An unusual cause of recurrent syncope in a patient with implantable cardioverter defibrillator.

Electromagnetic interferences (EMI) deriving from electrical devices may affect implantable cardioverter defibrillators (ICD). Improved algorithms have been developed in order to minimize adverse effects. However, caution should be still recommended in ICD recipients when handling electrical devices. Here we describe the case of an ICD patient with recurrent syncopal episodes due to inhibition of pacing by oversensing of electrical noise from a not properly grounded washing machine.

Introduction

The advent of washing machine has dramatically improved society since last century. However, in very selected cases this household appliance may be dangerous and cause life-threatening events. We describe the case of a patient with third degree AV block and biventricular ICD who suffered from syncopal episodes due to inhibition of pacing by oversensing of electrical noise from a not properly grounded washing machine.

Case report

A 75 years old lady with idiopathic dilated cardiomyopathy, left ventricular systolic dysfunction, chronic heart failure, optimized drug therapy, left bundle branch block, and paroxysmal third degree AV block received a biventricular ICD in 2011 (Protecta XT CRT-D, Medtronic, MN, USA). The device was programmed in DDDR mode with lower rate 50 bpm, upper rate 120 bpm, atrial sensing 0.3 mV, ventricular sensing 0.9 mV, ventricular fibrillation (VF) zone at 300 ms with number of intervals to detect (NID) of 18/24. The patient was regularly followed-up at pacemaker clinic and developed permanent third degree AV block. She maintained stable NYHA Class II with no episodes of arrhythmia or hypotension. In August 2014 she complained of recurrent syncopal episodes while standing and without palpitations. At ICD interrogation multiple episodes of noise with a pattern of typical 50/60 Hz interference were detected on both atrial and ventricular channel resulting in ventricular pacing inhibition with pauses up to 5.5 s and markers of VF detection (Fig. 1). The pacing thresholds and impedances of the 3 leads were normal. The memory of the device revealed some fast non-sustained ventricular tachycardias (VT) with very short non-physiological R–R intervals in the days preceding the syncopal episodes. On the basis of these recordings the Lead Integrity Alert (LIA, Medtronic, MN, USA) algorithm correctly extended the VF detection prolonging NID to 30/40 [1]. This algorithm is aimed to reduce the chance of inappropriate shock due to noise from right ventricular (RV) lead fracture by making automatic changes in ICD VT/VF detection parameters. It triggers if two of the following three criteria are met within 60 days of each other: abnormal RV lead impedance, two or more high rate non-sustained VT with intervals that are shorter than 220 ms, and at least 30 short R–R interval counts within 3 consecutive days. Once the LIA criteria are met an acoustic alarm sounds. The patient referred she heard beep coming from the device but she overlooked it. The implanted device is also provided with an additional algorithm, named RV Lead Noise Discrimination, aimed to differentiate RV noise from ventricular arrhythmias by comparing a far field electrogram (from ICD can to RV coil or RV coil to superior vena cava coil) to near field sensing (RV tip – RV ring sensing channel). However, in the present case this algorithm was not triggered because the fast electrical signals were recorded on both far field and near field channels and detected as VF. No leads lesions were observed at chest X-ray. Manipulation of the ICD and of the subcutaneous portion of the leads failed to generate noise. All the episodes occurred approximately at 2 pm. The patient explained that at that time she used to go in the laundry room. Further evaluation revealed that the washing machine was not properly grounded. No more syncopal episodes occurred after repairing the washing machine. Eventually the patient was included in a program of remote monitoring and provided with a CareLink monitor (Medtronic, MN, USA).

Fig. 1

Recording derived from the ICD showing intracardiac electrograms with electrical noise on both atrial (upper) and ventricular (lower) tracings (A), and graph with details of the device behaviour (B).

Comments

Electromagnetic interferences are rare with modern implantable cardiac devices. While in hospital expected adverse effects of EMI may be prevented however they remain a concern when patients use household appliances or run across certain electrical devices in daily life. Inappropriate ICD discharge in response to electrical noise detected as VF from not properly grounded washing machine has been previously reported [2], [3], [4]. In the present case the LIA algorithm avoided inappropriate ICD discharge by automatically prolonging the NID. It prevented shock delivery but not inhibition of ventricular pacing due to electrical noise derived from touching the washing machine. In conclusion, recent ICD are provided with effective algorithms in order to avoid inappropriate shock delivery. However oversensing of electrical signals from EMI remains a potential dangerous issue. For these reasons, it may be good to recommend precaution to ICD recipients by proper maintenance and grounding of electrical household appliances. Moreover the use of remote monitoring systems may provide early information about possible EMI occurrence in addition to usual data about device function and arrhythmic episodes.

Conflict of interest

No conflict of interest to declare.