title: Heart monitoring using left ventricle impedance and ventricular electrocardiography in left ventricular assist device patients.
abstract: BACKGROUND
  Patients who develop critical arrhythmia during left ventricular assist device (LVAD) perfusion have a low survival rate. For diagnosis of unexpected heart abnormalities, new heart-monitoring methods are required for patients supported by LVAD perfusion. Ventricular electrocardiography using electrodes implanted in the ventricle to detect heart contractions is unsuitable if the heart is abnormal. Left ventricular impedance (LVI) is useful for monitoring heart movement but does not show abnormal action potential in the heart muscle.
  
  
  OBJECTIVE
  To detect detailed abnormal heart conditions, we obtained ventricular electrocardiograms (v-ECGs) and LVI simultaneously in porcine models connected to LVADs.
  
  
  METHODS
  In the porcine models, electrodes were set on the heart apex and ascending aorta for real-time measurements of v-ECGs and LVI. As the carrier current frequency of the LVI was adjusted to 30 kHz, it was easily derived from the original v-ECG signal by using a high-pass filter (cutoff: 10 kHz). In addition, v-ECGs with a frequency band of 0.1 - 120 Hz were easily derived using a low-pass filter. Simultaneous v-ECG and LVI data were compared to detect heart volume changes during the Q-T period when the heart contracted. A new real-time algorithm for comparison of v-ECGs and LVI determined whether the porcine heartbeats were normal or abnormal. Several abnormal heartbeats were detected using the LVADs operating in asynchronous mode, most of which were premature ventricle contractions (PVCs). To evaluate the accuracy of the new method, the results obtained were compared to normal ECG data and cardiac output measured simultaneously using commercial devices.
  
  
  RESULTS
  The new method provided more accurate detection of abnormal heart movements. This method can be used for various heart diseases, even those in which the cardiac output is heavily affected by LVAD operation.
authors.affiliation: Department of Cardiovascular and Thoracic Surgery, Soonchunhyang University Hospital, Bucheon-si, South Korea. hktree@schmc.ac.kr.
authors.forename: Keun
authors.initials: K
authors.lastname: Her
authors.affiliation: Department of Mechanical and Biomedical Engineering, College of Engineering, Kangwon National University, 192-1 Hyoja-Dong, Chuncheon-si, South Korea. cutemole@gmail.com.
authors.forename: Chi Bum
authors.initials: CB
authors.lastname: Ahn
authors.affiliation: School of Medicine, Kangwon National University, Chuncheon-si, South Korea. heart@kangwon.ac.kr.
authors.forename: Sung Min
authors.initials: SM
authors.lastname: Park
authors.affiliation: Department of Mechanical and Biomedical Engineering, College of Engineering, Kangwon National University, 192-1 Hyoja-Dong, Chuncheon-si, South Korea. swchoe@kangwon.ac.kr.
authors.forename: Seong Wook
authors.initials: SW
authors.lastname: Choi
mesh_terms: D000465:Algorithms; D000818:Animals; D001011:Aorta; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy; D002302:Cardiac Output; D017097:Electric Impedance; D004562:Electrocardiography / Q000379:methods*; D004567:Electrodes, Implanted; D005121:Extremities; D006352:Heart Ventricles / Q000503:physiopathology*; D006353:Heart-Assist Devices; D018056:Hemorheology; D008991:Monitoring, Physiologic / Q000379:methods*; D009200:Myocardial Contraction; D034421:Sus scrofa; D018879:Ventricular Premature Complexes / Q000503:physiopathology