Safety of repetitive nerve stimulation in patients with cardiac implantable electronic devices

Introduction: Pacemakers and implantable cardioverter-defibrillators (ICDs) are vulnerable to inappropriate sensing of electromagnetic interference (EMI), such as from nerve conduction studies. We conducted a prospective study to assess the safety of repetitive nerve stimulation (RNS). Methods: Fourteen patients undergoing insertion of 10 ICDs and 4 pacemakers under general anesthesia received RNS of the median, axillary, and spinal accessory nerves at 2 HZ and 50 HZ . We recorded detection of EMI and whether or not this resulted in an arrhythmia diagnosis or change in pacing output. Results: EMI was visible in 2 ICDs, without spurious tachyarrhythmia detection. EMI was observed in 3 of the 4 pacemakers, which led to pacing inhibition and a pause in 2, both of which were programmed to a unipolar sensing configuration. Conclusions: RNS is safe in patients with ICDs. In pacemaker patients, RNS appears safe during bipolar sensing, but caution is recommended in pacemaker patients with unipolar sensing. Muscle Nerve 47: 840–844, 2013     

Incidence of Deep Venous Thrombosis Associated with Femoral Venous Catheterization

Objective : To determine in adult medical patients the incidence of deep venous thrombosis (DVT) resulting from femora] venous catheterization (FVC).
Methods : A prospective, observational study was performed at a 420-bed community teaching hospital. Hep-arin-coated 7-Fr 20-cm femoral venous catheters were inserted unilaterally into a femoral vein. Each contra-lateral leg served as a control site. Age, gender, number of FVC days. DVT risk factors, administration of DVT prophylaxis, and DVT formation and site were tabulated for each patient. Venous duplex sonography was performed bilaterally on each patient within 7 days of femoral venous catheter removal.
Results : Catheters were placed in 29 men and 13 women. Femoral DVT was identified by venous duplex sonography in 11 (26.2%) of the FVC legs and none (0%) in the control legs. Posterior tibial and popliteal DVT was identified in both the FVC and control legs of 1 patient. DVT formation at the site of FVC insertion was highly significant (p = 0.005). There were no statistically significant associations with age (p = 0.42), gender (p = 0.73), number of DVT risk factors (p = 0.17), number of FVC days (p = 0.89), or DVT prophylaxis (p — 099).
Conclusion : Placement of femoral catheters for central venous access is associated with a significant incidence of femoral DVT as detected by venous duplex sonography criteria at the site of femoral venous catheter placement. Physicians must be aware of this risk when choosing this vascular access route for adult medical patients. Further studies to assess the relative risk for DVT and its clinical sequelae when using the femoral vs other central venous catheter routes are indicated.     

Electrodiagnostic studies: Are they useful in clinical practice?

Objective: Electrodiagnostic testing (electromyography [EMG] and nerve conduction studies [Ncs]) may result in some patient discomfort. The justification for such testing should be based on the expectation that the results will affect patient management. This study was conducted to determine how frequently the results of EMG/NCS change the clinical management of the patient.Methods: One investigator (MB) spoke to each referring physician after EMG/NCS to determine if any management decisions were altered by the test.Results: One hundred forty consecutive EMG/NCS records were obtained. Follow-up was available on 100 patients. Of 78 patients with abnormal findings on EMG/NCS, 29 (37%) had a diagnosis different from the referring diagnosis. For 43 of the 78 (55%), the physician reported that additional diagnostic testing was undertaken or treatment plans were altered.Conclusion: EMG/NCS are useful, informative, and diagnostic in the management of various neurologic disorders.