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Left ventricular mechanics during synchronous left atrial-aortic bypass
O Kawaguchi1, J S Sapirstein, W B Daily
1Department of Surgery, Pennsylvania State University, College of Medicine, Milton S. Hershey Medical Center, Hershey 17033.
The Journal of Thoracic and Cardiovascular Surgery
|June 1, 1994
Summary
Pulsatile left atrial-aortic bypass did not alter left ventricular contractility in healthy or failing hearts. This bypass method reduced ventricular workload and oxygen demand without significantly impacting potential energy.
Area of Science:
- Cardiovascular Physiology
- Cardiac Mechanics
- Heart Failure Research
Background:
- Left ventricular (LV) function is crucial for cardiac output.
- Understanding LV mechanics under altered loading conditions is vital for treating heart failure.
- Pulsatile assist devices aim to improve cardiac performance.
Purpose of the Study:
- To evaluate the effects of asynchronous, pulsatile left atrial-aortic bypass on LV mechanics.
- To assess LV pressure-volume relationships before and after inducing heart failure.
- To determine if this bypass impacts LV contractile state.
Main Methods:
- Utilized micromanometry and ultrasonic dimension transducers in Holstein calves.
- Calculated LV volume using ellipsoidal geometry.
- Measured contractility index, pressure-volume area, external work, and potential energy.
- Induced heart failure via microsphere injection into the left main coronary artery.
Main Results:
- Pulsatile bypass did not change the LV contractility index in control or heart failure states.
- Significant reductions in end-diastolic volume, pressure-volume area, and external work were observed.
- End-systolic volume and potential energy remained unchanged during bypass.
Conclusions:
- Asynchronous pulsatile left atrial-aortic bypass does not impair LV contractile state.
- The reduction in pressure-volume area suggests decreased myocardial oxygen consumption.
- Unchanged potential energy indicates limited ventricular unloading, despite reduced workload.