BACKGROUND: The mechanical circulatory assistance is a therapeutic option in cases of cardiogenic shock refractory to the pharmacological treatment, and is frequently used as a bridge for heart transplantation. OBJECTIVE: To evaluate the action of the Ventricular Assist Device (VAD) developed by the Bioengineering Division of the Instituto do Coração, implanted as a substitute of the left heart. PATIENTS AND METHODS: Ten Girolando calves with medium weight of 73 kg were studied. The VAD-InCor implant was accomplished with the drainage cannula positioned in the left atrium (LA) or in the apex of the left ventricle and the replacement cannula implanted in the descending thoracic aorta. The pressures of the right and left heart, cardiac output and the flow of VAD were determined before and after the pharmacological induction of myocardial failure, at different levels of vacuum of the drainage system. RESULTS: Values of the flow of VAD with the drainage in LA were of 2.2 ± 0.5 l/min without vacuum, of 3.7 ± 0.4 with vacuum of 10 mmHg, of 4.3 ± 0.4 with vacuum of 20 mmHg and of 4.8 ± 0.6 with vacuum of 30 mmHg. The values of the pressure of LA were: 11.7 ± 6; 9.8 ± 5.3; 8.5 ± 4.4 and 5.6 ± 3.3 mmHg under the same conditions, respectively. With the ventricular cannula, the VAD flow was 4.2 ± 0.6 without vacuum and of 4.4 ± 0.7 with vacuum of 10 mmHg, with of LA pressure of 11.1 ± 2 and 10.3 ± 3.5 mmHg in the two conditions. Those results were observed in similar hemodynamic conditions, with the VAD flow responsible for a greater percentile of the total cardiac output according to the level of vacuum. That percentile was of 86 ± 13% with the atrial cannula and vacuum of 30 mmHg and of 97 ± 3% with the ventricular drainage and vacuum of 10 mmHg. CONCLUSIONS: The VAD-InCor demonstrated its effectiveness as a substitute of the left heart. The performance of this device was proportional to the level of vacuum of the drainage system and was better with the ventricular cannula.
Heart ventricle; Heart-assist devices
