P1033Impact of workflow modifications in atrial fibrillation ablation for reducing the incidence of silent cerebral lesions with a new multi-electrode radiofrequency balloon catheter

Background

Silent cerebral lesions (SCL) often occur after invasive cardiac procedures. Reported SCL incidence with AF ablation varies (incidence, up to 50%), depending on technology used, procedural workflow, and detection method.

Objective

To evaluate the impact of ablation workflow modifications on SCL incidence following pulmonary vein isolation radiofrequency (RF) ablation with a novel multi-electrode RF balloon catheter in patients with symptomatic paroxysmal AF (PAF).

Methods

In the RADIANCE feasibility study of the balloon catheter, all enrolled patients who underwent ablation were screened for SCL using pre- and post-procedural diffusion-weighted MRI. Several modifications were made to the ablation workflow in a subsequent European registration study (SHINE) of the same catheter: eliminating dual transseptal access, using an over-the-wire mini lasso, continuously irrigating all side ports, bolus dosing with heparin before transseptal puncture, maintaining activated clotting time (ACT) at 350–400 sec, and setting a maximum temperature limit of 55°C (previously, 60–65°C). Interim data are presented for SHINE (data cutoff, 22 Oct 2018).

Results

In the neurological assessment evaluable (NAE) populations of RADIANCE (n=38) and SHINE (n=30), respectively, mean ages were 60.8±10.04 and 59.7±7.83 years, and 57.9% and 70.0% were male. One patient in each study had a history of TIAs. SCL incidences were 23.7% (10 lesions in 9 patients) in RADIANCE and 7.1% (2 lesions in 2 patients) in SHINE (excluding 1 SCL that occurred in a patient who failed to meet inclusion criteria [age>75] and 1 SCL that occurred after data cut-off). SHINE NAE enrollment has since completed with no further SCL occurrences. Overall, mean ACTs were 344.3±24.55 sec in RADIANCE and 381.6±73.31 sec in SHINE (p=0.01); in patients with SCL, mean ACTs were 349.3±25.65 and 417.8±87.33 sec, respectively.

Conclusion(s)

Modifications to the workflow led to a decrease in the SCL incidence for PAF ablation using the novel RF balloon catheter.

Acknowledgement/Funding

These studies were sponsored by Biosense Webster, Inc.

Expert panel consensus recommendations for the pharmacological treatment of acute pain in the Middle East region

The findings of an expert panel convened to review critically how best to apply evidence-based guidelines for the treatment of acute pain in the Middle East region are presented. The panel recommended a three-step treatment protocol. Patients with mild-to-moderate levels of acute pain should be treated with paracetamol (step 1). If analgesia is insufficient after 1-2 days, a selective cyclo-oxygenase-2 inhibitor or, if gastrointestinal safety and bleeding risk are not an issue, a non-specific nonsteroidal anti-inflammatory drug, should be used (step 2). If analgesia remains inadequate, treatment with tramadol, or paracetamol plus codeine/tramadol is recommended (step 3). Patients reporting severe pain should be referred to a pain clinic or specialist for opioid analgesic treatment. Measures of pain and functioning that have been validated in Arabic, with culturally appropriate and easy to understand descriptors, should be used. Early and aggressive acute pain management is important to reduce the risk of pain becoming chronic, especially in the presence of neuropathic features.

Peroxynitrite mediates VEGF's angiogenic signal and functionviaa nitration‐independent mechanism in endothelial cells

The modulation of angiogenic signaling by reactive oxygen species (ROS) is an emerging area of interest in cellular and vascular biology research. We provide evidence here that peroxynitrite, the powerful oxidizing and nitrating free radical, is critically involved in transduction of the VEGF signal. We tested the hypothesis that VEGF induces peroxynitrite formation, which causes tyrosine phosphorylation and mediates endothelial cell migration and tube formation, by studies of vascular endothelial cells in vitro and in a model of hypoxia-induced neovascularization in vivo. The specific peroxynitrite decomposition catalyst FeTPPs blocked VEGF-induced phosphorylation of VEGFR2 and c-Src and inhibited endothelial cell migration and tube formation. Furthermore, exogenous peroxynitrite mimicked VEGF activity in causing phosphorylation of VEGFR2 and stimulating endothelial cell growth and tube formation in vitro and new blood vessel growth in vivo. The selective nitration inhibitor epicatechin enhanced VEGF's angiogenic function in activating VEGFR2, c-Src, and promoting endothelial cell growth, migration, and tube formation in vitro and retinal neovascularization in vivo. Decomposing peroxynitrite with FeTPPs or blocking oxidation using the thiol donor NAC blocked VEGF's angiogenic functions in vitro and in vivo. In conclusion, peroxynitrite is critically involved in transducing VEGF's angiogenic signal via nitration-independent and oxidation-mediated tyrosine phosphorylation.

TGF-beta increases retinal endothelial cell permeability by increasing MMP-9: possible role of glial cells in endothelial barrier function

PURPOSE

To determine transforming growth factor (TGF) beta effects on matrix metalloproteinases (MMPs) as a potential cause of the blood-retinal barrier breakdown at the onset of angiogenesis. Previously, glial cells were shown to play a role in the angiogenesis process and to express the angiogenic regulating factor TGF-beta, which becomes active under hypoxia conditions. Here, the authors demonstrate that retinal endothelial cells express MMP-9 when treated with TGF-beta or cocultured with glial cells and that both TGF-beta and MMP-9 increase endothelial cell permeability.

METHODS

Primary cultures of bovine retinal endothelial (BRE) cells grown on porous membranes were treated with TGF-beta or purified MMP-9, and permeability changes were assayed. The amount and distribution of the tight junction protein occludin also was analyzed by immunocytochemistry and Western blotting. Cell extracts or conditioned media from TGF-beta-treated BRE cells and from glial cell-BRE cocultures were analyzed for MMP-9 content by substrate gel electrophoresis (zymography) or Western blotting.

RESULTS

Both TGF-beta and MMP-9 increased the permeability of BRE monolayers and reduced the levels of the junction protein occludin. The effect of MMP-9 on permeability was rapid, but the TGF-beta-induced permeability required longer incubation and was blocked by anti-TGF-beta and anti-MMP-9 antibodies as well as by TGF-beta latency-associated peptide. Zymography showed that MMP-9 activity, which was very low or absent in untreated BRE cultures, was dramatically increased by TGF-beta as well as by coculturing with either astrocytes or Müller glial cells. Anti-TGF-beta antibody blocked the TGF-beta effect, but not the coculture effect on MMP-9 production.

CONCLUSIONS

These data indicate a direct correlation between TGF-beta-induced MMP-9 activity and increased endothelial cell permeability. Moreover, endothelial cell production of MMP-9 is regulated by glial cells through expression of TGF-beta or by direct cell-to-cell contact. During retinal disease, glial cell production of active TGF-beta may contribute to breakdown of the blood-retinal barrier by stimulating endothelial cell MMP-9 production.

U.S. experience with the AddVent VDD(R) pacing system. AddVent Phase I Investigators

The AddVent pacemaker generator and model 1328C AV single-pass lead is a new pacemaker system capable of VDD or VDDR modes. The purpose of this study was to present the initial experience with AddVent in the United States and Canada. Between May 10, 1995 and May 3, 1996, 53 devices were implanted in 52 patients and followed for a mean of 217 (+/- 39) days. At the predischarge, 1-, 3-, and 6-month follow-up evaluations, atrial sensing thresholds and ventricular sensing and capture thresholds were measured in the supine, sitting, and standing positions to evaluate stability of atrial sensing with respect to body posture at rest. At the 1-month follow-up, a treadmill exercise test was performed to evaluate atrial sensing during exercise and to evaluate two new features of the AddVent called "sensor-mediated rate smoothing" and "preferential P wave sensing." Atrial sensing thresholds were not significantly different (P > 0.05) among body postures for any follow-up period or among follow-up periods for each posture. At rest, the percentage of appropriately tracked P waves observed was > 99% at each follow-up period. During treadmill exercise, the percentage of appropriately tracked P waves was > 98.7%. Appropriate preferential P wave sensing and sensor-mediated rate smoothing (VDDR mode) was observed. The AddVent pacing system provides safe and effective pacing therapy. Several features of VDDR pacing offer advantages over standard VDD pacing.