Short-term hemodynamic effects of cardiac resynchronization therapy in patients with heart failure, a narrow QRS duration, and no dyssynchrony

Lynne K. Williams, Susan Ellery, Kiran Patel, Francisco Leyva, Robert A. Bleasdale, Thanh T. Phan, Berthold Stegemann, Vince Paul, Paul Steendijk, Michael Frenneaux

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27 Citations (Scopus)

Abstract

Background-Cardiac resynchronization therapy produces both short-term hemodynamic and long-term symptomatic/mortality benefits in symptomatic heart failure patients with a QRS duration > 120 ms. This is conventionally believed to be due principally to relief of dyssynchrony, although we recently showed that relief of external constraint to left ventricular filling may also play a role. In this study, we evaluated the short-term hemodynamic effects in symptomatic patients with a QRS duration < 120 ms and no evidence of dyssynchrony on conventional criteria and assessed the effects on contractility and external constraint.

Methods and Results-Thirty heart failure patients (New York Heart Association class III/IV) with a left ventricular ejection fraction <= 35% who were in sinus rhythm underwent pressure-volume studies at the time of pacemaker implantation. External constraint, left ventricular stroke work, dP/dtmax, and the slope of the preload recruitable stroke work relation were measured from the end-diastolic pressure-volume relation before and during delivery of biventricular and left ventricular pacing. The following changes were observed during delivery of cardiac resynchronization therapy: Cardiac output increased by 25 +/- 5% (P < 0.05), absolute left ventricular stroke work increased by 26 +/- 5% (P < 0.05), the slope of the preload recruitable stroke work relation increased by 51 +/- 15% (P < 0.05), and dP/dtmax increased by 9 +/- 2% (P < 0.05). External constraint was present in 15 patients and was completely abolished by both biventricular and left ventricular pacing (P < 0.05).

Conclusion-Cardiac resynchronization therapy results in an improvement in short-term hemodynamic variables in patients with a QRS <120 ms related to both contractile improvement and relief of external constraint. These findings provide a potential physiological basis for cardiac resynchronization therapy in this patient population. (Circulation. 2009;120:1687-1694.)

Original languageEnglish
Pages (from-to)1687-1694
Number of pages8
JournalCirculation
Volume120
Issue number17
Early online date12 Oct 2009
DOIs
Publication statusPublished - 27 Oct 2009

Keywords

  • cardiac output
  • heart failure
  • hemodynamics
  • pacing
  • systolic pressure-volume
  • dilated cardiomyopathy
  • parallel conductance
  • hypertonic saline
  • catheter
  • performance
  • delay
  • trial
  • block

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