title: Noninvasive assessment of right ventricular diastolic function by electrical impedance tomography.
abstract: OBJECTIVE
  Electrical impedance tomography (EIT) offers the possibility to study blood volume changes within the right atrium during the cardiac cycle. The aim of this study was to determine the applicability of EIT in the assessment of right ventricular diastolic function in COPD.
  
  
  METHODS
  By means of region of interest analysis, impedance changes within the right atrium during the cardiac cycle were plotted as a function of time. As a diastolic index of the right ventricle, the right atrium emptying volume (RAEV), defined as the ratio between the volume change during the rapid filling phase relative to the total ventricular filling volume, was calculated. In a first study, the validity of the EIT method was assessed by comparison of the RAEV measured by EIT and MRI in a group of eight patients with severe COPD and seven control subjects. A second study was undertaken to assess the relation between RAEV and pulmonary artery pressure in a group of 27 patients measured by right-sided heart catheterization.
  
  
  RESULTS
  The correlation coefficient between RAEV measured with MRI and EIT was 0.78. The difference between RAEV measured by MRI and EIT was 8.3 +/- 15.7% (mean +/- SD) for the control subjects and 3.5 +/- 10.9% for the COPD patients. RAEV values measured by EIT and MRI were larger in the control group (47.1 +/- 7.6%) compared with the patient group (38.1 +/- 10.4%). There was a clear nonlinear relationship between RAEV and the pulmonary artery pressure (y = 315 x-0.64, r = 0.83, p < 0.001).
  
  
  CONCLUSIONS
  Our results indicate that RAEV measured by EIT is a useful noninvasive and inexpensive method for assessing right ventricular diastolic function in COPD patients.
authors.affiliation: Department of Pulmonary Medicine, Institute for Cardiovascular Research (ICAR-VU), Academic Hospital Vrije Universiteit, Amsterdam, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Vonk Noordegraaf
authors.forename: T J
authors.initials: TJ
authors.lastname: Faes
authors.forename: A
authors.initials: A
authors.lastname: Janse
authors.forename: J T
authors.initials: JT
authors.lastname: Marcus
authors.forename: J G
authors.initials: JG
authors.lastname: Bronzwaer
authors.forename: P E
authors.initials: PE
authors.lastname: Postmus
authors.forename: P M
authors.initials: PM
authors.lastname: de Vries
mesh_terms: D001794:Blood Pressure; D001810:Blood Volume; D006328:Cardiac Catheterization; D002306:Cardiac Volume; D003971:Diastole; D017097:Electric Impedance; D005260:Female; D006325:Heart Atria / Q000503:physiopathology; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D011237:Predictive Value of Tests; D011651:Pulmonary Artery / Q000503:physiopathology; D015203:Reproducibility of Results; D013318:Stroke Volume; D014054:Tomography; D016278:Ventricular Function, Right