The impact of pre-existing blood pressure control in patients with acute aortic dissections.

OBJECTIVES: Arterial hypertension (HTN) is considered a seminal risk factor for aortic dissection (AD). The purpose of this study is to evaluate whether pre-existing blood pressure (BP) control lessens the extent of dissection and has a favorable impact on outcome of patients with acute AD. METHODS: Consecutive acute AD patients who had at least two BPs recorded within the 12 months preceding the AD were retrospectively analyzed. The two most recent BPs were averaged and defined per published guidelines as normal (BP≤ 130/80), Stage I HTN (BP >130/80 and <139/89), or Stage 2 or greater HTN (BP > 140/90). The number of hypertensive medications (MEDs) was also used as a surrogate marker of HTN severity. Patients with known genetic causes of AD were excluded. RESULTS: 89 subjects (55% men, 45% women; mean age, 64±14 years) with acute AD (58% Stanford type A and 42% Stanford type B) were included. Two most recent BPs were recorded a mean of 5±3 and 3±2.7 months before the AD, respectively. Twenty-nine (33%) subjects had normal BP, including nine subjects with no history of HTN and on no MEDs. Sixty (67%) subjects had elevated BP, including 21 (35%) with Stage I HTN and 39 (65%) with Stage 2 HTN. Compared to subjects with normal BP, subjects with Stage 1 and Stage 2 HTN were younger (70±13 years vs 62±1 year, p = 0.01), but there were no differences in other demographics, risk factors, comorbidities, or history of drug use. There were no group differences in the distal extent of the dissections, complications requiring thoracic endograft repair, mean length of hospital stay, final discharge status, or 30-day mortality. Compared to the number of MEDs before AD, all three groups had a higher mean number of MEDs to achieve normal BP at discharge that persisted at a mean follow-up of 18±15 months. CONCLUSIONS: These data show that approximately one-third of patients with acute AD had well controlled or no antecedent history of HTN. The degree of pre-existing HTN control had no bearing on the type or extent of AD, length of stay, or early outcome. Regardless of the state of HTN control before AD, the consistent and sustained increase in the severity of HTN after AD suggests that the dissection process has a profound and lasting effect on BP regulation. Further studies are indicated to elucidate the pathologic mechanisms involved in AD.

Editor's Choice - Optimal Threshold for the Volume-Outcome Relationship After Open AAA Repair in the Endovascular Era: Analysis of the International Consortium of Vascular Registries.

OBJECTIVE: As open abdominal aortic aneurysm (AAA) repair (OAR) rates decline in the endovascular era, the endorsement of minimum volume thresholds for OAR is increasingly controversial, as this may affect credentialing and training. The purpose of this analysis was to identify an optimal centre volume threshold that is associated with the most significant mortality reduction after OAR, and to determine how this reflects contemporary practice. METHODS: This was an observational study of OARs performed in 11 countries (2010 - 2016) within the International Consortium of Vascular Registry database (n = 178 302). The primary endpoint was post-operative in hospital mortality. Two different methodologies (area under the receiving operating curve optimisation and Markov chain Monte Carlo procedure) were used to determine the optimal centre volume threshold associated with the most significant mortality improvement. RESULTS: In total, 154 912 (86.9%) intact and 23 390 (13.1%) ruptured AAAs were analysed. The majority (63.1%; n = 112 557) underwent endovascular repair (EVAR) (OAR 36.9%; n = 65 745). A significant inverse relationship between increasing centre volume and lower peri-operative mortality after intact and ruptured OAR was evident (p < .001) but not with EVAR. An annual centre volume of between 13 and 16 procedures per year was associated with the most significant mortality reduction after intact OAR (adjusted predicted mortality < 13 procedures/year 4.6% [95% confidence interval 4.0% - 5.2%] vs. ≥ 13 procedures/year 3.1% [95% CI 2.8% - 3.5%]). With the increasing adoption of EVAR, the mean number of OARs per centre (intact + ruptured) decreased significantly (2010 - 2013 = 35.7; 2014 - 2016 = 29.8; p < .001). Only 23% of centres (n = 240/1 065) met the ≥ 13 procedures/year volume threshold, with significant variation between nations (Germany 11%; Denmark 100%). CONCLUSION: An annual centre volume of 13 - 16 OARs per year is the optimal threshold associated with the greatest mortality risk reduction after treatment of intact AAA. However, in the current endovascular era, achieving this threshold requires significant re-organisation of OAR practice delivery in many countries, and would affect provision of non-elective aortic services. Low volume centres continuing to offer OAR should aim to achieve mortality results equivalent to the high volume institution benchmark, using validated data from quality registries to track outcomes.

Pre-emptive thoracic endovascular aortic repair is unnecessary in extended type A (DeBakey type I) aortic dissections.

OBJECTIVE: Pre-emptive thoracic endovascular aortic repair (TEVAR) improves late survival and limits progression of disease after type B aortic dissection, but the potential value of pre-emptive TEVAR has not been evaluated after type A dissection extending beyond the aortic arch (DeBakey type I). The purpose of this study was to compare disease progression and need for aortic intervention in survivors of acute, extended type A (ExTA) dissections after initial repair of the ascending aorta versus acute type B aortic dissections. METHODS: Consecutive patients presenting with ExTA or type B dissections between 2011 and 2018 were studied. Forty-three patients with ExTA and 44 with type B dissections who survived to discharge and had follow-up imaging studies were included in the analysis. Study end points included progression of aortic disease (>5 mm growth or extension), need for intervention, and death. RESULTS: The groups were not different for age, sex, atherosclerotic risk factors, or extent of dissection distal to the left subclavian artery. Following emergent ascending aortic repair, five ExTA patients (12%) underwent TEVAR within 4 months after discharge. Despite optimal medical treatment, 29 type B patients (66%) underwent early or late TEVAR (P < .001). During a mean follow-up of 38 ± 30 months, 38 ExTA patients (88%) did not require intervention-23 (53%) of whom showed no disease progression. In comparison, during a mean follow-up of 18 ± 6 months, 14 type B patients (32%) did not require intervention-nine (20%) of whom showed no disease progression (P = .003). There was one aortic-related late death in the ExTA group and two in the type B group. Compared with ExTA patients, type B patients had significantly worse intervention-free survival and intervention/growth-free survival (log rank, P < .001). CONCLUSIONS: In contrast with type B dissections, these midterm results demonstrate that one-half of ExTA aortic dissections show no disease progression in the thoracic or abdominal aorta, and few require additional interventions. After initial repair of the ascending aorta, pre-emptive TEVAR does not seem to be justified in patients with acute, ExTA dissections.

Development of a pulsatile cadaver-based simulation for training of open abdominal vascular surgery skills.

OBJECTIVE: Developing competence in open aortic surgery is increasingly challenging in vascular surgery training programs. Although static cadaver models provide an opportunity for dissection and exposure, the lack of pulsatility limits further education in managing blood vessels. We developed an affordable pulsatile cadaver simulation model to improve training in open abdominal aortic surgery with the primary objective of determining whether it incorporated the fidelity required to teach critical surgical techniques. METHODS: The University of Minnesota Bequest program supported a pilot project to develop a fresh pulsatile cadaver. A written pretest on exposure of the aorta in various locations was given to all trainees. The external iliac artery was exposed, cannulated, then perfused in a pulsatile fashion using normal saline and a pump. Trainees were then evaluated and timed on location of the aorta, retractor placement, dissection, and creation of an aortic anastomosis. RESULTS: Twenty-six pulsatile cadaver procedures were performed with five fellows over 13 months. All procedures were performed under the supervision of the same faculty member. Total cost over the study period was $8800. Four abdominal aortic aneurysms were found (15%). With bilateral iliac artery ligation, adequate pulsatility was created for blind supraceliac aortic dissection. Abdominal wall and organ relationships were ideal for teaching proper retractor placement and techniques for vascular dissection, endarterectomy, and anastomosis. Although 100% of fellows documented written understanding of the steps for procedures on the pretest, no fellow successfully placed a supraceliac aortic clamp, properly positioned retractors for proper open AAA exposure, or placed all proximal aortic back wall sutures transmurally on the initial assessment. After training for a variable number of cases, all were able to place a supraceliac clamp blindly within 4 minutes from skin incision. Retractor placement and suturing technique improved significantly for all trainees during the study period. CONCLUSIONS: The implementation of a pulsatile cadaver-based simulation model for abdominal vascular surgery has the potential to be both affordable and provide necessary haptics and fidelity for training fellows in critical abdominal vascular techniques.

A Case Report of Thoracic Endovascular Aneurysm Repair under Local Anesthesia with Resolution of Acute Onset Lower Extremity Paraplegia from an Acute Complicated Type B Aortic Dissection.

Spinal cord ischemia (SCI) is a rare presenting symptom of acute complicated type B aortic dissection, occurring in approximately 3% of patients . We present a case report of a patient with this presentation who had observed resolution of his paraplegia symptoms immediately after placement of a thoracic stent graft under local anesthesia. The temporal association between true lumen flow restoration and paraplegia resolution intraoperatively is a novel finding. We feel that this case report may provide support for recognized cord perfusion theory , as well as contribute to the understanding of the time frame associated with SCI and reversibility of paraplegia.

Decreased mortality with local versus general anesthesia in endovascular aneurysm repair for ruptured abdominal aortic aneurysm in the Vascular Quality Initiative database.

BACKGROUND: Endovascular aneurysm repair (EVAR) is an accepted approach for patients presenting with ruptured abdominal aortic aneurysm (rAAA) and suitable anatomy. The effect of anesthesia modality on mortality outcomes in rAAA has not been well described. Using the Vascular Quality Initiative database, this study compares local anesthesia (LA) vs general anesthesia (GA) in EVAR for rAAA. METHODS: The Vascular Quality Initiative database was queried for patients presenting with rAAA managed with open surgical repair, EVAR under LA (rEVAR-LA), and EVAR under GA (rEVAR-GA) between 2003 and 2017. Patients were observed until the earlier end point of either death or 1-year follow-up. Kaplan-Meier event rates are presented at 30 days and 1 year. Cox proportional hazards regression was used to model risk of death, with adjustment for demographic and clinical factors. Additional multivariate Cox hazards analyses were used to assess effect modifiers for 1-year mortality for the different repair methods. RESULTS: A total of 3330 patients (77.4% male) met the inclusion criteria (1594 [47.9%] open surgical repair, 226 [6.8%] rEVAR-LA, and 1510 [45.3%] rEVAR-GA). Patients treated with rEVAR-LA compared with rEVAR-GA had decreased intraoperative time, number of intraoperative blood transfusions, intraoperative crystalloid administration, intensive care unit length of stay, and postoperative pulmonary complications. Mortality rates with rEVAR-LA were lower compared with rEVAR-GA at 30 days (15.5% vs 23.3%; adjusted hazard ratio [AHR], 0.70; 95% confidence interval [CI], 0.49-0.99; P = .04) and at 1 year (22.5% vs 32.3%; AHR, 0.71; 95% CI, 0.53-0.96; P = .02). Patients undergoing EVAR who were <75 years old and those without preoperative hypotension had the greatest survival benefit from LA compared with GA (both factors: AHR, 0.14 [95% CI, 0.03-0.57]; single factor: AHR, 0.57 [95% CI, 0.36-0.91]). CONCLUSIONS: This study demonstrates that rEVAR-LA for rAAA may be a safe alternative to rEVAR-GA for certain patients, with lower morbidity and improved mortality. Further prospective study is warranted to confirm mortality benefit in rEVAR-LA for rAAA.

The challenges of treating aspergillus abdominal aneurysm after hematopoietic cell transplant: Rapid voriconazole metabolizer.

Mycotic aneurysms are a fatal manifestation of disseminated fungal infections in immunocompromised hosts. We present a patient with an Aspergillus mycotic aneurysm after hematopoietic cell transplant. Due to CYP2C19 rapid metabolizer phenotype (*1/*17), therapeutic levels of voriconazole were unobtainable. Successful therapy was achieved with posaconazole salvage therapy and early, aggressive surgery. This case demonstrates the consequences of voriconazole rapid metabolism and the potential impact of genetic variants.

Variation in Transfusion Practices and the Association with Perioperative Adverse Events in Patients Undergoing Open Abdominal Aortic Aneurysm Repair and Lower Extremity Arterial Bypass in the Vascular Quality Initiative.

BACKGROUND: Blood transfusions are associated with adverse events. We examined perioperative transfusion practices and associated complications following open vascular procedures nationwide in the Vascular Quality Initiative (VQI). METHODS: Adults undergoing open abdominal aortic aneurysm repair (OAR) and lower extremity arterial bypass (Bypass) within VQI (2003-2016) were identified. All emergent cases, patients with preoperative hemoglobin <7 g/dL, preoperative hospitalization >1 day, or a return to operating room during the index hospitalization were excluded. Units of red blood cells transfused were the primary outcome. Secondary outcomes were postoperative myocardial infarction (MI) and death. Patient, center, and procedural factors were evaluated. Multivariable mixed effects negative binomial regression and multivariable logistic regression were performed. RESULTS: We identified 24,131 procedures (OAR 3885, 16.1%; Bypass 20,246, 83.9%) among 22,532 patients (10.1% had >1 procedure). Overall, 37.5% of OAR and 19.5% of Bypass were transfused. Transfusion rates varied across estimated blood loss quartiles and across various preoperative hemoglobin levels. The overall rate of postoperative MI and death was 4.0% and 1.8% for OAR, and 2.2% and 0.7% for Bypass, respectively. In univariate and multivariable analysis, transfusions were associated with an increased risk of postoperative MI and death. A mixed effects negative binomial model demonstrated variation in transfusions across centers (P < 0.001). Female gender and preoperative anemia were significantly associated with transfusions. CONCLUSIONS: Blood transfusions are variable across centers in VQI. Transfusions are associated with a higher postoperative MI and death after OAR and Bypass. Efforts to reduce transfusion may focus on center variability, gender, and preoperative anemia.

Variations in Abdominal Aortic Aneurysm Care: A Report From the International Consortium of Vascular Registries.

BACKGROUND: This project by the ICVR (International Consortium of Vascular Registries), a collaboration of 11 vascular surgical quality registries, was designed to evaluate international variation in the contemporary management of abdominal aortic aneurysm (AAA) with relation to recommended treatment guidelines from the Society for Vascular Surgery and the European Society for Vascular Surgery. METHODS: Registry data for open and endovascular AAA repair (EVAR) during 2010 to 2013 were collected from 11 countries. Variations in patient selection and treatment were compared across countries and across centers within countries. RESULTS: Among 51 153 patients, 86% were treated for intact AAA (iAAA) and 14% for ruptured AAA. Women constituted 18% of the entire cohort (range, 12% in Switzerland-21% in the United States; P<0.01). Intact AAAs were repaired at diameters smaller than recommended by guidelines in 31% of men (<5.5 cm; range, 6% in Iceland-41% in Germany; P<0.01) and 12% of women with iAAA (<5 cm; range, 0% in Iceland-16% in the United States; P<0.01). Overall, use of EVAR for iAAA varied from 28% in Hungary to 79% in the United States (P<0.01) and for ruptured AAA from 5% in Denmark to 52% in the United States (P<0.01). In addition to the between-country variations, significant variations were present between centers in each country in terms of EVAR use and rate of small AAA repair. Countries that more frequently treated small AAAs tended to use EVAR more frequently (trend: correlation coefficient, 0.51; P=0.14). Octogenarians made up 23% of all patients, ranging from 12% in Hungary to 29% in Australia (P<0.01). In countries with a fee-for-service reimbursement system (Australia, Germany, Switzerland, and the United States), the proportions of small AAA (33%) and octogenarians undergoing iAAA repair (25%) were higher compared with countries with a population-based reimbursement model (small AAA repair, 16%; octogenarians, 18%; P<0.01). In general, center-level variation within countries in the management of AAA was as important as variation between countries. CONCLUSIONS: Despite homogeneous guidelines from professional societies, significant variation exists in the management of AAA, most notably for iAAA diameter at repair, use of EVAR, and the treatment of elderly patients. ICVR provides an opportunity to study treatment variation across countries and to encourage optimal practice by sharing these results.

The Superficial Femoral Artery: An Alternative Access for Percutaneous Endovascular Aneurysm Repair.

BACKGROUND: The aim of this study was to report the results of percutaneous endovascular aortic aneurysm repair (PEVAR) using the superficial femoral artery (SFA) for large bore vessel access. METHODS: We reviewed all PEVAR procedures at our institution over an 18-month period, identifying all patients who underwent PEVAR with the use of one or both SFAs for endograft delivery with dual ProGlide large bore access closure. Indications for use of the SFA instead of the common femoral artery (CFA) included morbid obesity, CFA vessel wall disease, and scarring from previous CFA surgery. RESULTS: In total, 158 percutaneous access closures were performed in 79 patients. Ten patients had one or both SFAs used. We accessed a total of 13 SFAs: 6 for the endograft main body (size range 18- to 20-French) and 7 for the limb (14- to 16-French). The freedom from open conversion was 84.6%. In comparison, of 145 CFA accesses (in 76 patients) there were 9 conversions (93.7% success). Of the 13 SFAs accessed, there were no major access site complications (pseudoaneurysm, access site bleed, limb ischemia, or need to return to the operating room). All SFAs accessed remained patent at the latest follow-up (range 1-13 months, median 8 months). CONCLUSIONS: Our preliminary case series suggests that, in the absence of a healthy or percutaneously accessible CFA, a healthy SFA may be considered for PEVAR access. While likely carrying a higher risk of open conversion, this technique, when combined with intraoperative duplex ultrasound (both before and after the procedure) and with meticulous ultrasound-guided vascular access, appears safe for up to 20-French device diameters.

Impact of hospital-acquired infection on long-term outcomes after endovascular and open abdominal aortic aneurysm repair.

BACKGROUND: We hypothesized that infectious complications after open surgery (OPEN) and endovascular repair (EVAR) of nonruptured abdominal aortic aneurysms (AAAs) negatively affected long-term outcomes. METHODS: Elective OPEN and EVAR cases were selected from 2005-2007 Medicare databases, and rates of postoperative infection, readmission, and longitudinal mortality were compared. RESULTS: Forty thousand eight hundred ninety-two EVARs and 16,669 OPEN AAA repairs were evaluated. Patients with OPEN developed infection during and after the index hospitalization (12.8% and 4.9%, respectively) more often than those who had undergone EVAR (3.2% and 3.9%, respectively; P < 0.0001 for both). Patients with hospital-acquired infection compared to noninfectious ones were more likely to die during the index hospitalization (odds ratio [OR]: 3.7 [95% confidence interval {CI}: 3.22-4.30]) and within 30 days after discharge (OR: 3.6 [95% CI: 2.83-4.45]). They also were more likely to be readmitted to the hospital during 30 days after index discharge (OR: 1.8 [95% CI: 1.63-1.94]). Index infections associated with the greatest readmission were urinary tract infection after OPEN and sepsis after EVAR. Hospital-acquired infection significantly increased the duration of hospital stay (14.2 ± 13.2 vs 4.0 ± 4.4 days; P < 0.0001) and total hospital charges ($133,070 ± $136,100 vs $66,359 ± $45,186; P < 0.0001). The most common infections to develop 30 days after initial discharge were surgical site infection after EVAR (1.27%) and urinary tract infection after OPEN (1.38%). CONCLUSION: Hospital-acquired infections had a dramatic effect by increasing hospital and 30-day mortality, readmission rates, and hospital resource use after AAA repair. Programs minimizing infectious complications may decrease future readmissions and mortality after AAA repair.

Challenges of conversion from robotic surgery for vascular complications.

A 67-year-old woman with endometrial adenocarcinoma had sustained an aortic injury during robotically assisted retroperitoneal lymphadenectomy. Repair could not be performed laparoscopically; however, graspers were used to maintain hemostasis while conversion to open surgery was initiated. Safety mechanisms locked the graspers in place, preventing tissue release, but resulting in additional aortic injury. Forceful removal of the graspers was eventually successful, and definitive aortic repair was then performed. Vascular surgeons who are not familiar with robotic surgery techniques should be aware that removal of robotic hardware requires the use of stepwise algorithms, which, if performed out of order, can introduce significant challenges.

The shifting care and outcomes for patients with endangered limbs - Critical limb ischemia (SCOPE-CLI) registry overview of study design and rationale.

BACKGROUND: Critical limb ischemia (CLI), the most severe form of peripheral artery disease, is associated with pain, poor wound healing, high rates of amputation, and mortality (>20% at 1 year). Little is known about the processes of care, patients' preferences, or outcomes, as seen from patients' perspectives. The SCOPE-CLI study was co-designed with patients to holistically document patient characteristics, treatment preferences, patterns of care, and patient-centered outcomes for CLI. METHODS: This 11-center prospective observational registry will enroll and interview 816 patients from multispecialty, interdisciplinary vascular centers in the United States and Australia. Patients will be followed up at 1, 2, 6, and 12 months regarding their psychosocial factors and health status. Hospitalizations, interventions, and outcomes will be captured for 12 months with vital status extending to 5 years. Pilot data were collected between January and July of 2021 from 3 centers. RESULTS: A total of 70 patients have been enrolled. The mean age was 68.4 ± 11.3 years, 31.4% were female, and 20.0% were African American. CONCLUSIONS: SCOPE-CLI is uniquely co-designed with patients who have CLI to capture the care experiences, treatment preferences, and health status outcomes of this vulnerable population and will provide much needed information to understand and address gaps in the quality of CLI care and outcomes.ClinicalTrials.gov identifier (NCT Number): NCT04710563 https://clinicaltrials.gov/ct2/show/NCT04710563.

Horseshoe kidney and inflammatory abdominal aortic aneurysm: a case report and literature review.

The combined presence of an inflammatory abdominal aortic aneurysm and a horseshoe kidney is a rare event with only one reported case in previously published data. We present a case of a horseshoe kidney with a concomitant 6-cm inflammatory abdominal aortic aneurysm and a 3.6-cm right iliac artery aneurysm repaired through a transperitoneal approach with aortoiliac reconstruction.

Infection of an aortic stent graft with suprarenal fixation.

We report a case of an elderly man admitted with abdominal pain and fever, 5 months after endovascular aortic aneurysm repair of a suspected inflammatory abdominal aortic aneurysm. He underwent successful explantation of an infected stent graft with suprarenal fixation following extra-anatomic revascularization. After a prolonged hospitalization, he was discharged on antibiotics and at follow-up has returned to baseline activity level. Although explantation of an infected prosthesis following endovascular aortic aneurysm repair has been previously reported, our case prompted a review of the literature to evaluate mode of presentation, putative factors, and management decisions associated with reduced morbidity and mortality.

The use of the Amplatzer plug to treat dysphagia lusoria caused by an aberrant right subclavian artery.

Emerging technology with endovascular techniques has expanded our armamentarium to treat the aberrant right subclavian artery. We describe a hybrid technique using an Amplatzer plug in combination with a carotid subclavian bypass to treat a patient with dysphagia lusoria.

Conceptual Framework Development for a Double-Walled Aortic Stent-Graft to Manage Blood Pressure.

A double-walled stent-graft (DWSG) design with a compressible gas layer was conceived with the goal of treating hypertension in patients receiving an aortic stent-graft. Early prototypes were developed to evaluate the design concept through static measurements from a finite element (FE) model and quasi-static inflation experiments, and through dynamic measurements from an in vitro flow loop and the three-element Windkessel model. The amount of gas in the gas layer and the properties of the flexible inner wall were the primary variables evaluated in this study. Properties of the inner wall had minimal effect on DWSG behavior, but increased gas charge led to increased fluid capacitance and larger reduction in peak and pulse pressures. In the flow loop, placement of the DWSG decreased pulse pressure by over 20% compared to a rigid stent-graft. Capacitance measurements were consistent across all methods, with the maximum capacitance estimated at 0.07 mL/mmHg for the largest gas charge in the 15 cm long prototype. Windkessel model predictions for in vivo performance of a DWSG placed in the aorta of a hypertensive patient showed pulse pressure reduction of 14% compared to a rigid stent-graft case, but pressures never returned to unstented values. These results indicate that the DWSG design has potential to be developed into a new treatment for hypertensive patients requiring an aortic intervention.

Tissue-engineered transcatheter vein valve.

Chronic venous insufficiency affects over 2 million patients in the US alone, with severe cases involving thousands of patients with chronic leg ulcers and potential amputation. Current treatment options are limited, with surgical repair of vein valves being the most effective but challenging solution. A transcatheter vein valve made from a biologically-engineered matrix possessing the ability to regenerate has the potential to provide both valve function and long-term hemocompatibility and durability because the matrix becomes endothelialized and populated with host tissue cells. We have developed a novel tissue-engineered transcatheter vein valve (TEVV) on a Nitinol stent and demonstrated function and durability in vitro. Tissue was grown from fibroblasts in fibrin gel so as to embed the stent, with a tubular extension of the engineered tissue from one end of the stent that was stitched along opposite sides and everted into the stent to form a bileaflet valve. Following decellularization, to create an "off-the-shelf" TEVV comprised of the resulting collagenous matrix, it was tested in a pulse duplicator to evaluate hydrodynamic properties for a range of flow rates. The TEVV was shown to have forward pressure drops in the range of 2-4 mmHg, low closing volume, and nil regurgitation. Further hydrodynamic tests were performed after crimping and then again after 1 million cycle durability testing, showing no degradation of valve performance or any visual damage to the matrix. The TEVV held over 600 mmHg backpressure after the durability testing, ensuring the valve would withstand pressure spikes well outside of the normal in vivo range. Catheter-based delivery into the ovine iliac vein demonstrated TEVV closing 2 weeks p.o. and endothelialization without thrombosis 8 weeks p.o.