Thodur Vasudevan

Predictive factors for limb occlusions after endovascular aneurysm repair

OBJECTIVE Greater flexibility and smaller sizes for introducer sheaths in the newest stent grafts increase the feasibility of endovascular aneurysm repair but raise concerns about long-term limb patency. The aim of the study was to determine the incidence of and predictive factors for limb occlusion after use of the Endurant stent graft (Medtronic Inc, Minneapolis, Minn) for abdominal aortic aneurysm. METHODS The Endurant Stent Graft Natural Selection Global Postmarket Registry (ENGAGE) prospectively included 1143 patients treated with bifurcated devices who were observed for up to 2 years. Limb occlusions were evidenced by computed tomography, angiography, or ultrasound. To predict stent graft limb occlusion, a two-step model-building technique was applied. We first identified predictors from a total of 47 covariates obtained at baseline and in the periprocedural period. Subsequently, we reduced the set of potential predictors to key factors that are clinically meaningful. To handle large numbers of covariates, we used the Classification And Regression Tree (CART) method. RESULTS Forty-two stent graft limbs occluded in 39 patients (3.4% of the patients). At 2 years, the rate of freedom from stent graft limb occlusion calculated by Kaplan-Meier plot was 97.9% (standard error [SE], 0.33%). Of the 42 occlusions, 13 (31%) were observed within 30 days and 30 (71%) within 6 months. The strongest independent predictors were distal landing zone on the external iliac artery, external iliac artery diameter ≤10 mm, and kinking. High-risk vs low-risk patients were identified according to a decision tree based on the strongest predictors. Freedom from stent graft limb occlusion was 96.1% (SE, 0.64%) in high-risk patients vs 99.6% (SE, 0.19%) in low-risk patients. CONCLUSIONS After Endurant stent grafting, the incidence of limb occlusion was low. Classifying patients as high risk vs low risk according to the algorithm used in this study may help define specific strategies to prevent limb occlusion and improve the overall results of endovascular aneurysm repair using the latest generation of stent grafts.

Comparison of FLIXENE™ and standard PTFE arteriovenous graft for early haemodialysis.

Purpose The purpose is to compare the outcomes of FLIXENE™ arteriovenous graft (AVG) to standard polytetrafluoroethylene (PTFE) AVG for early haemodialysis. Methods This is a prospective observational study of all AVGs placed over a 40-month period between 2008 and 2011 at our vascular unit. Primary outcome was to examine early cannulation rates for FLIXENE™. Secondary outcomes included patency rates, usability of grafts, complications in particular infections, interventions and death in comparison to standard PTFE grafts. Results Forty-five FLIXENE™ and 19 standard PTFE AVGs were placed in the study period; 89% of FLIXENE™ grafts were used for dialysis, with 78% cannulated within 3 days. At 18 months, primary patency (FLIXENE™ 34% vs standard PTFE 24%), primary assisted patency (35% vs 36%) and secondary patency rate (51% vs 48%) were not statistically different; 20.2% of FLIXENE™ grafts were infected at 18 months requiring explantation compared with 40.3% of standard PTFE grafts (p=0.14). Conclusions FLIXENE™ can be cannulated for dialysis within 3 days. It has similar patency and complication rates as other prosthetic grafts in the market. In patients who have no access and require urgent dialysis, FLIXENE™ is a viable option.

Use of an implantable needle guide to access difficult or impossible to cannulate arteriovenous fistulae using the buttonhole technique

Purpose The aim of this work was to assess the safety and efficacy of the VWING Vascular Needle Guide to assist in cannulation of difficult or impossible to access fistulae using the buttonhole cannulation technique. Methods VWING devices were surgically implanted into patients with difficult to access fistulae. A nondevice site and a device site were used to access the fistula and perform dialysis over a six month period. The device site utilized the buttonhole cannulation technique. The performance of each access site was recorded. Results VWING devices were implanted in nine patients. A total of 387 cannulations took place over 1367 study days. The device site was successfully used 94% of the time compared to 77% for the nondevice site. Cannulation success was comparable between the device and nondevice sites. Ease of insertion, pain during insertion and complication rates were also comparable. No interventions were required at the device site to maintain access compared with four interventions for the nondevice access site. Conclusions The VWING performed as intended by facilitating required repeated access to the vascular system and access for hemodialysis treatment. The study has demonstrated that the VWING is a potential solution for access to difficult to cannulate fistulae.

Correlation of ABCD2 Score with Degree of Internal Carotid Artery Stenosis: An Observational Pilot Study

BACKGROUND ABCD(2) is a validated scoring system that predicts the risk of stroke after a transient ischemic attack (TIA). International guidelines suggest that patients with a low score can be investigated on an outpatient basis. The ABCD2 score, however, cannot identify which patients have significant internal carotid artery (ICA) disease, and this group of patients could benefit from rapid access carotid endarterectomy (RACE). Studies have shown that patients with significant carotid artery disease have a higher risk of neurologic events or recurrent stroke. The aim of this study was to document the range of ABCD2 scores in patients with carotid artery-related TIA, and investigate any correlation between the ABCD2 scores and ICA stenosis. METHODS Patients undergoing carotid duplex ultrasound scan for TIA from January 2009 to May 2010 from two vascular units were identified from the vascular database retrospectively. Clinical notes were reviewed and outcomes measures were recorded: ABCD2 scores (age, blood pressure, clinical features, diabetes, and duration) and carotid plaque morphology. RESULTS Ninety-seven patients with a mean age of 74 (range 56-90) years had ICA stenoses of ≥50% up to 100%. Fifty-seven patients had an ABCD2 score of ≤4. There was no significant correlation between ABCD2 scores and degree of ICA stenosis nor carotid plaque morphology (P=0.2, r=1.0, and P=1.0, r=0.0007, respectively). CONCLUSIONS Because no correlation between ABCD2 scores and the degree of ICA stenosis was found, all patients with carotid territory TIA should undergo urgent imaging of the carotid arteries because a high proportion of these patients may benefit from RACE.

Effects of topical negative pressure therapy on tissue oxygenation and wound healing in vascular foot wounds

Objective: Topical negative pressure (TNP) therapy is widely used in the treatment of acute wounds in vascular patients on the basis of proposed multifactorial benefits. However, numerous recent systematic reviews have concluded that there is inadequate evidence to support its benefits at a scientific level. This study evaluated the changes in wound volume, surface area, depth, collagen deposition, and tissue oxygenation when using TNP therapy compared with traditional dressings in patients with acute high‐risk foot wounds. Methods: This study was performed with hospitalized vascular patients. Forty‐eight patients were selected with an acute lower extremity wound after surgical débridement or minor amputation that had an adequate blood supply without requiring further surgical revascularization and were deemed suitable for TNP therapy. The 22 patients who completed the study were randomly allocated to a treatment group receiving TNP or to a control group receiving regular topical dressings. Wound volume and wound oxygenation were analyzed using a modern stereophotographic wound measurement system and a hyperspectral transcutaneous oxygenation measurement system, respectively. Laboratory analysis was conducted on wound biopsy samples to determine hydroxyproline levels, a surrogate marker to collagen. Results: Differences in clinical or demographic characteristics or in the location of the foot wounds were not significant between the two groups. All patients, with the exception of two, had diabetes. The two patients who did not have diabetes had end‐stage renal failure. There was no significance in the primary outcome of wound volume reduction between TNP and control patients on day 14 (44.2% and 20.9%, respectively; P = .15). Analyses of secondary outcomes showed a significant result of better healing rates in the TNP group by demonstrating a reduction in maximum wound depth at day 14 (36.0% TNP vs 17.6% control; P = .03). No significant findings were found for the other outcomes of changes in hydroxyproline levels (58.0% TNP vs 94.5% control; P = .32) or tissue perfusion by tissue oxyhemoglobin saturation (19.4% TNP vs 12.0% control; P = .07) at day 14. At 1 year of follow‐up, there were no significant outcomes in the analysis of wound failure, major amputation, and overall survival rates between the two groups. Conclusions: In this pilot study, applying TNP to acute high‐risk foot wounds in patients with diabetes or end‐stage renal failure improved the wound healing rate in reference to wound depth. This suggests that TNP may play a role in enhancing wound healing. This study sets the foundation for larger studies to evaluate the superiority of TNP over traditional dressings in high‐risk foot wounds.

Hybrid technique for the management of thoracoabdominal aortic thrombosis and symptomatic Trans-Atlantic Inter-Society Consensus “C” aorto-iliac disease

Objective Thrombotic disease of the thoracic and abdominal aorta co-existing with aorto-iliac disease is a rare clinical association, which poses a great therapeutic challenge and adds to the complexity of the open surgical repair. Method We describe a case of 53-year-old woman with symptomatic thrombus in the thoracic and abdominal aorta down to the aortic bifurcation, which was successfully treated by Thoracic EndoVascular Aortic Repair via the left subclavian artery, open thrombectomy and aorto-iliac bypass. Result Completion angiogram performed through the axillary cannula showed good flow in the aorta, visceral vessels and iliac arteries. Conclusion This hybrid technical approach was a safe and effective strategy to tackle diffuse aortic thrombus with minimal morbidity and visceral embolization. Simultaneous aorto bi iliac bypass with thoracic endovascular aortic repair is a viable approach that can be undertaken with lesser morbidity and mortality risk as compared to complex and highly stressful total open surgical repair.

Endovenous varicose vein treatment in patients with right heart failure and tricuspid valve regurgitation – A relative contraindication?:

In 2015, four patients in Hamilton New Zealand were identified to have failed endovenous varicose vein treatment. All the patients had one aspect in common, evidence of right heart failure and tricuspid valve regurgitation. This raised the question, should the presence of this cardiac pathology be a relative contraindication for endovenous treatment of varicose veins? There are reports in the literature of cases of varicose veins associated with right heart failure and tricuspid valve regurgitation. The first case was published in 1962 by Brickner et al. In all the cases published, surgical techniques were employed to exclude the refluxing vein if conservative measures failed to prevent complications. Today, intervention on varicose veins is achieved most frequently through endovenous methods. In Hamilton, we have used endovenous laser ablation therapy, radiofrequency ablation and the latest dual-injury system, ClariVein. Success with Clarivein is reported in initial trials to reach 97%, which is fairly consistent with other endovenous methods. New Zealand has a high rate of right heart failure compared to other parts of the world. The most common cause of right heart failure is left heart failure, and this is no different in New Zealand; however, we also suffer from a high rate of rheumatic heart disease, especially in the Maori population. If tricuspid valve regurgitation is present, due to primary valvular disease or high right ventricular pressures, the backflow into the veins from the right heart failure will also be pulsatile. We postulate that it is this pulsatile high-pressure reflux that not only contributes to the formation of varicose veins but also the inability of the current methods of endovenous varicose vein treatments to create the sufficient inflammation and collapse of the treated vein required for success. Another aspect potentially contributing to the failure of treatment may be the difficulty that a pulsating vein poses for accurate diameter measurement with vascular ultrasonography. Indications for use include that the diameter of the vein treated is under 15mm, and hence care needs to be taken that the measurement is under this size in all phases of the pulse cycle. This topic was recently presented for discussion at the Australia and New Zealand Society of Vascular Surgery annual meeting. Comments were limited, which we felt was due to differences in patient population and uptake of endovenous varicose vein treatments. The group did raise the question of the clinical importance of varicose vein pulsatility, because some patients can have it with no apparent negative effects. A prospectively collected database of all patients presenting to have varicose vein scanning in Hamilton who are shown to have pulsatility was initiated this year and will be analysed in a years’ time. The aim would be for all patients with pulsatile varicose veins to have cardiac echocardiography to investigate for cardiac pathology. For a scientific publication, we will aim to clarify the overall incidence of pulsatile varicose veins, the rate of correlating cardiac pathology, and the rate of failure of endovenous varicose vein treatment in this population and the overall population. We feel that right heart failure and tricuspid valve regurgitation should be a relative contraindication for endovenous varicose vein treatment. Thought needs to be given to open surgery in those patients with right heart failure and tricuspid regurgitation when endovenous treatment seems unlikely to succeed.

Treatment of infrapopliteal post‐PTA dissection with tack implants: 12‐month results from the TOBA‐BTK study

The Tack implant is designed for focal, minimal metal management of dissections. This study evaluated Tacks for treating postpercutaneous transluminal angioplasty (PTA) dissection in patients with below‐the‐knee (BTK) arterial occlusive disease.

Bridging stent repair of type III endoleak causing aortocaval fistula after branched aortic endovascular repair

A 62-year-old man presented to our department with abdominal pain and diarrhea for 3 weeks on a background of previous branched endovascular repair for a thoracoabdominal aneurysm. A triple-phase computed tomography scan of his abdomen and pelvis showed a large aortocaval fistula caused by a type III endoleak from a dislodged superior mesenteric artery stent. He was successfully treated with a BeGraft (Bentley Innomed, Hechingen, Germany) by using an endovascular technique.

Management of innominate artery true aneurysms: A single centre experience

Introduction: True aneurysms of the innominate artery are rare and continued controversy exists in literature regarding the best management of these aneurysms. Patients and Methods: The present study reviewed a 5-year experience of managing IA true aneurysms between 2010 and 2015. There were two patients aged 63 and 77 years who were treated successfully by a selective open debranching technique for the exclusion of the aneurysms. The mean follow-up was 2 years. Preoperative information was derived from spiral computed tomography (CT) scanning, magnetic resonance imaging, and color Doppler imaging (CDI). Results: One male and one female were treated successfully. The most common indication for intervention was transient ischemic attack (100%). The 30-day surgical mortality was zero. Graft patency at 6 months as confirmed by CDI was 100%. One patient had graft-related complication at 6 months and subsequently at 24 months which was revised successfully. Conclusion: Exclusion bypass is a satisfactory treatment of these proximal aneurysms and durable. The proximity to the aortic arch makes endovascular treatment challenging and would depend on the dimensions of the arch and ascending aorta. De-branching simplifies the treatment pathway. The natural history of these isolated aneurysms is unknown.