Formation of thermal coagulum on multielectrode catheters during phased radiofrequency energy ablation of persistent atrial fibrillation.

BACKGROUND: Radiofrequency ablation (RFA) can unfavorably cause coagulum on the ablation electrode. The aim of this study was to assess this phenomenon on three different multielectrode catheters used to treat persistent atrial fibrillation with duty-cycled RFA. METHODS AND RESULTS: Twenty-six consecutive patients have been treated with the pulmonary vein ablation catheter (PVAC) and the multiarray ablation catheter (MAAC). In 13 patients, additional ablation with the multiarray septal catheter (MASC) has been performed. The multichannel RF generator GENius™ (Medtronic Inc., Minneapolis, MN, USA) independently delivered energy in a bipolar and unipolar mode (ratio of 4/1, 2/1, or 1/1) to any of the electrodes. Versions 14.2, 14.3, and 14.4 of the generator were used. Coagulum presence was determined postablation by careful visual inspection of the catheter electrodes. No coagulum formation was visualized on the PVACs. Coagulum formation was visualized in 59% of the electrodes of the MAACs using a 2/1 mode and the 14.2 software version versus 69% using the 14.4 version and a 2/1 mode (P = 0.7) versus 14% of the electrodes applying a 1/1 ratio and the 14.4 software version (P < 0.001). CONCLUSIONS: Duty-cycled RFA in 2/1 bipolar/unipolar ratio generates a substantial frequency of coagulum formation on the multielectrode catheters MAAC and MASC. The use of the 14.4 version of the software to drive the RF generator and the use of energy in the default 1/1 bipolar/unipolar ratio could significantly reduce the frequency of coagulum formation, but so far, could not completely overcome it. The PVAC did not form coagulum, regardless of generator version or energy ratio used.

Unifocal Right-Sided Ablation Treatment for Neurally Mediated Syncope and Functional Sinus Node Dysfunction Under Computed Tomographic Guidance.

Background Biatrial, extensive, and complex ablation strategies have been published for the treatment of neurally mediated syncope, sinus node dysfunction, and functional atrioventricular block. We have developed a less extensive and more specific approach compared with previously published cardioneuroablation strategies, called cardio-neuromodulation. It is based on tailored vagolysis of the sinoatrial node through partial ablation of the anterior right-ganglionated plexus, preferentially through a right-sided approach. Methods Patients with syncope were enrolled between December 2016 and December 2017. They were assigned to group A if they had a positive head-up tilt test and to group B if they presented with a pause ≥3 seconds. The area to target during cardio-neuromodulation was designed offline on a computed tomographic scan. Slow heart rates and pauses were compared during 24-hour rhythm registration at baseline, at 1-month follow-up, and 6-month follow-up. Syncope burden was assessed before the procedure and at 3- and 6-month follow-up. Results Twenty patients underwent cardio-neuromodulation through a right-sided approach (12 in group A, 8 in group B). The first application of radiofrequency energy led to a P-P interval shortening >120 ms in all 20 patients. After a mean±SD ablation time of 7±4 minutes and mean ablated surface area of 11±6 mm2, the P-P interval shortened by 219±160 ms ( P<0.001). The number of beats <50/min during 24-hour rhythm registration was reduced by a median of 100% at 6-month follow-up ( P<0.001). Syncope burden was reduced by 95% at 6-month follow-up ( P<0.001). Conclusions These data indicate that cardio-neuromodulation, through a right-sided and computed tomographic-guided procedure, is safe, fast, and highly reproducible in preventing inappropriate functional sinus bradycardia and syncope recurrence.

Recombinant P-selectin glycoprotein ligand-immunoglobulin, a P-selectin antagonist, as an adjunct to thrombolysis in acute myocardial infarction. The P-Selectin Antagonist Limiting Myonecrosis (PSALM) trial.

BACKGROUND: Inflammatory responses induced by reperfusion of previously ischemic myocardial tissue may lead to further damage of the microvascular structures. A group of cell adhesion molecules, named selectins, initiate those inflammatory changes at the endothelial wall surface. Recombinant P-selectin glycoprotein ligand-immunoglobulin (rPSGL-Ig), a P-selectin antagonist, was shown to have beneficial effects in several animal models of acute myocardial ischemia. We performed a mechanistic study with positron emission tomography to test the potential benefits of rPSGL-Ig in patients with ST-segment elevation acute myocardial infarction. METHODS: Patients with ST-elevation acute myocardial infarction presenting within the first 6 hours of onset of chest pain were enrolled. All patients received alteplase. Patients were randomly assigned in a 1:1:1 ratio to 3 treatment groups: placebo; 75 mg rPSGL-Ig; 150 mg rPSGL-Ig, given intravenously. Coronary angiography was performed 90 minutes after the start of thrombolytic therapy for TIMI flow grading. Myocardial blood flow (MBF) was measured with 13NH3 at rest and after adenosine administration on day 5. Myocardial blood flow at rest was measured again at day 30, followed by measurement of 18FDG uptake. In addition, a multigated acquisition, gated equilibrium blood pool study was performed at day 30. Continuous 12-lead electrocardiogram recording was performed during the first 24 hours. RESULTS: The trial was prematurely stopped by the sponsor for lack of efficacy in an accompanying larger trial after enrolling 88 patients in the current study. Median MBF in the infarct-related territory (expressed as percentage of the normalized blood flow) at day 5 was similar in the 3 treatment groups (9.1% in the placebo group vs 3.8% in the 75-mg dose and 4.3% in the 150-mg rPSGL-Ig treatment group; P = not significant). No significant differences in MBF reserve, myocardial metabolism, ST-segment resolution, left ventricular ejection fraction, or TIMI flow grade were found among the 3 groups. CONCLUSIONS: In this prematurely stopped mechanistic study, there was no evidence of a benefit of rPSGL-Ig given as an adjunct to thrombolysis on epicardial vessel patency, myocardial tissue reperfusion, or recovery of function.