Sequential pulse defibrillation in man: comparison of thresholds in normal subjects and those with cardiac disease

We compared the parameters describing the defibrillation threshold in patients with normal hearts and in patients with ischemic heart disease, using a special electrode system and sequential pulses of current. Twenty-eight patients consented to the study (mean age: 36.6 +/- 10.1 years; mean mass: 80.7 +/- 13.8 kg). Twenty-one patients underwent surgery for Wolff-Parkinson-White syndrome (relatively normal hearts). Six patients had a history of previous myocardial infarction and aneurysm or coronary artery disease; and one patient had been resuscitated from an episode of sudden death, without evidence of consequent myocardial damage. For 26 patients, defibrillation thresholds were determined intraoperatively by passing sequential pulses through a catheter electrode and epicardial mesh electrode. For 2 patients defibrillation thresholds were determined during electrophysiologic study, after ventricular fibrillation was induced by programmed stimulation, by passing sequential pulses through a catheter and skin-patch electrode. Parameters for sequential pulse defibrillation thresholds between the two groups did not differ appreciably. Total energy for patients with normal hearts averaged 9.9 +/- 6.3 J compared to 8.9 +/- 4.6 J for patients with cardiac disease. No patient with cardiac disease had defibrillation parameters that exceeded the range of the normal patients. These results suggest that the presence of cardiac disease may not significantly alter the parameters necessary for successful defibrillation when using sequential pulses for delivery of energy.