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The cellular electrophysiologic changes induced by high-energy electrical ablation in canine myocardium
Abstract:
High-energy electrical ablation is a new experimental approach to control arrhythmias. In this study, the cellular electrophysiologic effects of high-energy shocks (5 to 40 J) delivered in vitro to 14 epicardial tissues from 11 dogs were studied in an attempt to understand the nature and extent of injury as well as potential arrhythmogenic mechanisms. In addition, this preparation was used to test the importance of cathode-anode configuration, current density, and fiber orientation in the induction of tissue injury in vitro. Electrophysiologic abnormalities were noted up to 10 mm from the electrode wall, and their extent was determined in part by current density and the cathode-anode orientation. A decrease in resting membrane potential, action potential amplitude, and dV/dT occurred in all tissues after high-energy shocks, which was worst nearest the cathode and of graded severity at increasing distances from the cathode. The most severe effects were noted with high current densities and in tissues located between the cathode and anode. In addition, impaired impulse conduction and abnormal repolarization were documented. Histologic study demonstrated contraction band necrosis immediately after delivery of high-energy shocks. The extent and distribution of the contraction bands was in part dependent on the energy delivered and the cathode-anode configuration. These findings suggest potential mechanisms for arrhythmogenesis and altered regional hemodynamic abnormalities that occur in vivo.
Insights
High-energy electrical ablation causes cellular damage and electrophysiologic abnormalities in cardiac tissue. Injury extent depends on energy, current density, and electrode placement, suggesting arrhythmogenic mechanisms.
Area of Science:
- Cardiovascular Electrophysiology
- Cardiac Ablation Technologies
- Tissue Injury Mechanisms
Background:
- High-energy electrical ablation is an emerging technique for managing cardiac arrhythmias.
- Understanding the cellular effects of electrical shocks is crucial for refining ablation strategies.
Purpose of the Study:
- To investigate the cellular electrophysiologic effects of high-energy electrical shocks on canine epicardial tissue.
- To determine the influence of energy, current density, and electrode configuration on tissue injury and arrhythmogenesis.
Main Methods:
- In vitro electrophysiologic assessment of canine epicardial tissues subjected to high-energy shocks (5-40 J).
- Evaluation of electrode-tissue parameters including cathode-anode configuration, current density, and fiber orientation.
- Histologic examination for contraction band necrosis.
Main Results:
- Electrophysiologic abnormalities extended up to 10 mm from electrodes, influenced by current density and cathode-anode orientation.
- Reduced resting membrane potential, action potential amplitude, and dV/dT were observed, most severe near the cathode.
- Impaired impulse conduction, abnormal repolarization, and contraction band necrosis were documented, related to energy and electrode configuration.
Conclusions:
- High-energy electrical ablation induces significant cellular electrophysiologic changes and tissue injury.
- Current density and electrode configuration are critical factors determining the extent and nature of ablation-induced damage.
- Findings provide insights into potential mechanisms of post-ablation arrhythmias and hemodynamic dysfunction.