Case report of an anomalous single azygos venous coil insertion to reduce the defibrillation threshold in a patient with a right-sided deltopectoral ICD implant

Implantable cardiac defibrillators (ICDs) reduce the incidence of sudden death in persons at high risk for lethal arrhythmias. The life-saving potential of ICDs depends on their ability to effectively deliver an adequate current density through a sufficient proportion of the ventricular myocardium to terminate ventricular fibrillation. High defibrillation thresholds (DFTs) are an important contributing factor to mortality in ICD recipients.1 High DFTs are more common in patients with right-sided implants, as well as patients on amiodarone, patients with hypertrophic cardiomyopathy and patients with large chest size. Some patients require right-sided ICD implants because of left innominate vein occlusion. A number of strategies have been described to improve the DFT in these patients, including using higher output devices, avoiding DFT raising drugs and using alternate vectors. The use of an extra coil in the superior vena cava (SVC), coronary sinus, azygos vein and hemiazygos vein have all been described in the literature.2–7 Other effective methods of lowering the DFT in this patient subpopulation include insertion of a subcutaneous array.8 A recent case report documented the use of a combination of an azygos venous coil and a subcutaneous array.6 There …