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.