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Myocardial oxygen consumption. Comparison between left atrial pulsatile synchronous and asynchronous bypass
P K Davis1, W E Pae, C A Miller
1College of Medicine, Division of Artificial Organs, Pennsylvania State University, Hershey 17033.
ASAIO Transactions
|July 1, 1989
Summary
R-wave synchronization (counterpulsation) during pulsatile bypass does not further reduce myocardial oxygen consumption (MVO2) beyond standard asynchronous bypass. Both methods significantly lower the tension time index (TTI), a marker for MVO2.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
Background:
- Myocardial oxygen consumption (MVO2) is a critical determinant of cardiac health.
- The tension time index (TTI) is a reliable indicator of MVO2.
- Pulsatile left atrial to aortic bypass is a technique used to support cardiac function.
Purpose of the Study:
- To quantify the impact of R-wave synchronization (counterpulsation) on MVO2 during pulsatile left atrial to aortic bypass.
- To compare the effectiveness of synchronous versus asynchronous bypass in reducing TTI.
Main Methods:
- Eight instrumented animals underwent implantation of pulsatile ventricular assist devices.
- Measurements of TTI, heart rate, cardiac output, and pressures were recorded during control, asynchronous bypass (LAPAS), and synchronous bypass (LAPS) periods.
- Heart rate and mean aortic pressure were actively controlled throughout the experiment.
Main Results:
- Baseline TTI was 1819 +/- 95 mmHg-sec.
- Asynchronous bypass (LAPAS) reduced TTI to 987 +/- 127 mmHg-sec.
- Synchronous bypass (LAPS) further reduced TTI to 763 +/- 89 mmHg-sec.
- Both bypass modes significantly reduced TTI compared to control.
Conclusions:
- Pulsatile left atrial to aortic bypass, whether synchronous or asynchronous, significantly reduces myocardial oxygen consumption (MVO2) as indicated by TTI.
- R-wave synchronization (counterpulsation) does not provide additional benefits in reducing TTI compared to less complex asynchronous bypass modes.