Comparative effects of amlodipine and benazepril on Left Atrial Pressure in Dogs with experimentally-induced Mitral Valve Regurgitation

Mean LAP decreased significantly after amlodipine (11.20？±？4.19？mmHg vs 14.61？±？3.81？mmHg at baseline, p？<？.01) but not after benazepril treatment (13.19？±？3.47？mmHg, p？>？.05). LAP was lower after 7？days of amlodipine treatment than after 7？days of benazepril treatment. Significant reduction was seen for the first time 4？days after the administration amlodipine. The rate of the maximal area of the regurgitant jet signals to the left atrium area (ARJ/LAA) of the amlodipine treatment was significantly lower (p？<？.05) after 7？days compared to baseline. Other echocardiographic parameters did not change significantly.LAP was significantly decreased after amlodipine treatment in dogs with surgically-induced MR but not after benazepril treatment. Although this study did not focus on adverse effects, amlodipine may be an effective drug for helping the patients with acute onset of severe MR, such as rupture of chordae tendinae or end stage patients were the LAP is likely to be elevated. Additional studies in clinical patients with degenerative mitral valve disease and acute chordal rupture are warranted because the blood-pressure lowering effects of amlodipine can decrease renal perfusion and this can further activate the RAAS.Mitral valve disease (MVD) is the most common cardiac disease in dogs. Moreover, as many as 75% of all dogs with signs of congestive heart failure suffer from mitral regurgitation (MR) caused by myxomatous degeneration of the valve leaflets or chordae tendineae [1,2]. Left atrial compliance maintains a relatively normal left atrial pressure (LAP) in dogs with MR [3]. However, if left atrial compliance decrease, LAP will increase. Increased LAP causes pulmonary edema, which can lead to cough, dyspnea, and even death [4]. Reduction of LAP is a desirable goal for drugs used to treat congestive heart failure in MVD. In general, calcium channel blockers are used for treatment of hypertrophic cardiomyopathy [5-7], atrial fibrillation [8-10], and systemic hyp