Determining the Safety of Radiofrequency Ablation in Cardiovascular Implantable Electronic Devices.

Radiofrequency catheter ablation (RFCA) is an effective treatment for arrhythmias. The effects of RFCA on cardiovascular implantable electronic devices (CIED) function have varied. We aim to study the effect of RFCA on device parameters and clinical outcomes in patients with CIED. We conducted a single-center retrospective cohort study between 2011 and 2018. Generator and lead parameters were compared pre- and post-ablation using paired sample t-test. The median follow-up interval for documentation of procedure-related complications and clinical outcomes was 8 weeks. We identified 119 eligible patients; whose mean age was 64.5 ± 11.91 years and 22 (18.4%) were females. Types of CIED include single-chamber implantable cardioverter defibrillators (8.93%), dual-chamber implantable cardioverter defibrillators (41.96%), and either dual-chamber or biventricular pacemakers (44.54%). Arrhythmias for which patients underwent RFCA include atrial fibrillation/atrial tachycardia (15.22%), atrial flutter (38.14%), atrioventricular node reentrant tachycardia (13.56%), and premature ventricular complex or ventricular tachycardia (20.34%). No statistically significant difference was observed in pre- and post-ablation: (1) atrial sensing thresholds, pacing thresholds, lead impedance; (2) right ventricle sensing and pacing thresholds; and (3) left ventricle pacing threshold and impedance. A decrease in right ventricle impedance after ablation (549.77 ± 173 ohm vs 507.40 ± 129.0 ohm, P-value <0.004) was observed. Zero complications or deaths were observed. In this single-center study, RFCA did not significantly impact CIED function and was not associated with short-term complications. However longer follow-up is required to confirm these findings.

Utilization of Non-Gated Chest Computed Tomography Scans in Predicting Acute Coronary Occlusion in Out-of-Hospital Cardiac Arrest.

Coronary artery disease is thought to be responsible for up to 60%-80% of out-of-hospital cardiac arrests. The utility of Computed Tomography (CT) chest when it comes to identifying acute coronary occlusion in patients following an arrest has not been studied. We evaluated whether myocardial perfusion on a contrast-enhanced chest CT performed for a non-cardiac cause can predict culprit coronary occlusion as the cause of cardiac arrest and if the absence of a perfusion defect can exclude an ischemic etiology. A retrospective cohort of 53 consecutive patients presenting with VT or VF arrest and successful resuscitation who had contrast chest CT before angiography were identified. CT scans were reviewed for myocardial perfusion defects by a cardiologist and radiologist blinded to angiogram findings. CT results were then compared with angiograms. On coronary angiography, 22 (42%) of the patients presenting with out-of-hospital arrest had critical stenosis. Sensitivity and specificity of perfusion defect on CT in identifying critical stenosis on catheterization was 0.45, 95% CI [0.24, 0.68] and 0.77, 95% CI [59%, 90%], respectively. The positive likelihood ratio was 2.01 (0.91, 4.46) and the negative likelihood ratio was 0.70 (0.46, 1.08). The diagnostic accuracy was 64.2%. Our study did not show much utility for the use of myocardial perfusion defect on an incidental pre-angiography contrast chest CT to predict acute thrombotic occlusion in out-of-hospital cardiac arrest patients. However, this shouldn't discourage further studies evaluating the utility of contrast-enhanced CT images in predicting acute coronary occlusion.

Society for Cardiovascular Magnetic Resonance 2019 Case of the Week series.

The Society for Cardiovascular Magnetic Resonance (SCMR) is an international society focused on the research, education, and clinical application of cardiovascular magnetic resonance (CMR). The SCMR web site ( https://www.scmr.org ) hosts a case series designed to present case reports demonstrating the unique attributes of CMR in the diagnosis or management of cardiovascular disease. Each clinical presentation is followed by a brief discussion of the disease and unique role of CMR in disease diagnosis or management guidance. By nature, some of these are somewhat esoteric, but all are instructive. In this publication, we provide a digital archive of the 2019 Case of the Week series as a means of further enhancing the education of those interested in CMR and as a means of more readily identifying these cases using a PubMed or similar search engine.

Twiddler's Syndrome: An Unusual Cause of Repeated Shocks by Implantable Cardioverter-Defibrillator in an Asymptomatic Patient.

Twiddler's syndrome refers to malfunction of pacemaker or implantable cardioverter-defibrillator (ICD) resulting from deliberate or unintentional twisting of pulse generator in device pocket, resulting in lead dislodgment. We report a case of a 65-year-old woman with multiple ICD shocks and antitachycardia pacing events on device interrogation, while she was unaware of the ICD discharges. Twiddler's syndrome is rare and mostly occurs in obese or elderly because of loose subcutaneous tissue allowing pulse generator to rotate in its pocket. It can be prevented by patient education against hand manipulating the generator. Smaller device pocket or suturing generator to fascia can also prevent future episodes.

Usefulness of Cardiac Resynchronization Therapy in Patients With Continuous Flow Left Ventricular Assist Devices.

The benefit of cardiac resynchronization therapy in patients supported by a left ventricular assist device (LVAD) is unknown. There are currently no guidelines regarding the continuation, discontinuation or pacemaker (PM) settings post-LVAD implant. The aim of the study was to assess the hemodynamic benefit of biventricular (BiV) pacing in LVAD patients. We studied 22 patients supported by LVADs (age 62 ± 9, 21 males) who had received a BiV PM before LVAD implant. A total of 123 complete sets of hemodynamics were obtained during BiV pacing (n = 54), right ventricular (RV) pacing (n = 54), and intrinsic rhythm (n = 15). There were no significant differences in right atrial (RA) pressure, mean pulmonary artery pressure (mPA), PCWP, cardiac output, PA saturation (PASat) and right ventricular stroke work index between BiV and RV pacing. Hemodynamics obtained during intrinsic rhythm in 15 non-PM-dependent patients were not significantly different compared with those obtained during BiV or RV pacing. Furthermore, hemodynamics were similar at different heart rates ranging 50 to 110 beats/min. Right ventricular stroke work index was significantly lower at the highest heart rate compared with baseline and lowest heart rates suggesting decreased RV performance at higher heart rate. In conclusion, BiV pacing does not have any acute hemodynamic benefit compared with RV pacing or intrinsic rhythm in LVAD patients. A lower heart rate may confer better RV performance.

Presence of gas in left ventricle due to infective endocarditis.

Gas in myocardium is a rare manifestation of infective endocarditis caused by gas producing bacteria. We present a case of infective endocarditis caused by Citrobacter Koseri initially diagnosed by computed tomography and confirmed with transesophageal echocardiogram.

Out in the cold: the hypothermic heart response.

We present an interesting case of a 49-year-old woman with hypothermia and associated Osborn waves (also called J waves) on ECG. She was found on the floor of her home and difficult to arouse. On arrival to the emergency department (ED), her rectal temperature was 87.5°F. ECG showed Osborn waves in diffuse leads. She was intubated in the ED and was started on vasopressor support for hypotension refractory to intravenous fluid boluses. She was transferred to the critical care unit for continued respiratory and cardiovascular support. With active external rewarming her core body temperature continued to improve. Blood pressure also improved and vasopressor was tapered off. She was extubated and was transferred to the medical floor for continued supportive care. Osborn waves on ECG resolved within 12 h of achieving normal range body temperature. The patient was eventually discharged home with medical follow-up.