Myocardial oxygen tension during left ventricular bypass.
The effect of an assist pump on the heart was evaluated on the basis that myocardial gas tensions reflect the balance between oxygen supply and consumption in local regions of the myocardium. A left ventricular assist device (LVAD) was implanted in dogs between the left ventricle (LV group), or the left atrium (LA group) and the aorta. The assist pump was driven in a counterpulsation mode. A silicone catheter for mass spectrometry was inserted into the myocardium to monitor continuously myocardial oxygen and carbon dioxide tensions (PmO2, PmCO2). Coronary sinus blood flow (CSBF) was measured by completing an extracorporeal flow loop between the coronary sinus and the jugular vein. During LVAD counterpulsation, the LV pressure was reduced and diastolic arterial pressure (i.e. coronary perfusion pressure) was increased. Total LV bypass was obtained in the LV group, and partial LV bypass in the LA group. In the LV group, PmO2 was 18.3 +/- 1.9 mmHg with pump-off and increased to 26.4 +/- 3.0 during LV bypass (N = 10, p less than 0.005). PmCO2 was 45.3 +/- 1.8 mmHg with pump-off and decreased to 40.2 +/- 1.5 during bypass (N = 10; p less than 0.005). CSBF significantly decreased during LV bypass from a control value of 24.1 +/- 2.74 ml/min/100g to 16.3 +/- 1.69 in LV group (N = 10; p less than 0.001). It was 43.4 +/- 8.0 ml/min/100g in the pump-off and 31.9 +/- 7.2 during LV bypass in the LA group (N = 7; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D001011:Aorta / Q000601:surgery; D002245:Carbon Dioxide / Q000097:blood; D003326:Coronary Circulation; D004285:Dogs; D009206:Myocardium / Q000378:metabolism*; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D010313:Partial Pressure; D016276:Ventricular Function
D002245:Carbon Dioxide; D010100:Oxygen