Standardized ejection fraction as a parameter of overall ventricular pump function
S Morita1, R L Kormos, J C Astbury
1Department of Surgery, School of Medicine, University of Pittsburgh, Pennsylvania, USA. morita@heart.med.kyushu-u.ac.jp
Japanese Circulation Journal
|August 10, 2000
Summary
This study introduces a novel method using ejection fraction (EF) to assess overall heart pump function, independent of preload and afterload. This technique effectively evaluates ventricular performance across varying physiological conditions.
Area of Science:
- Cardiovascular Physiology
- Cardiac Mechanics
- Hemodynamics
Background:
- Assessing ventricular pump function requires parameters that integrate systolic and diastolic performance while isolating the heart from preload and afterload influences.
- Existing methods may not adequately separate intrinsic cardiac function from external loading conditions.
Purpose of the Study:
- To evaluate a method for assessing overall ventricular pump function.
- To determine if ejection fraction (EF), calculated from the pressure-volume relationship (PVR), can effectively separate cardiac performance from preload and afterload.
Main Methods:
- Utilized ten isolated canine hearts with a left ventricular balloon to determine the end-systolic pressure-volume relationship (ESPVR) and end-diastolic pressure-volume relationship (EDPVR).
- Calculated EF using end-diastolic volume (EDV) at 15 mmHg and end-systolic volume (ESV) at 70 mmHg.
- Administered low-dose (8 microg/min) and high-dose (40 microg/min) dobutamine infusions to assess changes in EF and end-systolic elastance.
Main Results:
- Dobutamine infusion significantly increased EF from a baseline of 0.25+/-0.16 to 0.33+/-0.13 (low dose) and 0.57+/-0.08 (high dose) (p<0.01).
- End-systolic elastance also increased significantly with dobutamine, from 3.11+/-0.83 to 3.48+/-1.08 (low dose) and 5.38+/-1.91 mmHg/ml (high dose) (p<0.01).
Conclusions:
- The calculated ejection fraction (EF) effectively separates intrinsic cardiac function from preload and afterload.
- This EF estimation method holds potential for comparing the overall pump function of hearts under diverse loading conditions.
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