The effect of angiotensin-converting enzyme inhibitors of left atrial pressure in dogs with mitral valve regurgitation

Abstract

Background: Despite many epidemiological reports concerning the efficacy of angiotensin-converting enzyme (ACE) inhibitors in dogs with mitral regurgitation (MR), the hemodynamic effects of ACE inhibitor administration have not been fully evaluated. Objectives: To document left atrial pressure (LAP) in dogs with MR administered ACE inhibitors, in order to obtain interesting information about daily LAP changes with administration of ACE inhibitors. Animals: Five healthy Beagle dogs weighing 9.8 to 14.2kg (2 males and 3 females; aged 2 years). Methods: Experimental, crossover, and interventional study. Chordae tendineae rupture was induced, and a radiotelemetry transmitter catheter was inserted into the left atrium. LAP was recorded for 72 consecutive hours during which each of 3 ACE inhibitors-enalapril (0.5mg/kg/d), temocapril (0.1mg/kg/d), and alacepril (3.0mg/kg/d)-were administered in a crossover study. Results: Averaged diurnal LAP was significantly, but slightly reduced by alacepril (P=.03, -19.03±3.01-18.24 ± 3.07 mmHg). The nightly drops in LAP caused by alacepril and enalapril were significantly higher than the daily drops (P=.03, -0.98±0.19 to -0.07±0.25mmHg, and P=.03, -0.54±0.21-0.02±0.17 mmHg, respectively), despite the fact that the oral administrations were given in the morning. Systolic blood pressure (122.7±14.4-117.4±13.1 mmHg, P=.04) and systemic vascular resistance (5800±2685-5144±2077 dyne×s/cm5, P=.03) were decreased by ACE inhibitors. Conclusions and Clinical Importance: ACE inhibitors decrease LAP minimally, despite reductions in left ventricular after-load. ACE inhibitors should not be used to decrease LAP. © 2010 by the American College of Veterinary Internal Medicine.