Computational modeling of the cephalic arch predicts hemodynamic profiles in patients with brachiocephalic fistula access receiving hemodialysis.

BACKGROUND: The most common configuration for arteriovenous fistula is brachiocephalic which often develop cephalic arch stenosis leading to the need for numerous procedures to maintain access patency. The hemodynamics that contributes to the development of cephalic arch stenosis is incompletely understood given the inability to accurately determine shear stress in the cephalic arch. In the current investigation our aim was to determine pressure, velocity and wall shear stress profiles in the cephalic arch in 3D using computational modeling as tools to understand stenosis. METHODS: Five subjects with brachiocephalic fistula access had protocol labs, Doppler, venogram and intravascular ultrasound imaging performed at 3 and 12 months. 3D reconstructions of the cephalic arch were generated by combining intravascular ultrasounds and venograms. Standard finite element analysis software was used to simulate time dependent blood flow in the cephalic arch with velocity, pressure and wall shear stress profiles generated. RESULTS: Our models generated from imaging and flow measurements at 3 and 12 months offer snapshots of the patient's cephalic arch at a precise time point, although the remodeling of the vessel downstream of an arteriovenous fistula in patients undergoing regular dialysis is a dynamic process that persists over long periods of time (~ 5 years). The velocity and pressure increase at the cephalic bend cause abnormal hemodynamics most prominent along the inner wall of the terminal cephalic arch. The topology of the cephalic arch is highly variable between subjects and predictive of pathologic stenosis at later time points. CONCLUSIONS: Low flow velocity and wall pressure along the inner wall of the bend may provide possible nidus of endothelial activation that leads to stenosis and thrombosis. In addition, 3D modelling of the arch can indicate areas of stenosis that may be missed by venograms alone. Computational modeling reconstructed from 3D radiologic imaging and Doppler flow provides important insights into the hemodynamics of blood flow in arteriovenous fistula. This technique could be used in future studies to determine optimal flow to prevent endothelial damage for patients with arteriovenous fistula access.

A cohort study showing correspondence of low wall shear stress and cephalic arch stenosis in brachiocephalic arteriovenous fistula access.

BACKGROUND: A brachiocephalic fistula is frequently placed for hemodialysis; unfortunately, cephalic arch stenosis commonly develops, leading to failure. We hypothesized that a contribution to brachiocephalic fistula failure is low wall shear stress resulting in neointimal hyperplasia leading to venous stenosis. The objective of this investigation is to determine correspondence of low wall shear stress and the development of cephalic arch stenosis. METHODS: Forty subjects receiving hemodialysis with a primary brachiocephalic fistula access were followed from time of placement for 3 years or until cephalic arch stenosis. Venogram, Doppler, and viscosity were performed at time of fistula maturation, annually for 3 years or to time of cephalic arch stenosis. Computational hemodynamics modeling was performed to determine location and percent low wall shear stress in the arch. The relationship between wall shear stress at time of maturation and location of cephalic arch stenosis were estimated by correlating computational modeling and quadrant location of cephalic arch stenosis. RESULTS: In total, 32 subjects developed cephalic arch stenosis with 26 displaying correspondence between location of low wall shear stress at time of maturation and subsequent cephalic arch stenosis, whereas 6 subjects did not (p = 0.0015). Most subjects with correspondence had low wall shear stress areas evident in greater than 20% of the arch (p = 0.0006). Low wall shear stress was associated with a higher risk of cephalic arch stenosis in the 23-to-45 age group (p = 0.0029). CONCLUSIONS: The presence and magnitude of low wall shear stress in the cephalic arch is a factor associated with development of cephalic arch stenosis in patients with brachiocephalic fistula. Attenuation of low wall shear stress at time of maturation may help prevent the development of cephalic arch stenosis which is difficult to treat once it develops.

Short interposition with a small-diameter prosthetic graft for flow reduction of a high-flow arteriovenous fistula.

OBJECTIVE: The objective of this study was to evaluate the outcome of a short interposition using a small-diameter prosthetic graft as a flow-limiting procedure to manage symptomatic high-flow arteriovenous fistula (AVF). METHODS: A retrospective review of medical records on a case series was conducted. From June 2004 to April 2017, there were 25 patients with clinical symptoms of high output cardiac failure and progressive dilation of aneurysmal fistula vein due to high-flow AVF (≥1.5 L/min) who underwent short interposition with a 5-mm prosthetic graft at Saitama Medical Center. The primary outcome was the relief of clinical symptoms; other outcome measures included technical success, surgical complications, patency of vascular access, and postoperative changes in local and systemic hemodynamics as assessed by Doppler ultrasound. RESULTS: Twenty-five patients underwent short interposition for cardiac indications (n = 16) and aneurysmal dilation (n = 9). The technical success rate was 100%. The clinical symptoms were relieved in 24 patients (96.0%). Mean reduction in access blood flow was 52.4%. Cumulative primary unassisted patency rates (± standard error) at 1 year, 2 years, and 3 years were 76.2% ± 9.3%, 70.4% ± 10.3%, and 58.1% ± 11.6%, respectively. Secondary patency rates (± standard error) at 1 year, 2 years, and 3 years were 81.8% ± 8.2%, 71.5% ± 9.9%, and 71.5% ± 9.9%, respectively. Complications included access occlusion due to late thrombosis (n = 5 [21.7%]) and graft infection (n = 1 [4.3%]) in the median follow-up period of 3.9 years. CONCLUSIONS: Short interposition with a prosthetic graft is a simple, effective, and durable treatment option for end-stage renal disease patients with cardiac symptoms and progressive dilation of the fistula vein due to high-flow AVF, offering clinical symptom resolution while preserving the autologous behavior of the initial access.

Catheter-related obstruction of the right brachiocephalic vein following hemodialysis in a patient with lupus nephritis.

Vascular access is necessary for hemodialysis, and in some cases where it is difficult to establish an arteriovenous fistula or arteriovenous graft, a permanent hemodialysis catheter may be used. However, serious catheter-related complications, such as central vein stenosis or thrombosis, can occur. We herein present a case of complete brachiocephalic vein obstruction in a patient with lupus nephritis receiving hemodialysis using a tunneled hemodialysis catheter. A 64-year-old patient underwent maintenance hemodialysis while taking an anticoagulant, with a tunneled hemodialysis catheter in the right internal jugular vein, because of arteriovenous fistula failure when hemodialysis was introduced. However, the catheter was removed because of a catheter-related bloodstream infection. Following the administration of antibiotics, an arteriovenous graft was implanted between the brachial artery and axillary vein in the right arm. Surprisingly, arteriovenous graft failure and complete obstruction of the right brachiocephalic vein were observed 3 days after arteriovenous graft creation. In conclusion, we report the case of tunneled hemodialysis catheter-related complete obstruction of the right brachiocephalic vein in a lupus nephritis patient undergoing hemodialysis. Clinicians should be aware of this potential complication when tunneled hemodialysis catheters are used and consider the next vascular access type before a tunneled hemodialysis catheter has been indwelled for the long term.

Novel Reconstruction of Complex Central Venous Occlusion Using Supraclavicular Stent Graft in Hemodialysis Patients.

BACKGROUND: Subclavian vein and brachiocephalic vein occlusions are challenging problems in dialysis patients with ipsilateral upper extremity (UE) vascular access or in need of one. HeRO grafts (Hemodialysis Reliable Outflow, Merit Medical Systems, Inc, South Jordan, UT) have been used to manage such occlusions but patients with chronic hypotension treated with HeRO graft may have threatened patency. We describe an alternative technique using a supraclavicular stent graft to reconstruct the venous outflow, evaluate outcomes of this procedure, and discuss its role in complex hemodialysis patients. METHODS: From January 2019 to January 2020, we performed open surgical and endovascular dialysis access procedures in 297 patients. Eight patients (2.7%) with failing or failed access and subclavian and or brachiocephalic vein occlusion were treated with supraclavicular stent graft placement. Mean age was 52 years, ranging from 32 to 70. Five patients had failed access and were dialyzed using catheters (two femoral). Three patients with failing fistulas had severe arm edema. Two patients had recurrent HeRO graft thrombosis. We performed a retrospective review of these 8 patients and evaluated access patency and complications. RESULTS: Technical success and access function were 100% in all patients. One patient developed ischemic neuropathy and underwent proximalization of the arterial inflow with improvement. Already-existing fistulas were used for dialysis the day after the procedure and new grafts within 2-4 weeks. Arm edema resolved within one week after the procedure. Median follow-up was 254.5 days, range 24-408 days, with primary patency rate of 87.5% and secondary patency rate of 100%. Only one patient has required reintervention. Postoperative evaluation with ultrasound has revealed patent stent graft in the area of the subcutaneous cervical tunnel over the clavicle. CONCLUSIONS: Supraclavicular stent graft placement to a central vein can be used successfully to reconstruct venous outflow in hemodialysis patients with complex central vein occlusions. A supraclavicular extra-anatomic path can be used safely and effectively to place new UE vascular access or salvage threatened access in this challenging patient population.

Fontan venovenous collaterals and hepatic fibrosis.

OBJECTIVE: We hypothesized that a relationship might exist between angiographically demonstrable, post-Fontan venovenous collaterals, and hepatic fibrosis. METHODS: We analyzed data from post-Fontan patients that underwent cardiac catheterization and transvenous-hepatic biopsy procedures between March 2012 and March 2020. From innominate vein angiography, we determined those that either had or lacked venovenous collaterals. Additionally, we examined data from post-Fontan patients that underwent hepatic ultrasound, shear-wave elastography between January 2017 and March 2020. RESULTS: We identified 164 patients that met inclusion criteria. Of the 164, 101 (62%) had venovenous collaterals. Of the 101 with collaterals, average total fibrosis score (TFS) was 3.2 and the average rate of fibrosis progression was 0.28 vs an average TFS of 2.1 and an average fibrosis progression rate of 0.22 for those without collaterals (P = .00001 and P = .01, respectively). Of the 101 with collaterals, oxygen saturation was 91% ± 4% vs 93% ± 3% (P = .048) without collaterals. Of the 164, 86 (52%) underwent ultrasound shear-wave elastography. Of the 86 patients undergoing elastography, 50 (58%) were performed in those with collaterals, and 36 (42%) in those without collaterals. For the 50 with collaterals, average elastography values were 13.3 vs 11.2 kPa for the 36 without collaterals (P = .006). We found no statistically significant differences for age at biopsy, Fontan duration, Fontan-type, type of functional univentricle, laboratory, clinical, or hemodynamic values between those with or without collaterals. CONCLUSIONS: The presence of angiographically demonstrated venovenous collaterals was associated with statistically, significantly more advanced liver fibrosis than those without collaterals.

Percutaneous Extra-Anatomic Double-Barrel Bypass for Salvage of Hemodialysis Access and Treatment of Venous Occlusive Disease.

A woman with an upper extremity brachioaxillary arteriovenous dialysis graft presented with a 9-month history of profound ipsilateral arm swelling and numbness secondary to chronic axillosubclavian vein occlusion. Previous endovascular and open venous recanalization attempts were unsuccessful. A totally percutaneous extra-anatomic venous bi-bypass was created to salvage the dialysis access circuit and reconstruct the deep venous system. Using overlapping Viabahn stent-grafts, two parallel bypasses were created from the arteriovenous graft and brachial vein, respectively, to the brachiocephalic vein. The hemodialysis graft regained function. Upper extremity symptoms resolved within 48 h. This is the first reported percutaneous double-barrel technique of extra-anatomic venous bypass creation for simultaneous management of a failed dialysis access and chronic venous occlusive disease.

A novel technique to restore access in patients with central venous occlusion using the Surfacer® Inside-Out® Access Catheter System.

Exhausted central venous access is a potentially life-threatening situation for patients dependent on haemodialysis. If standard guidewire recanalisation fails, unconventional venous access or central venous needle recanalisation can be considered but are often associated with higher rates of complications and/or dysfunction. Here, we report about two patients treated successfully with the Surfacer® Inside-Out® Access Catheter System (Bluegrass Vascular Technologies, San Antonio, TX, USA) to achieve transmediastinal central venous access.

Surgical Treatment of Cephalic Arch Stenosis through Rotation of the External Jugular Vein.

The percutaneous transluminal balloon angioplasty or cephalic vein transposition is the treatment for cephalic arch stenosis. In some cases, rotation of the external jugular vein may be a good option for the cephalic arch problems. We describe a new technique to treat cephalic arch stenosis. The technique enables the cephalic arch and subclavian vein to be bypassed altogether through the rotation of the external jugular vein. It consists of 3 small incisions, thus causing minimal surgical damage.

Fluid dynamics of thoracic cavity venous flow in multiple sclerosis.

This paper hypothesizes, based on fluid dynamics principles, that in multiple sclerosis (MS) non-laminar, vortex blood flow occurs in the superior vena cava (SVC) and brachiocephalic veins (BVs), particularly at junctions with their tributary veins. The physics-based analysis demonstrates that the morphology and physical attributes of the major thoracic veins, and their tributary confluent veins, together with the attributes of the flowing blood, predict transition from laminar to non-laminar flow, primarily vortex flow, at select vein curvatures and junctions. Non-laminar, vortex flow results in the development of immobile stenotic valves and intraluminal flow obstructions, particularly in the internal jugular veins (IJVs) and in the azygos vein (AV) at their confluences with the SVC or BVs. Clinical trials' observations of vascular flow show that regions of low and reversing flow are associated with endothelial malformation. The physics-based analysis predicts the growth of intraluminal flaps and septa at segments of vein curvature and flow confluences. The analysis demonstrates positive correlations between predicted and clinically observed elongation of valve leaflets and between the predicted and observed prevalence of immobile valves at various venous flow confluences. The analysis predicts the formation of sclerotic plaques at venous junctions and curvatures, in locations that are analogous to plaques in atherosclerosis. The analysis predicts that increasing venous compliance increases the laminarity of venous flow and reduces the prevalence and severity of vein malformations and plaques, a potentially significant clinical result. An over-arching observation is that the correlations between predicted phenomena and clinically observed phenomena are sufficiently positive that the physics-based approach represents a new means for understanding the relationships between venous flow in MS and clinically observed venous malformations.

Stent-retriever thrombectomy in the treatment of infants with acute thrombosis of the superior vena cava and innominate vein.

OBJECTIVES: To describe the efficacy and safety of stent-retriever thrombectomy in infants with thrombosis of the superior vena cava (SVC) and innominate vein. BACKGROUND: Thrombosis of the SVC and of the innominate vein is a potentially life threatening complication in infants during intensive care treatment following major surgical procedures. To avoid reoperations, we evaluated interventional revascularization by stent-retriever thrombectomy. METHODS: From 2015 to 2017, five infants were diagnosed with acute thrombosis of the SVC and innominate vein following major cardiac or pediatric surgery. Using a femoral venous access and 4 or 5 French guiding catheters stent-retriever systems (4/20 mm or 6/30 mm) were placed into the thrombus and retrieved under suction. We aimed to revascularize not only the SVC but also the innominate, jugular, and subclavian veins. RESULTS: Following repeated stent retrieving manoeuvers, we were able to reestablish flow in the major veins of all patients. Due to significant residual thrombotic material, we decided to perform additional balloon dilatation of the SVC and innominate vein in 3/5 patients. There were no complications related to the procedure and none of our patients required blood transfusion. Following the intervention, the patients received treatment with low-molecular-weight heparin. Interventional treatment achieved persistent patency of the SVC and innominate vein in all patients. CONCLUSION: Stent-retriever thrombectomy is a safe and effective method for interventional treatment of acute thrombosis of the central veins in infants. Due to the large amount of thrombotic material, it is frequently required to combine this method with balloon compression of residual thrombotic material.

Percutaneous intervention for symptomatic central vein stenosis in patients with upper limb arteriovenous dialysis access.

Central venous stenosis is an important hindrance to long-term maintenance of arteriovenous access in the upper extremities in dialysis patients. AIM: The present study was done to determine feasibility and clinical success of endovascular approach for the treatment of symptomatic central venous stenosis associated with significant ipsilateral limb edema in dialysis patients with vascular access in the upper limb. METHODS: A database of hemodialysis patients who underwent endovascular treatment for central venous stenosis from January 2014 to January 2017 at our institute was retrospectively reviewed. Follow-up was variable. RESULTS: The study included ten patients (6 men and 4 women) with a mean age of 45.2 years, who underwent thirteen interventions during a period of 3 years. The technical success rate for endovascular treatment was 100%. One patient underwent primary PTA (percutaneous transluminal angioplasty). Seven patients underwent primary PTA and stenting. Three patients underwent secondary PTA. One among these patients underwent secondary PTA twice along with fistuloplasty. One patient underwent secondary PTA with stenting. No immediate complications were encountered during the procedure. Our study shows a primary patency rate of 67% and 33% at 6 months and 12 months for PTA with stenting. Our study also shows secondary or assisted primary patency of 75% at 6 months of follow-up. CONCLUSIONS: Endovascular therapy (PTA) with or without stenting for central venous stenosis is safe, with low rates of technical failure. Multiple additional interventions are the rule and long-term patency rate is not very good.

Dual drainage total anomalous pulmonary venous connection: a rare mixed variant.

The mixed type of total anomalous pulmonary venous connection is the least common variant, occurring in approximately 5% of all patients. Dual drainage through a common venous confluence is much rarer. Computed tomography to delineate the exact pulmonary venous anatomy is a must in such cases. Correct preoperative recognition and intraoperative confirmation to check the drainage of all 4 pulmonary veins is essential in all cases of total anomalous pulmonary venous connection. We report the case of an adult patient with dual drainage to coronary sinus and left vertical vein to innominate vein.

Surgical Treatment of Cephalic Arch Problems in Arteriovenous Fistulas: A Center Experience.

BACKGROUND: Cephalic arch problems, mainly stenosis, are a common cause of arteriovenous fistulas (AVFs) failure, and the most effective treatment is yet to be clearly defined. Restenosis usually occurs soon, and multiple interventions become necessary to maintain patency and functionality. The authors present the experience of their center with cephalic vein transposition in a group of patients with different problems involving the cephalic arch. METHODS: After consultation of the medical records, an observational retrospective analysis was performed to evaluate the outcomes of surgical treatment in cephalic arch problems of AVFs treated at the author's center between January 2013 and December 2015. The considered outcomes were endovascular intervention rate, thrombosis rate, and primary and secondary patencies. RESULTS: Seven patients were treated by venovenostomy with transposition of the cephalic arch and anastomosis to the axillary vein. The average patient age was 72 years (59-81), and most patients were female (71%) and diabetic (71%). All accesses were brachiocephalic AVFs with a mean duration of 4 years (1-7). The underlying problems were intrinsic cephalic arch stenosis (n = 5), entrapment of the cephalic vein (n = 1), and clinically significant vein tortuosity at the cephalic arch (n = 1). These last 2 problems conducted to a surgical approach as first-line therapy instead of endovascular intervention, the initial treatment in the other 5 cases (all with high-pressure balloons, with cutting balloon in one case). Previous thrombotic episodes were reported in 57% of the patients. The mean access flow before surgical intervention was 425 mL/min (350-1,500). No complications related with the surgical procedure were reported. One patient underwent surgical thrombectomy after AVF thrombosis, followed by transposition of the vein. In another case, a simultaneous flow reduction was performed. Most of the patients on dialysis (5/6) used the AVF after surgery. After a mean follow-up period of 9 months (1-22), surgical treatment was associated with a reduction in endovascular intervention rate (1.9 interventions per patient-year presurgery versus 0.4 postsurgery; P < 0.05) and thrombosis rate (0.93 thrombotic episodes per patient-year presurgery versus 0.17 postsurgery; P < 0.05). The problems leading to endovascular reintervention were as follows: new venous anastomosis stenosis (57%), axillary vein stenosis (29%), and swing-point stenosis (14%). Primary and secondary patencies at 6 months were 57% and 71%, respectively. CONCLUSIONS: In this group of patients with cephalic arch problems and multiple previous procedures, surgical treatment was associated with a reduction in endovascular intervention and thrombosis rate but did not avoid reintervention. Facing the complexity and multiplicity of the cephalic arch complications, treatment should be individually decided.

Laser Recanalization of Central Venous Occlusion to Salvage a Threatened Arteriovenous Fistula.

Central venous occlusion is conventionally managed with balloon angioplasty, stent extension, or sharp recanalization. Here, we describe recanalization of a chronically occluded innominate vein using excimer laser after conventional techniques were unsuccessful. Patient clinical improvement and fistula patency have been sustained 2 years postintervention. This technique may provide new hemodialysis access options for patients who would not otherwise be candidates for hemodialysis access on the ipsilateral side of a central venous occlusion.

Success Rate and Complications of Sharp Recanalization for Treatment of Central Venous Occlusions.

PURPOSE: To evaluate success and safety of needle (sharp) recanalization as a method to re-establish access in patients with chronic central venous occlusions. MATERIALS AND METHODS: Thirty-nine consecutive patients who underwent this procedure were retrospectively reviewed to establish success rate and associated complications. In all cases, a 21- or 22-gauge needle was used to restore connection between two chronically occluded segments after conventional wire and catheter techniques had failed. The needle was guided toward a target placed through a separate access by fluoroscopic guidance. When successful, the procedure was completed by placing a catheter, ballooning the segment, and/or stenting. RESULTS: The procedure was successful in 37 of the 39 patients (95%). The vast majority of the treated lesions were in the SVC and/or right innominate vein. Occlusions ranged in length between 10 and 110 mm, and the average length of occluded venous segment was 40 mm in the treated group. There were four minor (SIR classification B) complications involving pain management after the procedure. There were two major (SIR classification D) complications both of which involved hemorrhage into the pericardium treated with covered stents (5.1%). CONCLUSIONS: Sharp recanalization is a viable procedure for patients who have exhausted standard wire and catheter techniques. The operator performing this procedure should be familiar with potential complications so that they can be addressed urgently if needed.

Resolution of reactive angioendotheliomatosis in an arteriovenous fistula with innominate vein angioplasty.

INTRODUCTION: Arteriovenous fistulae (AVF)-associated reactive angioendotheliomatosis (RAE) is a very rare entity (three previously reported cases in the literature) that can manifest as extremity wounds. RAE's etiopathology is unknown. CASE DESCRIPTION: We report a case of severe limb-threatening upper extremity wound with pathology-proven RAE. This lesion was previously refractory to standard wound care. There was no evidence of limb ischemia or steal syndrome, previously deemed to be the underlying cause of AVF-associated RAE in other reports. CONCLUSIONS: Successful endovascular treatment of an ipsilateral innominate vein stenosis led to reduction of venous hypertension, resolution of associated arm edema, and subsequent wound healing. We therefore propose that venous engorgement and hypertension from central venous stenosis is the likely underlying cause for AVF-associated RAE. If this rare entity is encountered in the setting of AVF, there is utility in treating the wound as a sentinel lesion and venography should be conducted to rule out central venous pathology. Vascular intervention complements aggressive local wound management and biopsy is requisite for prompt diagnosis.