Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology
-
The growing indications for permanent pacemaker and implantable cardioverter defibrillator (ICD) implantation have increased the number of patients with these cardiac rhythm management devices (CRMDs). Cardiac rhythm management devices occasionally perform inappropriately in response to electromagnetic interference (e.g. surgical electrocautery) or lead noise over-sensing (e.g. lead fracture). Temporary reprogramming of the CRMDs using device programmers can prevent these untoward device responses. ⋯ Alternatively, clinical magnets, when appropriately positioned over the device site, can change the pacing to an asynchronous mode in pacemakers and suspend tachycardia therapies in ICDs. Although readily available, clinical magnets have not been widely used for this purpose, perhaps due to the unfamiliarity with the variable responses of CRMDs to magnet application. This article provides a comprehensive overview of the current literature on the mechanism of action and the specific responses of various CRMDs to clinical magnets.
-
European standards specify that pacemakers (PM) should be resistant to electromagnetic interference (EMI) up to an upper borderline voltage as a function of frequency. Electromagnetic interference fields should either remain below this upper borderline voltage level or be identified and isolated from the general population. Physicians caring for PM patients need to be aware of potential problems relating to EMI. For example, sensitivity should be programmed to avoid sensing EMI below the recommended borderline voltage level. The susceptibility of a pacemaker (PM) to 50 Hz noise is an important parameter of EMI and depends on the programmed sensitivity [sensitivity setting (SS)]. We studied SS and 50 Hz noise thresholds in a large population and determined the borderline SS, defined as the SS below which 50 Hz noise was sensed. Our results should be taken into consideration in programming the SS to protect patients from the adverse effects of EMI. ⋯ All tested PMs reacted to pulsed 50 Hz waves as if they were heart signals and were inhibited. Continuous noise above noise threshold evoked asynchronous pacing at noise rate. All PMs had an S/N ratio <1, indicating that the heart signals were amplified less than noise. The European Standard requires that unipolarly sensing PMs tolerate noise up to 2 mV. However, an SS of 2 mV does not guarantee a noise tolerance of 2 mV. In order to fulfil this requirement, SS in the majority of PMs must be programmed >2 mV. In Medtronic PMs, the continuous noise threshold is paradoxical as it is higher with decreasing SS. As a good compromise in Medtronic PMs, SS should be ∼3 mV to guarantee sufficient protection from pulsed and continuous noise, assuming ventricular heart signals of 10 mV or more.
-
To assess the risk of bleeding and thromboembolism (TE) of bridging therapy with low molecular weight heparin (LMWH) in patients undergoing pacemaker implantation. ⋯ Oral anticoagulation can be safely interrupted before pacemaker implantation under overlapping therapy with enoxaparin. Reducing heparin doses in patients with low thromboembolic risk and renal insufficiency led to a low incidence of major bleeding without increasing thromboembolic events.