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A comparison of nitroglycerin and nitroprusside: I. Treatment of postoperative hypertension
Insights
Nitroglycerin and nitroprusside both lowered blood pressure post-surgery, but nitroglycerin more effectively reduced left ventricular stroke work index and improved myocardial lactate flux, suggesting better myocardial perfusion.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Hypertension following coronary bypass surgery requires effective management.
- Nitroglycerin offers theoretical advantages over sodium nitroprusside for improving myocardial perfusion in ischemic regions.
Purpose of the Study:
- To compare the efficacy of nitroglycerin and sodium nitroprusside in managing post-coronary bypass hypertension.
- To assess the impact of these agents on hemodynamic parameters and myocardial metabolism.
Main Methods:
- A randomized crossover trial involving 33 hypertensive patients post-coronary bypass.
- Infusion of nitroglycerin or sodium nitroprusside to reduce mean arterial pressure (MAP).
- Measurements included cardiac output, left ventricular stroke work index (LVSWI), ejection fraction, volumes, coronary sinus blood flow, and myocardial lactate flux (MVL).
Main Results:
- Both nitroglycerin and nitroprusside reduced MAP similarly.
- Nitroglycerin significantly reduced LVSWI more than nitroprusside (p<0.01).
- Nitroglycerin increased MVL, while nitroprusside decreased it (p<0.05), indicating differential effects on myocardial metabolism.
Conclusions:
- Nitroglycerin demonstrates superior hemodynamic effects compared to nitroprusside in reducing left ventricular workload post-surgery.
- Nitroglycerin may offer benefits in improving myocardial perfusion and metabolic function in patients with post-coronary bypass hypertension.
Abstract:
Nitroglycerin improves perfusion to ischemic myocardial regions and therefore has theoretical advantages over sodium nitroprusside to treat hypertension (mean arterial pressure [MAP] greater than 95 mm Hg) following coronary bypass operation. Thirty-three hypertensive patients were randomized to an initial infusion of either nitroglycerin or nitroprusside in a crossover trial designed to reduce MAP to 85 mm Hg. Thermodilution cardiac output measurements permitted calculation of left ventricular stroke work index (LVSWI), and nuclear ventriculograms permitted estimation of left ventricular ejection fraction, left ventricular end-diastolic volume index (LVEDVI), and left ventricular end-systolic volume index (LVESVI). Coronary sinus blood flow was measured by the continuous thermodilution technique, and arterial and coronary sinus lactate measurements permitted calculation of myocardial lactate flux (MVL). Both nitroglycerin and nitroprusside reduced MAP (-25 +/- 12 mm Hg and -20 +/- 10 mm Hg, respectively; not significant [NS]). Nitroglycerin reduced LVSWI more than did nitroprusside (-15 +/- 13 gm-m/m2 and -7 +/- 9 gm-m/m2, respectively; p less than 0.01). Both agents increased left ventricular ejection fraction (nitroglycerin, +8 +/- 8%, and nitroprusside, +10 +/- 7%; NS), and decreased LVEDVI (-20 +/- 22 ml/m2 and -11 +/- 17 ml/m2, respectively; NS) and LVESVI (-13 +/- 14 ml/m2 and -10 +/- 12 ml/m2, respectively; NS). Coronary sinus blood flow decreased with both drugs (NS), but MVL increased with nitroglycerin (+0.02 +/- 0.14 mmol/min) and decreased with nitroprusside (-0.02 +/- 0.02 mmol/min) (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)