Cardiac fibrillation and heart weight

The existence of a minimal mass of tissue is an essential condition to trigger fibrillation. We asked whether the current required to induce fibrillation of this Mass is the saae as that required for larger masses. Fibrillation thresholds were determined in canine and feline ventricles of a wide range of sizes (1.7–102g) by using combinations of electrode leads and stimili directly applied to the myocardium. No significant differences were found among values nor definite trends could be observed when plotting stimulus amplitude as a function of ventricular weight. It was concluded that heart weight did not affect the fibrillation threshold.