External Stenting (Exostenting) to Correct Vascular Torsion and Angulation.

Organ transplantation can be associated with vascular torsions and angulations of both recipient and donor vessels. Such kinks and/or torsions of vessels can compromise the vascular integrity, obstruct inflow and/or outflow, and result in loss of the organ and/or body parts. On many occasions, mild angulations and torsions can be successfully addressed by repositioning the organ. In cases where the abnormal findings persist, maneuvers such as placing a fat pad to create a smoother curve, or even opening the peritoneum (in the case of kidney transplants) to allow for a better positioning of the organ, are associated with successful outcomes. When such torsions/angulations persist despite these approaches, further innovative tactics are required. In the current report, we propose a technique that involves longitudinally opening of a synthetic graft that is rigid enough to maintain its shape, such as a ringed polytetrafluoroethylene graft, and placing it as an external stent around the angulated/torsioned vessel. This maneuver will correct the underlying vascular compromise without having to perform any further invasive interventions, such as reimplanting the organ or resecting part of the involved vessel. Although primarily illustrated for application by describing an instance in which exostenting was applied during kidney transplantation, our approach could be applied to any vessel under many circumstances where angulations/twists are encountered. In this report, we describe the use of an external stent, also called exostenting, to correct a severe torsion/angulation of the external iliac artery in a kidney transplant recipient where all other measures were unsuccessful.

Implications of COVID-19 Infection on Arteriovenous Fistula Thrombosis.

Objective: This study aims to identify and analyze implications of COVID-19 positivity on AVF occlusion, subsequent treatment patterns, and ESRD patient outcomes. Our aim is to provide a quantitative context for vascular access surgeons in order to optimize surgical decision making and minimize patient morbidity. Methods: The de-identified national TriNetX database was queried to extracted all adult patients who had a known AVF between January 1, 2020 and December 31, 2021. From this cohort individuals who also were diagnosed with COVID-19 prior to creation of their AVF were identified. Cohorts were propensity score matched according to age at AVF surgery, gender, ethnicity, diabetes mellitus, nicotine dependence, tobacco use, use of anticoagulant medications, and use of platelet aggregation inhibitors, hypertensive diseases, hyperlipidemia, and prothrombotic states. Results: After propensity score matching there were 5170 patients; 2585 patients in each group. The total patient population had 3023 (58.5%) males and 2147 (41.5%) females. The overall rate of thrombosis of AV fistulas was 300 (11.6%) in the cohort with COVID-19 and 256 (9.9%) in the control group (OR 1.199, CI 1.005-1.43, P =.0453). Open revisions of AVF with thrombectomy were significantly higher in the COVID-19 cohort compared to the non-COVID-19 group (1.5% vs .5% P = .0002, OR 3.199, CI 1.668-6.136). Regarding the time from AVF creation to intervention, the median days for open thrombectomy in COVID-19 patients was 72 vs 105 days in controls. For endovascular thrombectomy, the median was 175 vs 168 days for the COVID-19 and control cohorts respectively. Conclusion: As for this study, there were significant differences in rates of thrombosis and open revisions of recent created AVF, however endovascular interventions remained remarkably low. As noted in this study, the persistent prothrombotic state of patients with a history of COVID-19 may persist beyond the acute infectious period of the disease.

Characterizing the geographic distribution of vascular surgeons in the United States.

OBJECTIVE: The shortage of vascular surgeons can be attributed to multiple factors, including an aging population, the increasing demand for vascular surgeons, and an aging vascular surgery workforce. The distribution of vascular surgeons across the United States varies by locale; thus, the shortage affects regions of different sizes disproportionately. We collated the geographic data to characterize the current distribution of vascular surgeons with an emphasis on the practice location, population density, and population age. METHODS: Vascular surgeons were identified using the Physician Compare National Downloadable file from the Centers for Medicare and Medical Services. The counties were matched with each surgeon's practice location. The locations were categorized into metropolitan, urban, or rural using the rural-urban continuum codes. Census Bureau data were used to match all counties with their population-level metrics. The distribution of vascular surgeons was analyzed by comparing the number of counties served, total patient population served, and patient population aged >50 and >65 years served. Finally, the density of vascular surgeons in the United States for the total population and for those aged >50 and >65 years was calculated. RESULTS: In 2018, the U.S. population was 309.8 million, and there were 3145 counties. Of the 3145 counties, 533 (17%) had had a practicing vascular surgeon. The combined population of these counties was 213.8 million people (69% of the U.S. population). Stratified by age, the vascular surgeons in these 533 counties could treat 37.3 million people aged >50 years and 17.4 million people aged >65 years. However, 2612 counties (83%), with a total population of 96 million people (31% of the U.S. population), had had no practicing vascular surgeon. When stratified by age, 78.1 million people in the uncovered counties were aged >50 years and 35 million were aged >65 years. Of the 2612 uncovered counties, 48% were urban and 24% were rural. CONCLUSIONS: We found a nationwide shortage of vascular surgeons, with urban and rural areas disproportionately affected negatively. Although encouraging vascular surgeons to practice in underserved areas would be an ideal solution, it is not pragmatic. Therefore, developing alternatives such as using primary care providers, investing in telehealth and developing transfer systems could be viable methods of providing vascular care to geographically isolated populations. These findings have significant implications for hospitals, patients, and vascular surgeons, who would all stand to benefit from efforts to address these disparities.

Propranolol kinetics in plasma from severely burned adults.

OBJECTIVES: The aim of this study was to determine the appropriate propranolol dosing strategy for reducing heart rate in severely burned adults. METHODS: A total of 26 patients (≥18 years) with burns covering ≥30% of the total body surface area were included in this IRB-approved study. Plasma propranolol concentrations were determined in a placebo group (n=10) or following one of three dosing strategies: Q6 (n=4), Q8 (n=6), and Q24 (n=6). Blood was collected just before dosing and at regular intervals over two dosing periods with corresponding heart rate and blood pressure recordings. Statistical significance was determined by one-way ANOVA followed by the appropriate post-hoc test. RESULTS: Heart rate was 86±2 bpm for Q6, 93±3 bpm for Q8, and 90±4 bpm for Q24. The Q8 group had a significantly higher heart rate than the Q6 group (p=0.0001). Plasma propranolol concentrations were significantly higher in the Q6 dosing strategy than in the Q8 dosing strategy (p=0.02). CONCLUSIONS: Heart rate can be decreased to a similar degree with Q6 and Q24 dosing strategies, with the Q8 dosing strategy being less effective. Q6 dosing is recommended to maintain reduced heart rate throughout dosing periods.

Oxandrolone Coadministration Does Not Alter Plasma Propranolol Concentrations in Severely Burned Pediatric Patients.

The systemic impact of severe burn injury results in a variety of disorders that require therapeutic intervention. Propranolol, a nonselective ß1, ß2-adrenergic receptor antagonist, reduces resting heart rate and cardiac work caused by elevated circulating catecholamines. Oxandrolone, a testosterone mimetic, promotes protein synthesis and anabolism to counter muscle wasting. Coadministration of these drugs is expected to synergistically improve patient outcomes. Testosterone administration is known to alter ß-adrenergic receptor-mediated signaling. Here, we determined whether the coadministration of oxandrolone alters plasma propranolol concentrations. Ninety-two pediatric patients with burns covering ≥30% of the TBSA were enrolled in this institutional review board-approved study and randomized to receive propranolol (n = 49) or oxandrolone + propranolol (n = 43). Plasma propranolol concentrations were determined following two dosing strategies: Q6 (liquid formulation; n = 86) and Q24 (extended-release capsule; n = 22). Samples were drawn before drug administration and at regular intervals throughout the next two dosing periods. Heart rate and blood pressure were recorded throughout the study. Propranolol half-life was 3.3 hours for the Q6 drug dosing frequency (P < .0001) and 11.2 hours for the Q24 strategy (P < .0001). Percentage of predicted heart rate declined by 2.8% for each doubling of the propranolol concentration in the Q6 dosing schedule (P < .0001). Percentage of predicted heart rate declined by 2.5% for each doubling of propranolol concentration on the Q24 dosing schedule (P < .0001). Maximum and minimum propranolol plasma concentrations were similar with either dosing regimen. The addition of oxandrolone did not affect any of the measured parameters. Oxandrolone coadministration does not alter propranolol's plasma concentration, half-life, or effect on heart rate. This study is registered at clincialtrials.gov: NCT00675714.

Endovascular repair of hemodialysis graft-related pseudoaneurysm: an alternative treatment strategy in salvaging failing dialysis access.

INTRODUCTION: Hemodialysis access-related pseudoaneurysm is a known complication in patients requiring hemodialysis via prosthetic arteriovenous grafts (AVGs). The traditional treatment strategy of AVG-related pseudoaneurysms is either AVG ligation or interposition replacement with another prosthetic graft segment or autogenous veins. PATIENTS AND METHODS: From June 2002 to August 2007, 32 self-expanding stent grafts were implanted in 26 patients with AVG pseudoaneurysms. Indications for treatment consisted of large AVG pseudoaneurysm size, localized pain at pseudoaneurysm site, enlarging pseudoaneurysm, and skin site breakdown. AVG pseudoaneurysm exclusion was accomplished with Wallgrafts, Viabahn endoprosthesis, and Fluency endograft. Technical success was achieved in all patients. Nineteen patients experienced a marked decrease in the size of their pseudoaneurysm following endograft exclusion. Successful hemodialysis was resumed through endograft-excluded AVG in all patients within 48 hours. CONCLUSIONS: Endoluminal exclusion of AVG pseudoaneurysms using endografts is a safe and effective treatment strategy in patients with hemodialysis-related pseudoaneurysm.

Biological coating for arterial stents: the next evolutionary change in stents.

PURPOSE: To describe the in vivo results of a promising new stent-graft lined with peritoneum. METHODS: Eighteen dogs underwent balloon angioplasty injury to the bilateral iliac arteries followed by placement of either an 8-mm x 5-cm glutaraldehyde-fixed bovine peritoneum- lined balloon-expandable stent (PLS) or a similarly sized, commercially prepared, polyester-lined self-expanding stent (DLS) as a control. Animals were sacrificed at 1 and 6 months. Biplanar arteriography and intravascular ultrasound were done at the time of sacrifice, and the vessels were harvested after perfusion fixation for histology/morphometry. Immunofluorescence with CD34 and factor VIII staining was used to evaluate endothelialization, while alpha-actin was used to quantify smooth muscle cell (SMC) deposition. RESULTS: At 1 month, all vessels were patent in both groups. At 6 months, 8 of 9 vessels were open in the PLS group versus 6 of 9 in the control DLS group. Vessel lumen diameter at 1 month was significantly greater in the PLS vessels compared to the DLS group at 1 cm above the stent (35.9 +/- 4.4 versus 29.4 +/- 4.7 mm2; p = 0.02) and 1 cm below the stent (37.2 +/- 7.1 versus 25.2 +/- 3.2 mm2; p = 0.005); these results persisted to 6 months. Histological morphometry demonstrated progression of neointimal hyperplasia in the DLS stent between 30 and 180 days (8.3 +/- 1.79 versus 14.9 +/- 6.6 mm2; p = 0.03), whereas the peritoneum-lined stent had no change during the same time period (4.62 +/- 0.98 versus 4.72 +/- 0.97 mm2; p = 0.85). The same patterns were true for the intima:media ratio. Immunohistochemistry demonstrated complete endothelialization at 6 months in both DLS and PLS. However, SMC staining with alpha-actin demonstrated more smooth muscle actin-positive cells in the DLS compared to the PLS (327 +/- 87 versus 262 +/- 73 counts/5 high-powered fields; p = 0.04). CONCLUSION: Peritoneum-lined stents offer a novel method to improve patency of lower extremity arterial stents.

What are the key factors in setting up a successful carotid stent program?

Carotid stenting will drastically alter the management of carotid bifurcation stenosis. Key factors to include when initiating a carotid stent program are discussed. Questions addressed include the following: Who has clinical responsibility for patients with carotid disease? What is the rationale for a carotid stent program? How does one initiate a carotid stent program? How does one deal with endovascular realities? Training, patient selection, quality improvement, and proctoring are also reviewed.

Safety and efficacy of carotid arteriography in vascular surgery practice.

OBJECTIVE: Carotid arteriography (CA) is an important method of assessing carotid artery occlusive disease and is the best method of planning for carotid angioplasty and stent placement (CAS). This study compared the results of CA performed by vascular surgeons in a contemporary series against widely recognized interdisciplinary quality standards for this procedure. Although many vascular surgeons perform CA, there is a paucity of data about its safety, efficacy, and compliance with quality standards in vascular practice. The importance of quality CA will likely increase as CAS emerges to assume a broader clinical role. METHOD: Carotid arteriograms performed by seven vascular surgeons at three institutions from September 2000 to May 2004 were reviewed. These results were compared with quality standards for the performance of CA. RESULTS: Five hundred three carotid arteriograms were performed over 45 months. Indications for the procedure were extracranial cerebrovascular disease (86%), trauma (5%), and other conditions (9%). Indications for the procedure were appropriate in 100% of patients (as determined by guidelines document) and exceeded the recommended standard of appropriate indications in 99%. All procedures successfully provided the information required, exceeding the threshold of 98% for procedural success. Reversible neurologic deficits occurred in 0.6% (two transient ischemic attacks and one stroke) compared with the threshold of 2.5%. A permanent neurologic deficit occurred in 0.2% (1 patient) compared with the published guideline of 1% after carotid arteriography. Major non-neurologic complications occurred in 1.2% (6 patients), less than the standard of 2.0%. CONCLUSIONS: The safety and efficacy of a contemporary series of CA performed in vascular surgery practice compared favorably with recognized interdisciplinary quality standards for this procedure. Ensuring safe and effective CA is likely to support the successful growth of CAS as a treatment option.

Endoluminal retrieval of a dislodged umbilical vein catheter--a case report.

Endoluminal retrieval of foreign bodies in the pediatric and infant population is an uncommon and challenging procedure for the endovascular specialist. The alternative is an open exploration of these often-fragile patients. The availability of smaller catheter systems allows retrieval with minimally invasive techniques. We report retrieval of a catheter fragment using an Amplatz loop snare through the umbilical vein and review the literature.

Technical note on renal angioplasty and stenting: new developments that facilitate its performance.

Technologic advances in percutaneous catheter-based therapy for renovascular occlusive disease have resulted in progressively miniaturized wires, balloon catheters, stents, and delivery systems. The technique of angioplasty and stenting of renal artery stenoses has been shown to be a safe and effective option for severe hypertension and ischemic nephropathy. Renal artery stenting, especially when performed with the newer lower-profile systems, can be performed with minimal morbidity and a reliably high degree of initial technical success. In this article, we describe our technique using a lower-profile platform of balloons and stents and review data supporting renal artery stenting.

Value, limitations, and techniques of renal artery stenting.

Percutaneous therapy for renovascular occlusive disease has become the preferred alternative to open renal artery revascularization. Angioplasty and stenting of renal artery stenoses has been shown to be a safe and effective option for severe hypertension and ischemic nephropathy. Catheter-based treatment, especially when performed with lower-profile systems can be performed with minimal morbidity and a reliably high degree of initial technical success. The long-term beneficial effects on blood pressure control and renal function, while debated, appear to be valid. In this article, data supporting the value and limitations of renal artery stenting are reviewed, and our technique for renal artery stenting using a lower-profile platform of balloons and stents is described.

Durability and cumulative functional patency of transposed and nontransposed arteriovenous fistulas.

OBJECTIVES: Preoperative duplex scanning of arm and forearm veins has increased the creation of autogenous arteriovenous (AV) fistulas. However, the cumulative functional patency and durability of transposed AV fistulas (TAVF) compared with nontransposed AV fistulas (AVF) and prosthetic bridging grafts (AVG) remains ill-defined. METHODS: From January 1998 to December 2002, 245 dialysis access procedures were performed at University Hospital and the Veteran Affairs Medical Center in New Jersey. Follow-up data were available for 125 procedures (TAVF, n = 42; AVF, n = 30; AVG, n = 53) performed in 97 patients. All access procedures were planned on the basis of preoperative duplex scans of arm and forearm veins. Functional patency was defined as ability to cannulate and hemodialyze patients successfully. Primary and secondary cumulative functional patency of TAVFs, AVFs, and AVGs was determined with life table analysis, and differences were analyzed with the log-rank test. Differences in revision rates, including thrombolysis, thrombectomies, and operative revisions, were determined with the Fisher exact t test. RESULTS: Mean follow-up was 18 months (range, 4-24 months). For TAVFs, AVFs, and AVGs, primary functional patency rate at 1 year was 76.2%, 53.3%, and 47.2%, respectively, and at 2 years was 67.7%, 34.4%, and 25.5%, respectively. Similarly, secondary functional patency rate at 1 year was 83.2%, 66.7%, and 58.5%, respectively, and at 2 years was 74.6%, 56.2%, and 40.2%, respectively. Primary and secondary functional patency rates for TAVFs were superior to those for AVGs at 1 and 2 years (P <.001). AVFs had superior secondary functional patency rate at 2 years, compared with AVGs (P <.05), and TAVFs had superior primary and secondary patency rates at 2 years, compared with AVFs (P <.05). AVGs required significantly more revisions than did TAVFs (28.5% vs 54.7%; P <.001) or AVFs (36.7% vs 54.7%; P <.05). CONCLUSIONS: Preoperative duplex scanning of upper arm and forearm veins facilitated successful creation of all types of autogenous fistulas at our institution. TAVF cumulative functional patency rates were superior compared with AVGs and AVFs. Furthermore, TAVFs and AVFs were more durable and required fewer revisions than did AVGs. When preoperative duplex criteria indicate that TAVFs can be performed, they should be the initial access of choice, because of their superior long-term patency and durability.

Abdominal aortic aneurysm demonstrated on renal scintigraphy.

A 74-year-old hypertensive woman presented with abdominal discomfort and a pulsatile abdominal mass. Anterior abdominal angiography during cardiac blood pool, and renal scintigraphic imaging demonstrated a large abdominal aortic aneurysm. 1, 2 Before endovascular repair with an aortoiliac endograft, the abdominal aneurysm measured 7.5 x 7.0 cm on abdominal computed tomography. This study demonstrates that a suspected abdominal aortic aneurysm can be confirmed using the addition of anterior abdominal imaging with normal posterior imaging at the time of renal scintigraphy.