[Control of afterload by intravenous nitroglycerin in patients undergoing myocardial revascularisation (author's...

In 18 patients undergoing aortocoronary bypass grafting haemodynamic measurements were made before and after hypertensive episodes and intravenous administration of nitroglycerin (NTG). Patients of group I (n = 10) had good left heart function before operation. The mean arterial pressure (MAP) rose during the hypertensive episode from 82 +/- 12 mm Hg to 119 +/- 8 mm Hg (p less than 0.001), the pulmonary capillary wedge pressure (PCWP) increased from 11 +/- 3 mm Hg to 15 +/- 2 mm Hg (p less than 0.05). The cardiac index (CI) was not significantly altered. Infusion of NTG decreased the MAP to 84 +/- 3 mm Hg (p less than 0.001), the PCWP to 9 +/- 3 mm Hg (p less than 0.01). The CI remained unchanged. Patients of group II (n = 8) had poor left heart function before operation. During the hypertensive episode the MAP increased from 77 +/- 15 mm Hg to 115 +/- 6 mm Hg (p less than 0.001), the PCWP from 13 +/- 4 mm Hg to 25 +/- 5 mm Hg (p less than 0.001). The CI decreased from 2.2 +/- 0.3 1/min x m2 to 1.5 +/- 3.41/min x m2. Infusion of NTG decreased the MAP to 83 +/- 4 mm Hg (p less than 0.001), the PCWP to 11 +/- 3 mm Hg (p less than 0.001). The CI rose to 2.3 +/- 0.3 1/min x m2 (p less than 0.01). The authors conclude that NTG is an effective antihypertensive agent. No untoward side effects were noted.