Background-The purpose of the present study was to evaluate a strategy for safe performance of extrathoracic magnetic resonance imaging (MRI) in non-pacemaker-dependent patients with cardiac pacemakers. Methods and Results-Inclusion criteria were presence of a cardiac pacemaker and urgent clinical need for an MRI examination. Pacemaker-dependent patients and those requiring examinations of the thoracic region were excluded. The study group consisted of 82 pacemaker patients who underwent a total of 115 MRI examinations at 1.5T. To minimize radiofrequency-related lead heating, the specific absorption rate was limited to 1.5 W/kg. All pacemakers were reprogrammed before MRI: If heart rate was Ͻ60 bpm, the asynchronous mode was programmed to avoid magnetic resonance (MR)-induced inhibition; if heart rate was Ͼ60 bpm, sense-only mode was used to avoid MR-induced competitive pacing and potential proarrhythmia. Patients were monitored with ECG and pulse oximetry. All pacemakers were interrogated immediately before and after the MRI examination and after 3 months, including measurement of pacing capture threshold (PCT) and serum troponin I levels. All MR examinations were completed safely. Inhibition of pacemaker output or induction of arrhythmias was not observed. PCT increased significantly from pre-to post-MRI (Pϭ0.017). In 2 of 195 leads, an increase in PCT was only detected at follow-up. In 4 of 114 examinations, troponin increased from a normal baseline value to above normal after MRI, and in 1 case (troponin pre-MRI 0.02 ng/mL, post-MRI 0.16 ng/mL), this increase was associated with a significant increase in PCT. Conclusions-Extrathoracic MRI of non-pacemaker-dependent patients can be performed with an acceptable risk-benefit ratio under controlled conditions and by taking both MR-and pacemaker-related precautions.

In stable angina the platelet count is unchanged compared to patients with normal coronary arteries but the platelet size is increased. However, in unstable angina there is a decrease in platelet count and an even larger increase in platelet size. We interpret this as meaning that unstable angina might be associated or preceded by an increase in platelet destruction rate that is not completely compensated for by an increase in platelet production rate. The large, more reactive platelets might be causally related to an ongoing coronary artery obstruction in unstable angina.

This is the first study using highly sensitive DW-MRI of the brain to detect asymptomatic cerebral embolism after left atrial catheter ablation. Even small, clinically silent, embolic lesions can be demonstrated with this technique. DW-MRI can be used to monitor and compare the thrombogenicity of different AF ablation approaches.

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PV ablation with the cryoballoon technique is feasible and seems to have a similar success rate in comparison to RF ablation. Procedure- and fluoroscopy duration are not longer than in conventional RF ablation.

Background-Data regarding the freedom from atrial fibrillation (AF) in the follow-up of persistent AF patients is limited.The second-generation cryoballoon has better cooling properties compared with first-generation cryoballon. In this study, we aimed to assess the medium-term efficacy of second-generation cryoballoon in patients with persistent AF. Methods and Results-A total of 100 patients (63±10 years, 80% male) with symptomatic persistent AF, despite ≥1 antiarrhythmic drug(s), who were scheduled for pulmonary vein isolation using second-generation cryoballoon were enrolled in this study. Follow-up was based on outpatient clinic visits, including Holter ECGs. Recurrence was defined as a symptomatic or documented arrhythmia episode of >30 seconds excluding a 3-month blanking period. As a result, 393 pulmonary veins (7 patients with common ostium) were successfully isolated. Mean procedural and fluoroscopy times were 96.2±21.3 and 19.7±6.7 minutes, respectively. Phrenic nerve palsy occurred in 3% (3/100) of the patients. At a mean follow-up duration of 10.6±6.3 months, 67% of the patients were in sinus rhythm. Stepwise multivariable Cox proportional hazard regression analysis showed that early AF recurrence (hazard ratio 3.83, 95% confidence interval 1.91-7.68, P<0.001) was the only independent predictor for late AF recurrence apart from other clinical and echocardiographic variables. Conclusions-Our findings indicated that second-generation cryoballoon use is associated with favorable outcomes in patients with persistent AF. Recurrence at blanking period was the only predictor of long-term AF recurrence.

This study demonstrates that it is possible to reproducibly induce self-terminating AF and supraventricular arrhythmias in mice by transesophageal atrial burst stimulation. The presented method allowing serial testings of the same animal can be a useful tool in further investigations with transgenic mice and might be helpful in the characterization of underlying genetic or molecular mechanisms of AF.

Background & Aims ZBP-89 (also ZNF148 or Zfp148) is a butyrate-inducible zinc finger transcription factor that binds to GC-rich DNA elements. Deletion of the N-terminal domain is sufficient to increase mucosal susceptibility to chemical injury and inflammation. We investigated whether conditional deletion of ZBP-89 from the intestinal and colonic epithelium of mice increases their susceptibility to pathogens such as Salmonella typhimurium. Methods We generated mice with a conditional null allele of Zfp148 (ZBP-89FL/FL), using homologous recombination to flank Zfp148 with LoxP sites (ZBP-89FL/FL), and then breeding the resulting mice with those that express VillinCre. We used microarray analysis to compare gene expression patterns in colonic mucosa between ZBP-89FL/FL and C57BL/6 wild-type mice (controls). Mice were gavaged with 2 isogenic strains of S typhimurium after administration of streptomycin. Results Microarray analysis revealed that the colonic mucosa of ZBP-89FL/FL mice had reduced levels of tryptophan hydroxylase 1 (Tph1) mRNA, encoding the rate-limiting enzyme in enterochromaffin cell serotonin (5HT) biosynthesis. DNA affinity precipitation demonstrated direct binding of ZBP-89 to the mouse Tph1 promoter, which was required for its basal and butyrate-inducible expression. ZBP-89FL/FL mice did not increase mucosal levels of 5HT in response to S typhimurium infection and succumbed to the infection 2 days before control mice. The ΔhilA isogenic mutant of S typhimurium lacks this butyrate-regulated locus and stimulated, rather than suppressed, expression of Tph1 approximately 50-fold in control, but not ZBP-89FL/FL mice, correlating with fecal levels of butyrate. Conclusions ZBP-89 is required for butyrate-induced expression of the Tph1 gene and subsequent production of 5HT in response to bacterial infection in mice. Reductions in epithelial ZBP-89 increase susceptibility to colitis and sepsis following infection with S typhimurium, partly due to reduced induction of 5HT production in response to butyrate and decreased secretion of anti-microbial peptides.