Comparative haemodynamic and peripheral vasodilator effects of oral and chewable isosorbide dinitrate in patients with refractory congestive cardiac failure.

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Abstract
The effects of oral (30 mg) and chewable (10 mg) isosorbide dinitrate on hemodynamics, venous capacitance and calf blood flow were compared in a double-blind trial in 18 patients with refractory chronic congestive heart failure with pulmonary artery end-diastolic pressure .gtoreq. 18 mmHg. Cardiac output and right heart pressures were measured with a Swan-Ganz thermodilution catheter, arterial pressure through an indwelling radial artery cannula and venous capacitance and calf blood flow by vascular occlusion plethysmography. The agents reduced pulmonary artery end-diastolic pressures > 10% in 15 patients (responders) but by .ltoreq. 10% in 3 others (non-responders). In the responders, both agents produced significant decreases in mean arterial pressure, in pulmonary artery end-diastolic pressures, and in mean right atrial pressure. Oral (but not chewable) isosorbide dinitrate produced a significant increase in cardiac index and stroke volume index while decreasing systemic vascular resistance and heart rate. Both agents increased venous capacitance significantly but without a comparable effect on calf blood flow. The onset of action for both agents was apparent within 10 min; the peak effect occurred significantly earlier for the chewable isosorbide dinitrate; the duration of action was longer for oral isosorbide dinitrate. Apparently, both oral and chewable isosorbide dinitrate may have significant effects on vascular capacitance bed. Due to its more pronounced effect on ventricular function and its more prolonged duration of action, oral isosorbide dinitrate is probably the preferred agent for protracted oral treatment in congestive cardiac failure.