title: Wave recognition and use of the intraoperative unipolar esophageal electrocardiogram.
abstract: OBJECTIVE
  To evaluate the automated determination of onset and offset times and amplitudes of all the PQRST waves from simultaneously recorded surface electrocardiogram (SECG) and unipolar esophageal ECG (EsECG). The occurrence of ST segment deviation is also examined.
  
  
  METHODS
  Prospective, observational study.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  30 patients undergoing coronary artery bypass graft (CABG) surgery.
  
  
  METHODS
  SECG and two-lead unipolar EsECG were recorded after induction of anesthesia and before cardiopulmonary bypass (CPB).
  
  
  RESULTS
  The amplitudes of the P and T waves and the ST segment deviation were measured. EsECG had more noise than SECG. Slight movement of the esophageal electrodes occasionally caused substantial changes in the wave amplitudes and ST segment deviation in the unipolar EsECG. The maximum P wave amplitude in EsECG was, on average, 97% greater than the maximum P wave amplitude in SECG, ST segment deviation in EsECG was observed in the absence of ST segment deviation in SECG and vice versa.
  
  
  CONCLUSIONS
  The recognition and measurement of all the PQRST waves can be improved and automated by simultaneous use of EsECG and SECG. The P wave amplitude is greater in EsECG than in SECG, which may faciliate the identification of supraventricular versus ventricular arrhythmias. ST segment deviation in the unipolar EsECG may not be suitable for the routine detection of ischemia.
authors.affiliation: Department of Anesthesia, University of California at San Francisco, USA.
authors.forename: U
authors.initials: U
authors.lastname: Jain
mesh_terms: D001145:Arrhythmias, Cardiac / Q000453:epidemiology / Q000209:etiology; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D004562:Electrocardiography / Q000379:methods*; D004947:Esophagus; D006801:Humans; D015994:Incidence; D007430:Intraoperative Care / Q000379:methods*; D017202:Myocardial Ischemia / Q000453:epidemiology / Q000209:etiology; D011446:Prospective Studies; D014481:United States