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Complete unloading alone may not adequately protect the left ventricle
M Komeda1, A DeAnda, J R Glasson
1Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, CA 94305-5247, USA.
The Annals of Thoracic Surgery
|December 5, 1997
Summary
Complete left ventricular (LV) unloading during cardiopulmonary bypass requires high coronary perfusion pressure (CPP) to preserve systolic function. However, elevated CPP leads to diastolic dysfunction, indicating incomplete LV protection.
Area of Science:
- Cardiovascular Physiology
- Cardiac Surgery
- Hemodynamics
Background:
- Left ventricular (LV) unloading is accepted for preserving LV function.
- Its precise efficacy, especially during prolonged procedures, requires further definition.
Purpose of the Study:
- To investigate the influence of complete LV unloading on LV systolic and diastolic mechanics.
- To assess the impact of different coronary perfusion pressures (CPPs) on LV function during normothermic cardiopulmonary bypass.
Main Methods:
- Utilized an in situ isovolumic canine preparation (n=12) for prolonged normothermic cardiopulmonary bypass.
- Studied LV systolic and diastolic mechanics under two CPP conditions: moderate (107 +/- 18 mm Hg) and high (143 +/- 36 mm Hg).
Main Results:
- High CPP significantly preserved systolic LV function (LV end-systolic elastance, P < 0.001) compared to moderate CPP.
- Dobutamine improved systolic function only in the high-CPP group.
- High CPP was associated with impaired LV diastolic function (increased stiffness, P < 0.001), while moderate CPP did not alter diastolic function.
Conclusions:
- Complete LV unloading may inadequately preserve LV systolic function over time within the standard clinical CPP range.
- Higher CPP is necessary to prevent systolic deterioration during extended cardiopulmonary bypass.
- Despite improved systolic preservation, elevated CPP leads to diastolic dysfunction.