title: Cardiac resynchronization therapy optimization by ultrasonic cardiac output monitoring (USCOM) device.
abstract: OBJECTIVE
  We investigated the accuracy and feasibility of a 2D echo-independent ultrasonic continuous wave Doppler cardiac output monitoring device (USCOM) operated by trained nurse for the atrio-ventricular interval (AVI) optimization in cardiac resynchronization therapy (CRT).
  
  
  BACKGROUND
  CRT is of proven benefit in patients with advanced chronic heart failure and ventricular conduction delay. Appropriate AVI selection is critical to optimize hemodynamic in CRT. Currently, most non-invasive methods for AVI optimization are often complicated and labor-intensive.
  
  
  METHODS
  USCOM method, Ritter method, and aortic outflow cardiac output method were used to determine the optima AVI in 20 patients with CRT. The accuracy and time for measurement of each method were determined.
  
  
  RESULTS
  The optimal AVI determined by USCOM method had good correlation with Ritter's method and aortic outflow estimated cardiac output method (r2= 0.78, P < 0.01 and r2= 0.73, P < 0.01, respectively). The optimal AVI determined USCOM method showed good agreement (within 10 msec range) with Ritter's method (85% patients) and aortic outflow estimated cardiac output method (80%). The mean time for determining AVI using USCOM method was shorter than that with aortic outflow method (7.1 +/- 0.7 min vs 12.7 +/- 1.1 min, P < 0.01), whereas the mean time was shortest for Ritter method (4.7 +/- 1.6 min vs 7.1 +/- 0.7 min, P < 0.01).
  
  
  CONCLUSIONS
  USCOM device operated by trained nurse can provide a simple, accurate, and fast non-invasive method for the AVI optimization in CRT population.
authors.affiliation: Cardiology Division, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong.
authors.forename: Chung-Wah
authors.initials: CW
authors.lastname: Siu
authors.forename: Hung-Fat
authors.initials: HF
authors.lastname: Tse
authors.forename: Kathy
authors.initials: K
authors.lastname: Lee
authors.forename: Hon-Wah
authors.initials: HW
authors.lastname: Chan
authors.forename: Wai-Hong
authors.initials: WH
authors.lastname: Chen
authors.forename: Cindy
authors.initials: C
authors.lastname: Yung
authors.forename: Stephen
authors.initials: S
authors.lastname: Lee
authors.forename: Chu-Pak
authors.initials: CP
authors.lastname: Lau
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002302:Cardiac Output; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004452:Echocardiography / Q000295:instrumentation*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic