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Angiotensin converting enzyme inhibition has no effect on blood pressure and splanchnic perfusion after cardiac
I Parviainen1, A Rantala, E Ruokonen
1Department of Anesthesiology and Intensive Care, Kuopio University Hospital, Finland.
Insights
Enalaprilat showed poor blood pressure control and no benefits for splanchnic circulation post-cardiac surgery. This suggests renin-angiotensin system activation is not a primary driver of hypertension or perfusion issues in these patients.
Area of Science:
- Cardiovascular Surgery
- Pharmacology
- Critical Care Medicine
Background:
- Post-cardiac surgery hypertension and impaired splanchnic perfusion are significant clinical concerns.
- The renin-angiotensin system is a potential target for managing these complications.
Purpose of the Study:
- To evaluate the efficacy of enalaprilat, an angiotensin-converting enzyme inhibitor, in managing blood pressure and splanchnic perfusion following coronary artery bypass grafting.
- To investigate the role of the renin-angiotensin system in post-cardiac surgery hemodynamic alterations.
Main Methods:
- A randomized controlled trial involving 16 patients undergoing coronary artery bypass grafting.
- Systemic hemodynamics, oxygen transport, and gastric tonometry were assessed at baseline and post-intervention.
- Enalaprilat was administered to 10 patients to achieve a target mean arterial pressure, while 6 patients served as controls.
Main Results:
- Enalaprilat administration resulted in a statistically significant decrease in mean arterial pressure in the treatment group, but the targeted reduction was achieved in only 40% of patients.
- No significant improvements in systemic or regional blood flow, including splanchnic circulation, were observed with enalaprilat.
- While angiotensin-converting enzyme activity decreased, plasma renin and endothelin-1 levels remained unchanged, indicating limited impact on the broader renin-angiotensin system.
Conclusions:
- Enalaprilat demonstrated limited effectiveness in controlling blood pressure and provided no discernible benefits to splanchnic circulation after cardiac surgery.
- The findings suggest that renin-angiotensin system activation may not be a primary contributor to hypertension or compromised splanchnic perfusion in the post-cardiac surgery setting.
Purpose:
The purpose of this study was to study the effect of the angiotensin-converting enzyme inhibitor, enalaprilat, on blood pressure and splanchnic perfusion after cardiac surgery.
Materials And Methods:
Sixteen patients were studied after coronary artery bypass grafting. After admission to the intensive care unit, a 30-minute baseline measurement of systemic hemodynamics, oxygen transport, and gastric tonometry was performed. In 6 of 10 patients receiving enalaprilat and in each of 6 control patients, regional (splanchnic and leg) blood flows were measured also. After the baseline measurement period, 10 patients received a 0.5 mg bolus of enalaprilat and thereafter an incremental infusion of enalaprilat up to a total dose of 10 mg (mean 8.3; range 4 to 10 mg) was continued to reduce the mean arterial pressure (MAP) to 70 to 80 mm Hg. A 30-minute measurement period was repeated 2 to 3 hours after the first measurement period. In the control group, the second measurement was performed at corresponding time points.
Results:
Though MAP decreased in the enalaprilat group (enalaprilat 99 +/- 14 mm Hg v 89 +/- 21 mm Hg, P < .05; control 95 +/- 13 mm Hg v82 +/- 10 mm Hg, P = NS) in only 4 of 10 patients was the targeted MAP reduction achieved. No significant changes were observed either in systemic or regional blood flows. Systemic, pulmonary, and femoral vascular resistance indices decreased significantly in both groups. Gastric-arterial PCO2 difference did not change in either groups. Angiotensin-converting enzyme activity decreased in the enalaprilat group (10.0 +/- 2.3 v 1.3 +/- 0.3 U x l(-1), P < .01), but plasma renin and endothelin-1 concentrations did not change in either group.
Conclusions:
The effect of enalaprilat on blood pressure was poor and it had no beneficial effects on splanchnic circulation. Renin-angiotensin activation is not a major factor in hypertension and splanchnic perfusion after cardiac surgery.