Análise da função ventricular direita em dois protocolos de treinamento com bandagem ajustável do tronco pulmonar / Assessment of right ventricular function in two training protocols with adjustable pulmonary banding

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

13/12/2011

RESUMO

The ideal surgical treatment of transposition of the great arteries is the Jatene operation during the neonatal period. If the neonate remains untreated for several reasons, the left ventricle may become unprepared to sustain systemic circulation. The preparation of the subpulmonary ventricle by pulmonary trunk (PT) banding is an option for the 2-stage Jatene operation. The hypothesis of PT banding with an adjustable device to retrain the subpulmonary ventricle could minimize the inadequacies of conventional banding and improve the preparation of those ventricles. Previous studies have shown no differences on systolic function between two different protocols of subpulmonary ventricle retraining, during resting condition. The aim of the present study was to assess ventricular function during two protocols of PT banding and the impact on systolic and diastolic function of the right ventricle (RV), at rest and under pharmacological stress. Nineteen healthy young goats, aged approximately 60 days and with comparable weights, were divided into three groups: Sham (n = 7, surgery control with no systolic overload), Continuous (n = 6, 96 hours of continuous RV systolic overload), Intermittent (n = 6, four 12-hour periods of systolic overload paired with a 12-hour resting period). before and after systolic overload every day postoperatively. Cardiac function at rest and under pharmacological stress induced by dobutamine was assessed on two occasions: baseline and after 96 hours. After 96-hour study period, all the animals were euthanized for morphologic assessment. There was a significant increase in RV free wall thickness of the Intermittent Group (+64.8% ± 23.37%) at the end of the protocol, when compared to Continuous Group (+43.9% ± 19.26%, p = 0.015). Both study groups presented a dilated RV after starting systolic overload (time zero, p <0.001), as compared to Sham group. However, only Continuous group remained with significant RV dilation throughout the protocol (p <0.006). Worsening of RV ejection fraction was observed in the two study groups after beginning systolic overload as well (time zero and 24 hours, p <0.002), with recovery to normal levels at the end of the protocol. Nevertheless, RV ejection fraction of the Continuous Group remained lower than Intermittent Group for a longer period (72 hours versus 48 hours, p <0.001). At rest, RV myocardial performance of the Continuous Group was significantly worse than Sham Group, after 72 hours and 96 hours of protocol (p <0,039). Under dobutamine stress, Continuous Group presented worsening myocardial performance indexes, as compared to both Intermittent and Sham Group (p <0.01). Regarding morphological analysis, both study groups presented an increased RV mass of similar magnitude, despite less exposure of Intermittent Group to pressure overload. Although both protocols of RV systolic overload had induced similar RV mass gain, intermittent systolic overload was more efficient in preserving RV myocardial performance in goats

ASSUNTO(S)

cabras cardiac surgical procedures/methods echocardiography stress ecocardiograma sob estresse goats heart ventricles/physiopathology hipertrofia ventricular direita hipertrofia/fisiopatologia hypertrophy right ventricular hypertrophy/physiopathology procedimentos cirúrgicos cardíacos/métodos transposição dos grandes vasos/cirurgia transposition of great vessels/surgery ventrículos cardíacos/fisiopatologia

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