title: Esophageal countershock: anthropometric determinants of impedance.
abstract: OBJECTIVE
  To examine the use of a novel esophageal electrode system for countershock of atrial and ventricular tachyarrhythmias, with particular regard to the measurement of transesophageal and transthoracic impedances and their association with anthropometric variables.
  
  
  METHODS
  Transesophageal cardioversion was attempted during 131 episodes of arrhythmia in 105 patients (including 109 episodes of atrial fibrillation). The esophageal system also used in 29 patients undergoing electrophysiologic studies for investigation of ventricular tachyarrhythmias. Transesophageal and transthoracic impedances were estimated during passage of a high-frequency, low-amplitude current between the respective electrodes. Impedance estimates were associated with anthropometric measurements using linear regression (least-squares method).
  
  
  RESULTS
  In the group of patients undergoing attempted transesophageal cardioversion, the mean estimated transesophageal impedance of 52.6 +/- 11.7 omega was significantly lower than the mean estimated transthoracic impedance of 63.1 +/- 16.4 omega (n = 104, p < 0.01). For all the patients, transesophageal impedance was associated with weight, body mass index, and chest circumference (all r > or = 0.65, p < 0.01). Transthoracic impedance was associated with the same factors (all r > or = 0.55, p < 0.01).
  
  
  CONCLUSIONS
  This esophageal electrode system results in lower impedance values for countershock between the esophagus and the cutaneous cardiac apex in comparison with standard transthoracic cutaneous electrode placement. Both techniques are dependent on anthropometric factors.
authors.affiliation: Regional Medical Cardiology Centre, Royal Victoria Hospital, Belfast, North Ireland.
authors.forename: P P
authors.initials: PP
authors.lastname: McKeown
authors.forename: S
authors.initials: S
authors.lastname: Croal
authors.forename: J D
authors.initials: JD
authors.lastname: Allen
authors.forename: J
authors.initials: J
authors.lastname: Anderson
authors.forename: M M
authors.initials: MM
authors.lastname: Khan
authors.forename: A A
authors.initials: AA
authors.lastname: Adgey
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000886:Anthropometry; D001281:Atrial Fibrillation / Q000628:therapy*; D001824:Body Constitution / Q000502:physiology; D004554:Electric Countershock / Q000379:methods*; D017097:Electric Impedance; D004566:Electrodes; D004594:Electrophysiology; D004947:Esophagus; D005260:Female; D006321:Heart / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D017180:Tachycardia, Ventricular / Q000628:therapy*