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Evaluation of left ventricular function utilizing transesophageal echocardiography during and after thoracic aortic
Insights
Left heart bypass (LHB) provides better left ventricular (LV) function stability during aortic cross-clamping (ACC) compared to simple aortic cross-clamping (SC). LHB reduces preload and afterload, maintaining LV performance.
Area of Science:
- Cardiovascular Surgery
- Cardiac Physiology
- Medical Devices
Background:
- Aortic cross-clamping (ACC) is a critical step in thoracic aortic surgeries, posing risks to left ventricular (LV) function.
- Maintaining adequate LV function during ACC is crucial for patient outcomes.
- Current methods like simple aortic cross-clamping (SC) may compromise LV performance due to increased afterload and preload.
Purpose of the Study:
- To compare the effects of left heart bypass (LHB) using a centrifugal pump versus SC on LV function during ACC.
- To evaluate hemodynamic parameters including end-diastolic volume index (EDVI), ejection fraction (EF), fractional shortening (FS), and end-systolic stress (ESS).
Main Methods:
- Transesophageal echocardiography was used to measure LV function parameters.
- Measurements were taken at multiple time points: before ACC, during ACC (2 and 20 min), and after unclamping (2 min and 1 h).
- Two groups were compared: patients undergoing LHB and patients undergoing SC.
Main Results:
- LHB group showed a decrease in EDVI and EF during ACC, but parameters returned to baseline post-unclamping.
- SC group exhibited a sustained increase in end-systolic stress (ESS) and transiently elevated systolic blood pressure during ACC.
- Post-unclamping, the SC group experienced significant decreases in EDVI and ESS.
Conclusions:
- Left heart bypass (LHB) demonstrates superior stability of left ventricular (LV) function during thoracic aortic cross-clamping (ACC) compared to simple aortic cross-clamping (SC).
- LHB mitigates the detrimental effects of ACC by reducing preload and afterload on the LV.
- These findings suggest LHB as a potentially safer alternative for preserving LV function during complex aortic procedures.
Abstract:
This study was designed to evaluate left ventricular (LV) function during aortic cross-clamping (ACC) by comparing left heart bypass (LHB) with a centrifugal pump and simple aortic cross-clamping (SC). The end-diastolic volume index (EDVI), ejection fraction (EF), fractional shortening (FS) and end-systolic meridional stress (ESS) were measured by transesophageal echocardiography. The measurements were performed 1) before ACC, 2) 2 min after ACC, 3) 20 min after ACC, 4) 2 min after unclamping and 5) 1 h after unclamping. With cross-clamping, a significant decrease was observed in both EDVI (108 vs 83 ml/m2) and EF (73 vs 67%) in patients with LHB. Patients utilizing SC showed a sustained increase in ESS (43 vs 64 10(3) dyne/cm2). The systolic blood pressure did not vary during LHB, but a transient increase occurred in patients with SC. With release of the cross-clamping, EDV and EF returned to the baseline values in patients with LHB. A significant decrease occurred in EDVI (101 vs 71 ml/m2) and ESS (61 vs 36 10(3) dyne/cm2) in the SC group. We conclude that circulatory support with LHB may offer greater stability of the LV function during thoracic aortic cross-clamping than SC because of the lower preload and afterload.