Heart Rhythm
Volume 3, Issue 3 , Pages 296-310, March 2006

Electrocardiographic imaging of cardiac resynchronization therapy in heart failure: Observation of variable electrophysiologic responses

  • Ping Jia, PhD

      Affiliations

    • Cardiac Bioelectricity Research and Training Center, Case Western Reserve University, Cleveland, Ohio
    • ,
  • Charulatha Ramanathan, PhD

      Affiliations

    • Cardiac Bioelectricity Research and Training Center, Case Western Reserve University, Cleveland, Ohio
    • ,
  • Raja N. Ghanem, PhD

      Affiliations

    • Cardiac Bioelectricity Research and Training Center, Case Western Reserve University, Cleveland, Ohio
    • ,
  • Kyungmoo Ryu, PhD

      Affiliations

    • Cardiac Bioelectricity Research and Training Center, Case Western Reserve University, Cleveland, Ohio
    • ,
  • Niraj Varma, MD

      Affiliations

    • Cardiac Bioelectricity Research and Training Center, Case Western Reserve University, Cleveland, Ohio
    • University Hospitals of Cleveland, Cleveland, Ohio
    • ,
  • Yoram Rudy, PhD

      Affiliations

    • Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, Missouri
    • Corresponding Author InformationAddress reprint requests and correspondence: Dr. Yoram Rudy, Cardiac Bioelectricity & Arrhythmia Center, Washington University in St. Louis, Campus Box 1097, 290 Whitaker Hall, One Brookings Drive, St. Louis, Missouri 63130-4899

Received 2 August 2005; accepted 22 November 2005. published online 02 December 2005.

Background

Cardiac resynchronization therapy (CRT) for congestive heart failure patients with delayed left ventricular (LV) conduction is clinically beneficial in approximately 70% of patients. Unresolved issues include patient selection, lead placement, and efficacy of LV pacing alone. Being an electrical approach, detailed electrical information during CRT is critical to resolving these issues. However, electrical data from patients have been limited because of the requirement for invasive mapping.

Objectives

The purpose of this study was to provide observations and insights on the variable electrophysiologic responses of the heart to CRT using electrocardiographic imaging (ECGI).

Methods

ECGI is a novel modality for noninvasive epicardial mapping. ECGI was conducted in eight patients undergoing CRT during native rhythm and various pacing modes.

Results

In native rhythm (six patients), ventricular activation was heterogeneous, with latest activation in the lateral LV base in three patients and in the anterolateral, midlateral, or inferior LV in the remainder of patients. Anterior LV was susceptible to block and slow conduction. Right ventricular pacing improved electrical synchrony in two of six patients. LV pacing in three of four patients involved fusion with intrinsic excitation resulting in electrical resynchronization similar to biventricular pacing. Although generally electrical synchrony improved significantly with biventricular pacing, it was not always accompanied by clinical benefit.

Conclusion

Results suggest that (1) when accompanied by fusion, LV pacing alone can be as effective as biventricular pacing for electrical resynchronization; (2) right ventricular pacing is not effective for resynchronization; and (3) efficacy of CRT depends strongly on the patient-specific electrophysiologic substrate.

Keywords:  Heart failure , Resynchronization , Pacing , Imaging , Electrophysiology

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 The study was supported by Merit Award R37-HL-33343 and Grant R01-HL-49054 from the National Heart, Lung, and Blood Institute of the National Institutes of Health to Dr. Rudy. Dr. Rudy is the Fred Saigh Distinguished Professor at Washington University in St. Louis. Drs. Jia and Ramanathan are employees and stockholders of Cardioinsight, Inc., a company that plans to commercialize electrocardiographic imaging as a clinical tool. Dr. Rudy is a coinventor of the ECGI technology.

PII: S1547-5271(05)02359-3

doi:10.1016/j.hrthm.2005.11.025

Heart Rhythm
Volume 3, Issue 3 , Pages 296-310, March 2006

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