The magnetic fields emitted by electronic article surveillance (EAS) systems (shoplifting gates) are a source of interference for implanted medical devices. In the Study of Pacemaker and Implantable Cardioverter Defibrillator Triggering by Electronic Article Surveillance Devices (SPICED TEAS), 25 adult volunteers with ICDs and 50 with pacemakers were exposed to the fields of six different EAS systems. These EAS systems used three modes of operation: magnetic audio frequency, swept radiofrequency, and acoustomagnetic technology. No ICD exhibited interference mimicking sensing of tachyarrhythmias with any EAS system. Pacemakers interacted variably, depending on the type of EAS system. Swept radiofrequency systems produced no interaction with any implanted medical device. One magnetic audio frequency system interacted with 2 of 50 pacemakers. The acoustomagnetic system interacted with 48 of 50 pacemakers. Interactions included asynchronous pacing, atrial oversensing (producing "EAS induced tachycardia" in the ventricle), ventricular oversensing (with pacemaker inhibition), and paced beats resulting from the direct induction of current in the pacemaker ("EAS induced pacing"). These interactions produced symptoms in some patients (palpitations, presyncope) only while patients were in the EAS field. No pacemaker was reprogrammed. We conclude that high energy, pulsed low frequency EAS systems such as acoustomagnetic systems interfere with most pacemakers. Pacemaker patients should be advised to minimize exposure to the fields of such systems to prevent the possibility of serious clinical events.
Coronary artery spasm is a known complication of coronary interventions, for which intracoronary nitroglycerin (ICN) is the treatment of choice. Some forms of intense spasm are resistant to ICN. Calcium channel antagonists are also known to be effective for coronary artery spasm, including nitroglycerin-resistant spasm. Here we describe a protocol for the clinical use of intracoronary diltiazem (ICD). By this protocol, ICD can be safely given without disturbing the clinical status of patients. ICD (2.5 mg) given slowly over 1 minute produced no vasodilitation of normal vessel segments but did produce significant dilatation of stenotic segments above and beyond the effects of nitrates. Mean minimum lumen diameter increased 18%, from 0.89 +/- 0.06 mm to 1.06 +/- 0.07 mm (mean +/- SEM, P < 0.001). ICD produced clinically insignificant changes in systolic blood pressure, diastolic blood pressure, heart rate, and PR, QRS, and QT intervals. This protocol has been employed to safely use ICD to relieve both nitroglycerin-resistant epicardial artery spasm and nitroglycerin-resistant distal microvascular spasm (the no-reflow phenomenon).
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