Bandagem ajustável do tronco pulmonar: comparação de dois métodos de hipertrofia aguda do ventrículo subpulmonar Adjustable pulmonary trunk banding: comparison of two methods of acute subpulmonary ventricle hypertrophy

Abstract

OBJETIVO: Este estudo compara a sobrecarga contínua versus intermitente do ventrículo direito (VD) de cabritos, para induzir a hipertrofia ventricular. MÉTODO: Foram utilizados três grupos de sete cabritos jovens (controle, contínuo, intermitente). A sobrecarga sistólica foi imposta por 96 horas, no contínuo e por quatro períodos de 12 horas, alternados com 12 horas de descanso, no intermitente. Avaliações ecocardiográficas e hemodinâmicas foram feitas diariamente. Os animais foram, então, mortos para avaliar o conteúdo de água e peso das massas cardíacas. RESULTADOS: O Intermitente mostrou aumento dos pesos de VD e de septo, em relação ao controle (pOBJECTIVE: This study compares ventricular hypertrophy induced by continuous versus intermittent systolic overload of the pulmonary ventricle (RV) of young goats. METHODS: Three groups of seven goats were used (control, continuous, and intermittent). Systolic overload was maintained for 96 hours in the continuous group, while the intermittent group suffered four 12-hour periods of systolic overload, alternating with 12-hour resting periods. Echocardiographic and hemodynamic evaluations were performed every day. The animals were then killed for myocardial water content and weight evaluation. RESULTS: Both study groups achieved significant increases in RV mass (p<0.05). However, significant increases of the septum mass were observed only in the Intermittent Group (p<0.05). A greater increase in the RV wall thickness was observed in the Intermittent Group (p<0.05). There was a significant difference in RV diastolic volume between the two groups (p= 0.01), with a greater RV dilation in the Continuous Group after 24 hours of continuous overload (p< 0.03). In both groups, the RV ejection fraction was maintained within the normal range throughout the protocol. A smaller RV perimeter was observed in the Intermittent Group after 96 hours of systolic overload (p<0.05). There was no significant difference in RV myocardial water content between the study groups and the Control Group. CONCLUSIONS: Adjustable pulmonary artery bandages permit rapid RV hypertrophy in both groups. Nevertheless, it is more efficient in the Intermittent Group. This study suggests that preparation of the pulmonary ventricle with intermittent systolic overload might provide better results for the 2-stage arterial switch operation.

Keywords

• Ventrículos cardíacos
• Hipertrofia
• Hipertrofia ventricular direita
• Transposição dos grandes vasos
• Procedimentos cirúrgicos cardíacos
• Cabras
• Heart ventricles
• Hypertrophy
• Right ventricular hypertrophy
• Transposition of great vessels
• Cardiac surgical procedures
• Goats