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Depressed mechanoenergetics and compensatory responses in idiopathic dilated cardiomyopathy
1First Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Insights
Idiopathic dilated cardiomyopathy (DCM) shows depressed cardiac mechanoenergetics due to compensatory responses for reduced contractility. Ventriculoarterial coupling is mismatched in DCM patients, impacting heart function.
Area of Science:
- Cardiology
- Biomedical Engineering
- Physiology
Background:
- Idiopathic dilated cardiomyopathy (DCM) is characterized by impaired left ventricular contractility.
- Understanding the mechanoenergetic consequences of reduced contractility in DCM is crucial for patient management.
- Compensatory mechanisms in DCM can affect cardiac efficiency and hemodynamics.
Purpose of the Study:
- To elucidate the relationship between depressed mechanoenergetics and compensatory responses in idiopathic dilated cardiomyopathy (DCM).
- To investigate the ventriculoarterial coupling (Ea/Ees) in DCM patients compared to healthy controls.
- To determine the role of volume enlargement in maintaining cardiac function in DCM.
Main Methods:
- Utilized a dual-field volume conductance catheter with a micromanometer-tipped catheter for measurements.
- Measured left ventricular end-systolic elastance (Ees), effective arterial elastance (Ea), external work (EW), and pressure-volume area (PVA).
- Evaluated ventriculoarterial coupling (Ea/Ees) as an indicator of the heart's interaction with the arterial system.
Main Results:
- Patients with DCM exhibited significantly lower Ees compared to controls, while Ea was similar between groups.
- Ventriculoarterial coupling (Ea/Ees) was significantly mismatched (Ea > Ees) in DCM patients, deviating from the optimal condition (Ea/Ees = 1/2).
- Depressed mechanoenergetics in DCM were identified as a compensatory response to maintain adequate blood pressure despite decreased contractility.
Conclusions:
- The observed mismatch in ventriculoarterial coupling (Ea/Ees) in DCM patients contributes to depressed cardiac mechanoenergetics.
- Compensatory mechanisms, including volume enlargement, are vital for sustaining blood pressure and cardiac output in DCM.
- These findings highlight the complex interplay between contractility, ventriculoarterial coupling, and overall cardiac energetics in DCM.
Abstract:
The aim of this study was to clarify that the depressed mechanoenergetics in patients with idiopathic dilated cardiomyopathy (DCM) resulted from compensation for the decreased contractility. The study population consisted of eight control subjects, with normal left ventricular size and ejection fraction and 31 patients with DCM. Left ventricular end-systolic elastance (Ees), effective arterial elastance (Ea), external work (EW), and the pressure-volume area (PVA) were measured, using a dual-field volume conductance catheter equipped with a micromanometer-tipped catheter. Ea/Ees was evaluated as ventriculoarterial coupling. Normal hearts worked at almost optimal condition (defined as Ea/Ees = 1/2), while ventriculoarterial coupling was far from the optimum (Ea > Ees) in patients with DCM. Ees in patients with DCM was less than that in control subjects; however, Ea was similar in the two groups. The mismatch of Ea/Ees observed in DCM leads to depressed mechanoenergetics as a result of the compensatory response to maintain adequate blood pressure. Volume enlargement plays an important role in maintaining adequate blood pressure and cardiac output in the course of chronic deterioration of contractility.