title: Design of an acute dP/dt hemodynamic measurement protocol to isolate cardiac effect of pacing.
abstract: BACKGROUND
  Invasively measured maximum increase in left ventricular pressure (LV dP/dtmax) has been used to assess biventricular (BiV) pacing. We quantified extracardiac factors contributing to its variability, and developed a protocol to minimize these effects in an acute pacing experiment.
  
  
  RESULTS
  Continuous pressure was recorded by a guidewire sensor placed in the LV. Four to six test pacing interventions were performed, each repeated 3 times and followed by a baseline pacing configuration. Maximum increase in LV dP/dtmax from any measurement of BiV pacing was median 20.3% in 25 patients, compared with BiV pacing off. When directly comparing sequential measurements with BiV pacing on and off, median increase was 7.4%. Noncardiac sources of modulation included respiratory variation (6.4%), drift from first to last baseline measurement (5.0%), and discrepancy among repeated recordings of the same pacing intervention (3.3%). Comparing test interventions to interleaved baseline measurements reduced discrepancy among recordings to 2.1%; P < .001.
  
  
  CONCLUSIONS
  With repeated measurements of baseline state, and by comparing test interventions only to baseline measurements performed before and after, it is possible to minimize extracardiac factors and focus on the effects of test pacing interventions.
authors: Montreal Heart Institute/Université de Montréal, Montreal, Quebec, Canada. Electronic address: ablation2000@bellnet.ca.
authors: Bernard
authors: B
authors: Thibault
authors: Montreal Heart Institute/Université de Montréal, Montreal, Quebec, Canada.
authors: Marc
authors: M
authors: Dubuc
authors: St Jude Medical, Sylmar, California.
authors: Edward
authors: E
authors: Karst
authors: Montreal Heart Institute/Université de Montréal, Montreal, Quebec, Canada.
authors: Jason
authors: J
authors: Andrade
authors: Montreal Heart Institute/Université de Montréal, Montreal, Quebec, Canada.
authors: Katia
authors: K
authors: Dyrda
authors: Montreal Heart Institute/Université de Montréal, Montreal, Quebec, Canada.
authors: Peter G
authors: PG
authors: Guerra
authors: Montreal Heart Institute/Université de Montréal, Montreal, Quebec, Canada.
authors: Laurent
authors: L
authors: Macle
authors: Montreal Heart Institute/Université de Montréal, Montreal, Quebec, Canada.
authors: Lena
authors: L
authors: Rivard
authors: Montreal Heart Institute/Université de Montréal, Montreal, Quebec, Canada.
authors: Denis
authors: D
authors: Roy
authors: Montreal Heart Institute/Université de Montréal, Montreal, Quebec, Canada.
authors: Mario
authors: M
authors: Talajic
authors: St Jude Medical, Sylmar, California.
authors: Kyungmoo
authors: K
authors: Ryu
authors: St Jude Medical, Sylmar, California.
authors: Taraneh G
authors: TG
authors: Farazi
authors: Cleveland Clinic, Cleveland, Ohio.
authors: Niraj
authors: N
authors: Varma
authors: Montreal Heart Institute/Université de Montréal, Montreal, Quebec, Canada.
authors: Paul
authors: P
authors: Khairy
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012107:Research Design / Q000592:standards*; D013997:Time Factors; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy*
keywords: Heart failure; resynchronization therapy