Single-Coil Defibrillator Leads Yield Satisfactory Defibrillation Safety Margin in Hypertrophic Cardiomyopathy
Hideo Okamura1, Paul A Friedman, Yuko Inoue
1Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center.
Insights
Single-coil defibrillator leads are effective for hypertrophic cardiomyopathy (HCM) patients. Biphasic 25-J shocks with the superior vena cava coil off successfully terminated ventricular fibrillation, ensuring a safety margin.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Single-coil defibrillator leads offer easier extraction but raise concerns about high defibrillation thresholds in hypertrophic cardiomyopathy (HCM) patients.
- Dual-coil leads have been commonly used for HCM patients due to these concerns.
- Limited data exists on the efficacy of single-coil leads in HCM patients.
Purpose of the Study:
- To evaluate the efficacy and safety of single-coil defibrillator leads in patients with hypertrophic cardiomyopathy (HCM).
- To assess defibrillation thresholds and shock parameters when using single-coil leads with the superior vena cava (SVC) coil deactivated.
Main Methods:
- Twenty HCM patients received left-sided implantable cardioverter-defibrillators (ICDs) with dual-coil leads.
- Defibrillation tests were conducted with the SVC coil both on and off, delivering 25 J and maximum energy shocks.
- Shock impedance, pulse width, and termination of ventricular fibrillation were analyzed.
Main Results:
- All 25-J shocks successfully terminated ventricular fibrillation, regardless of SVC coil status.
- Shock impedance and pulse width significantly increased when the SVC coil was programmed off (66.4±6.1 ohm, 14.0±1.3 ms) compared to on (41.9±5.0 ohm, 9.3±0.8 ms).
- These findings suggest a viable safety margin for 35-J devices.
Conclusions:
- Biphasic 25-J shocks with the SVC coil off are effective in terminating ventricular fibrillation in HCM patients.
- Single-coil leads are deemed appropriate for left-sided ICD implantation in this patient population.
- The study supports the use of single-coil leads, offering potential benefits in extraction and management.
Background:
Single-coil defibrillator leads have gained favor because of their potential ease of extraction. However, a high defibrillation threshold remains a concern in patients with hypertrophic cardiomyopathy (HCM), and in many cases, dual-coil leads have been used for this patient group. There is little data on using single-coil leads for HCM patients.
Methods And Results:
We evaluated 20 patients with HCM who received an implantable cardioverter-defibrillator (ICD) on the left side in combination with a dual-coil lead. Two sets of defibrillation tests were performed in each patient, one with the superior vena cava (SVC) coil "on" and one with the SVC coil "off". ICDs were programmed to deliver 25 joules (J) for the first attempt followed by maximum energy (35 J or 40 J). Shock impedance and shock pulse width at 25 J in each setting as well as the results of the shock were analyzed. All 25-J shocks in both settings successfully terminated ventricular fibrillation. However, shock impedance and pulse width increased substantially with the SVC coil programmed "off" compared with "on" (66.4±6.1 ohm and 14.0±1.3 ms "off" vs. 41.9±5.0 ohm and 9.3±0.8 ms "on", P<0.0001 respectively).
Conclusions:
Biphasic 25-J shocks with the SVC coil 'off' successfully terminated ventricular fibrillation in HCM patients, indicating a satisfactory safety margin for 35-J devices. Single-coil leads appear appropriate for left-sided implantation in this patient group. (Circ J 2016; 80: 2199-2203).
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