Mitral valve repair under cardiopulmonary bypass in small-breed dogs: 48 cases (2006-2009)

Objective To determine whether mitral valve repair (MVR) under cardiopulmonary bypass would be an effective treatment for mitral regurgitation in small-breed dogs. Design-Retrospective case series. Animals-48 small-breed dogs (body weight, 1.88 to 4.65 kg [4.11 to 10.25 Ib]; age, 5 to 15 years) with mitral regurgitation that underwent surgery between August 2006 and August 2009. Procedures Cardiopulmonary bypass was performed with a cardiopulmonary bypass circuit. After induction of cardiac arrest, a mitral annuloplasty was performed, and the chordae tendineae were replaced with expanded polytetrafluoroethylene chordal prostheses. After closure of the left atrium and declamping to restart the heart, the thorax was closed. Results-Preoperatively, cardiac murmur was grade 3 of 6 to 6 of 6, thoracic radiography showed cardiac enlargement (median vertebral heart size, 12.0 vertebrae; range, 9.5 to 14.5 vertebrae), and echocardiography showed severe mitral regurgitation and left atrial enlargement (median left atrium-to-aortic root ratio, 2.6; range, 1.7 to 4.0). 45 of 48 dogs survived to discharge. Three months after surgery, cardiac murmur grade was reduced to 0/6 to 3/6, and the heart shadow was reduced (median vertebral heart size, 11.1 vertebrae, range, 9.2 to 13.0 vertebrae) on thoracic radiographs. Echocardiography confirmed a marked reduction in mitral regurgitation and left atrium-to-aortic root ratio (median, 1.7; range, 1.0 to 3.0). Conclusions and Clinical Relevance-We successfully performed MVR under cardiopulmonary bypass in small-breed dogs, suggesting this may be an effective surgical treatment for dogs with mitral regurgitation. Mitral valve repair with cardiopulmonary bypass can be beneficial for the treatment of mitral regurgitation in small-breed dogs. (J Am Vet.Med Assoc 2012;240:1194-1201)