Elevated defibrillation threshold when right-sided venous access is used for nonthoracotomy implantable defibrillator lead implantation. The Endotak Investigators.

INTRODUCTION

Although myriad factors influence the defibrillation threshold, the relation between the site of transvenous lead entry into the vascular system and the defibrillation threshold has not been reported. This study examines the influence that venous entry site has on defibrillation success for a transvenous implantable cardioverter defibrillator lead with two defibrillating coils.

METHODS AND RESULTS

The study population comprised 345 patients. Their mean age was 61 +/- 13 years and, left ventricular ejection fraction was 0.33 +/- 0.13. A left-sided approach was used in 324 (93.9%) of the patients, and a right-sided approach was used in the remaining 21 (6.1%) patients. There was no difference in the gender, age, left ventricular ejection fraction, or underlying cardiac disease in the two groups. For all patients, with a transvenous lead used either alone or with a submuscular or subcutaneous patch, the biphasic defibrillation threshold was 9.9 +/- 4.8 J when a left-sided approach was used, and 14.0 +/- 7.3 J when a right-sided approach was used (P = 0.02). When a transvenous lead was used with a submuscular or subcutaneous patch (115 patients), the biphasic defibrillation threshold was 9.5 +/- 4.3 J when a left-sided approach was used, and 12.0 +/- 10.0 J when a right-sided approach was used (P = 0.98). When a transvenous lead was used without a submuscular or subcutaneous patch (230 patients), the biphasic defibrillation threshold was 10.1 +/- 5.0 J when a left-sided approach was used, and 14.6 +/- 6.6 J when a right-sided approach was used (P < 0.01). For the entire group of patients and for each specific lead arrangement, there was no significant difference in the defibrillating lead system impedance when right-sided versus left-sided approaches were compared.

CONCLUSION

Left-sided approaches to implant transvenous leads with two coils for defibrillation result in lower biphasic defibrillation thresholds than when right-sided approaches are used.