title: The middle cardiac vein--a novel pathway to reduce the defibrillation threshold.
abstract: Defibrillation energy requirements of epicardial implantable cardioverter defibrillator systems are generally lower than endovascular systems currently used. The former has the disadvantage of requiring a thoracotomy and so has a greater morbidity and mortality than an endovascular procedure. The middle cardiac vein (MCV) is an epicardial structure that is accessible by a non-thoracotomy approach. This study investigated the merits of ventricular defibrillation from the middle cardiac vein. METHODS AND RESULTS. Defibrillation thresholds (DFT) were measured in 10 anesthetized pigs, weighing 34.5 +/- 44.1 kg (mean 39 kg). An Angeflex electrode (1.7 mm x 50 mm) was introduced via the left external jugular vein to the right ventricular apex. The MCV was identified with standard angiography techniques and a 4080 (Angeion Corp.) defibrillation electrode (1.6 mm x 65 mm) introduced into the vein. An active can was implanted in the left subpectoral region. The defibrillation thresholds (DFT) of the following defibrillation configurations were assessed using a modified four-reversal binary search: RV-->Can, RV + MCV-->Can and MCV-->Can. The DFT's for the three configurations were 15.5 +/- 2.8 J, 10.8 +/- 3.4 J and 13.7 +/- 2.4 J. Analysis of variance showed that the DFT with the RV + MCV combination was significantly less than the RV alone (p < 0.05)
  
  
  CONCLUSIONS
  Defibrillation is possible through the MCV and that incorporating an electrode in the MCV with RV-Can configuration can reduce the DFT by 30%.
authors.affiliation: Angeion Corporation, Minneapolis, MN, USA. JMM@cardiology.co.uk
authors.forename: P R
authors.initials: PR
authors.lastname: Roberts
authors.forename: J F
authors.initials: JF
authors.lastname: Urban
authors.forename: D E
authors.initials: DE
authors.lastname: Euler
authors.forename: M J
authors.initials: MJ
authors.lastname: Kallok
authors.forename: J M
authors.initials: JM
authors.lastname: Morgan
mesh_terms: D000818:Animals; D002406:Catheterization, Peripheral; D017023:Coronary Angiography; D003331:Coronary Vessels; D004195:Disease Models, Animal; D004554:Electric Countershock / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D005471:Fluoroscopy; D013552:Swine; D014680:Veins; D014693:Ventricular Fibrillation / Q000628:therapy