Evaluation of Cardiac Loading Condition by Plasma ANP and NT-pro-BNP After Mitral Valve Plasty in Dogs
The objective was to evaluate whether plasma ANP and NT-pro-BNP detect a reduction in the cardiac volume load in dogs with moderate and severe mitral regurgitation before and after mitral valve plasty (MVP) using cardiopulmonary bypass (CPB). The cases were eight dogs (BW 3.4-10.6 kg) in which MVP was performed from April 2006 to September 2007. All cases indicated cough, cardiac enlargement and pulmonary oedema by X-ray, and the preoperative ISACHC classification was II to IIIa. These were difficult to maintain with medication. MVP using a CPB was performed by annuloplasty of the mitral valve and rebuilding of the chordae tendineae by artificial sutures. Plasma ANP and NT-pro-BNP were measured preoperatively, and postoperatively at 1 and 3 months. Preoperative ANP was 263 ± 74 pg/ml (n = 8), and NT-pro-BNP was 3846 ± 1664 pg/ml (n = 4). The clinical symptom was improved remarkably one month postoperatively, and the ISACHC classification decreased in Ib. ANP (127 ± 59 pg/ml and 121 ± 52 pg/ml, n = 8, P < 0.001) and NT-pro-BNP (2415 ± 2146 pg/ml and 1202 ± 568 pg/ml, n = 4) 1 and 3 months postoperatively, respectively, significantly decreased compared with preoperatively. A significant reduction in the LA/Ao ratio and heart size was shown by echocardiography, and X-ray, respectively. Medication was withdrawn with the improvement of clinical signs in 4 of 8 cases. ANP and/or NT-pro-BNP levels after cardiac surgery were useful as an indicator of cardiac load in dogs.