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Effects of the left ventricular assist device on right ventricular function
J R Elbeery1, C H Owen, M A Savitt
1Department of Surgery, Duke University Medical Center, Durham, N.C. 27710.
Summary
Left ventricular assist devices (LVADs) can cause right ventricular failure. This study found that LVADs do not significantly alter right ventricular systolic function, despite changes in biventricular geometry.
Area of Science:
- Cardiology
- Cardiovascular Surgery
- Biomedical Engineering
Background:
- Right ventricular failure is a significant cause of mortality in patients with left ventricular assist devices (LVADs).
- Previous studies suggested potential right ventricular dysfunction with LVADs, but lacked adequate methods for quantification.
- Accurate assessment of right ventricular function is crucial for managing LVAD patients.
Purpose of the Study:
- To investigate the impact of left ventricular volume unloading on right ventricular systolic function.
- To quantify right ventricular performance using the stroke work/end-diastolic volume relationship, a load-insensitive index.
- To evaluate changes in right ventricular function during maximal LVAD support.
Main Methods:
- Utilized an open-chested canine model (n=12) under anesthesia.
- Measured right and left ventricular pressures using micromanometers.
- Employed ultrasonic dimension transducers to measure ventricular diameters.
- Calculated biventricular volumes using modified ellipsoidal geometry.
- Assessed right ventricular systolic function via linear regression of stroke work versus end-diastolic volume during vena caval occlusion and LVAD support.
Main Results:
- Left ventricular unloading by LVAD significantly reduced left ventricular end-diastolic volume (-31%) and septal-free wall diameter (-7%).
- The right ventricular stroke work/end-diastolic volume relationship (slope and x-intercept) showed no significant change during maximal LVAD support compared to control conditions.
- Right ventricular peak positive pressure rise decreased slightly (-13%), but overall systolic performance remained stable.
Conclusions:
- Marked changes in biventricular geometry during LVAD-induced left ventricular unloading do not significantly impair right ventricular systolic performance in a normal heart.
- The stroke work/end-diastolic volume relationship is a reliable index for assessing RV function under LVAD conditions.
- These findings suggest that RV failure in LVAD patients may stem from factors beyond direct mechanical unloading effects on systolic function.