Distal Brachial Artery Research Articles

3-Fr steerable microcatheter system via the upper limb artery in RADPLAT for right maxillary cancer

Background To evaluate the efficacy of a catheter system using a 3-Fr sheath with a steerable microcatheter through right upper limb artery access for superselective intra-arterial cisplatin infusion and concomitant radiotherapy (RADPLAT) to treat right maxillary sinus squamous cell carcinoma (MS-SCC). Material and methods We retrospectively studied 46 sessions in eight patients treated between November 2020 and February 2023 using the catheter system briefly described below. A 3-Fr sheath was inserted into the distal radial, conventional radial, or brachial arteries. A coaxial catheter system with a 2.9-Fr steerable microcatheter and a 1.9-Fr microcatheter was advanced into the brachiocephalic artery. The right common carotid artery was selected by bending the tip of the steerable microcatheter. Coil embolization and intra-arterial cisplatin infusion after selecting each external carotid artery branch were achieved using this catheter system. Results Cisplatin infusion and coil embolization were successful in all sessions. Arterial occlusion at the sheath insertion sites was found in 29.4% (5/17) of the distal radial arteries and 33.3% (3/9) of the conventional radial arteries. No other major complications were observed during the procedure. Conclusion Using a 3-Fr catheter system with a steerable microcatheter through right upper limb artery access is a feasible method for RADPLAT in treating right MS-SCC.

Increased diameter and stiffness of elastic but not muscular arteries in men with abdominal aortic aneurysm.

It has been proposed that formation of abdominal aortic aneurysm (AAA) is part of a systemic arterial dilatative disease. However, arteries in the upper extremities are scarcely studied and it remains unclear whether both muscular and elastic arteries are affected by the proposed systemic arterial dilatation. The aim of this study was to investigate the diameter and stiffness of muscular and elastic arteries in arterial branches originating from the aortic arch. Twenty-six men with AAA (69 ± 4 yr) and 57 men without AAA (70 ± 5 yr) were included in the study. Ultrasound was used to examine the distal and proximal brachial artery, axillary artery, and common carotid artery (CCA), and measurement of diameter and diameter change was performed with wall-tracking software. Blood pressure measurements were used to calculate local arterial wall stiffness indices. The AAA cohort presented larger arterial diameters in the CCA and axillary artery after adjustment for body surface area (P = 0.002, respectively), whereas the brachial artery diameters were unchanged. Indices of increased stiffness in CCA (e.g., lower distensibility, P = 0.003) were seen in subjects with AAA after adjustments for body mass index and mean arterial blood pressure. This study supports the theory of a systemic arterial dilating diathesis in peripheral elastic, but not in muscular, arteries. Peripheral elastic arteries also exhibited increased stiffness, in analogy with findings in the aorta in AAA.NEW & NOTEWORTHY We present data partially supporting the notion of abdominal aortic aneurysm being a systemic vascular disease with focal manifestation in the abdominal aorta, from two well-defined groups recruited from a regional screening program. We show that elastic arteries distal from the aorta exhibit vascular alterations without aneurysmal formation in subjects with AAA compared with controls while muscular arteries seem unaffected.

Abstract No. 205 Percutaneous angioplasty of distal brachial artery stenosis in dialysis access steal syndrome can result in clinically successful outcomes

There is a common belief, grounded in previous hemodynamic research,1 that PTA of a brachial artery (BA) stenosis peripheral to hemodialysis access anastomosis would worsen dialysis access steal syndrome (DASS) by permitting greater retrograde flow into the access. To test this theory, this study compared outcomes of DASS patients who did versus did not receive PTA for distal BA stenosis.

Giant bilateral axillary artery aneurysms with left complete obstructive thrombus in intravenous immunoglobulin-sensitive Kawasaki disease: a case report

BackgroundKawasaki disease (KD) is a systemic vasculitis that predominantly affects medium-sized arteries. In addition to well-known coronary artery aneurysms (CAAs), peripheral systemic artery aneurysms (SAAs) have also been sporadically reported. In the literatures, SAAs occurred mainly in untreated, intravenous immunoglobin (IVIG)-resistant, or severe refractory KD, and thrombotic events in SAAs were rarely reported.Case presentationA 10-month-old boy with a history of KD was referred to our hospital for suspected pseudoaneurysm of the axillary arteries. Four months prior to presentation, he had persistent fever, conjunctival congestion, and rash. On the 10th day of fever echocardiogram showed biliteral CAAs. He was then diagnosed with KD and given IVIG 2 g/kg and aspirin at a local hospital. His fever and symptoms soon subsided and he was discharged with low dose aspirin and dipyridamole. One month prior to presentation, his parents incidentally palpated swellings in his bilateral axillae. On admission, physical examination revealed a pulsatile swelling in his right axilla and a non-pulsatile swelling in the left with impalpable left brachial and radial pulses, cooler and less active left upper limb than the right one. While the pulses of other three limbs were normal. Ultrasound examination revealed giant bilateral axillary artery aneurysms (AAAs) with massive thrombus in the left. Angiography confirmed giant bilateral AAAs with left AAAs completely occluded and fine collateral vessels connecting to the distal brachial artery, in addition to giant bilateral multiple CAAs without stenoses. The patient was given intravenous prostaglandin for 10 days to allow for formation of collateral circulation, as well as aspirin, low molecular weight heparin (which was switched to warfarin before discharge) and metoprolol. At discharge, the temperature and movement of his left upper limb improved significantly. On follow-up at 7 months, his left upper limb further improved and was similar to the right with no occurrence of cardiovascular events. The images of CAAs and AAAs on echocardiogram and computerized tomography remained the same.ConclusionsThis case highlights the importance of evaluating peripheral SAAs in KD patients with CAAs, even if their course of treatment appears smooth. For both large non-aortic SAAs and CAAs in KD patients, antithrombotic therapy is of utmost importance.

Distal Brachial Artery Perforator flap: a new chimeric option for complex hand and digits defects

Reconstruction of fingers pose unique challenges, as a thin and flexible flap is needed in order to guarantee a good functional outcome. For the first time, in this report, we present the DBAp (distal brachial artery perforator) flap, based on the distal perforator closer to the medial epicondyle. The DBAp flap was used to reconstruct complex digit defects as free flap, and to cover an elbow defect while raised as a propeller. Four patients underwent finger reconstruction (free flaps): two patients presented an unstable finger scar following previous surgery, whereas the other two patients presented a terminalized finger at the level of the middle phalanx. A further patient presented a post-traumatic loss of substance at the elbow and was reconstructed using a perforator propeller DBAP flap. Loss of tissues included skin and subcutaneous tissue in all patients and in one patient it included a bone component. Flap dimensions ranged from 48 to 18 cm2 (average: 32 cm2). Among complications, patient n.2 flap presented a marginal flap necrosis requiring a small skin graft after necrosis debridement. The DBAp flap provides a slim, glabrous and pliable skin tissue with a well-hidden donor site scar and thanks to the anatomic location of the distal perforator can be designed to include a vascularized bone graft from the medial epicondyle. Despite the low number of cases, we believe that this flap should be considered as a dependable and effective source for complex reconstructions of both soft tissue and bone in fingers.

Conversion of Arterio-Venous Access of Hemodialysis to Arterio-Arterial Access for Treatment of Venous hypertension with Central Venous Occlusion

This report describes conversion of arterio-venous graft or fistula to arterio-arterial vascular access as a new surgical treatment option for central venous occlusion. It starts with control of the axillary vein and the synthetic graft or superficialized vein proximally, the suture line of venous anastomosis is closed and end-to-side anastomosis of the synthetic graft or vein to the brachial artery (BA) is done, then ligation of the BA distal to the anastomosis is done. Now the blood flow is directed through synthetic graft or vein from proximal to distal BA that can be used as arterio-arterial vascular access for hemodialysis.

Masson Hemangioma in a Brachial Artery Aneurysm

Masson hemangioma is a rare benign vascular tumor characterized by intravascular papillary endothelial hyperplasia (IPEH). Numerous case reports have described lesions in the digits, neck, oral cavity, and intracranially. IPEH involving primary brachial artery aneurysm is extremely rare, with only a handful of reported cases. We present a 43-year-old female with a true distal brachial artery aneurysm who presented with a painful pulsatile mass in the antecubital region. She underwent aneurysm resection and end-to-end repair with a saphenous vein graft. Histology confirmed the diagnosis of IPEH with characteristic features of papillary hyperplasia within the intravascular thrombus.

A Stopped Pilot Study of the ProGlide Closure Device After Transbrachial Endovascular Interventions

Purpose: To evaluate the feasibility and safety of the suture-mediated ProGlide device in closure of the brachial artery after endovascular interventions. Materials and Methods: From 2016 to 2017, a pilot study was performed using the ProGlide to achieve hemostasis after percutaneous access of distal brachial arteries >4 mm in diameter. In an interim analysis, the results were compared to a matched control group taken from a 60-patient historical cohort who underwent brachial artery access and manual compression to achieve hemostasis between 2014 and 2017. The primary outcome was access-related reintervention and the secondary outcome was the incidence of access-site complications. Results: Seven patients (mean age 67.9 years; 6 men) were enrolled in the study before it was stopped in 2017. Four patients experienced 6 access-site complications (neuropathy, hematoma, occlusion, and pseudoaneurysm). These resulted in 3 access-related reinterventions: surgical evacuation of a hematoma, thrombectomy of the occluded brachial artery, and surgical repair of the pseudoaneurysm. In the interim comparison to the 19 matched patients (mean age 61.9 years; 6 men), the ProGlide group had proportionally more patients experiencing access-related complications (57% vs 16% for manual compression, p=0.035) and resultant reinterventions (43% vs 11%, p=0.064). Based on this data the trial was stopped. Conclusion: Considering this experience, it is not advisable to use the ProGlide in transbrachial endovascular interventions due to the high incidence of complications and access-related reinterventions.

Brachial Artery Catheterization in Swine.

The video describes in detail the catheterization of the distal brachial artery in swine. This technique enables researchers to measure arterial blood pressure continuously and collect arterial blood samples to assess arterial blood gas measurements. Arterial blood pressures and arterial blood gases are important physiological parameters to monitor during experimental procedures. In swine, four common methods of arterial catheterization have been described, including catheterization of the carotid, femoral, auricular, and medial saphenous arteries. Each of these techniques have advantages, such as ease of access for the auricular artery, and disadvantages that include deep tissue dissection for carotid artery catheterization. The described alternative method of arterial catheterization in swine, the catheterization of the distal aspect of the brachial artery, is a rapid procedure that requires relatively minimal tissue dissection and provides information that is in line with data collected from other arterial catheterization sites. The procedure uses a medial approach along an oblique plane of the lower brachium, positioned between the olecranon and the flexor aspect of the elbow joint, and this approach allows researchers the major advantage of unimpeded freedom for procedures that involve the caudoventral, caudodorsal back, or hind limbs of the pig. Due to the location of the upper forelimb of the catheterized vessel and potential challenges of effective homeostasis following catheter removal from the artery, this technique may be limited to non-recovery procedures.

Blunt trauma to the antecubital fossa causing brachial artery injury and minor fractures around the elbow joint, an easily missed diagnosis with potential devastating consequences: a case report

BackgroundBlunt trauma causing brachial artery injury in a young patient is very rare. Cases of brachial artery injury may be associated with closed elbow dislocation or instability. Elbow dislocation may not be evident clinically and radiologically on initial presentation.Case presentationThis is a case of a 37-year-old, right-hand dominant, Malay man who fell approximately 6 meters from a rambutan tree and his left arm hit the tree trunk on his way down. He was an active tobacco smoker with a 20 pack year smoking history. On clinical examination, Doppler signals over his radial and ulnar arteries were poor. He proceeded with emergency computed tomography angiogram of his left upper limb which showed non-opacification of contrast at the distal left brachial artery just before the bifurcation of the left brachial artery at his left elbow joint. Radiographs and computed tomography scan also showed undisplaced fracture of left lateral epicondyle and radial head with no evidence of elbow dislocation. He subsequently underwent left brachial to brachial artery bypass which was done using reversed saphenous vein graft and recovered well. His fractures were treated using 90 degree long posterior splint for 2 weeks and he was then allowed early range of motion of the left elbow. This patient developed left elbow dislocation 6 weeks postoperatively. Closed manipulative reduction of his left elbow resulted in incomplete reduction. The functional outcome of his left elbow was limited with a range of motion of left elbow of 0–45 degrees. However, he was not keen for surgery to stabilize his elbow joint during his last follow-up 6 months post injury.ConclusionsThis is an uncommon case of brachial artery injury in a civilian caused by blunt trauma associated with occult elbow instability/dislocation and minor fractures around the elbow joint. The treatment of brachial artery injury with clinical evidence of distal ischemia is surgical revascularization. The possibility of elbow instability and dislocation need to be considered in all cases of brachial artery injury because early radiographs and computed tomography scans may be normal. Short-term posterior splint immobilization is not sufficient to prevent recurrent dislocations.

A Limb-Threatening Long Arterial Dissection Caused by Humerus Neck Fracture: A Case Report

Proximal humerus fracture is a common arm trauma and rarely occurs with vascular injury which however is a serious complication. In this case report, we present a long segment dissection of the axillary and brachial arteries as a rare complication due to fragmented proximal humerus fracture and shoulder dislocation. An 80-year old female patient was seen at the emergency department. Radiograph examination has revealed a fragmented proximal humerus fracture besides dislocation of the head of humerus towards the axillary area. On vascular examination, acute arterial occlusion such as absence of radial and ulnar pulses were observed in her left hand. The patient was immediately taken to the operating room. The dissection included the entire segment approximately 20cm between the distal subclavian artery and the distal brachial artery. This injured segment was removed and a 6mm Polytetrafluroethylene (PTFE) graft with rings was interpositoned between subclavian and brachial arteries. This case is a rarity because of such a significant complication after a small injury. Axillary artery injuries caused by humeral neck fractures are rare but should not be missed by the physician.

Efficacy of endovascular interventional minimally invasive techniques in treatment of acute brachial artery injury

Objective To evaluate the efficacy of endovascular interventional minimally invasive techniques in treatment of acute brachial artery injury. Methods A retrospective case series study was designed to analyzed data of 16 cases (11 males and 5 females) sustaining acute brachial artery injury treated from March 2011 to August 2016. Mean age was 47.9 years (range, 27-66 years). Left upper extremity vascular injury occurred in 7 cases and right upper extremity vascular injury occurred in 9. There were 13 cases of arterial intima injury and 3 of arterial pseudoaneurysm. All patients underwent endovascular therapy including stent implantation and balloon dilatation. Angiography was used to evaluate the repair of brachial artery and the operation time was recorded. Improvements of distal limb arterial pulse and limb ischemic symptoms were observed, and the patients who were followed up with stent lumen stenosis more than 50% received endovascular treatment again. Results The procedures was successful in all patients, with operation time of 30-75 minutes (mean, 45 minutes). After the insertion of a stent, recovered brachial artery blood flow and disappeared pseudoaneurysm were observed on angiography, without occurrence of stent stenosis or contrast extravasation. Symptoms of local pain and numbness were alleviated, and blood supply of the distal brachial artery was improved after operation. All patients were followed up for 3-36 months(mean, 16.7 months). The false aneurysm did not recur. Two cases of stent stenosis more than 50% had a second balloon dilation procedure and the blood flow returned to normal. Stent patency was found in 14 cases with stent stenosis of less than 50%. During the follow-up period, no ischemic necrosis, displacement of the stent or stent fracture were found. Conclusion For acute brachial artery injury, endovascular management exhibits higher technical success rate and good clinical outcome with a low incidence of complications. Key words: Brachial artery; Stents; Vascular system injuries

Hand-arm vibration syndrome with distal brachial artery occlusion

Abstract Hand-arm vibration syndrome (HAVS) is a complex disorder of the peripheral extremities that is associated with occupational or recreational exposure to hand-transmitted vibration. Digital artery occlusion in HAVS is a common finding; however, proximal involvement is less likely. We present a case of HAVS with the initial presentation of acute limb ischemia and with thrombus burden extending from the distal brachial artery and into the ulnar and radial arteries. To our knowledge, no case of HAVS syndrome of similar severity has been previously described. This case emphasizes the potential dangers of HAVS and the necessity for proper prophylactic interventions at the workplace.

True aneurysm of proximal radial artery

True aneurysm of upper limb arteries is a rare entity with very few reported cases. Here, we report a case of true aneurysm of proximal radial artery starting from its origin at brachial artery bifurcation. A 50-year-old female presented with a painful pulsatile mass in the left cubital fossa of 1 year duration. Duplex examination revealed partially thrombosed large aneurysm of proximal radial artery. Aneurysmal segment was resected and end of distal brachial artery anastomosed end-to-end with ulnar artery. Radial artery was reconstructed with interposition reversed saphenous vein graft from side of brachial artery to end of radial artery.

Occlusion of acute distal brachial, proximal radial and ulnar arteries in a young thrower

Summary Acute arterial occlusion, a rare condition in throwers, requires early detection and treatment for avoiding further complications. Thus far, no study has mentioned the occurrence of distal brachial, proximal radial, and ulnar artery occlusion in baseball players. An adolescent baseball pitcher presented with acute occlusion of the distal brachial, proximal radial, or ulnar artery. The patient complained of a cold sensation in the hand, wrist, and distal forearm. On physical examination, decreased surface skin temperature, and no radial pulse in the wrist suggested arterial occlusion. Emergency angiography validated the clinical suspicion, and identified the arteries and sites of vascular occlusion. Surgery was performed to alleviate the occlusions, thereby resolving the preoperative complaints and abnormal findings. Furthermore, postoperative magnetic resonance imaging of the shoulder and elbow joint was conducted to determine the causes of arterial occlusion. The patient resumed pitching 4 months postoperatively, and has remained active and symptom free. Magnetic resonance imaging examination revealed no vascular abnormalities or bony or soft tissue in the shoulder or elbow region. With early detection and treatment, a favorable prognosis can be achieved in baseball pitchers with acute upper extremity arterial occlusion so that their pitching career is not jeopardized.

The Addition of Ultrasound Arterial Examination to Upper Extremity Vein Mapping before Hemodialysis Access

Routine upper extremity vein mapping by ultrasound (Ven-US) is recommended by current National Kidney Foundation/Kidney Disease Outcomes Quality Initiative guidelines before arteriovenous fistula (AVF) creation. However, the impact of concomitant arterial US (Art-US) examination is not clear. The Ven-US protocol at our institution was modified to include Art-US starting January 2013. Therefore, retrospective review of patients who received Ven-US with Art-US between January 2013 and July 2014 was performed. The Art-US component included distal brachial and radial artery diameters, level of brachial bifurcation, and Doppler Allen's test. A plan for hemodialysis (HD) access was proposed by 2 attending vascular surgeons (VS1 and VS2) and based on a set of criteria for fistula creation (CFC) using Ven-US findings alone. The Art-US findings were subsequently reviewed, and the plan was changed based on either vascular surgeon judgment (VS1 and VS2) or predetermined arterial anatomic criteria (CFC). In total, 163 patients (326 arms) were included. The mean age was 53years, most patients were male (60%), and most were HD dependent at the time of US evaluation (67%). The initial plan based on Ven-US was: 17-19% radiocephalic (RC) AVF, 33-48% brachiocephalic AVF, 20-27% brachiobasilic AVF, and 14-23% grafts. The Art-US revealed 159 radial arteries (49%) with diameter <2mm, 16 brachial arteries (5%) with high bifurcation, 93 (29%) incomplete palmar arches, and 7 arms (2%) with arterial waveform blunting. Review of Art-US findings resulted in an overall change to the operative plan from 4% to 12% of patients. Those with an initially planned RC AVF were more likely to have a change in operative approach (21-57%) compared with all other types of planned access (1-3%, P<0.001). Preoperative Art-US may significantly change the operative plan, particularly when planning a RC AVF, and should be performed before HD access surgery at the wrist.

Vascular Complications Following Transradial and Transulnar Coronary Angiography in 1600 Consecutive Patients.

Major, noncoronary complications are rarely encountered following transradial coronary procedures. Among 1600 prospectively studied patients with complete follow-up, 7 patients experienced major complications following coronary forearm procedures corresponding to an incidence of 0.44%. We found inadvertent symptomatic intramyocardial contrast medium injection, 2 cases with compartment syndrome of which 1 was managed surgically, exertional hand ischemia due to radial artery occlusion, a large ulnar artery pseudoaneurysm, an ulnar arteriovenous fistula, and 1 critical hand ischemia due to late occlusion of the distal brachial artery. Although infrequent, surveillance for major complications should be encouraged after forearm coronary procedures.

Revision Using Distal Inflow: A Safe and Effective Treatment for Ischemic Steal Syndrome After Access Creation

Ischemic steal syndrome (ISS) is a dreaded complication after hemodialysis access creation. Its management is complex and varied, with most requiring surgical revision for correction of symptoms. Revision using distal inflow (RUDI) has been described in small series for the treatment of ISS. We present our experience with RUDI for the treatment of ISS and pathologic high flow (HF). We retrospectively reviewed consecutive patients who underwent RUDI for ISS from April 2010 to March 2014. Data collection included demographics, medical histories, subsequent procedures, volume flows, access usage, limb salvage, and patient survival. We performed 32 RUDI procedures in 31 patients (18 women, 13 men). Indications for surgery were pathologic HF in 15 and ISS in 21. Sixteen percent had prior plication for ISS or HF. Seventy-one percent of patients had a history of diabetes, and 52% had a history of atherosclerotic disease. Time to intervention from creation was 40 months (range, 6-88 months). Accesses included one upper arm graft and 30 brachial artery-based fistulas. Outflow included 26 cephalic veins and four basilic veins. Distalization targets were 20 radial arteries, nine ulnar arteries, and three distal brachial arteries. Mean flow reduction was 994 mL/min. Primary assisted patency at 1 year was 73%, and secondary patency was 88%. The RUDI in one patient was revised from a distal brachial to radial inflow. A single access was ligated for continued heart failure after RUDI. ISS symptom resolution was reported as complete in 81% and partial in 19%. RUDI is an effective and lasting treatment of ISS and HF and comparable to reported experiences with distal revascularization-interval ligation, proximalization of the arterial inflow, and plication. Patient selection is key for optimizing relief of symptoms and maintaining use of the access.

Pioglitazone prevents the endothelial dysfunction induced by ischemia and reperfusion in healthy subjects.

No study has investigated whether pioglitazone (an agonist of peroxisome proliferator-activated receptor gamma) protects against ischemia and reperfusion (IR)-induced endothelial dysfunction in humans. In the first crossover study, 20 volunteers were randomized to 1 week of pioglitazone (30 mg/d, postoperatively) or control (no treatment). In the second single-arm study, 15 volunteers received pioglitazone and the cyclooxygenase-2 inhibitor meloxicam for 1 week. On day 7, endothelium-dependent flow-mediated dilation (FMD) of the distal brachial artery was measured before and after IR (15 minutes of ischemia followed by 15 minutes of reperfusion in the proximal upper arm). Pre-IR brachial-artery diameter and FMD were similar across the 2 sessions (control, pioglitazone) in protocol 1 and between the 2 protocols. IR significantly blunted FMD after no treatment (pre-IR FMD: 10.2% ± 2.6%; post-IR FMD: 3.5% ± 1.9%, P < 0.01) but not after pioglitazone administration (pre-IR FMD: 9.7% ± 2.5%; post-IR FMD: 8.8% ± 2.9%, P = 0.11). This protective effect was accompanied by an increase in serum levels of the antioxidant enzyme extracellular superoxide dismutase and was not affected by concomitant administration of the cyclooxygenase-2 inhibitor meloxicam (P = 0.10). In humans, pioglitazone provides potent protection against IR-induced endothelial dysfunction.

A Simple Cost-Effective Method of Microsurgical Simulation Training: The Turkey Wing Model

The rat femoral artery (RFA) anastomosis model has been the gold standard in microsurgical simulation training. While effective, live animal use requires animal use committee regulation and costly maintenance. Our institution's animal laboratory is remote to the hospital, limiting access by our busy surgical residents with their limited duty hours. We present an alternative convenient, cost-effective model. Ten frozen turkey wings were divided into distal and proximal segments. Vessel diameter, length, and anastomosis perfusion were assessed. Proximal brachial arteries ("humeral" segments) measured 8.85 ± 1.14 cm long with diameter 1.69 ± 0.27 mm. Distal brachial arteries ("forearm") measured 10.5 ± 2.06 cm long with diameter 1.25 ± 0.25 mm. An 8-lb box (~20 wings) cost $13.76. Separate use of the segments provides two training sessions with $0.35 per session effective cost. Our average cost for RFA microsurgical training sessions was $120 dollars for a single rat 2-hour session and $66 per rat if a maximum crate load of six rats was used. Besides significant cost, not all training programs are equipped to house, care for, and use rats in microsurgical training. We now use turkey wings for microvascular training. They are cheap, abundant, readily accessible for training, and consistent with tissue quality and vessel size approximating human systems.