Department of Veterinary Surgery, Faculty of Veterinary Medicine, Tokyo University of Agriculture and Technology, Tokyo, Japan.
BMC Vet Res. 2012 Sep 18;8:166. doi: 10.1186/1746-6148-8-166.
One of the purposes of treatment for dogs with mitral regurgitation (MR) is lowering left atrial pressure (LAP). There has been few study of the amlodipine in dogs with MR and amlodipine's effect on LAP has not been fully evaluated in a quantitative manner because of difficulties in directly measuring LAP. The objective of our study was to compare the short-term effects of amlodipine (0.2 mg/kg PO q12h) vs benazepril (0.5 mg/kg PO q12h), on LAP and echocardiographic parameters in five beagle dogs with experimentally-induced MR. LAP of eight dogs that has own control were measured using radiotelemetry system at baseline and again on days 1, 2, 3, 4, 5, 6, 7 of the drug administration.
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.
治疗二尖瓣反流（MR）犬的目的之一是降低左心房压力（LAP）。已有研究发现氨氯地平对 MR 犬的作用，但由于直接测量 LAP 存在困难，尚未对其进行全面的定量评估。我们的研究目的是比较氨氯地平（0.2 mg/kg PO q12h）和贝那普利（0.5 mg/kg PO q12h）对五只实验性诱导 MR 的比格犬的 LAP 和超声心动图参数的短期影响。在药物治疗的第 1、2、3、4、5、6、7 天，使用无线电遥测系统测量 8 只自身对照犬的 LAP。
氨氯地平治疗后 LAP 显著降低（11.20 ± 4.19 mmHg 与基线时的 14.61 ± 3.81 mmHg，p < .01），但贝那普利治疗后 LAP 无显著降低（13.19 ± 3.47 mmHg，p > .05）。氨氯地平治疗 7 天后的 LAP 低于贝那普利治疗 7 天后。氨氯地平给药后第 4 天首次出现显著降低。氨氯地平治疗 7 天后，最大反流射流信号与左心房面积（ARJ/LAA）比值显著降低（p < .05）。其他超声心动图参数无显著变化。
在手术诱导的 MR 犬中，氨氯地平治疗后 LAP 显著降低，但贝那普利治疗后 LAP 无显著降低。虽然本研究未关注不良反应，但氨氯地平可能是治疗急性重度 MR 患者的有效药物，如腱索断裂或终末期患者，此时 LAP 可能升高。由于氨氯地平的降压作用可能降低肾灌注，从而进一步激活 RAAS，因此有必要在退行性二尖瓣疾病和急性腱索断裂的临床患者中开展进一步的研究。
