Right pectoral implantable cardioverter defibrillators: Role of the proximal (SVC) coil

Niraj Varma*, Igor Efimov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Introduction: Increased defibrillation thresholds (DFTs) with right active pectoral implantable cardioverter defibrillators (ICDs) and/or right proximal coils (SVC) are attributed to poorer vector. However, SVC affects impedance, current flow, and shock waveform phase duration (PD), which exert independent DFT effects. Objective: Compare DFTs and shock characteristics in SVC On with SVC Off in right ICDs. Methods and Results: DFT+ testing (n = 42, 62% males, 62 ±15 years, left ventricular ejection fraction (LVEF) 26 ± 11%, ischemic cardiomyopathy 65%, amiodarone 26%) revealed >20% incidence of high DFT (>20J). Dilated cardiomyopathy and amiodarone increased DFT. Individual impedance variability (25-74 Ω) generated a wide PD range (2.6-8.7 ms). Overall, SVC On reduced impedance by 33% (from 54 ± 10 to 35 ± 5Ω, P< 0.0001), and shortened PD (from 5.45 ± 1.20 to 3.67 ± 0.74 ms, P< 0.01). SVC On affected DFTs in 19/42 (45%) patients. SVC On was beneficial in 12/19. PD shortened but current flow remained unaltered. (In these, SVC Off impedance was >45Ω and PD >5 ms.) SVC On was detrimental in 7/19 despite increasing current flow. In these, PD shortened excessively (median 2.9 ms) because impedance was low (31 ± 4Ω). In 3/6 cases with DFTs >20 J in both SVC On and Off, PD optimization reduced DFT. Overall, selection of best SVC configuration or deliberate PD programming yielded DFTs ≤20 J in >90% patients, reducing need for system modification to <7%. Conclusions: Right pectoral active ICDs have high DFTs. The SVC coil may be detrimental when pulse waveform excessively shortens. Noninvasive maneuvers, for example, SVC and waveform optimization, may improve DFT.

Original languageEnglish (US)
Pages (from-to)1025-1035
Number of pages11
JournalPACE - Pacing and Clinical Electrophysiology
Volume31
Issue number8
DOIs
StatePublished - Aug 2008

Keywords

  • DFT
  • ICD
  • Impedance
  • Phase duration
  • Right-sided
  • Shock waveform

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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