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Transcatheter Endocardial Ablation: Acute Effects of Direct Current Countershock on Regional Myocardial Blood Flow
Author(s) -
TCHOU PATRICK,
REEVES WILLIAM,
AKHTAR MASOOD,
HARE JOHN,
RIEDER MICHELLE,
CHRISTENSEN CARL
Publication year - 1992
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/j.1540-8167.1992.tb01094.x
Subject(s) - medicine , cardiology , shock (circulatory) , ablation , blood flow , catheter ablation , anesthesia
Effect of DC Shock Ablation on Myocardial Blood Flow. Introduction: High energy direct current ablative shocks delivered through endocardial electrode catheters have been used as a treatment for various cardiac arrhythmias including ventricular tachycardia. Frequently, these shocks result in depression of myocardial function, at least transiently. Methods and Results: This study assessed the effect of a 200‐joule direct current shock delivered endocardially to the apex of the heart in ten adult mongrel dogs. Arterial blood pressures were monitored continuously. Myocardial contraction was monitored via two‐dimensional echocardiography. Regional myocardial blood flows were measured using radionuclide labeled microspheres before delivery of the shock, 30 seconds after delivery of the shock, and at 5 and 10 minutes after the shock. The results of the study demonstrated that there was a marked drop in arterial blood pressure immediately after the shock that gradually recovered over a 20‐minute period. Regional myocardial blood flow at the site of catheter ablation was severely depressed immediately after the shock. The degree of myocardial blood flow depression was inversely related to the distance from the site of ablation. At 5–10 minutes after ablation there was a marked hyperemic response in areas that suffered from depressed flow immediately after the shock. Two‐ dimensional echocardiography demonstrated depressed contractile function immediately after the shock with gradual recovery over a 10‐ to 20‐minute period. The catheter shock also generated prominent echo densities within the myocardium surrounding the ablative site. In contrast to the intracavitary echo densities that cleared quickly, the intramyocardial densities cleared much more slowly. Conclusion: The results of the study confirm the clinical observation that human left ventricular function is depressed acutely following a high‐energy ablative shock delivered to the left ventricular endocardium. Our results also demonstrated for the flrst time the effect of such ablative shocks on regional myocardial blood flow. Such depressions of blood flow may help explain the sudden drop in contractile function of the heart. The persistent intramyocardial echoes seen after the shock probably represented generation of intramyocardial bubbles that could obstruct arterial flow as well as disrupt cellular function. ( J Cardiovasc Electrophysiol, Vol. 3, pp. 40–47, February 1992 )