title: Low-energy endocardial defibrillation using dual, triple, and quadruple electrode systems.
abstract: The feasibility of achieving both universal application of nonthoracotomy leads and low (< or = 15 J) defibrillation energy requirements by optimizing lead system configuration for use with low-output (<30 J) biphasic shock pulse generators was examined. Sixteen patients (mean age 62 +/- 8 years and mean left ventricular ejection fraction of 38 +/- 15%) were included in the study. All patients had either experienced syncope with induced ventricular tachycardia (n = 4) or had documented sustained ventricular tachycardia (n = 7) or ventricular fibrillation (n = 5). Defibrillation threshold testing was performed in 2 stages on different days in these patients. In the first stage, 2 defibrillation catheter electrodes were positioned in the right ventricle and superior vena cava with an axillary cutaneous patch. Fifteen-joule, 10- and 5-J biphasic shocks were delivered across 3 different electrode configurations-right ventricle to superior vena cava, right ventricle to axillary patch, right ventricle to a combination of superior vena cava and axillary patch. In the second stage, an 80-ml can electrode was added subcutaneously in a pectoral location to the previous leads. Configurations compared were the right ventricle to pectoral can, and right ventricle to an "array"-combining superior vena cava, can, and axillary patch leads. The defibrillation threshold was determined using a step-down method. In stage 1, mean defibrillation threshold for the right ventricle to axillary patch (12.7 +/- 5.9 J) and right ventricle to superior vena cava plus axillary patch (9.8 +/- 5.2 J) configurations was lower than the right ventricle to superior vena cava configuration (14.2 +/- 6.4 J, p <0.05). In stage 2, the defibrillation was higher for the right ventricle to pectoral can (9.2 +/- 5.1 J) configuration compared with the right ventricle to the array (5.6 +/- 3.6 J, p < or =0.05). The right ventricle to array had the lowest defibrillation threshold, whereas the right ventricle to pectoral can was the best dual electrode system. Low-energy endocardial defibrillation (< or =10 J) was feasible in 72% of tested patients with > 1 electrode configuration at 10 J, whereas only 53% of successful patients could be reverted at >1 electrode configuration at 5 J (p <0.05). Reduction in maximum pulse generator output to < or =25 J using these electrode configurations with bidirectional shocks is feasible and maintains an adequate safety margin.
authors.affiliation: Arrhythmia & Pacemaker Service, Eastern Heart Institute, Passaic, New Jersey, USA.
authors.forename: A N
authors.initials: AN
authors.lastname: Munsif
authors.forename: S
authors.initials: S
authors.lastname: Saksena
authors.forename: P
authors.initials: P
authors.lastname: DeGroot
authors.forename: R B
authors.initials: RB
authors.lastname: Krol
authors.forename: P
authors.initials: P
authors.lastname: Matthew
authors.forename: I
authors.initials: I
authors.lastname: Giorgberidze
authors.forename: R R
authors.initials: RR
authors.lastname: Kaushik
authors.forename: R
authors.initials: R
authors.lastname: Mehra
mesh_terms: D000368:Aged; D004554:Electric Countershock / Q000295:instrumentation / Q000379:methods*; D017097:Electric Impedance; D004566:Electrodes; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013318:Stroke Volume; D017180:Tachycardia, Ventricular / Q000503:physiopathology / Q000628:therapy*; D014693:Ventricular Fibrillation / Q000503:physiopathology / Q000628:therapy*; D016277:Ventricular Function, Left