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ELECTROPHYSIOLOGY
Implantable cardioverter-defibrillators
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  1. Derek T Connelly
  1. The Cardiothoracic Centre—Liverpool NHS Trust, Liverpool, UK
  1. Dr Derek T Connelly, The Cardiothoracic Centre—Liverpool NHS Trust, Thomas Drive, Liverpool L14 3PE, UKconnelly{at}liv.ac.uk

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Sudden cardiac death is a common problem, and increasing numbers of patients are surviving a first episode of a life threatening ventricular arrhythmia. In the absence of an acute myocardial infarction, patients who survive either ventricular fibrillation or sustained ventricular tachycardia have a high risk of further episodes, which may be fatal.1 Until recently, class I and class III antiarrhythmic drugs have been the standard treatment for patients with malignant ventricular arrhythmias. Amiodarone2 and sotalol3 have been shown to be superior to class I drugs, but despite using the best appropriate medical treatment, arrhythmia recurrence rates are still 40–50% at five years.

There is now growing evidence to support the wider use of implantable cardioverter-defibrillators (ICDs) as primary treatment in certain patients with serious ventricular arrhythmias. These devices were developed in the 1970s, with the first human implant in 1980.4 Original devices had a single therapy option of defibrillation only; the generator was implanted in the abdomen, and thoracotomy was required for electrode placement. With advances in technology the units have become smaller (current ICDs are little bigger than a pacemaker) and can be implanted pectorally. With improvements in sensing, the latest devices offer graded therapeutic responses to a sensed ventricular arrhythmia. Antitachycardia pacing, low energy synchronised cardioversion, and high energy defibrillation shocks can be given via a single transvenous lead.

Implant procedure

Implantation of an ICD is now technically very straightforward, and only a little more complicated than pacemaker implantation. As with pacemaker implantation, strict attention to asepsis is necessary, and prophylactic antibiotics are generally used. In the past, ICD implants were performed under general anaesthesia; however, many centres now implant these devices using a combination of local anaesthesia and intravenous sedation. Usually an incision 5–8 cm in length is made in the left infraclavicular region, and a …

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