Experimental study
Termination of ventricular fibrillation in dogs by depolarizing a critical amount of myocardium

https://doi.org/10.1016/0002-9149(75)90865-6Get rights and content

Abstract

The role of a critical myocardial mass required to maintain ventricular fibrillation initiated by rapid ventricular pacing was studied by two methods in dogs placed on total cardiopulmonary bypass. In the first method, depolarization of a limited myocardial mass was accomplished by injecting potassium chloride into one or two coronary arteries. Injection of potassium chloride simultaneously into the left circumflex and left anterior descending coronary arteries abolished ventricular fibrillation more often than did injection into any other single or combination of two coronary arteries (P < 0.0001). Ventricular fibrillation could not be reinitiated as long as the left ventricle remained inexcitable. Immersing the heart in a solution of potassium chloride or injecting the solution into the right and left ventricular cavities failed to terminate ventricular fibrillation. The second method evaluated the amount of current necessary to terminate ventricular fibrillation when the current was passed between two right ventricular electrodes, between two left ventricular electrodes and between one right ventricular and one left ventricular electrode. Electrical shocks of equal magnitude terminated ventricular fibrillation most often when those shocks were delivered between an electrode located at the right ventricular apex and an electrode located at the posterior base of the left ventricle, and least often when the shock was delivered between two right ventricular electrodes. Successful defibrillation results when a critical amount of myocardium becomes depolarized by either potassium chloride or electrical discharge; depolarization of every cell in both ventricles is not necessary to terminate ventricular fibrillation in the entire heart.

References (12)

There are more references available in the full text version of this article.

Cited by (397)

  • Low-energy, single-pulse surface stimulation defibrillates large mammalian ventricles

    2022, Heart Rhythm
    Citation Excerpt :

    To extinguish all focal sources of reentry while also preventing the generation of new rotors, that is, the critical mass hypothesis, this new approach requires a very dense pattern of electrodes to be placed on the surface of large mammalian hearts. In defibrillation studies using field shocks,23 defibrillation success is highest when a voltage gradient of 5 V/cm is generated throughout 95% of the myocardium. Importantly, we achieved >95% refractory myocardium when capturing >75% of the EG with surface stimulation at only a fraction of the energy, which could be reduced even further with a more efficient means to target EG than line electrodes.

  • Cardioversion

    2022, Small Animal Critical Care Medicine
  • Optogenetics for cardiac pacing, resynchronization, and arrhythmia termination

    2020, Emerging Technologies for Heart Diseases: Volume 2: Treatments for Myocardial Ischemia and Arrhythmias
View all citing articles on Scopus

This study was supported in part by the Herman C. Krannert Fund, Indianapolis, Ind., Grants HL06308, HL-05963 and HL-05749 from the National Heart and Lung Institute, National Institutes of Health, Bethesda, Md. and the Indiana Heart Association, Indianapolis, Ind.

View full text