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Aortic input impedance and ventriculoarterial coupling following cardioversion/defibrillation
R Bauernschmitt1, H Mehmanesh, S Schulz
1Department of Cardiac Surgery, University of Heidelberg, Germany.
Pacing and Clinical Electrophysiology : PACE
|August 24, 1999
Summary
Low energy defibrillation does not affect hemodynamics or ventriculoarterial coupling. High energy defibrillation temporarily increases ventricular load, impacting arterial hemodynamics, which is crucial for patients with reduced left ventricular function.
Area of Science:
- Cardiovascular Physiology
- Electrophysiology
- Hemodynamics
Background:
- Defibrillation shocks are vital post-cardiac surgery and during device implantation.
- The hemodynamic effects of defibrillation, particularly on ventriculoarterial coupling, require further elucidation.
Purpose of the Study:
- To evaluate the impact of defibrillation shocks on arterial hemodynamics and ventriculoarterial coupling.
- To differentiate the effects of low-energy versus high-energy defibrillation on circulatory dynamics.
Main Methods:
- Mongrel dogs underwent thoracotomy with continuous monitoring of aortic/ventricular pressure and aortic flow.
- Atrial or ventricular fibrillation was induced and terminated using low (3-5J) or high (34J) energy epicardial shocks.
- Aortic input impedance and ventriculoarterial coupling (Ea/Ees ratio) were calculated.
Main Results:
- Low-energy defibrillation showed no significant changes in aortic impedance or ventriculoarterial coupling.
- High-energy defibrillation significantly increased total peripheral resistance and the Ea/Ees ratio (P < 0.005).
- These high-energy shock effects were reversible within 15 minutes.
Conclusions:
- Low-energy defibrillation is hemodynamically neutral in this model.
- High-energy defibrillation transiently elevates ventricular load and alters arterial hemodynamics.
- Findings are relevant for managing patients with compromised left ventricular function.