Duplex ultrasound criteria for in-stent restenosis of mesenteric arteries.

OBJECTIVE: Duplex ultrasound (DUS) criteria are well defined for evaluating high-grade stenosis (≥70%) of the native superior mesenteric artery (SMA) and celiac artery (CA). It has been shown that native vessel criteria overestimate the degree of in-stent restenosis (ISR) and that velocity criteria for SMA and CA ISR are not well established. The objective of this study was to define DUS velocity criteria for high-grade ISR of the SMA and CA. METHODS: A retrospective review of all patients who underwent SMA or CA stenting from a single institution was performed from 2004 to 2013. Patients were excluded if they did not have a DUS examination <4 months before angiography to assess stent patency or adequate angiographic visualization of the ISR. RESULTS: There were 103 paired DUS scans and angiograms analyzed: 66 SMA studies and 37 CA studies. The average peak systolic velocity (PSV) for SMAs was 367 cm/s with <70% ISR and 536 cm/s with ≥70% ISR. The average PSV for CAs was 302 cm/s with <70% ISR and 434 cm/s with ≥70% ISR. For an ISR ≥70% in the SMA, a PSV ≥445 cm/s produced the highest sensitivity (83%) and specificity (83%), with a positive predictive value of 81% and a negative predictive value of 86%. For an ISR ≥70% in the CA, a PSV ≥289 cm/s produced the highest sensitivity (100%) and specificity (57%), with a positive predictive value of 79% and negative predictive value of 100%. CONCLUSIONS: Increasing PSV correlates with an increasing degree of ISR for both the SMA and CA. Stented vessels have increased PSV, and therefore native PSV criteria are unreliable for the determination of ISR. The PSV criteria for ≥70% stenosis are higher for ISR than for native visceral vessel stenosis. The proposed new velocity criteria define ≥70% ISR as ≥445 cm/s in stented SMAs and ≥289 cm/s in stented CAs.

Arteriovenous graft configuration in hemodialysis: does it matter?

PURPOSE: The current guidelines for arteriovenous graft (AVG) configuration in hemodialysis state the following sequence: forearm loop, upper arm straight or curved and upper arm looped. These recommendations are based upon literature from the 1980s. Modern patient demographics and patient treatment algorithms, i.e., the Fistula First initiative (FFI), have greatly changed the current practice environment. It is not clear if these changes alter the outcomes of AVGs based upon configuration. METHODS: The most recent National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF/K-DOQI) guidelines for vascular access were reviewed. Articles cited to support recommendations for AVG configuration were evaluated. The following search terms: arteriovenous graft configuration, access configuration, PTFE configuration in hemodialysis and straight, looped, curved graft configuration were used to search PubMed, Ovid, Medline and Google scholar. Articles that included data comparing AVG configuration were included. Citations within those articles were examined for publications overlooked in the initial search. Four articles and one abstract were reviewed and separated into pre- and post-FFI groups. RESULTS: Pre-FFI articles demonstrate superiority of forearm looped AVG over straight forearm grafts. Post-FFI, the literature suggests that primary patency, thrombosis and steal are not affected by configuration and location, although looped configuration may have superior secondary patency. CONCLUSIONS: The available literature is mixed regarding the effect of configuration on AVG outcomes. Current studies illustrate the effect may be limited and that larger randomized controlled trials are necessary to draw firm conclusions. Regardless, adequate inflow and an appropriately sized outflow vein are paramount for optimal graft performance.

Outcomes of combined somatosensory evoked potential, motor evoked potential, and electroencephalography monitoring during carotid endarterectomy.

BACKGROUND: While much has been written about multiple methods of neuromonitoring during carotid endarterectomy (CEA), there has been relatively little discussion of the use of triple monitoring via somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) in conjunction with electroencephalography (EEG). Our objective was to evaluate the rate of detection and prevention of neurologic events by multinerve SEP, MEP, and EEG in patients undergoing CEA while under general anesthesia. METHODS: A prospective study of 181 consecutive patients undergoing CEA between June 2005 and September 2010 was reviewed. Intraoperative changes, including a 50% reduction in the amplitude of SEP waveforms, loss of MEP, and/or a 50% change in EEG frequency were noted as indications for shunting. This was correlated with the actual use of intraoperative shunting and postoperative neurologic sequelae at both 24 hours and 30 days. Median and tibial nerve SEPs and MEPs were also correlated. RESULTS: Eleven patients (6%) experienced intraoperative monitoring changes (SEP: 11/11; MEP: 6/11). Five of 11 patients with MEP/SEP changes underwent shunting, while the other 6 had normalization with the elevation of their blood pressure. Of the 11 patients that had neurophysiologic changes, 54% (6/11) were patients with symptomatic disease. No patients had significant EEG changes. The total shunt rate was 2.7% (5/181). No postoperative neurologic sequelae were noted. CONCLUSION: The ratio of shunting at 2.7% is equal to the lowest rates reported in the awake patient literature. Interestingly, the predicted synergy of multimodality monitoring cannot be directly attributed to an increased specificity resulting from the addition of SEP and MEP to EEG, because no patients had EEG changes. In addition, in today's cost-conscious world of health care, our results do not justify implementing this particular technique of neuromonitoring across the board-but it is apparent that the combination of these 3 modalities is both safe and effective with potential applications in symptomatic patients.