Seth H. Sheldon

Safety and Outcomes of Magnetic Resonance Imaging in Patients with Abandoned Pacemaker and Defibrillator Leads

Abandoned cardiovascular implantable electronic device (CIED) leads remain a contraindication to magnetic resonance imaging (MRI) studies, largely due to in vitro data showing endocardial heating secondary to the radiofrequency field. We tested the hypothesis that abandoned CIED leads do not pose an increased risk of clinical harm for patients undergoing MRI.

Multicenter study of the safety and effects of magnetic resonance imaging in patients with coronary sinus left ventricular pacing leads

BACKGROUND Magnetic resonance imaging (MRI) in patients with left ventricular (LV) leads may cause tissue or lead heating, dislodgment, venous damage, or lead dysfunction. OBJECTIVE The purpose of this study was to determine the safety of MRI in patients with LV pacing leads. METHODS Prospective data on patients with coronary sinus LV leads undergoing clinically indicated MRI at 3 institutions were collected. Patients were not pacemaker-dependent. Scans were performed under pacing nurse, technician, radiologist, and physicist supervision using continuous vital sign, pulse oximetry, and ECG monitoring and a 1.5-T scanner with specific absorption rate <1.5 W/kg. Devices were interrogated pre- and post-MRI, programmed to asynchronous or inhibition mode with tachyarrhythmia therapies off (if present), and reprogrammed to their original settings post-MRI. RESULTS MRI scans (n = 42) were performed in 40 patients with non-MRI conditional LV leads between 2005 and 2013 (mean age 67 ± 9 years, n = 16 [40%] women, median lead implant duration 740 days with interquartile range 125-1173 days). MRIs were performed on the head/neck/spine (n = 35 [83%]), lower extremities (n = 4 [10%]), chest (n = 2 [5%]), and abdomen (n = 1 [2%]). There were no overall differences in pre- and post-MRI interrogation LV lead sensing (12.4 ± 6.2 mV vs 12.9 ± 6.7 mV, P = .38), impedance (724 ± 294 Ω vs 718 ± 312 Ω, P = .67), or threshold (1.4 ± 1.1 V vs 1.4 ± 1.0 V, P = .91). No individual LV lead changes required intervention. CONCLUSION MRI scanning was performed safely in non-pacemaker-dependent patients with coronary sinus LV leads who were carefully monitored during imaging without clinically significant adverse effect on LV lead function.

Occurrence of atrial fibrillation during dobutamine stress echocardiography: Incidence, risk factors, and outcomes

BACKGROUND The reported incidence of atrial fibrillation (AF) occurring during dobutamine stress echocardiography (DSE) ranges from 0.5% to 4%. The aim of this study was to characterize the incidence, risk factors, and outcomes of AF precipitated during DSE. METHODS The clinical and echocardiographic data of consecutive patients over a 50-month period who were in sinus rhythm and underwent DSE were retrospectively reviewed. RESULTS A total of 11,806 consecutive patients underwent DSE and met all inclusion criteria. AF developed during DSE in 122 patients (1%), 71 of whom had histories of AF. The duration of AF was <1 hour in 74 patients (61%) and<24 hours in 117 patients (96%). Of the 47 patients who were still in AF when dismissed from the echocardiography laboratory, 21 had outpatient follow-up within 24 hours, eight were already inpatients, and 18 were triaged to the emergency department or hospital. Spontaneous cardioversion occurred in 114 patients (93%). There were no reported complications. The clinical characteristic most strongly associated with the development of AF during DSE was a history of AF (odds ratio, 18.4 if no history of congestive heart failure; P<.001). The presence or extent of stress-induced myocardial ischemia was not predictive of the development of AF. CONCLUSIONS AF is an infrequent complication of DSE. Most patients return to sinus rhythm spontaneously within 1 hour. Patients with persistent AF can be safely dismissed from the echocardiography laboratory to have outpatient follow-up within 24 hours unless they have suboptimal heart rate control, hypotension, significant symptoms, or markedly abnormal findings on DSE.

Coexistent Types of Atrioventricular Nodal Re-Entrant Tachycardia: Implications for the Tachycardia Circuit

Background—There is evidence that atypical fast–slow and typical atrioventricular nodal re-entrant tachycardia (AVNRT) do not use the same limb for fast conduction, but no data exist on patients who have presented with both typical and atypical forms of this tachycardia. We compared conduction intervals during typical and atypical AVNRT that occurred in the same patient. Methods and Results—In 20 of 1299 patients with AVNRT, both typical and atypical AVNRT were induced at electrophysiology study by pacing maneuvers and autonomic stimulation or occurred spontaneously. The mean age of the patients was 47.6±10.9 years (range, 32–75 years), and 11 patients (55%) were women. Tachycardia cycle lengths were 368.0±43.1 and 365.8±41.1 ms, and earliest retrograde activation was recorded at the coronary sinus ostium in 60% and 65% of patients with typical and atypical AVNRT, respectively. Thirteen patients (65%) displayed atypical AVNRT with fast–slow characteristics. By comparing conduction intervals during slow–fast and fast–slow AVNRT in the same patient, fast pathway conduction times during the 2 types of AVNRT were calculated. The mean difference between retrograde fast pathway conduction during slow–fast AVNRT and anterograde fast pathway conduction during fast–slow AVNRT was 41.8±39.7 ms and was significantly different when compared with the estimated between-measurement error (P=0.0055). Conclusions—Our data provide further evidence that typical slow–fast and atypical fast–slow AVNRT use different anatomic pathways for fast conduction.

Emergency Cardiac Support With Extracorporeal Membrane Oxygenation for Cardiac Arrest

A 46-year-old woman with no major medical history presented to the emergency department with chest pain and evidence of anterior, anterolateral, and inferior ST-elevation myocardial infarction. Her condition quickly deteriorated into cardiogenic shock with ventricular arrhythmia. Despite revascularization of the left anterior descending artery and intravenous inotrope and antiarrhythmic therapy, her unstable hemodynamics and arrhythmias persisted. Early emergency initiation of venoarterial extracorporeal membrane oxygenation (ECMO) led to prompt hemodynamic and rhythm stability; however, adequate endogenous cardiac output did not ensue, and she was not able to be weaned from ECMO until hospital day 8. She subsequently recovered and continues to do well in the outpatient setting. This case demonstrates the remarkable hemodynamic and rhythm stability that early initiation of ECMO can provide in the setting of unstable myocardial infarction.

Low incidence of left atrial delayed enhancement with MRI in patients with AF: A single-centre experience

Background Atrial fibrillation (AF) is the most common sustained atrial arrhythmia. One potential target for ablation is left atrial (LA) scar (LAS) regions that may be the substrate for re-entry within the atria, thereby sustaining AF. Identification of LAS through LA delayed gadolinium enhancement (LADE) with MRI has been proposed. Objectives We sought to evaluate LADE in patients referred for catheter ablation of AF. Methods Prospective analysis was conducted of consecutive patients who underwent pulmonary vein antrum isolation (PVAI) ablation for AF at a single institution. Patients underwent LADE with MRI to determine LAS regions before ablation. MRI data were analysed independently in accordance with prespecified institutional protocol by two staff cardiac radiologists to whom patient outcomes were masked, and reports of LADE were documented. Where no initial consensus occurred regarding delayed enhancement (DE), a third staff cardiac radiologist independently reviewed the case and had the deciding vote. Results Of the 149 consecutive patients (mean (SD) age, 59 (9) years), AF was persistent in 64 (43%) and paroxysmal in 85 (57%); 45 (30%) had prior ablation. Only five patients (3%) had identifiable DE in LA walls (persistent AF, n=1; paroxysmal AF, n=4). LADE was present in two (4%) of the 45 patients with previous left PVAI. The presence of LADE was not associated with a higher recurrence rate of AF. Conclusions In contrast to previous studies, the finding of DE within LA walls was uncommon and, when present, did not correlate with AF type or risk of AF recurrence. It therefore is of unclear clinical significance.

Parahisian pacing: technique, utility, and pitfalls.

Several observations and maneuvers in the electrophysiology (EP) laboratory are employed to identify whether retrograde ventriculoatrial conduction is via the atrioventricular (AV) node or an accessory pathway. Parahisian pacing is a unique maneuver where there is no change in the position of the catheter, the position of the stimulating electrode, nor the cycle length for pacing, but rather the pacing output is varied. The primary value for parahisian pacing is to distinguish between a septal accessory pathway and AV nodal conduction. However, more nuanced but just as reliable interpretation is possible to also help identify free-wall accessory pathways, intermittently conducting pathways, multiple accessory pathways, and various combinations of pathway and AV nodal retrograde conduction. In this review, we discuss the importance of correct technique and explain with examples some uncommon, yet instructive, findings when performing parahisian pacing.

Central hyperadrenergic state after lightning strike

ObjectiveTo describe and review autonomic complications of lightning strike.MethodsCase report and laboratory data including autonomic function tests in a subject who was struck by lightning.ResultsA 24-year-old man was struck by lightning. Following that, he developed dysautonomia, with persistent inappropriate sinus tachycardia and autonomic storms, as well as posttraumatic stress disorder (PTSD) and functional neurologic problems.InterpretationThe combination of persistent sinus tachycardia and episodic exacerbations associated with hypertension, diaphoresis, and agitation was highly suggestive of a central hyperadrenergic state with superimposed autonomic storms. Whether the additional PTSD and functional neurologic deficits were due to a direct effect of the lightning strike on the central nervous system or a secondary response is open to speculation.

PentaRay entrapment in a mechanical mitral valve during catheter ablation of atrial fibrillation

Figure 1 Retrieval of sheared PentaRay remnant. Still-frame fluoroscopy image in anteroposterior view demonstrating the Jawz Biopsy Forcep and steerable Agilis sheath directed toward the catheter remnant in the area of the antrum of the right inferior pulmonary vein. Case report A 32-year-old woman with a mechanical Carbomedics (Sorin Group, Milan, Italy) bileaflet MV for MV endocarditis in the setting of hypertrophic cardiomyopathy presented for catheter ablation of persistent, symptomatic atrial fibrillation). A PRM catheter was used in the left atrium for electroanatomic (EA) mapping on CARTO (Biosense Webster, Inc). Monoplane fluoroscopy was used owing to planned stereotaxis ablation. Despite careful monitoring and avoidance of ventricular electrograms, one of the spines of the PRM catheter became entrapped in the mechanical MV. Gentle traction and clockwise–counterclockwise rotation on the PRM catheter did not free the catheter tip. The sheath was advanced to provide support on the catheter and traction freed the PRM catheter from the MV. Subsequent inspection of the PRM catheter demonstrated that the distal bipole of one of the linear spines had sheared off. Fluoroscopy was used to locate the remaining catheter tip in the area of the antrum of the right inferior pulmonary vein. A steerable Agilis NxT (St Jude Medical, St Paul, MN) sheath was directed toward the catheter remnant and a 2.4 mm Jawz Biopsy Forcep (Agron Medical Devices, Athens, TX) was then advanced through the sheath and used to grasp the fragment while advancing the sheath and simultaneously retracting the bioptome. Once the fragment was in the sheath, it was withdrawn to the right heart and the fragment remnant was successfully retrieved (Figure 1; see online supplement for Movie 1). The patient did not have any appreciable

MULTICENTER STUDY OF THE SAFETY AND EFFECTS OF MAGNETIC RESONANCE IMAGING IN PATIENTS WITH CORONARY SINUS LEFT VENTRICULAR PACING LEADS

Magnetic resonance imaging (MRI) in patients with left ventricular (LV) leads may cause tissue or lead heating, dislodgement, venous damage, or lead dysfunction. MRI conditional LV leads are not available. We therefore investigated the safety of MRI in patients with LV pacing leads. Prospective