First experience with the wearable cardioverter de

Authors: R E Knops K M Kooiman J N ten Sande J R de Groot A A M Wilde

Publish Date: 2011/12/06

Volume: 20, Issue: 2, Pages: 77-81

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Abstract

The implantable cardioverter defibrillator ICD has significantly improved survival in patients with an increased risk of sudden cardiac death SCD The wearable cardioverter defibrillator WCD is an alternative to the ICD in patients with a transient ICD indication or those in whom an ICD temporarily cannot be implanted We describe here the technical details of the WCD and report three patients who were treated with a WCD in an outpatient setting The WCD allowed the cardiac condition of two patients to improve to such an extent that permanent ICD implantation was deemed unnecessary This new form of therapy may result in significant cost reduction avoidance of unnecessary ICD implantation and increased patient satisfactionThe implantable cardioverter defibrillator ICD has significantly improved survival in patients with an increased risk of sudden cardiac death SCD 1 2 Patients who are at risk of or have survived a lifethreatening arrhythmia are eligible for ICD treatment according to the current guidelines 3 4 However proarrhythmic conditions may modify over time in particular the left ventricular ejection fraction LVEF may improve resulting in a change in ICD indication It might therefore take time before a definitive indication for ICD implantation can be established On the other hand if an ICD needs to be removed due to infection or technical problems the patient’s risk of SCD remains unalteredThe first clinical use of the WCD was described in 2000 5 It is effective in defibrillating lifethreatening ventricular arrhythmias without bystander intervention 6 We describe here the first use of the WCD in the Netherlands In this contribution we report the technical details and clinical practice in three casesDirectly prior to delivering a defibrillating shock gel is released from the electrodes to lower skin impedance and yield optimal shock efficacy The entire event from arrhythmia detection to shock delivery typically takes less than one minute If the arrhythmia continues after the first shock up to 5 additional shocks may be given The shock energy can be programmed to between 75 and 150 joules ±5 with a default setting of 150 joulesThe key difference between the WCD and conventional ICDs is the opportunity given to the patient to interrupt the treatment cycle When the alarm sounds as a result of arrhythmia detection a conscious patient can stop the treatment This prevents inappropriate arrhythmia detection from becoming inappropriate shocks If the patient holds the two response buttons at any time during the treatment sequence the alarm will stop and no shocks will be delivered If the patient releases the response buttons the device continues to give alarms spoken warnings to bystanders and ultimately delivers a shock

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