title: Defibrillation thresholds are increased by right-sided implantation of totally transvenous implantable cardioverter defibrillators.
abstract: Whether an ICD is placed via a left- or right-sided approach depends on venous access, the presence of a preexisting pacemaker, and other factors. Since the DFT is affected by lead position, which in turn is determined in part by the side of access, right-sided venous access could adversely affect DFTs. Furthermore, right-sided active can placement directs electric current toward the right hemithorax, which could further increase DFTs. This study sought to determine whether DFTs were increased by right-sided vascular access, and whether active can technology was beneficial or detrimental with right-sided ICD placement. Stepdown to failure DFTs were found in 290 patients receiving transvenous systems at the time of initial ICD implantation. Of these, 271 (93%) received left-sided systems and 19 (7%) received right-sided systems. The mean DFT in systems placed via left-sided vascular access was 11.3 +/- 5.3 J versus 17.0 +/- 4.9 J for right-sided implantation (P < 0.0001); right-sided DFTs were elevated for both active can and cold can systems. Right-sided active can devices had a lower DFT than right-sided cold can systems (15 +/- 4.1 J vs 19 +/- 4.8 J, P = 0.05). The right-sided implantation of implantable defibrillators results in significantly higher DFTs than the left-sided approach. This may be due to the less favorable distribution of the defibrillating field relative to the myocardium with the devices on the right. When right-sided implantation is clinically mandated, active can devices result in lower thresholds and should be used.
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905, USA. pfriedman@mayo.edu
authors.forename: P A
authors.initials: PA
authors.lastname: Friedman
authors.forename: M J
authors.initials: MJ
authors.lastname: Rasmussen
authors.forename: S
authors.initials: S
authors.lastname: Grice
authors.forename: J
authors.initials: J
authors.lastname: Trusty
authors.forename: M
authors.initials: M
authors.lastname: Glikson
authors.forename: M S
authors.initials: MS
authors.lastname: Stanton
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008452:Maximum Allowable Concentration; D008875:Middle Aged; D019919:Prosthesis Implantation; D013902:Radiography, Thoracic; D012189:Retrospective Studies; D013350:Subclavian Vein; D016896:Treatment Outcome; D014683:Vena Cava, Superior