RESUMO
OBJECTIVE: We tested a unique new device, the Myosplint device (Myocor, Inc, Maple Grove, Minn), which is designed to change left ventricular shape, reduce left ventricular wall stress, and improve left ventricular systolic function. METHODS: Heart failure was induced in 15 dogs over 27 days by rapid pacing (230 beats/min). Seven animals underwent sham surgery, and 8 animals received 3 transventricular Myosplint devices each. Myosplint devices were tightened to create a symmetric bilobular left ventricular shape and were adjusted to produce a calculated 20% reduction in wall stress. Hemodynamic, 2-dimensional, and 3-dimensional echocardiographic studies were recorded at baseline, immediately after Myosplint placement (acute change), and at 1 month after both groups had a reduced rate (190 beats/min) of pacing designed to maintain heart failure. RESULTS: The Myosplint group had significant sustained improvements in left ventricular ejection fraction from baseline, to the acute change, to 1 month (19% +/- 5%; 36% +/- 8%; 39% +/- 13%) and reductions of left ventricular end-systolic volumes (73 +/- 9 mL; 34 +/- 5 mL; 42 +/- 12 mL) and end-systolic wall stress by 39% (341 +/- 68 10(3) dynes x cm(- 2) to 206 +/- 28 10(3) dynes x cm(-2)) acutely and 31% (372 +/- 83 10(3) dynes x cm(-2) to 250 +/- 40 10(3) dynes x cm(-2)) at 1 month. There were no significant changes in mitral regurgitation. CONCLUSION: Application of a Myosplint device to a dilated impaired left ventricle resulted in reduced wall stress and improved left ventricular systolic function that was sustained at 1 month. Device-based shape change is a promising new opportunity to treat patients with dilated cardiomyopathy.
Assuntos
Cardiomiopatia Dilatada/fisiopatologia , Cardiomiopatia Dilatada/terapia , Modelos Animais de Doenças , Coração Auxiliar/normas , Contenções/normas , Remodelação Ventricular , Animais , Cardiomiopatia Dilatada/diagnóstico por imagem , Cardiomiopatia Dilatada/patologia , Cães , Ecocardiografia , Ecocardiografia Tridimensional , Desenho de Equipamento , Hemodinâmica , Teste de Materiais , Pressão Propulsora Pulmonar , Volume Sistólico , Sístole , Fatores de Tempo , Resultado do Tratamento , Função VentricularRESUMO
The Myocor Myosplint is designed to decrease left ventricular (LV) wall stress by changing LV shape, thus improving contractile function in dilated hearts. This shape change is accomplished by surgically placing three Myosplints perpendicular to the LV long axis, drawing the LV walls inward, and creating a symmetric, bilobular LV. Specially designed instruments aid in the precise delivery of these devices. The purpose of this study was to test the safety and feasibility of the procedure in dogs. Dilated cardiomyopathy was induced in 40 healthy dogs (26.3+/-1.7 kg) by ventricular pacing at 230 beats per minute for an average of 25+/-4 days. Using epicardial echocardiography, we placed the Myosplints across the LV chamber, avoiding the major coronary arteries, papillary muscles, and mitral valve. Once placed, the Myosplints were used to draw the LV walls inward to a prescribed distance. In all cases, we successfully implanted three Myosplints without using cardiopulmonary bypass. There were no complications related to the device or procedure. Myosplint implantation to change LV shape is safe and repeatable on a beating cardiomyopathic canine heart. Further study of the procedure will be needed in humans.
