Copenhagen, Denmark – 3 April 2022: Recommendations on the prevention and management of interference caused by medical procedures in patients with implanted electronic cardiac devices is published today in EP Europace,1 a journal of the European Society of Cardiology (ESC) and presented at EHRA 2022,2 a scientific congress of the ESC.

“Interference is frequently caused by numerous medical interventions, but rare consequences are largely avoidable if preventive actions are taken,” said lead author Professor Markus Stühlinger of the Medical University of Innsbruck, Austria. “The document outlines what medical staff should do before and during different types of medical procedures. Patients can also contribute by carrying their device card which specifies the type, model and manufacturer.”

The paper covers pacemakers, which keep the heart beating regularly and not too slowly; defibrillators, which stop potentially fatal heart rhythms by delivering a shock; and loop recorders, used to detect and diagnose arrhythmias.
Interference that may affect the functioning of these devices can occur during medical procedures due to electromagnetic fields (for example during surgery), a magnetic field (i.e. magnetic resonance imaging; MRI), radiation (e.g. cancer treatment), or acoustic waves (e.g. lithotripsy to destroy kidney stones). The result is that the electronic cardiac device may stop working temporarily or permanently, or deliver an unneeded shock.

Modern surgery typically uses electrocautery, where an electrical current is delivered via a scalpel. “If the procedure is close to the generator of a pacemaker or defibrillator, the device may recognise the signal and respond to it inappropriately,” explained Professor Stühlinger. “This can cause inhibition of pacing, leading to a drop in heart rate, or an unnecessary shock because the device erroneously detects a dangerous arrhythmia.”

The authors outline the steps that should be taken to prevent device malfunctioning due to interference. For surgery, the first step is to check how reliant the patient is on the device – for example, does he or she need constant pacing or not? In addition, medical staff should check that the device and its battery are working properly. The second step is to test how the device responds to having a magnet placed next to it. If the device reacts as expected, then surgery can proceed normally, and the ECG and pulse should be monitored. If the device behaviour is abnormal, a magnet can be placed near the device during surgery to inhibit interference from electrocautery.

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