Outcomes for forearm and upper arm arteriovenous fistula creation with the transposition technique.

OBJECTIVE: To study the outcomes of three different types of arteriovenous fistula (AVF) transpositions (forearm cephalic vein transposition [FACVT], upper arm cephalic vein transposition [UACVT], and upper arm basilic vein transposition [UABVT]) for dialysis patients in a single center. METHODS: A 6-year retrospective review, from 2006 to 2012, was conducted at a single institution in which the surgical outcomes for three different types of AVF transposition were reviewed. Preoperative duplex vein mapping was obtained in all patients to choose the best vein for access. RESULTS: There were 165 patients identified with 77 FACVTs, 52 UACVTs, and 36 UABVTs. Primary access maturation rates for the FACVT, UACVT, and UABVT groups were 86%, 90%, and 97%, respectively (P = .19). All transposed, matured primary AVFs were used after a mean of 9.9 weeks, without additional intervention. Primary 1-year patency for the FACVT, UACVT, and UABVT groups were 63%, 61%, and 70%, respectively (P = .71). Primary assisted 1-year patency for the FACVT, UACVT, and UABVT groups were 93%, 93%, and 100%, respectively (P > .999). Mean operating room times and time to intervention were not significantly different between the groups. The postoperative hematoma rate was 2% and wound infection rate was 2%. Multivariate analysis indicated no significant predictors of time to failure (P > .05). CONCLUSIONS: With low primary failure rates, reduced need for secondary interventions before maturation, and 1-year primary assisted patency rates in excess of 93%, our study showed that the transposition technique, in our experience, is superior to previously published literature in hemodialysis access creation.

Vasculature of the hive: heat dissipation in the honey bee (Apis mellifera) hive.

Eusocial insects are distinguished by their elaborate cooperative behavior and are sometimes defined as superorganisms. As a nest-bound superorganism, individuals work together to maintain favorable nest conditions. Residing in temperate environments, honey bees (Apis mellifera) work especially hard to maintain brood comb temperature between 32 and 36 °C. Heat shielding is a social homeostatic mechanism employed to combat local heat stress. Workers press the ventral side of their bodies against heated surfaces, absorb heat, and thus protect developing brood. While the absorption of heat has been characterized, the dissipation of absorbed heat has not. Our study characterized both how effectively worker bees absorb heat during heat shielding, and where worker bees dissipate absorbed heat. Hives were experimentally heated for 15 min during which internal temperatures and heat shielder counts were taken. Once the heat source was removed, hives were photographed with a thermal imaging camera for 15 min. Thermal images allowed for spatial tracking of heat flow as cooling occurred. Data indicate that honey bee workers collectively minimize heat gain during heating and accelerate heat loss during cooling. Thermal images show that heated areas temporarily increase in size in all directions and then rapidly decrease to safe levels (<37 °C). As such, heat shielding is reminiscent of bioheat removal via the cardiovascular system of mammals.

Evaluation of techniques to model bend loss in multimode fibers for endoscopic application.

Bend loss from optical fibers can have positive applications, which need to be characterized and related to fiber curvature in a systematic approach to be useful. One potential application for optical fibers is a shape sensor for tracking flexible bodies in remote access environments, such as in endoscopy or boroscopy. We conducted a review of bend-loss characterization and evaluated several methods for characterizing bend loss in multimode optical fibers for an endoscopic shape-tracking application. Specifically, closed-form equation-based methods and numerical simulations were examined. Beam propagation method (BPM) simulations were determined to be the most applicable characterization tool. Results from simulations using BPM software were compared to experimentally obtained data. BPM simulation was sufficiently accurate for modeling 50 mum fibers but impractical for larger, multimode fibers.

Do different sitting postures affect spinal biomechanics of asymptomatic individuals?

BACKGROUND: Static sitting is thought to be related to low back pain. Of various common seated postures, slouched sitting has been suggested to cause viscoelastic creep. This, in turn, may compromise trunk muscle activity and proprioception, and heightening the risk of low back pain. To date, no research has evaluated immediate and short-term effects of brief exposures to different sitting postures on spinal biomechanics and trunk proprioception. RESEARCH QUESTION: This study aimed to compare the impacts of 20 min of static slouched, upright and supported sitting with a backrest on trunk range of motion, muscle activity, and proprioception immediately after and 30 min after the sitting tasks. METHODS: Thirty-seven adults were randomly assigned to the three sitting posture groups. Surface electromyography of six trunk muscles during maximum voluntary contractions were measured at baseline for normalization. Pain intensity, lumbar range of motion, and proprioceptive postural control strategy were assessed at baseline, 20 min (immediately post-test) and at 50 min (recovery). Trunk muscle activity during sitting was continuously monitored by surface electromyography. RESULTS: While the slouched sitting group demonstrated the lowest bilateral obliquus internus/transversus abdominis activity as compared to other sitting postures (F = 4.87, p < 0.05), no significant temporal changes in pain intensity, lumbar range of motion nor proprioceptive strategy were noted in any of the groups. SIGNIFICANCE: Sitting for 20 min of duration appears to have no adverse effects on symptoms or spinal biomechanics regardless of the posture adopted. Future research should determine if there is a point at which does slouched sitting cause significant changes in pain/spinal biomechanics in people both with and without low back pain.

Ruptured abdominal aortic aneurysm repair in pediatric Marfan syndrome patient.

Marfan syndrome is a well-described autosomal dominant connective tissue disorder with a constellation of anatomic characteristics including aortic degeneration as a result of the spontaneous mutation of the fibrillin gene, FBN1. Whereas life-threatening dissection and ascending aneurysmal rupture have been thoroughly documented in the literature, aneurysms of the abdominal aorta and those present in the pediatric population have only rarely been reported. In this case report, we describe presentation, successful open surgical repair, and recovery of a pediatric Marfan syndrome patient with a ruptured abdominal aortic aneurysm.

Outcomes of a single-center experience with classification and treatment of endothermal heat-induced thrombosis after endovenous ablation.

OBJECTIVE: Endothermal heat-induced thrombosis (EHIT) is a known complication of endothermal venous ablation procedures. EHIT can lead to deep vein thrombosis/pulmonary embolism, which cause significant disability and, rarely, death. Other studies have evaluated risk factors for EHIT. There is an accepted grading system for EHIT, but there is no consensus on treatment type, duration, or follow-up. We retrospectively evaluated all cases of EHIT after radiofrequency ablation or endovenous laser ablation at our institution during a 7-year period, focusing on classification, treatment, and outcomes of EHIT. METHODS: The analysis included all patients aged >18 years who underwent radiofrequency ablation or endovenous laser ablation at our institution, Spectrum Health Hospital Vein Solutions (Grand Rapids, Mich), between January 1, 2008, and December 31, 2014. Electronic medical records were queried retrospectively to identify patients with EHIT during the study interval by International Classification of Diseases-Ninth Revision code. Demographic data, including age, gender, comorbidities (eg, history of deep venous thrombosis, hypercoagulable state, family history of blood clots, etc), body mass index, Clinical, Etiology, Anatomy, and Pathophysiology (CEAP) classification, and use of preoperative anticoagulation were collected for each patient in the registry. Each patient had a required postoperative duplex ultrasound (US) examination within 1 to 2 weeks of the procedure. Preoperative and postoperative US imaging data and procedure-specific data were also recorded for each patient. EHIT was graded from 1 to 4 by review of the US studies. Each patient's treatment course was reviewed for type of anticoagulation, duration of treatment, follow-up imaging, and outcome. RESULTS: From 2008 to 2014, 4799 ablations were performed at Spectrum Health Hospital Vein Center, and EHIT was identified in 70 patients. At presentation, 87% of patients were asymptomatic, 10% reported pain, and 2.9% reported swelling. Patients with EHIT grades 1 or 2 were treated with daily aspirin, and most of those with grades 3 or 4 were treated with systemic anticoagulation. Repeat US imaging was performed at 1 to 2 weeks to evaluate progression. Progression was not seen in any patients treated with systemic anticoagulation (grades 3-4). Thrombus progression occurred in two patients with grades 1 or 2 EHIT treated with aspirin. A bleeding complication occurred in one patient. CONCLUSIONS: EHIT after endovenous ablation occurred in ∼1.5% of patients, which is similar to that reported in the literature. Our review shows that systemic anticoagulation is effective in the prevention of progression with a low risk of bleeding complications. Patients with EHIT grades 1 or 2 can be treated with aspirin alone with a low risk of progression (3%).

Preliminary results of Zenith Fenestrated abdominal aortic aneurysm endovascular grafts.

BACKGROUND: Patients with juxtarenal aortic aneurysms who are unfit for open repair may be considered for fenestrated endovascular repair (fenEVAR). We report our initial experience with fenEVAR. METHODS: We reviewed the data on all our patients receiving fenEVAR for juxtarenal aortic aneurysms. RESULTS: Eight patients, average age 75 years, underwent fenEVAR. Endografts were designed from details obtained from preoperative computed tomography angiography. There were 6 grafts with superior mesenteric scallops and bilateral renal fenestrations, 1 with bilateral renal scallops, and 1 with a single renal fenestration. All patients survived 30 days. There was no renal failure requiring dialysis. At 10 weeks, 1 patient died from acute intestinal ischemia and multisystem organ failure, and another died from respiratory failure. CONCLUSIONS: It is feasible to offer fenEVAR to patients who are poor candidates for open repair. However, these procedures are technically challenging. Early outcomes are less favorable than other aortic endovascular procedures.

Endovascular repair of traumatic thoracic aortic tears.

BACKGROUND: Patients with thoracic aorta injuries (TAI) present a unique challenge. The purpose of this study was to review the outcomes of thoracic endovascular aortic repair (TEVAR) in patients with TAI. METHODS: A retrospective chart review of all patients admitted for TEVAR for trauma was performed. RESULTS: In a 5-year period, 19 patients (6 women and 13 men; average age, 42 y) were admitted to our trauma center with TAI. Mechanism of injury was a motor vehicle crash in 12 patients, motorcycle crash in 2 patients, automobile-pedestrian accident in 2 patients, 1 fall, 1 crush injury, and 1 stab wound to the back. A thoracic endograft was used in 6 patients and proximal aortic cuffs were used in 13 patients (68%). One patient (5%) died. There were no strokes, myocardial infarctions, paraplegia, or renal failure. CONCLUSIONS: TEVAR for TAI appears to be a safe option for patients with multiple injuries. TEVAR in young patients is still controversial because long-term endograft behavior is unknown.

Vascular procedures in nonagenarians and centenarians are safe.

BACKGROUND: An increasing number of elderly patients present for elective and emergent vascular procedures. The purpose of this study was to analyze the 30-day and long-term outcome of patients in their 10th decade of life undergoing vascular procedures. METHODS: We reviewed the outcomes of all patients in the 10th decade of life included in our registry. RESULTS: In a 15-year period, there were 176 patients, 102 women and 74 men, with a mean age of 92 (range 90-102) undergoing 196 vascular operations for acute and chronic limb ischemia, aortic and popliteal aneurysms, and carotid stenosis. Overall morbidity and mortality rates were comparable as well as the return to preoperative functional status. CONCLUSIONS: Patients in their 90s can safely undergo vascular procedures with reasonable early outcomes. Most patients return to their preoperative status. Age alone should not be a determinant in refusing surgery in this age group.

Complication rates for percutaneous lower extremity arterial antegrade access.

HYPOTHESIS: The antegrade access (AA) for percutaneous arterial interventions is associated with a higher complication rate than is the retrograde access (RA). DESIGN: Retrospective case review. SETTING: A statewide consortium for peripheral vascular interventions consisting of 13 Michigan hospitals collecting data on their endovascular procedures. PATIENTS: Demographic and procedure data on all patients receiving a percutaneous peripheral arterial intervention were entered prospectively by a full-time clinical nurse specialist in each hospital site. MAIN OUTCOME MEASURES: We evaluated vascular complications as a composite of retroperitoneal hematoma, pseudoaneurysm, hematoma requiring blood transfusion, arteriovenous fistula, acute thrombosis, or the need for surgical repair of the access site. RESULTS: In a 2-year period, we collected 6343 cases, of which 5918 had complete data regarding arterial access; of these, 745 (12.6%) were performed via an AA. There were fewer women and smokers (P < .001) in the AA group but more diabetic patients (P < .001). The indications for intervention were more frequently rest pain (P < .001) and limb salvage (P < .001) in the AA group. Multivariate regression analysis showed that the odds of complications were significantly higher with a larger sheath (95% confidence interval, 1.53-4.06; P < .001). Also, the incidence of blood transfusion and subsequent amputation was significantly higher in the AA group (P < .001). CONCLUSION: Endovascular procedures performed via an AA are more likely to result in perioperative complications and therefore should be used cautiously.