The use of digitalis in mitral stenosis without right heart failure

Reliability and efficacy of metoprolol and diltiazem in patients having mild to moderate mitral stenosis with sinus rhythm

The authors evaluated the effects of beta blockers (metoprolol) and calcium channel blockers (diltiazem) in patients having mild to moderate mitral stenosis (MS) with sinus rhythm. Eighty patients with a complaint of dyspnea with diagnosed MS were included in this study. Patients were randomized into metoprolol and diltiazem groups. The first group received oral diltiazem treatment for 3 months following an i.v. dose of 25 mg diltiazem. The second group received oral metoprolol for 3 months following an i.v. dose of 5 mg metoprolol. All patients performed a treadmill exercise test at the beginning of and after 3 months of treatment. Transthoracic echocardiographic studies were also performed following the i.v. drug administration and after 3 months of treatment. In addition, oxygen uptakes of patients were measured before and after the stress and after 3 months of treatment. Decreases in peak gradient (PG) and mean transmitral gradient (MG) were observed in the metoprolol group after i.v. and oral metoprolol treatment. A prolongation of exercise time in treadmill exercise test (TET) and a decrease in the maximum heart rate after oral metoprolol treatment were noted. Eighteen patients in the metoprolol group had benefited symptomatically from this treatment and complaints of dyspnea were alleviated, whereas no symptomatic relief was seen in the diltiazem group. No significant prolongation was observed in effort times (p>0.05) of the diltiazem group. Transmitral gradients measured via echocardiographic examination did not change (p>0.05). With respect to oxygen uptake rates, a statistically significant decrease was determined in the metoprolol group, whereas no difference was found in diltiazem group. The authors conclude that metoprolol may be useful in patients with MS and can provide symptomatic relief. They did not observe any beneficial effect of diltiazem in these patients.

The cardiovascular response to digoxin in conscious dogs with left atrial obstruction

In addition to positive inotropic and atrioventricular conduction-blocking properties, digoxin is capable of producing systemic and pulmonary vasoconstriction. However, whether chronic digoxin treatment exacerbates the pulmonary hypertension that results from left atrial (LA) outflow obstruction has not been specifically examined. This study assessed the vascular and inotropic responses to 5 days of digoxin treatment in six conscious dogs before and after filling a permanently implanted LA balloon. Dogs were also instrumented to measure left ventricular (LV) pressure, LV dP/dt, mean systemic arterial (MAP), right atrial (RAP), pulmonary arterial, and pulmonary capillary wedge pressures, as well as cardiac output (CO). Under normal conditions with the balloon empty, digoxin treatment (40 micrograms/kg loading dose and 12 micrograms/kg/d for 5 days) reduced CO (-17%) and increased systemic (SVR) and pulmonary (PVR) vascular resistances 27% and 37%, respectively; heart rate (HR) and LV dP/dt were not changed. Filling the balloon with enough saline to double PVR also increased SVR (52%), HR (42%), and RAP (92%), and reduced CO (-24%). During LA outflow obstruction, 5 days of digoxin reduced HR (-17%), SVR (-29%), and RAP (-23%), but did not alter PVR, CO, or LV dP/dt. This study demonstrates that although systemic and pulmonary vasoconstriction result from chronic digoxin treatment under normal conditions, the drug produces systemic vasodilation and no change in PVR during LA outflow obstruction.

Failure of oral atenolol and verapamil to increase the capacity and duration of exercise in patients in sinus rhythm with mitral stenosis

The efficacy of oral atenolol in increasing the capacity and duration of exercise in 43 patients in sinus rhythm with mitral stenosis was evaluated and compared with that of oral verapamil in an open-label cross-over design. It was observed that although oral atenolol (100 mg per day) caused significant reductions in heart rate while resting and during exercise (P less than 0.001), the increases in capacity and duration of exercise were not significant. Oral verapamil (80 mg three times per day) also caused significant reductions in the heart rates at rest and during exercise (P less than 0.05) but the increases observed, although greater than that with atenolol, failed to reach the level of statistical significance. Occasional side effects occurred with both the drugs. Subjective symptoms of dyspnoea at rest and on exertion were relieved with both the drugs. We conclude that, although both drugs reduce the symptoms of dyspnoea, they cause only minor increases in the objective parameters. They do not, therefore, provide an alternative to surgery and have only a temporary place in the management of patients in sinus rhythm with mitral stenosis who are awaiting surgery.

Hemodynamic response to exercise after propranolol in patients with mitral stenosis

Hemodynamic response to exercise before and 10 minutes after propranolol (5 mg intravenously) was studied in 10 young patients with pure mitral stenosis who had normal sinus rhythm and no cardiac failure. After propranolol the mean heart rate and cardiac index at rest were lower than during the control state (respectively, 95 +/- 4 versus 82 +/- 3 beats/min, P less than 0.005; 3.4 +/- 0.2 versus 2.8 +/- 0.1 liters/min per m2, P less than 0.025). As a result, the mean pulmonary wedge pressure and mean mitral valve gradient at rest were lower (respectively, 22 +/- 2 versus 18 +/- 2 mm Hg, P less than 0.005; 24 +/- 2 versus 17 +/- 2 mm Hg, P less than 0.001). During exercise after propranolol the values of pulmonary wedge pressure and mitral valve gradient were lower than control values during exercise (respectively, 39 +/- 3 versus 30 +/- 2 mm Hg, P less than 0.005; 44 +/- 3 versus 32 +/- 3 mm Hg, P less than 0.005), again because of the lower heart rate and cardiac index (130 +/- 6 versus 104 +/- 6 beats/min, P less than 0.001; 4.6 +/- 3 versus 3.7 +/- 2 liters/min per m2, P less than 0.01). Left ventricular end-diastolic pressure and stroke index showed no significant changes. Thus, propranolol may benefit patients with pure mitral stenosis with sinus rhythm and no cardiac failure whose symptoms occur during those reversible conditions characterized by an increase in heart rate or cardiac output, or both.

Propranolol in mitral stenosis during sinus rhythm

Patients with early symptomatic mitral stenosis usually suffer from pulmonary congestion on the basis of left atrial and pulmonary venous hypertension. They are often in sinus rhythm, and cardiac output is usually well maintained. Symptoms occur most often when heart rate, cardiac output, or both are increased. In this study, intravenous propranolol administered to patients with pure mitral stenosis in sinus rhythm resulted in significant reductions in mitral diastolic gradient (-7.1 mm. Hg +/- 1.6 SED), mean pulmonary wedge pressure (--6.9 mm. Hg +/- 1.2) and mean pulmonary artery pressures (--9.0 mm. Hg +/- 1.2). This was due to simultaneous reduction of heart rate (--13.0 beats/minute +/- 2.6 and cardiac output (--0.5 L./minute +/- 0.2). A small associated reduction of left ventricular systolic pressure (--5.1 mm. Hg +/- 2.6) was not accompanied by adverse clinical effects. A potential role for propranolol in medical management of pure mitral stenosis in the presence of sinus rhythm is suggested.