume. This enhanced stroke volume after hydralazine therapy was maintained during exercise. Hydralazine therapy did not change either the left ventricular filling pressure at rest or the magnitude of increase in left ventricular filling pressure during exercise. Nevertheless, increased cardiac output and stroke volume with similar changes in left ventricular filling pressure during exercise indicated improved left ventricular performance after hydralazine therapy. After short-term hydralazine therapy, symptom-limited peak exercise work load, duration of exercise and maximal oxygen consumption during exercise did not increase. Clinical follow-up at 2 months after long-term therapy revealed subjective improvement in exercise tolerance in 13 of the 14 patients.

Immediate effects of hydralazine-isosorbide dinitrate combination on exercise capacity and exercise hemodynamics in patients with left ventricular failure

Resting hemodynamics improve during vasodilator administration in patients, with congestive heart failure (CHF), but the effects of these agents on exercise is unknown. Twenty-two patients with class II or III CHF performed bicycle exercise to symptomatic maximum before and 90 minutes after random double-blind administration of oral hydralazine (100 mg) and isosorbide dinitrate (40 mg) (11 patients, group 1) or placebo (11 patients, group 2). Exercise duration was unchanged after treatment in either group. Maximal oxygen consumption changed insignificantly in both groups, from 12.6 +/- 1.2 (SEM) to 13.6 +/- 1.6 ml/kg/min in group 1, and from 11.7 +/- 1.4 to 13.4 +/- 1.7 ml/kg/min in group 2. Maximal cardiac index was unchanged in both group 1 (4.00 +/- 0.33 to 4.41 +/- 0.29 l/min/m2) and group 2 (4.11 +/- 0.43 to 4.14 +/- 0.42 l/min/m2). Systemic vascular resistance at peak exercise was also unchanged in both group 1 (14.1 +/- 1.6 to 11.8 +/- 1.0 units) and group 2 (14.7 +/- 1.6 to 13.5 +/- 1.6 units). at submaximal exercise (300 kilopond-meters/min), however, cardiac index after treatment increased in group 1 (0.51 +/- 0.18 l/min/m2, p less than 0.05) and systemic vascular resistance decreased (-3.3 +/- 1.3 units, p less than 0.05), but were unchanged in group 2. Thus, although vasodilators do not improve maximal exercise capacity acutely, they can improve hemodynamics at lower work loads which may, therefore, be better tolerated in patients with CHF.

Effect of isosorbide dinitrate on response to submaximal and maximal exercise in patients with congestive heart failure

Isosorbide dinitrate is an effective vasodilator that improves resting left ventricular performance in patients with congestive heart failure, but little is known of the effect of the drug on the response to exercise. Bicycle exercise to symptomatic maximum was performed by 18 patients with class II to IV congestive heart failure before and 90 minutes after administration of isosorbide dinitrate, 40 mg orally. Although resting pulmonary wedge pressure and systemic vascular resistance were significantly reduced after isosorbide dinitrate, exercise duration was not altered and maximal oxygen consumption was not significantly changed (13.6 +/- 1.3 [SEM] standard error of the mean versus 13.8 +/- 1.2 ml/kg per min). At peak exercise pulmonary wedge pressure of 37.1 +/- 1.7 mm Hg, cardiac index of 4.19 +/- 0.35 liters/min per m2, and systemic vascular resistance of 14.7 +/- 1.3 units were not significantly different after nitrate administration. However, at submaximal loads, pulmonary wedge pressure was reduced from 33.6 +/- 1.7 to 27.9 +/- 1.8 mm Hg (P less than 0.01), and systemic resistance from 16.5 +/- 1.5 to 13.7 +/- 1.0 units (P less than 0.01) after administration of isosorbide dinitrate. Thus, short-term administration of nitrates does not improve maximal exercise capacity or left ventricular performance at maximal exercise in patients with congestive heart failure, but it does appear to improve pump function at submaximal work loads and may therefore enable patients to perform limited exercise more comfortably.

Paradox of improved exercise but not resting hemodynamics with short-term prazosin in chronic heart failure

In patients with chronic heart failure exercise allows the simultaneous observation of the cardiovascular pathophysiology and the symptoms of these patients. We administered short-term, oral prazosin to 10 patients with severe chronic heart failure. Prazosin increased cardiac output and stroke volume significantly during exercise (both P less than 0.05) but not at rest (both P greater than 0.10). Prazosin decreased the arteriovenous oxygen difference and left ventricular filling pressure significantly during exercise (both P less than 0.05) but not at rest (both P greater than 0.10). There was no significant correlation between prazosin-induced changes at rest and during exercise in cardiac output (r = 0.12), stroke volume (r = 0.02), arteriovenous oxygen difference (r = 0.33) or left ventricular filling pressure (r = 0.43). Prazosin predominantly affects hemodynamics during exercise because its pharmacologic activity as an alpha-adrenergic blocking agent is most prominent during exercise. The full evaluation of prazosin-induced changes in the hemodynamics of patients of patients with chronic heart failure requires evaluation during exercise.

Afterload reduction and cardiac performance. Physiologic basis of systemic vasodilators as a new approach in treatment of congestive heart failure

Digitalis and diuretics constitute conventional therapy of congestive heart failure, but systemic vasodilators offer an innovative approach in acute and chronic heart failure of decreasing increased left ventricular systolic wall tension (ventricular afterload) by reducing aortic impedance and/or by reducing cardiac venous return. Thus, vasodilators increase cardiac output (CO) by diminishing peripheral vascular resistance (PVR) and/or decrease increased left ventricular end-diastolic pressure (LVEDP) (ventricular preload) by diminishing venous tone. Concomitantly, there is reduction of myocardial oxygen demand, thereby reliably reducing angina pectoris in coronary disease, and potentially limiting infarct size and ischemia provided systemic arterial pressure remains normal. The vasodilators produce disparate modifications of cardiac function depending upon their differing alterations of preload versus impedance: nitrates principally cause venodilation (decrease LVEDP); nitroprusside, phentolamine and prazosin produce balanced arterial and venous dilation (decrease LVEDP and increase CO) provided left ventricular filling pressure is maintained at the upper limit of normal; whereas hydralazine predominantly effects arteriolar dilation (increases CO). With depressed CO plus highly increased LVEDP and increased PVR, nitrates also induce some increase of CO by reducing PVR. Combined nitroprusside and dopamine synergistically enhance CO and decrease LVEDP. Mechanical counterpulsation aids nitroprusside in acute myocardial infarction. The 30-minute venodilator action of sublingual nitroglycerin is extended for 4 to 6 hours by cutaneous nitroglycerin ointment, by sublingual and oral isosorbide dintrate, and by oral pentaerythritol tetranitrate and sustained-release nitroglycerin capsules. Ambulatory oral vasodilator therapy is provided by long-acting nitrates (relieve pulmonary congestion); hydralazine (improves fatigue); prazosin alone, combined nitrate-hydralazine combined prazosin-hydralazine (improve both dyspnea and fatigue).