title: Acute hemodynamic effect of left ventricular endocardial pacing in cardiac resynchronization therapy: assessment by pressure-volume loops.
abstract: BACKGROUND
  During cardiac resynchronization therapy (CRT) device implantation, the pacing lead is usually positioned in the coronary sinus (CS) to stimulate the left ventricular (LV) epicardium. Transvenous LV endocardial pacing via transseptal puncture has been proposed as an alternative method. In the present study, we evaluated the acute hemodynamic effects of CRT through LV endocardial pacing in heart failure patients by analyzing LV pressure-volume relationships.
  
  
  RESULTS
  LV pressure and volume data were determined via conductance catheter during CRT device implantation in 10 patients. In addition to the standard epicardial CS pacing, the following endocardial LV sites were systematically assessed: the site transmural to the CS lead, the LV apex, the septal midwall, the basal lateral free wall, and the midlateral free wall. Four atrioventricular delays were tested. There was a significant improvement of systolic function with CRT in all LV pacing configurations, whereas no differences in systolic or diastolic function were detected between LV epicardial and endocardial transmural sites. The optimal pacing site varied among patients but was rarely related to relatively longer activation delays, as assessed by analyzing endocardial electric activation maps. Nonetheless, positioning the pacing lead at the optimal endocardial LV site in each patient significantly improved LV performance in comparison with conventional CS site stimulation (stroke volume, 83 [79-112] mL versus 73 [62-89] mL; P=0.034).
  
  
  CONCLUSIONS
  Pacing at the optimal individual LV endocardial site yields enhanced LV performance in comparison with conventional CS site stimulation. Endocardial LV pacing might constitute an alternative approach to CRT, when CS pacing is not viable.
authors.affiliation: Institute of Internal Medicine and Cardiology, University of Florence, Florence, Italy. lpadeletti@interfree.it
authors.forename: Luigi
authors.initials: L
authors.lastname: Padeletti
authors.forename: Paolo
authors.initials: P
authors.lastname: Pieragnoli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ricciardi
authors.forename: Laura
authors.initials: L
authors.lastname: Perrotta
authors.forename: Gino
authors.initials: G
authors.lastname: Grifoni
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Porciani
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Lionetti
authors.forename: Sergio
authors.initials: S
authors.lastname: Valsecchi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D002306:Cardiac Volume / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy*; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D011379:Prognosis; D016277:Ventricular Function, Left / Q000502:physiology*; D017725:Ventricular Pressure / Q000502:physiology*