Transapical wire-assisted endovascular repair of thoracic aortic dissection.

PURPOSE: To describe a technique for transapical wire-assisted endograft deployment under rapid ventricular pacing for a type B dissection involving the proximal left subclavian artery and extending to the aortic bifurcation. CASE REPORT: A 58-year-old man presented with a symptomatic thoracic aneurysm as a complication of a chronic type B dissection, with a short proximal neck in zone 1. After arch vessel debranching, the patient underwent endoluminal repair with deployment of a closed web, tapered Valiant thoracic endograft over a through-and-through wire from the left groin to the apex of the left ventricle, using rapid ventricular pacing to reduce cardiac output. The remaining dissected aorta was covered with a second Valiant endograft down to the distal third of the descending thoracic aorta and bare Z stents down to the aortic bifurcation to re-expand the true lumen. A freeflow Valiant endograft was deployed as a proximal extension to treat a proximal type I endoleak. The recovery was complicated by retrograde type A aortic dissection, considered secondary to the bare stent. The complication was repaired surgically; postoperative computed tomography after recovery was unremarkable. CONCLUSION: Transapical wire-assisted deployment with rapid ventricular pacing is feasible and may provide improved stability for stenting within the aortic arch. The use of a stent-graft with a proximal bare stent is associated with a higher risk of retrograde extension of the dissection and warrants lifelong imaging follow-up.

Prosthetic lower extremity hemodialysis access grafts have satisfactory patency despite a high incidence of infection.

INTRODUCTION: Prosthetic arteriovenous grafts (AVGs) in the lower extremity represent a useful alternative for hemodialysis vascular access when all upper limb access sites have been used or in some patients when freedom of both hands is necessary during dialysis. Reported complications include an increased risk of infection and limb ischemia. This study evaluated our experience with the patency outcomes and complication rates of polytetrafluoroethylene (PTFE) AVGs placed in the thigh. METHODS: A retrospective outcomes analysis was performed of all femoral AVGs inserted between January 1992 and July 2007. Data were obtained by review of medical records for patient demographics, comorbidities, and AVG-related outcomes. Patency, complication rates, and risk factors for infection were determined. RESULTS: A total of 153 prosthetic AVGs were placed in 127 patients (63 men). Mean patient age was 52.7 ± 16.3 years. Median follow-up was 25 months (range, 1-169 months). The most common underlying renal disease was glomerulonephritis in 27 (21%). Hypertension and coronary artery disease were common comorbidities, respectively, in 49 (39%) and 23 patients (18%). The primary and secondary AVG patency rates at 12 months were 53.9% and 75.3%, respectively, and 2- and 5-year patency rates were, respectively, 39.6% and 19.3% (primary) and 63.8% and 50.6% (secondary). The mean AVG survival for all cases was 31.6 months (range, 0-149 months). Surgical thrombectomy was required in 82 (54%), and 22 AVGs (14%) required surgical revision for stenosis. Infection occurred in 41 AVGs (27%), and limb ischemia occurred in 2 (1.3%). Statistical analysis did not reveal a significant risk factor for infection. CONCLUSIONS: Femoral AVGs are a suitable alternative to upper limb vascular access, with acceptable primary and secondary patency rates. Infection occurred in approximately one-quarter of cases, whereas steal was uncommon.

Animal models for the assessment of novel vascular conduits.

The development of an ideal small-diameter conduit for use in vascular bypass surgery has yet to be achieved. The ongoing innovation in biomaterial design generates novel conduits that require preclinical assessment in vivo, and a number of animal models have been used for this purpose. This article examines the rationale behind animal models used in the assessment of small-diameter vascular conduits encompassing the commonly used species: baboons, sheep, pigs, dogs, rabbits, and rodents. Studies on the comparative hematology for these species relative to humans are summarized, and the hydrodynamic values for common implant locations are also compared. The large- and small-animal models are then explored, highlighting the characteristics of each that determine their relative utility in the assessment of vascular conduits. Where possible, the performance of expanded polytetrafluoroethylene is given in each animal and in each location to allow direct comparisons between species. New challenges in animal modeling are outlined for the assessment of tissue-engineered graft designs. Finally, recommendations are given for the selection of animal models for the assessment of future vascular conduits.

Vascular biliopathy as a cause of common bile duct obstruction successfully treated by mesocaval shunt and endoscopic retrograde cholangiopancreatography biliary stent placement.

Common bile duct stenosis owing to extrahepatic portal varices is termed "portal hypertensive biliopathy" (PHB) and is a rare occurrence. We report a case of PHB owing to portal vein thrombosis with cavernous transformation successfully managed by mesocaval shunt and endoscopic retrograde cholangiopancreatography (ERCP) biliary stent placement. A 44-year-old male, who presented with hematemesis, melena, jaundice, and abdominal pain, underwent gastroscopy, which revealed bleeding gastric varices. Computed tomography with arterial and venous imaging demonstrated portal vein thrombosis with cavernous transformation and extensive extrahepatic varices within the porta hepatis causing common bile duct obstruction from extrinsic compression. Biliary decompression was achieved with ERCP, and a small common bile duct stone was retrieved. A mesocaval shunt with a 16 mm Dacron graft successfully treated the portal hypertension. PHB is rare. We report a case successfully treated by mesocaval shunt and ERCP.

Endovascular grafting of the thoracic aorta, an evolving therapy: ten-year experience in a single centre.

BACKGROUND: Surgical therapy for the thoracic aorta carries a high morbidity and mortality. Endovascular therapy for aneurysms and its adaptation to the thoracic aorta over the past 10 years is an exciting advance. This is a retrospective review of endovascular grafting of the thoracic aorta during the past decade at Royal Prince Alfred Hospital and the outcomes achieved over this period. METHODS: A retrospective review of all patients at our institution who underwent endovascular grafting of the thoracic aorta between March 1995 and March 2005 was carried out. Data were analysed using Stata version 8.0 (Stata corporation, College Station, TX, USA). RESULTS: Sixty-five patients underwent endovascular stent grafting of the thoracic aorta. The indications were degenerative aneurysm (31), Stanford type B dissection (23) both acute (12) and chronic (11), traumatic transection (9) and penetrating ulcer (2). There were no conversions to open repair. Twenty-two patients required additional procedures, six of which were unplanned. The median age was 65 (range 18-85), 68% of patients were men. The median procedure time was 115 min (range 55-240 min). Mean hospital stay was 9.8+/-7.3 days and high dependency/intensive care unit stay 1.5+/-3.2 days. Thirty-day mortality was 0 in 41 for elective cases (one patient (2.5%) died 37 days post-procedure) and 12% (3 of 25) for emergency cases. Complications occurred in 20 of 41 (49%) elective cases and 14 of 24 (58%) emergency cases within the first 30 days. The most frequent major complications were neurological including paraplegia (transient 2 of 65, permanent (2 of 65)) and stroke (4 of 65). Other complications included endoleak (12 of 65), acute renal failure (1 of 65), and brachial artery false aneurysm (1 of 65). The mean length of follow up was 22.5 months (range, 1-97 months). Six patients required further endovascular procedures for persistent endoleak or ongoing perfusion of chronic dissection. Late deaths (>30 days) related to the endovascular treatment occurred in two patients (3%). CONCLUSION: Endovascular grafting of the thoracic aorta is an evolution in the treatment of thoracic aortic pathology. The results of elective endovascular grafts were acceptable. Emergency procedures had a higher incidence of complications and death. Improvement in graft technology, design and deployment are required.

Anatomic factors associated with acute endograft collapse after Gore TAG treatment of thoracic aortic dissection or traumatic rupture.

OBJECTIVE: The potentially devastating complication of total or near total thoracic endoprosthesis collapse has been described with the TAG device (W. L. Gore & Associates, Flagstaff, Ariz). This rare complication has resulted in a warning to clinicians and speculation about the etiology of this problem. This report evaluates potential causative anatomic factors that may increase the probability of endoprosthesis collapse in patients undergoing endovascular thoracic aneurysm repair (TEVAR). METHODS: Preoperative and postoperative computed tomography scans were collected worldwide representing six patients who had experienced radiologically confirmed TAG endoprosthesis collapse. These were compared with a matched cohort of five patients with a TAG endoprosthesis in the same anatomic position in which no collapse occurred. Anatomic variables of aortic arch angulation, apposition, intraluminal lip length, proximal aortic diameter, distal aortic diameter, intragraft aortic diameter, percentage of oversizing, and angle of the proximal endograft to the aortic arch were compared between groups. Differences between groups were determined using the Student t test, with P < .05 considered significant. RESULTS: The two groups (collapse vs no collapse) were evenly matched demographically, and all underwent endoluminal treatment with the TAG device, with no differences in gender, graft position in the aorta, operative indication, or age (P = NS). Distal sealing zone aortic diameter +/- standard deviation of 18.9 +/- 1.7 mm vs 22.7 +/- 2.7 mm and minimum aortic diameter within the endograft of 18.6 +/- 1.7 mm vs 22.4 +/- 3.1 mm predicted collapse (P < .05). Proximal aortic diameter, apposition, intraluminal lip length, aortic arch angle, and angle of proximal endograft to aortic arch did not predict collapse (P = NS). CONCLUSION: Thoracic endograft collapse is an exceedingly rare event. In this series, endoprosthesis collapse occurred in patients who were treated outside the manufacturer's instructions for use for minimum required aortic diameter. Although distal aortic diameter and minimum intragraft aortic diameter predicted collapse, other variables may also influence this complication but were not significant owing to potential type II statistical errors. In the future, caution should be exercised when contemplating TEVAR in patients with small (<23 mm) aortic diameters.

Durability of autogenous vein and polytetrafluoroethylene bypass grafts to the carotid arteries.

BACKGROUND: Bypass for extra-cranial arterial disease is infrequently carried out. We reviewed our experience to determine the outcome of carotid artery grafting using either an autogenous vein or polytetrafluoroethylene (PTFE). METHODS: Details of patients were recorded prospectively as part of a vascular surgical registry. Patients identified from the registry as having carotid artery bypass procedures were classified according to the type of conduit used. Comparison was made between patients with autogenous vein and PTFE grafts. RESULTS: Between 1978 and 2002, 24 patients (13 men and 11 women) mean age 60.0 +/- 13.4 years (range, 20-81 years) underwent 28 bypass procedures (three were bilateral and one was a reoperation). Symptomatic carotid disease was the clinical indication in 20 of 28 procedures (71.4%). Pathological indications included advanced atherosclerosis of the carotid arteries (15), past radiotherapy (4), failed stenting (3), resection of carotid body tumour (2), trauma (1), reoperation on a failed graft (1), carotid aneurysm (1) and iatrogenic carotid occlusion (1). An autogenous vein was used in 16, PTFE in 11 and autogenous artery in 1 of the patients. Using the Kaplan-Meier method, the overall patient cumulative 5-year survival was 84% and cumulative 5-year stroke-free survival was 93%. The combined perioperative stroke and mortality rate was 7.1%. Two patients had transient ischaemic attacks (7.1%), one had cranial nerve palsies (3.6%) and one required reoperation for bleeding (3.6%). Five-year cumulative graft primary patency using the Kaplan-Meier method was 74% for PTFE grafts and 92% for autogenous vein grafts (P = 0.37). CONCLUSION: Carotid artery bypass is a safe and a useful treatment option for complex extra-cranial arterial disease. Either PTFE or autogenous veins may be used as conduits.

Clinical significance of type II endoleak after endovascular repair of abdominal aortic aneurysm.

Type II endoleaks after endovascular repair of abdominal aortic aneurysm (EVAR) are a result of retrograde flow from arterial branches (e.g., lumbar and inferior mesenteric) refilling the aneurysm sac, which has been excluded by the stent graft. Controversy continues with regard to the clinical significance and treatment of type II endoleaks. To develop recommendations for management, we analyzed outcome data from 10 EVAR trials completed over the last 5 years involving a total of 2,617 cases. The incidence of type II endoleak at discharge or 30 days was 6-17%, at 6 months 4.5-8%, and at 1 year 1-5%. Successful resolution of endoleak following secondary interventions was observed in 11-100% of cases. There were 10 conversions to open repair and no ruptures related to type II endoleak. In patients observed for 12 months with computed tomography and/or ultrasound, approximately one-half of type II endoleaks disappeared spontaneously. In the absence of a type I endoleak, our analysis of the current literature suggests that intervention for type II endoleak should be undertaken for abdominal aortic aneurysm sac enlargement occurring after 6 months, persistence for >12 months without abdominal aortic aneurysm sac enlargement, or an aneurysm sac pressure >20% of systolic blood pressure; translumbar aneurysm sac thrombosis and intra-arterial feeding vessel occlusion appear to be prudent management options.

Right arm ischemia following intentional stent-graft coverage of an anomalous right subclavian artery.

PURPOSE: To report thoracic aortic stent-graft repair in a patient with abnormal aortic arch anatomy. CASE REPORT: An anomalous right subclavian artery was covered with a stent-graft in a 38-year-old woman being treated for a false aneurysm after coarctation repair. The right arm became relatively ischemic, but was viable and managed conservatively. CONCLUSIONS: Aneurysms close to left or aberrant right subclavian arteries can be safely and effectively treated by endoluminal repair without the need for revascularization procedures; ischemic symptoms that develop are often mild and transient.

Rupture of abdominal aortic aneurysm: concurrent comparison of outcome of those occurring after endovascular repair versus those occurring without previous treatment in an 11-year single-center experience.

OBJECTIVE: The purpose of this single-center study was to compare findings at presentation and surgical outcome in patients in whom abdominal aortic aneurysms (AAAs) ruptured after endovascular repair and patients in whom AAAs ruptured before any treatment, over a defined period. METHODS: From May 1992 to September 2003, 1043 patients underwent elective repair of intact infrarenal AAAs. Endovascular repair was performed in 609 patients, and open repair in 434 patients. Eighteen of 609 patients (3%) who underwent endovascular AAA repair required treatment because of rupture of the aneurysm after a mean of 29 months (group 1). During the same 11-year period, another 91 patients without previous treatment required urgent repair of a ruptured AAA (group 2). Rupture was diagnosed at contrast material-enhanced computed tomography or by presence of extramural extravasation of blood at open repair. Except for a higher incidence of women in group 2, patients in both groups were similar with regard to demographics and clinical characteristics but differed in findings at presentation. Eight patients in group 1 had a known endoleak before AAA rupture, whereas contrast-enhanced computed tomography, performed in 15 patients at presentation, demonstrated an endoleak in all. Hypotension (systolic blood pressure <100 mm Hg) was noted at presentation in 4 of 18 patients (22%) in group 1 and 76 of 91 patients (84%) in group 2. All patients underwent open repair via a transperitoneal approach, except for 4 patients in group 1 and 3 patients in group 2 who underwent endovascular repair of ruptured AAAs. RESULTS: The proportion of patients with hypotension at presentation in group 1 (4 of 18) was significantly less than in group 2 (76 of 91; P < .01). The difference in perioperative (30 day) mortality rate in group 1 (3 of 18; 16.6%) compared with group 2 (49 of 91; 53.8%) was also significant (P < .01). The outcome in group 1 was therefore superior to that in group 2. CONCLUSIONS: This study confirms that endovascular AAA repair complicated by endoleak does not prevent rupture. The data suggest, however, that rupture, when it occurs in these circumstances, may not be accompanied by such major hemodynamic changes and high mortality as rupture of an untreated AAA. Further long-term follow-up and analysis in a larger group of patients are required to confirm the apparent intermediate level of protection afforded by failed endovascular repair, which does not prevent rupture but enhances survival after operation to treat rupture, possibly by ameliorating the hemodynamic changes associated with the rupture process.

Endoluminal repair of abdominal aortic aneurysm prevents enlargement of the proximal neck: a 9-year life-table and 5-year longitudinal study.

OBJECTIVE: Endoluminal repair of abdominal aortic aneurysm (AAA) is predicated on stability of the proximal neck of the aneurysm. Reports on morphologic changes in the proximal neck after endoluminal repair of AAA have thus far been limited in duration to 3 years or less. The aim of this study was to document changes in diameter of the proximal neck of AAA in a group of patients who had undergone endoluminal repair between 5 and 9 years previously. METHODS: Between May 1992 and December 1996, 61 patients with AAA were treated with endoluminal repair by the senior author. The following patients were excluded from the study group: those requiring primary conversion to open repair at the original operation (n = 8), those with false aneurysm (n = 1), and those with dissection in the proximal neck (n = 1). Fifty-one patients (48 men and three women) with a mean age of 71 years remained in the study group. The endoprostheses used were modified Parodi (n = 4), Endovascular Technologies (n = 14), White-Yu (n = 10), Stentor/Vanguard (n = 21), and Bard 1996 prototype (n = 2). Morphologic changes in the proximal aortic neck were studied with contrast computed tomographic scan with the methodology recommended by the Ad Hoc Committee for Standardized Reporting Practices for Endovascular AAA Repair (revised version). The maximum transverse diameter of the proximal neck was measured 1 cm below the most inferior renal artery. A Kaplan-Meier analysis was performed showing the proportion of patients at risk with a demonstrated enlargement of the neck at each interval of time compared with the predischarge computed tomographic scan. A longitudinal study of morphologic changes in the proximal aortic neck was also undertaken in 28 patients with successful endoluminal repair who survived 5 years. RESULTS: The Kaplan-Meier curve showed a probability of no dilatation of the proximal neck of 0.943 at 7 years after endoluminal AAA repair. Of 28 patients with 5 years of follow-up after discharge, only two had increases in the diameter of the proximal neck greater than 2 mm. The endograft in both patients had undergone migration before any proximal neck dilation. A paired t test showed that the overall average increase of 0.4 mm (standard error, 0.3 mm) in these 28 patients was not statistically significant (P =.23). CONCLUSION: A high probability (0.943 at 7 years) exists of no enlargement of the proximal neck of AAA after endoluminal repair. We hypothesize that endografts positioned correctly immediately below the renal arteries protect the proximal neck from dilatation in a manner that does not occur after open repair of AAA.

Nature and significance of endoleaks and endotension: summary of opinions expressed at an international conference.

OBJECTIVE: Endoleaks and endotension are critically important complications of some endovascular aortic aneurysm repairs (EVARs). For the resolution of controversial issues and the determination of areas of uncertainty relating to these complications, a conference of 27 interested leaders was held on November 20, 2000. METHODS: These 27 participants (21 vascular surgeons, five interventional radiologists, one cardiologist) had previously answered 40 key questions on endoleaks and endotension. At the conference, these 40 questions and participant answers were discussed and in some cases modified to determine points of agreement (consensus), near consensus (prevailing opinion), or disagreement. RESULTS: Conference discussion added two modified questions for a total of 42 key questions for the participants. Interestingly, consensus was reached on the answers to 24 of 42 or 57% of the questions, and near consensus was reached on 14 of 42 or 33% of the questions. Only with the answers to four of 42 or 10% of the questions was there persistent controversy or disagreement. CONCLUSION: The current endoleak classification system with some important modifications is adequate. Types I and II endoleak occur after 0 to 10% and 10% to 25% of EVARs, respectively. Many (30% to 100%) type II endoleaks will seal and have no detrimental effect, which never or rarely occurs with type I endoleaks. Not all endoleaks can be visualized with any technique, and increased pressure (endotension) can be transmitted through clot. Aneurysm pulsatility after EVAR correlates poorly with endoleaks and endotension. An enlarging aneurysm after EVAR mandates surgical or interventional treatment. These and other conclusions will help to resolve controversy and aid in the management of these vexing complications and should also point the way to future research in this field.

Intra-operative Coronary Angioscopy.

A goal of this article is to demonstrate how easily angioscopy can be incorporated into coronary artery bypass grafting. Intra-operative angioscopy has been used in a number of applications including prebypass arterial evaluation, inspection of the interior of the vein graft, examination of graft to coronary anastomoses and outflow. And adjunctive guidance during adjunctive revascularisation procedures. Despite promising initial trials of the use of intraoperative angioscopy, this technology has not been widely adopted because of perceived demanding technique, excessive effort required, and potential complications. Moreover, the possible benefits of the additional information gained during cardiac surgery operations have thus far only been partially demonstrated.