TY - JOUR
T1 - Right pectoral implantable cardioverter defibrillators
T2 - Role of the proximal (SVC) coil
AU - Varma, Niraj
AU - Efimov, Igor
PY - 2008/8
Y1 - 2008/8
N2 - 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.
AB - 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.
KW - DFT
KW - ICD
KW - Impedance
KW - Phase duration
KW - Right-sided
KW - Shock waveform
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U2 - 10.1111/j.1540-8159.2008.01130.x
DO - 10.1111/j.1540-8159.2008.01130.x
M3 - Article
C2 - 18684259
AN - SCOPUS:48249102680
SN - 0147-8389
VL - 31
SP - 1025
EP - 1035
JO - PACE - Pacing and Clinical Electrophysiology
JF - PACE - Pacing and Clinical Electrophysiology
IS - 8
ER -