Paroxysmal atrioventricular block (AVB) is a poorly defined clinical entity characterized by abrupt and unexpected change from 1:1 atrioventricular conduction to complete heart block, leading to syncope and potential sudden cardiac death. Although a dangerous condition because of unreliable escape mechanism, proper diagnosis of paroxysmal AVB is often missed and overlooked because of its unfamiliarity, unpredictability, and in some cases, no clear evidence of atrioventricular conduction disease during normal 1:1 conduction.

BACKGROUND:Little is known about the magnetic field strength of portable headphones and their potential to cause magnetic interference with implanted pacemakers (PMs) and implantable cardioverter-defibrillators (ICDs). OBJECTIVE:The purpose of this study was to evaluate the magnetic field strength of portable headphones and to determine if they can cause clinically relevant magnetic interference. METHODS:PM or ICD function was assessed in 100 patients during exposure to eight different models of portable headphones to determine the incidence of clinically relevant magnetic interference. The magnetic field strength of the headphones also was measured in vitro. RESULTS:Clinically relevant magnetic interference from portable headphones occurred in 30 (30%) of 100 patients and more commonly affected ICD than PM patients (21/55 [38.2%] vs 9/45 [20.0%]; P = .048). All patients affected by magnetic interference experienced a magnet response, characterized by asynchronous pacing in PM patients and by inhibition of tachyarrhythmia detection in ICD patients. In all but one of the 30 cases of magnetic interference, removal of the headphones from the patient's chest immediately restored normal device function. Headphones with a measured magnetic field strength > or =10 gauss at 2 cm were much more likely to cause magnetic interference than were those with lower magnetic field strength (30/100 [30%] patients vs 0/100 [0%] patients; P <.0001). Magnetic interference was not observed when headphones were placed > or =3 cm from the skin surface. CONCLUSION:Clinically significant magnetic interference can occur when portable headphones are placed in close proximity to implanted PMs and ICDs. Patients with such a device should be advised to keep portable headphones at least 3 cm from their device.

Enoxaparin is a low-molecular-weight heparin (LMWH) derivative that exerts its anticoagulant activity through antithrombin III, an endogenous inhibitor of factor Xa and thrombin IIa. Unlike its unfractionated heparin (UFH) counterparts, enoxaparin has a greater bioavailability, lower incidence of heparin-induced thrombocytopenia and more stable and predictable anticoagulation, allowing fixed dosing without the need for monitoring. These advantages make it an attractive anticoagulant to be used in acute coronary syndrome management. Indeed, several clinical trials and meta-analyses have consistently demonstrated the efficacy of enoxaparin in reducing cardiovascular events and mortality in this population. Although initial clinical trials with enoxaparin during the early conservative approach suggested superior efficacy without differences in safety compared with UFH, emerging data in the current era of early revascularization approach indicate that superior effects of enoxaparin over heparin in reducing clinical events should be balanced against an increase in major hemorrhagic complications. Enoxaparin is a rational alternative to UFH in patients presenting with either unstable angina/non-ST-elevation myocardial infarction or ST-elevation myocardial infarction, with a clinically modest increase in bleeding complications.