Relationship between sympathetic neural activity, coronary dynamics, and vulnerability to ventricular fibrillation during myocardial ischemia and reperfusion

Federico Lombardi, Richard L. Verrier, Bernard Lown

Research output: Contribution to journalArticlepeer-review

Abstract

The relationship between neural sympathetic discharge and vulnerability to ventricular fibrillation during myocardial ischemia and reperfusion was studied in 26 chloralose-anesthetized dogs. Preganglionic cardiac sympathetic impulse activity and ventricular fibrillation thresholds were separately determined before and during a 10-minute period of left anterior descending coronary artery occlusion and during release-reperfusion. Within 2 minutes of occlusion the ventricular fibrillation threshold was significantly decreased (from 25 ± 1.3 to 16 ± 2.3 mA, p <0.05) corresponding with the period of maximal activation of cardiac sympathetic preganglionic fibers (from 4.4 ± 0.2 to 6.3 ± 0.5 impulses/sec). Coronary sinus blood flow and oxygen tension decreased significantly. All these changes persisted for 5 to 6 minutes, thereafter returning to control levels despite continued obstruction of the coronary artery. A transient but significant reduction in ventricular fibrillation threshold also occurred with release of the occlusion but was unaccompanied by increases in sympathetic neural discharge. Bilateral stellectomy completely prevented the ventricular fibrillation threshold changes observed during coronary artery occlusion. However, there was no change in coronary sinus oxygen tension or blood flow. During reperfusion, stellectomy increased rather than decreased vulnerability to ventricular fibrillation. Stellectomy augmented the reactive hyperemic response to release-reperfusion. These findings indicate that enhanced cardiac sympathetic neural activity contributes to ventricular vulnerability associated with coronary artery obstruction. An opposite action results during release-reperfusion. Cardiac sympathetic neural discharge, by reducing the magnitude of reactive hyperemic response through influence on coronary vascular tone, exerts an antifibrillatory effect.

Original languageEnglish
Pages (from-to)958-965
Number of pages8
JournalAmerican Heart Journal
Volume105
Issue number6
DOIs
Publication statusPublished - 1983

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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