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Heart failure enhances susceptibility to arrhythmogenic cardiac alternans

Lance D Wilson1, Darwin Jeyaraj, Xiaoping Wan

  • 1Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio 44109-1998, USA.

Heart Rhythm
|February 4, 2009
PubMed

Insights

Heart failure (HF) increases susceptibility to dangerous cardiac alternans, a key factor in sudden cardiac death (SCD). This occurs due to impaired calcium cycling in failing hearts, leading to electrical instability.

Area of Science:

  • Cardiology
  • Electrophysiology
  • Heart Failure Research

Background:

  • Heart failure (HF) is linked to sudden cardiac death (SCD), but mechanisms are unclear.
  • Cardiac alternans are associated with SCD and electrical instability.
  • Previous studies on alternans in HF myocardium are limited.

Purpose of the Study:

  • To investigate if HF enhances susceptibility to arrhythmogenic cardiac alternans.
  • To understand the role of calcium cycling in HF-associated alternans.

Main Methods:

  • High-resolution transmural optical mapping in canine wedge preparations.
  • Comparison between normal and HF hearts induced by rapid ventricular pacing.
  • Dual optical mapping of action potentials and intracellular calcium (Ca) cycling.

Main Results:

  • HF lowered the heart rate (HR) threshold for action potential duration alternans (APD-ALT) and Ca alternans (Ca-ALT).
  • Ca-ALT magnitude correlated with APD-ALT, and HF enhanced cellular alternans independently of repolarization changes.
  • HF significantly lowered the HR threshold for spatially discordant alternans (DIS-ALT), preceding ventricular fibrillation (VF) in 88% of HF preparations.

Conclusions:

  • Heart failure increases susceptibility to arrhythmogenic cardiac alternans.
  • HF-induced impairment in calcium cycling is a primary driver of alternans.
  • Cardiac alternans, particularly DIS-ALT, are critical in the development of VF in HF.
Abstract

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