Cathy Shaw

Electromagnetic Interference of Communication Devices on ECG Machines

Use of communication devices in the hospital environment remains controversial. Electromagnetic interference (EMI) can affect different medical devices. Potential sources for EMI on ECG machines were systematically tested.

Electromagnetic interference produced by a hearing aid device on electrocardiogram recording.

An 85-year-old male was implanted with a single-chamber permanent pacemaker because of atrial fibrillation with slow ventricular response. The patient had a chronic hearing impairment and decided to buy a hearing aid device. The MyLink device (MyLink, Phonak, Stafa, Switzerland) is a multifrequency FM transmitter/receiver (169.40-176.00 MHz and 214.00-220.00 MHz) with a neck-loop antenna that is designed to be used in combination with a second FM transmitter, which detects sound, produced by an audio source or person, and transmits this information to the MyLink wearer. These transmissions are subsequently converted by the MyLink and sent to the patients existing hearing aids wirelessly. Given the proximity of the receiver to the left-sided pacemaker pocket, a concern about possible interaction was brought to our attention. Normal functioning of the pacemaker was observed during the test. However, potent electromagnetic interference on electrocardiogram (ECG) recording was induced when the MyLink loop antenna was placed on top or near the ECG electrodes.

Emergency Department Re-Presentation for Atrial Fibrillation and Atrial Flutter.

BACKGROUND Identification and appropriate management of patients with atrial fibrillation (AF) is critical to mitigate the consequences of the disease. We sought to assess the frequency and pattern of the emergency department (ED) use by patients who presented with AF and/or atrial flutter (AFL) in a midsized Canadian hospital. METHODS We conducted a retrospective cohort analysis of patients who presented to the ED with AF and/or AFL during the calendar years 2010-2012. Patients were identified using the MUSE (General Electric Healthcare, Bucks, United Kingdom) electrocardiogram database and matched with the National Ambulatory Care Reporting System and Discharge Abstract Database up to and including December 31, 2013, a follow-up period of 12 months. The number of presentations and time between visits was assessed. Admissions were identified and lengths of stay and reason for admission were recorded. RESULTS We identified 1361 patients who represented a total of 4783 visits to the ED, a mean of 2.8 ± 2.9 visits per patient with 949 (69.7%) who returned for a subsequent ED visit in the subsequent 12 months. Mean time between base and subsequent visits was 136.8 ± 114.2 days. ED visits generated 1462 admissions (63.0% at repeat ED visits); mean length of stay was 9.7 ± 16.0 days. Stroke or transient ischemic attack accounted for 80 return visits and 8 deaths in 77 patients, 74% of whom with subtherapeutic or no anticoagulation medication. CONCLUSIONS Presentation to the ED with AF and/or AFL, either as a primary reason for consultation or as a secondary diagnosis, was associated with a high risk of subsequent re-presentation and hospital admission.

Concealed antegrade penetration of the atrio-ventricular node

We present a patient with paroxysmal, non-sustained atrial tachycardia (AT) on routine surveillance 24-hour Holter post pulmonary vein isolation (PVI). Several asymptomatic ventricular pauses are noted to follow each burst of AT. We postulate that these pauses are due to the resultant concealed penetration of the atrio-ventricular node (AVN) in combination with sino-atrial node overdrive suppression. Recognition of this physiological phenomenon may help avoid unnecessary intervention arising from Holter recording misinterpretation.