title: Alteration of the QT variability index in end-stage liver disease.
abstract: BACKGROUND
  A prolonged QT interval can lead to malignant ventricular arrhythmias and sudden cardiac death, and has frequently been found in end-stage liver disease (ESLD). However, myocardial repolarization lability has not yet been fully investigated. We evaluated the QT variability index (QTVI), a marker of temporal inhomogeneity in ventricular repolarization and an abnormality associated with re-entrant malignant ventricular arrhythmias. We determined whether QTVI is affected by the head-up tilt test in ESLD.
  
  
  METHODS
  We assessed 36 ESLD patients and 12 control subjects without overt heart disease before and after the 70-degree head-up tilt test. The electrocardiography signal (lead II) was recorded on a computer with an analog-to-digital converter. The RR interval (RRI) and QT interval were measured after recording 5 min of the digitized electrocardiography. Then, the QT intervals were corrected with Bazett's formula (QTc). QTVI was calculated through the following formula: QTVI = log10 [(QTv/QTm2)/(RRIv/RRIm2)], QTv/RRIv: variance of QTI/RRI, QTm/RRIm: mean of QT interval/RRI.
  
  
  RESULTS
  Cirrhotic patients exhibited an elevated QTVI. In particular, Child class C patients had a significantly increased QTVI compared to Child class A patients and the control subjects in the supine position. However, the head-up tilt test did not cause a significant difference in QTVI in relation to the severity of ESLD.
  
  
  CONCLUSIONS
  Myocardial repolarization lability was significantly altered in end-stage liver disease. Our data suggest that the severity of ESLD is associated with the degree of the alteration in the QT variability index.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ulsan University Hospital, Ulsan, Korea.
authors.forename: In Young
authors.initials: IY
authors.lastname: Huh
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ulsan University Hospital, Ulsan, Korea.
authors.forename: Eun Sun
authors.initials: ES
authors.lastname: Park
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ulsan University Hospital, Ulsan, Korea.
authors.forename: Kang-Il
authors.initials: KI
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ulsan University Hospital, Ulsan, Korea.
authors.forename: A-Ran
authors.initials: AR
authors.lastname: Lee
authors.affiliation: Department of Anesthesiology and Pain Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Gyu-Sam
authors.initials: GS
authors.lastname: Hwang
keywords: End-stage liver disease; Head-up tilt; QT interval; QT variability index
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