title: Non-invasive cardiac output measurements based on bioreactance for optimization of atrio- and interventricular delays.
abstract: OBJECTIVE
  Non-invasive cardiac output monitoring (NICOM) based on bio-reactance offers a portable method to assess ventricular function. Optimization of cardiac resynchronization therapy (CRT) by echocardiography is labour-intensive. We compared the ability of NICOM and echocardiography to facilitate optimum CRT device programming.
  
  
  RESULTS
  Forty-seven patients in sinus rhythm were evaluated within 14 days of CRT implantation. The atrio- (AV) and interventricular (VV) delay intervals were incrementally adjusted and at each setting, NICOM and echocardiographic data were recorded. Left ventricular (LV) volumes and function were assessed by echocardiography at baseline and 3 months. Response to CRT was defined as a reduction in LV end-systolic volume (LVESV) by >15%. In all patients, cardiac output (CO) increased significantly at optimized settings compared with baseline (5.66 +/- 1.4 vs. 4.35 +/- 1.1 L/min, P < 0.001). A 20% increase in acute CO following CRT predicted LVESV reduction of >15% with a sensitivity of 81% and specificity of 92% (AUC 0.86). The optimum AV delay determined by NICOM was confirmed by echocardiography in 40 of 47 patients (85%, r = 0.89, P < 0.01) and for VV delay in 39 of 47 patients (83%, r = 0.89, P < 0.01).
  
  
  CONCLUSIONS
  Non-invasive cardiac output monitoring is a simple, reliable, and portable alternative to echocardiography to program CRT devices.
authors.affiliation: Addenbrooke's Hospital, Hills Road, Cambridge, UK.
authors.forename: Fakhar Z
authors.initials: FZ
authors.lastname: Khan
authors.forename: Munmohan S
authors.initials: MS
authors.lastname: Virdee
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Pugh
authors.forename: Philip A
authors.initials: PA
authors.lastname: Read
authors.forename: Simon P
authors.initials: SP
authors.lastname: Fynn
authors.forename: David P
authors.initials: DP
authors.lastname: Dutka
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000517:prevention & control*; D002302:Cardiac Output; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D010992:Plethysmography, Impedance / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome