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The effects of mechanical cardiac stabilization on left ventricular performance
W R Burfeind1, F G Duhaylongsod, D Samuelson
1Department of Surgery, DUMC-3457, Durham, NC 27710, USA.
Summary
Mechanical cardiac stabilization temporarily reduces cardiac output due to ventricular compression, not impaired function or ischemia. Tissue injury from this stabilization technique is negligible.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Cardiac Physiology
Background:
- Mechanical cardiac stabilization aids precise coronary anastomoses on a beating heart.
- The impact of mechanical stabilization on hemodynamics, left ventricular performance, and tissue injury remains unclear.
Purpose of the Study:
- To evaluate the effects of mechanical cardiac stabilization on hemodynamics and left ventricular performance.
- To assess the degree of tissue injury caused by mechanical cardiac stabilization.
Main Methods:
- Twelve swine underwent median sternotomy with a mechanical stabilizing device placed on the left anterior descending coronary artery (LAD).
- Measurements included coronary blood flow (Doppler), regional myocardial function (sonomicrometry, PRSW relationship), and left ventricular pressure (micromanometer).
- Data were collected before, during, and after stabilizer application; tissue biopsies were obtained.
Main Results:
- Mechanical stabilization decreased cardiac output (4.2 to 3.6 l/min, P < 0.05), returning to baseline post-removal.
- Regional myocardial function, blood pressure, heart rate, and LAD blood flow remained unchanged.
- Histology revealed minimal myocyte necrosis (<1 mm depth) directly beneath the stabilizer.
Conclusions:
- Mechanical stabilization of the LAD can transiently reduce cardiac output via direct ventricular compression, not impaired contractility or ischemia.
- The observed reduction in stroke volume is a primary hemodynamic consequence.
- Underlying myocardial tissue injury associated with this stabilization method is negligible.