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Revisiting the relationship between left ventricular ejection fraction and ventricular-arterial coupling.
Serban Mihaileanu1, Elena-Laura Antohi2,3
1Institut Mutualiste Montsouris, Paris, France.
ESC Heart Failure
|July 21, 2020
Summary
This study questions the physiological validity of simplified formulas for ventricular-arterial coupling (VAC), highlighting mathematical inconsistencies with normal left ventricular ejection fraction (LVEF) and suggesting the Ea/Ees ratio may be a more sensitive clinical tool.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
- Mathematical Modeling in Medicine
Background:
- Left ventricular ejection fraction (LVEF) is a key indicator of cardiac function.
- Ventricular-arterial coupling (VAC) formulas, including elastance (Ees), volume intercept (V0), and arterial elastance (Ea), are widely used.
- Existing VAC formulas may have limitations in accurately reflecting physiological conditions.
Purpose of the Study:
- To analyze the relationship between LVEF and common VAC calculation formulas.
- To evaluate the mathematical consequences and physiological validity of these formulas.
- To explore the potential of the Ea/Ees ratio as a clinical tool.
Main Methods:
- Mathematical analysis of established VAC formulas.
- Application of Euclid's golden ratio (Phi) to LVEF-VAC relationships.
- Comparison of formula outputs with normal LVEF distribution (modal LVEF ~62%).
Main Results:
- Simplified VAC formulas with V0=0 yield physiologically inaccurate results.
- Chen's formula V0 extraction shows high negative values in normal subjects.
- LVEF equals Ea/Ees at a ratio of 0.618 (62%) only when V0 is 0 mL.
- The Ea/Ees ratio demonstrates more dynamic behavior than LVEF, potentially aiding in heart failure management.
Conclusions:
- Simplified VAC formulas require cautious application due to mathematical oversimplifications.
- The Ea/Ees ratio may offer greater sensitivity than LVEF in specific hemodynamic scenarios.
- Further understanding of VAC formula limitations is crucial for accurate clinical practice, especially in heart failure with preserved ejection fraction.
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