Objective: To evaluate the mass acquisition of the right ventricle (RV) of young goats, submitted to 24, 48, 72 and 96 hours of intermittent pressure load.
Methods: Four groups of seven young goats were submitted to 12-hour period of RV systolic overload, alternated with a resting period of 12 hours. The groups were divided in 24, 48, 72 and 96-hour training periods. Echocardiographic and hemodynamic evaluations were performed every day. After completing the training program of each group, the animals were killed for water content and cardiac masses evaluation. Another seven animals were used as a control group.
Results: Important RV dilation was observed at 24-hour period, with significant increase in the RV wall thickness starting at the 48-hour group(p<0.05). There was a significant increase in the RV volume to mass ratio at 24-hour training period(p=0.003), with a trend for recovery throughout the protocol. The RV mass of the 96-hour trained group (1.76±0.52 g/Kg) was significantly greater than the other groups (p<0.0001), with no significant myocardial water content changes in that group. The daily mean increase in RV mass was 21.57% ± 26.78%, with 104.7% increase in the 96-hour trained group as compared to the control group. The rate of RV mass acquisition for the overall study period was 0.084±0.035 g/h. RV wall stress peaked rapidly at 48-hour period, followed by progressive decrease throughout the protocol.
Conclusions: Intermittent banding of the pulmonary trunk has permitted a significant RV mass acquisition only in the 96-hour trained group.