Intermittent systolic overload promotes better myocardial performance in adult animals

Corrected transposition of great arteries often evolves with right ventricular dysfunction. The ventricular preparation for anatomic correction in adult patients has produced disappointing results.

To assess right ventricular hypertrophy (RV) induced by conventional and intermittent pulmonary banding (PB) in adult animals.

Nineteen adult goats were divided into three groups: conventional (six animals), intermittent (six animals) and control (seven animals). The Conventional group underwent fixed PB with cardiac tape, while the intermittent group received PB adjustable device, which generated systolic overload for 12 hours, alternated with 12 hours of rest of RV. The pressures of the RV, pulmonary artery and aorta were measured throughout the study. Echocardiography was performed weekly. After four weeks, the animals were euthanized for morphological evaluation of the ventricles. The Control group was put to euthanasia for analysis at baseline.

Pressure overload was lower in the intermittent group (p = 0.001), compared to the conventional group. There was an increase in the thickness of the RV of the Intermittent group measured by echocardiography compared to their baseline values (p < 0.05). The myocardial performance index in the RV group was better in the Intermittent group (p = 0.024), compared to the Conventional group. The groups stimulated showed increased muscle mass compared to the Control group (p = 0.001). There was no difference in myocardial water content.

The intermittent BP developed hypertrophy of better performance, suggesting this protocol as the preferred method of ventricular preparation.