Kent S. MacKenzie

Paraplegia prevention branches: A new adjunct for preventing or treating spinal cord injury after endovascular repair of thoracoabdominal aneurysms

In this report, we describe a technique that could potentially be used for both prevention and treatment of spinal cord ischemia (SCI) in endovascular repair of thoracoabdominal aneurysms. This technique involves using a specially designed endograft with side branches (paraplegia prevention branches [PPBs]), which are left patent to perfuse the aneurysmal sac and any associated lumbar or intercostal arteries in the early postoperative period. The use of PPBs with this technique is feasible and allows for a temporary controlled endoleak that may be useful for preventing or reversing spinal cord injury. This technique may be considered as an adjunct to the more standard perioperative physiological manipulations such as permissive hypertension and spinal fluid drainage.

B-mode ultrasound measurement of carotid bifurcation stenoses: is it reliable?

In the majority of cases, duplex ultrasonography (DU) is the sole imaging study necessary before carotid interventions. Duplex-derived internal carotid artery (ICA) peak systolic velocity (PSV), ICA end-diastolic velocity (EDV) and ICA/common carotid artery (CCA) PSV ratio are the most commonly utilized parameters for predicting critical carotid stenoses. However, the role of direct B-mode image measurement of maximal ICA narrowing is ill defined. The images and records of 192 patients who underwent both arteriography and duplex ultrasonography (DU) of 375 carotid arteries from January 1995 to November 2000 were reviewed. All DUs were performed by registered vascular technologists (n = 6). Maximum arteriographic stenosis was determined according to the NASCET study design. With arteriography as the “gold standard,” B-mode image (BMI) measurement of the maximal ICA luminal narrowing relative to the carotid bulb (n = 162) as well as the peak systolic velocity in the internal carotid artery (PSVICA) (n = 330), end-diastolic velocity in the internal carotid artery (EDVICA) (n = 198), and the ratio of the PSVs in both the ICA and the CCA (PSVICA/CCA) ratio (n = 319) were subjected to receiver operator characteristics (ROC) curves for 3 clinically relevant stenoses thresholds: 50-99%, 60-99%, and 70-99%. A strong correlation was found between B-mode image (BMI) and the NASCET arteriographic measures of carotid stenosis (r=0.80; p<0.001) and was similar among the 6 technologists (r=0.74-0.89; p>0.2). The overall accuracy of BMI measurement to diagnose 50%, 60%, and 70% arteriographic carotid stenosis was 85.3%, 82.2%, and 87%, respectively. BMI measurement was similar to the most accurate PSVICA, EDVICA, and PSVICA/CCA ratio at all 3 threshold stenoses levels (p>0.3). When combined with the velocity criteria, BMI measurement improved the positive predictive value (PPV) for all arteriographic stenoses thresholds by an average of 12.6% for PSVICA, 21.2% for EDVICA, and 14.2% for PSVICA/CCA ratio. BMI measurement of carotid bifurcation narrowing is as reliable as duplex-derived velocity criteria in evaluating clinically relevant threshold ICA stenoses. The routine use of B-mode ultrasound in conjunction with the velocity parameters enhances the PPV of carotid DU. Our experience suggests that with current refinements in B-mode resolution, BMI stenosis measurements are accurate among experienced technologists and are a useful adjunct to duplex-derived velocity parameters.

Intraoperative duplex scanning for carotid endarterectomy

OBJECTIVES To evaluate the results of intraoperative duplex scans during carotid endarterectomy. DESIGN Retrospective case review. MATERIALS One-hundred consecutive intraoperative carotid duplex scans performed during carotid endarterectomy between July 1993 and December 1995 at a university teaching hospital. METHODS Abnormalities of the B-mode image and/or the Doppler flow analysis were classified. The result of intraoperative carotid duplex scans (ICDS) were related to the events of the intraoperative course, perioperative neurologic morbidity and mortality, and to residual carotid stenosis. RESULTS Abnormalities of the ICDS were demonstrated in 13 cases (13%). Abnormalities were classified into four types: I, internal carotid artery spasm (n = 9); II, high distal resistance flow (n = 2); III, high grade residual stenosis (n = 1); IV, intraluminal thrombosis (n = 1). Immediate intraoperative exploration and revision of the endarterectomy was performed based on the ICDS in two cases (type III and IV) and the findings of ICDS were confirmed. The other 11 cases with abnormal ICDS (types I, II) were not revised and duplex scans done 1 month postoperatively (available in 10 cases) showed normal carotid artery flow. Intraoperative angiography was performed selectively in five cases and confirmed the results of ICDS. Reversible abnormalities of the ICDS were not associated wit perioperative morbidity or residual carotid stenosis. CONCLUSIONS Intraoperative carotid duplex scanning can be used to assess the immediate technical adequacy of carotid endarterectomy. B-mode image and Doppler flow abnormalities which are reversible can be distinguished from those which require immediate revision.

Association of Ultrasonic Texture and Echodensity Features Between Sides in Patients with Bilateral Carotid Atherosclerosis

OBJECTIVES Our objective was to estimate the correlation of echodensity and textural features, using ultrasound and digital image analysis, between plaques in patients with bilateral carotid stenosis. DESIGN Cross-sectional observational study. METHODS Patients undergoing carotid endarterectomy were recruited from Vascular Surgery at the Royal Victoria and Jewish General hospitals in Montreal, Canada. Bilateral pre-operative carotid ultrasound and digital image analysis was performed to extract echodensity and textural features using a commercially available Plaque Texture Analysis software (LifeQMedical Ltd). Principal component analysis (PCA) was performed. Partial correlation coefficients for PCA and individual imaging variables between surgical and contralateral plaques were calculated with adjustment for age, sex, contralateral stenosis, and statin use. RESULTS In the whole group (n = 104), the six identified PCA variables and 42/50 individual imaging variables were moderately correlated (r = .211-.641). Correlations between sides were increased in patients with ≥50% contralateral stenosis and symptomatic patients. CONCLUSION Textural and echodensity features of carotid plaques were similar between two sides in patients with bilateral stenosis, supporting the notion that plaque instability is determined by systemic factors. Patients with unstable features of one plaque should perhaps be monitored more closely or treated more aggressively for their contralateral stenosis, particularly if this is hemodynamically significant.

Videoendoscopic thoracic aorta-to-femoral artery bypassA feasibility study in a canine model

PURPOSE This study was undertaken to determine whether videoendoscopic thoracic aorta-to-femoral artery bypass is a technically feasible operation. METHODS An acute canine study involving five mongrel dogs was carried out. After the dogs had been given a general anesthetic, the femoral arteries were exposed in the traditional fashion. On the left side, a retroperitoneal, retrorenal tunnel was extended from the common femoral artery to the diaphragm. Under videoendoscopic control, the tunnel was opened through the posterior thoracic attachments of the diaphragm into the thoracic cavity. A Dacron graft was tunneled from the thoracic cavity on the left to the left groin. The thoracic aorta was controlled with a side-biting clamp, and an endoscopically performed end graft-to-side thoracic aortic anastomosis was created. After completion of the thoracic anastomosis, the left femoral anastomosis was created in a traditional manner. A left-to-right femoral bypass completed the lower extremity vascular procedure. An open thoracotomy was avoided. RESULTS Videoendoscopic thoracic aorta-to-femoral artery bypass was successfully performed in all five animals. All components of the thoracic procedure, including exposure, dissection, vessel control, cross-clamping, and anastomosis, were performed through the thoracic ports with conventional laparoscopic instruments. Blood loss was minimal. All animals survived the procedure before being killed. CONCLUSION Videoendoscopic thoracic aorta-to-femoral artery bypass is a technically feasible operation in a canine model. Advantages of this unique approach over the experimental laparoscopic and the traditional transperitoneal open aortofemoral bypass include ease of aortic exposure, ability to control a segment of disease-free aorta, and anastomosis in a disease-free segment of aorta. Potential advantages include decreased perioperative morbidity rates with the videoendoscopic approach. Before there is clinical consideration of this surgical approach, long-term experiments are required to demonstrate the safety of the procedure.

Midterm Results Following Endovascular Repair of Blunt Thoracic Aortic Injuries

Objective: Previous studies have focused on early outcomes of thoracic endovascular repair (TEVAR) of blunt thoracic aortic injuries (BTAIs). Late results remain ill-defined. The purpose of this study is to review the midterm results of our experience with endovascular repair of BTAIs. Methods: A retrospective analysis was performed reviewing all endovascular repairs of BTAIs from 2002 to present. Preoperative, operative, and postoperative variables were recorded. Clinical end points included aortic-related mortality, stroke and paraplegia, hospital length of stay, procedure-related complications, endoleaks, and reinterventions. Computed tomography data sets were postprocessed for assessing integrity of stent grafts and late complications. Results: A total of 24 cases of BTAIs treated with TEVAR were identified. Thoracic endovascular repair was successful in treating BTAIs in all patients and there were no instances of procedure-related death, stroke, or paraplegia. One access complication occurred, requiring an iliofemoral bypass. Actuarial survival estimates and freedom from reintervention at 5 years were 88.7% and 95.8%, respectively. No late endoleaks, stent fractures, or device migration were identified. One patient required a secondary intervention 1 year following the initial repair to treat a pseudocoarctation syndrome caused by a diaphragm at the distal half of the stented aorta. This was treated successfully with repeated endografting. Conclusions: Thoracic endovascular repair for BTAIs can be performed safely with low periprocedural mortality and morbidity. Midterm follow-up data presented in this report further support the therapeutic role of endoluminal approach for treating BTAIs in anatomically suitable patients.

Heparin-induced thrombocytopenia causing graft thrombosis and bowel ischemia postendovascular aneurysm repair

Heparin-induced thrombocytopenia (HIT) is an immune-mediated thrombocytopenia resulting from prior heparin exposure. It can be associated with limb- or life-threatening thrombotic events. Patients undergoing any vascular procedures including endovascular procedures that require heparin administration are at risk. There is very little reported in the literature with regards to thrombosis associated with HIT after endovascular aortic aneurysm repair. All reported cases of HIT thrombosis presented as acute arterial lower limb ischemia or deep vein thrombosis. In this report, we present a case of HIT complicated by stent graft thrombosis and bowel ischemia.

Canadian vascular surgery residents' perceptions regarding future job opportunities

The objective was to determine the employment environment for graduates of Canadian vascular surgery training programs. A cross-sectional survey of residents and graduates (2011–2012) was used. Thirty-seven residents were invited with a response rate of 57%, and 14 graduates with a response rate of 71%; 70% of graduates felt the job market played an important role in their decision to pursue vascular surgery as a career compared to 43% of trainees. The top three concerns were the lack of surgeons retiring, the overproduction of trainees, and saturation of the job market. The majority (62%) of trainees see themselves extending their training due to lack of employment. All of the graduates obtained employment, with 50% during their second year (of two years) of training and 30% after training was completed. Graduates spent an average of 12 ± 10.6 months seeking a position and applied to 3.3 ± 1.5 positions, with a mean of 1.9 ± 1.3 interviews and 2 ± 1.2 offers. There was a discrepancy between the favorable employment climate experienced by graduates and the pessimistic outlook of trainees. We must be progressive in balancing the employment opportunities with the number of graduates. Number and timing of job offers is a possible future metric of the optimal number of residents.

Carotid artery angioplasty and stenting: introduction of a new technique into an established vascular surgery center.

Background: The aim of this study was to review our initial experience with the introduction of carotid artery angioplasty and stenting as a treatment for carotid stenosis in high-risk patients and compare clinical outcomes to carotid endarterectomy patients treated over the same time period at our center. Methods: A total of 265 carotid revascularization procedures (45 carotid artery angioplasty and stenting and 220 carotid endarterectomy) were performed over 3 years period. In the carotid artery angioplasty and stenting group, 93% were at high risk according to the current reporting standards. Death, neurological events, and restenosis rates were compared at 30 days and at most recent follow-up. Results: Mean follow-up for all patients was 18 months (range 0-48 months). Carotid artery angioplasty and stenting group had higher cardiac risk than carotid endarterectomy group (13% vs 2%, P < .05). High-risk carotid lesions were present in 67% of carotid artery angioplasty and stenting patients. There was a tendency toward higher restenosis rate in carotid artery angioplasty and stenting than in carotid endarterectomy patients (35% vs 15%, P = .06). Combined stroke and death was higher in the carotid stenting group (4% and 9%) compared to the carotid endarterectomy group (0.5% and 0.5%) at 30 days and at late follow-up, respectively (P = .04 and .00). Conclusion: Restenosis and stroke were observed more frequently in our initial experience in patients undergoing carotid artery angioplasty and stenting compared with carotid endarterectomy patients during the same time period. These differences disappeared in high-risk patients. Further studies, to evaluate the effect of the learning curve on early results as well as follow-up for intermediate and long-term durability of carotid artery angioplasty and stenting in high-risk patients, are required.

Long-Term Survival After Endovascular Aneurysm Repair and Open Repair in Patients With Anatomy Outside Endovascular Aneurysm Repair Instructions for Use Criteria

Objective: Percutaneous access for endovascular aneurysm repair (PEVAR) is less invasive compared with surgical access (S-EVAR) and is associated with faster recovery and fewer wound complications. However, vascular closure devices (VCDs) are costly, and better understanding of the precise economic impact of P-EVAR has important implications for resource allocation. The objective was to determine the differences in cost between P-EVAR and S-EVAR. Methods: We used a decision tree to analyze costs from a payer’s perspective during the course of the index hospitalization. Probabilities, relative risks, and mean difference summary measures were obtained from a systematic review and meta-analysis. We modeled differences in surgical site infection, lymphocele, and length of hospitalization. Cost parameters were derived from the 2014 U.S. National Inpatient Sample using International Classification of Diseases, Ninth Revision, Clinical Modification codes. Attributable costs were estimated using generalized linear models adjusted by age, sex, and comorbidities. Results: A total of 6876 abdominal and thoracic EVARs were identified. P-EVAR resulted in a cost saving of