Achieving low defibrillation thresholds at implant: pharmacological influences, RV coil polarity and position, SVC coil usage and positioning, pulse width settings, and the azygous vein

Approximately 30% of implantable cardioverter defibrillator (ICD) patients still die of sudden death. A major cause of these sudden deaths is the failure to defibrillate because of failure to achieve a low defibrillation threshold (DFT). Anti‐arrhythmic drugs can have a profound positive or negative...

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Bibliographic Details
Published in:Fundamental & clinical pharmacology 2010-10, Vol.24 (5), p.561-573
Main Authors: Kroll, Mark W., Schwab, Joerg O.
Format: Article
Language:English
Subjects:
Animals
Anti-Arrhythmia Agents - pharmacology
Atrium
Biological and medical sciences
Death, Sudden, Cardiac - prevention & control
defibrillation
Defibrillators
Defibrillators, Implantable
DFT
Drugs
Heart
Humans
ICD
Medical sciences
Pharmacology. Drug treatments
Polarity
Reviews
Tachycardia, Ventricular - therapy
threshold
Veins
Vena Cava, Superior
Ventricle
Ventricular Fibrillation - therapy
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Summary:Approximately 30% of implantable cardioverter defibrillator (ICD) patients still die of sudden death. A major cause of these sudden deaths is the failure to defibrillate because of failure to achieve a low defibrillation threshold (DFT). Anti‐arrhythmic drugs can have a profound positive or negative effect on the DFT. Unfortunately, present clinical practice continues to feature many procedures and tactics that have minimal to negative DFT benefit. In addition, many demonstrated helpful tactics are not understood or followed. This review covers the optimal RV (right ventricular) coil position and polarity, superior vena cava (SVC) coil positioning and usage, pulse width settings, and azygous vein coil implants. Specifically, the RV coil should be set to an anodal polarity and never ‘reversed’. The optimal RV coil position appears to be along the mid‐septum. The SVC coil should be kept out of the right atrium and placed in the innominate vein junction. The SVC coil should be always on for high impedance patients. For low impedance patients, the SVC coil should be set on or off depending on which setting gives the lowest DFT. Pulse widths should be set to correspond to optimally charging and discharging a cardiac membrane time constant of between 3.5 and 4.5 ms. For the highest DFT patients, a separate coil should be placed in the azygous vein and connected to the ICD ‘SVC’ port. Anachronistic approaches such as the use of polarity reversal, apical RV coil tip forcing, and subcutaneous arrays are also discussed.
ISSN:0767-3981
1472-8206
DOI:10.1111/j.1472-8206.2010.00848.x