title: Automated left ventricular capture management.
abstract: BACKGROUND
  The stimulation thresholds of left ventricular (LV) leads tend to be less reliable than conventional leads. Cardiac resynchronization therapy (CRT) requires continuous capture of both ventricles.
  
  
  OBJECTIVE
  The purpose of this study is to evaluate a novel algorithm for the automatic measurement of the stimulation threshold of LV leads in cardiac resynchronization systems.
  
  
  METHODS
  We enrolled 134 patients from 18 centers who had existing CRT-D systems. Software capable of automatically executing LV threshold measurements was downloaded into the random access memory (RAM) of the device. The threshold was measured by pacing in the left ventricle and analyzing the interventricular conduction sensed in the right ventricle. Automatic LV threshold measurements were collected and compared with manual LV threshold tests at each follow-up visit and using a Holter monitor system that recorded both the surface electrocardiograph (ECG) and continuous telemetry from the device.
  
  
  RESULTS
  The proportion of Left Ventricular Capture Management (LVCM) in-office threshold tests within one programming step of the manual threshold test was 99.7% (306/307) with a two-sided 95% confidence interval of (98.2%, 100.0%). The algorithm measured the threshold successfully in 96% and 97% of patients after 1 and 3 months respectively. Holter monitor analysis in a subset of patients revealed accurate performance of the algorithm.
  
  
  CONCLUSIONS
  This study demonstrated that the LVCM algorithm is safe, accurate, and highly reliable. LVCM worked with different types of leads and different lead locations. LVCM was demonstrated to be clinically equivalent to the manual LV threshold test. LVCM offers automatic measurement, output adaptation, and trends of the LV threshold and should result in improved ability to maintain LV capture without sacrificing device longevity.
authors: Mid-State Cardiology Associates, Nashville, Tennessee, USA. ghcmd@comcast.net
authors: George H
authors: GH
authors: Crossley
authors: Hardwin
authors: H
authors: Mead
authors: Karen
authors: K
authors: Kleckner
authors: Todd
authors: T
authors: Sheldon
authors: Lynn
authors: L
authors: Davenport
authors: Manya R
authors: MR
authors: Harsch
authors: Purvee
authors: P
authors: Parikh
authors: Brian
authors: B
authors: Ramza
authors: Robert
authors: R
authors: Fishel
authors: J Russell
authors: JR
authors: Bailey
mesh_terms: D000368:Aged; D000465:Algorithms; D001145:Arrhythmias, Cardiac / Q000628:therapy; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D017147:Defibrillators, Implantable; D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D012984:Software; D016276:Ventricular Function