Tortuosity is the Significant Predictive Factor for Renal Branch Occlusion after Branched Endovascular Aortic Aneurysm Repair.

OBJECTIVE: After multi-branched endovascular aneurysm repair (mbEVAR), renal branch occlusion is the most frequent form of branch failure. Pre-operative renal angulation and post-operative morphology of the renal branch were quantified and their impact on occlusion was analyzed. METHODS: Patients who underwent mbEVAR between January 2010 and December 2013 were reviewed retrospectively. Only renal branches constructed with caudally directed cuffs were included. Patients without post-operative computed (CT) angiography were excluded. The main outcome was the primary patency of the renal branches. The renal angulation and the morphology of renal branch (bridging length, renal coverage length, tortuosity index, and angulation of distal renal artery) were quantified using CT. The impacts of morphology, implanted stents, and patient characteristics were investigated by time to event analyses. RESULTS: Ninety renal arteries in 49 patients were enrolled. Median follow up was 12 months (IQR 6-20 months). Balloon expandable stent grafts were used in 93% (84/90) of renal branches. Self expandable stent grafts were used in 12. Ninety-one percent (82/90) were lined with self expandable bare stents. Ten branches occluded after 8 months (median; IQR 1-14 months). Four of them underwent re-interventions, achieving secondary patency. The median renal angulation was -10° (IQR -40 to 0). The median bridging length was 42 mm (IQR 39-46 mm) and renal coverage 17 mm (IQR 12-22 mm). Median tortuosity index was 1.11 (IQR 1.04-1.19). The angulation of the distal renal artery was 140.7 ± 20.5°. In multivariate analysis, a tortuosity index > 1.11 was identified as the only significant predictor for occlusion (hazard ratio: 4.94; 95% CI: 1.01-24.30, p = .04). CONCLUSIONS: High tortuosity was a significant predictor for the occlusion of renal branches, but renal angulation, bridging length, and the extent of renal coverage were not. By avoiding highly tortuous renal branch paths, good outcomes are expected even in upwardly directed renal arteries. Longer paths are acceptable.

Performance of Bridging Stent Grafts in Fenestrated and Branched Aortic Endografting.

OBJECTIVE/BACKGROUND: Bridging stent grafts (BSGs) are used to connect the target vessel with the main body during fenestrated or branched aortic endografting (f/bEVAR). No dedicated devices are available for BSG. The aims of this study were to assess the performance of BSGs. METHODS: Between January 2004 and May 2014 the data of patients treated with f/bEVAR were prospectively collected. Only patients treated after January 2010 were included. The main measurement outcome was any BSG related complications. A logistic regression analysis, including target vessel type, type of joint (fenestration or cuff), and type of BSG identified potential risk factors. RESULTS: One hundred and fifty consecutive patients underwent f/bEVAR, and 523 target vessels were involved. These included 104 celiac, 140 superior mesenteric, 275 renal, and four other arteries. The technical success rate was 99% (520/523 target vessels). Balloon expandable BSGs were mainly used (n = 494; 95%), and in 336 (65%) relining stents were combined. The primary reasons for technical failure were the dislocation of the main body (n = 1) and unsuccessful cannulation (n = 2). One was revascularized by means of the periscope technique. Four target vessel injuries were recorded and four renal arteries occluded peri-operatively. After a median follow up of 14 months (interquartile range 5.5-23.0), 13 (2%) BSGs occluded and 19 (4%) required re-interventions. Two SMA occlusions occurred, leading to death in both patients. The patency and freedom from re-intervention rates at 3 years amounted to 85% and 91%, respectively. Use of a branched main body was the only independent risk factor for re-intervention and for the composite event (hazard ratio [HR] 3.5, 95% confidence interval [CI] 1.3-9.9 [p = .02]; and HR 2.8, 95% CI 1.2-7.0 [p < .01], respectively). Of note, the use of relining stents seemed not to prevent BSG related complications. CONCLUSION: The currently used BSGs had low occlusion and re-intervention rates. Modifications of the branched design or dedicated BSG devices may improve outcome, especially after bEVAR.

In vitro ictogenesis and parahippocampal networks in a rodent model of temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) is a chronic epileptic disorder involving the hippocampal formation. Details on the interactions between the hippocampus proper and parahippocampal networks during ictogenesis remain, however, unclear. In addition, recent findings have shown that epileptic limbic networks maintained in vitro are paradoxically less responsive than non-epileptic control (NEC) tissue to application of the convulsant drug 4-aminopyridine (4AP). Field potential recordings allowed us to establish here the effects of 4AP in brain slices obtained from NEC and pilocarpine-treated epileptic rats; these slices included the hippocampus and parahippocampal areas such as entorhinal and perirhinal cortices and the amygdala. First, we found that both types of tissue generate epileptiform discharges with similar electrographic characteristics. Further investigation showed that generation of robust ictal-like discharges in the epileptic rat tissue is (i) favored by decreased hippocampal output (ii) reinforced by EC-subiculum interactions and (iii) predominantly driven by amygdala networks. We propose that a functional switch to alternative synaptic routes may promote network hyperexcitability in the epileptic limbic system.

Laser-evoked potentials as a tool for assessing the efficacy of antinociceptive drugs.

Laser-evoked potentials (LEPs) are brain responses to laser radiant heat pulses and reflect the activation of Adelta nociceptors. LEPs are to date the reference standard technique for studying nociceptive pathway function in patients with neuropathic pain. To find out whether LEPs also provide a useful neurophysiological tool for assessing antinociceptive drug efficacy, in this double-blind placebo-controlled study we measured changes induced by the analgesic tramadol on LEPs in 12 healthy subjects. We found that tramadol decreased the amplitude of LEPs, whereas placebo left LEPs unchanged. The opioid antagonist naloxone partially reversed the tramadol-induced LEP amplitude decrease. We conclude that LEPs may be reliably used in clinical practice and research for assessing the efficacy of antinociceptive drugs.

Conversion to open repair after endografting for abdominal aortic aneurysm: causes, incidence and results.

OBJECTIVE: To evaluate frequency, causes and results of conversion to Open repair (OR) after endovascular repair (EVAR) in a single centre during an 8-year period. DESIGN: Six hundred and forty-nine consecutive patients undergoing EVAR were followed up prospectively for endograft-related complications. OUTCOMES: Early conversion was any OR during or within 30 days from the primary EVAR. Late conversion was any OR with removal of the endograft after 30 days since a completed EVAR procedure. RESULTS: Median patient follow-up was 38 months (1-93 months). Conversion to OR was performed in 38 patients; nine early and 29 late. Most (7/9) early conversions were due to extensive vessel calcification. Peri-operative mortality was 22% (2/9). Late conversions occurred at a median of 33 months after primary EVAR: 29 were elective and 4 urgent. During the same interval, 79 secondary endovascular interventions were performed, 7 of which failed. The risk of conversion to OR was 9% at 6 years. At multivariate logistic regression analysis, no single factor (short, large or angulated neck, suprarenal fixation, large pre-operative diameter, iliac aneurysms, ASA score risk) was associated with the risk of late failure requiring conversion to OR. CONCLUSION: The risk of death after early conversion should be recognized, to avoid forcing morphological indications for primary EVAR. Occurrence of late conversion after EVAR is not negligible, affecting almost 1 out of 10 patients after 6 years. In the presence of an expanding aneurysm after EVAR, especially after a failed secondary endovascular correction, an aggressive attitude in fit patients allows outcomes at similar to those of primary OR.

Repetitive low-frequency stimulation reduces epileptiform synchronization in limbic neuronal networks.

Deep-brain electrical or transcranial magnetic stimulation may represent a therapeutic tool for controlling seizures in patients presenting with epileptic disorders resistant to antiepileptic drugs. In keeping with this clinical evidence, we have reported that repetitive electrical stimuli delivered at approximately 1 Hz in mouse hippocampus-entorhinal cortex (EC) slices depress the EC ability to generate ictal activity induced by the application of 4-aminopyridine (4AP) or Mg(2+)-free medium (Barbarosie, M., Avoli, M., 1997. CA3-driven hippocampal-entorhinal loop controls rather than sustains in vitro limbic seizures. J. Neurosci. 17, 9308-9314.). Here, we confirmed a similar control mechanism in rat brain slices analyzed with field potential recordings during 4AP (50 microM) treatment. In addition, we used intrinsic optical signal (IOS) recordings to quantify the intensity and spatial characteristics of this inhibitory influence. IOSs reflect the changes in light transmittance throughout the entire extent of the slice, and are thus reliable markers of limbic network epileptiform synchronization. First, we found that in the presence of 4AP, the IOS increases, induced by a train of electrical stimuli (10 Hz for 1 s) or by recurrent, single-shock stimulation delivered at 0.05 Hz in the deep EC layers, are reduced in intensity and area size by low-frequency (1 Hz), repetitive stimulation of the subiculum; these effects were observed in all limbic areas contained in the slice. Second, by testing the effects induced by repetitive subicular stimulation at 0.2-10 Hz, we identified maximal efficacy when repetitive stimuli are delivered at 1 Hz. Finally, we discovered that similar, but slightly less pronounced, inhibitory effects occur when repetitive stimuli at 1 Hz are delivered in the EC, suggesting that the reduction of IOSs seen during repetitive stimulation is pathway dependent as well as activity dependent. Thus, the activation of limbic networks at low frequency reduces the intensity and spatial extent of the IOS changes that accompany ictal synchronization in an in vitro slice preparation. This conclusion supports the view that repetitive stimulation may represent a potential therapeutic tool for controlling seizures in patients with pharmaco-resistant epileptic disorders.