Distal Circulation Research Articles

Perforator Flap versus Conventional Flap.

The introduction of perforator flaps represented a significant advance in microsurgical reconstruction. However, confusion has developed due to the erroneous belief that perforator flaps are different from conventional flaps. The concept of the perforator is not new, but is an idea that evolved from the conventional flap. In fact, some of the flaps used by microsurgeons were perforator flaps. The only difference is the anatomical level of the blood vessels involved; the perforator concept is focused on the distal circulation, so-called 'perforator'. Therefore, thinner sections of tissue can be taken from the conventional donor sites of myocutaneous flaps. With the use of perforators, there are no longer "flap of choice" for specific reconstructions, because conventional donor sites have become universal donor sites, enabling the harvesting of a variety of flaps. Moreover, depending on the surgeon's ability, any flap can be utilized as a perforator-based island flap whose source vessel has been completely preserved. Therefore, tissues can be efficiently customized and tailored into any configuration required for reconstruction. The application of perforator flap technique enables more precise dissection, and allows more selective harvesting of thinner flaps, which will expand options in reconstructive surgery. No doubt the technique will continue to evolve.

Anterior spinal artery as a collateral pathway in a case of unilateral vertebrobasilar occlusion: A case report and literature review

Background: Vertebral artery (VA) occlusion is an important cause of stroke in the posterior circulation along with basilar artery occlusion. Intracranial VA disease accounts for 21% of patients with posterior circulation stroke and is bilateral in nearly half of them. Anterior Spinal Artery (ASA) originating from cervical VA to intracranial distal VA and Basilar artery is a possible and infrequent source of collaterals. Case description: We report a case of acute unilateral vertebral artery occlusion with retrograde flow from ASA as the only collateral pathway reconstituting distal circulation. Conclusion: Anterior Spinal Artery can play an important role in the setting of unilateral or bilateral vertebral occlusion. Retrograde flow through ASA could reconstitute distal circulation. Adequacy of flow and neurological improvement in this situation depends on the presence of other collateral channels, other vertebral artery and on patency of vertebrobasilar junction.

Percutaneous thrombin and trans-arterial coil embolization in post pancreatitis gastroduodenal artery pseudo-aneurysm

Visceral artery pseudo-aneurysm is a rare but one of the dreaded complications of pancreatitis. Early treatment is advocated in all patients to decrease associated mortality. Transarterial coil embolization is the treatment of choice in such pseudo-aneurysm. However in cases with absent distal circulation, percutaneous thrombin can be used successfully. Here we present a case of post pancreatitis gastroduodenal artery pseudoaneurysm in which percutaneous thrombin was injected in addition to selective coil embolization as an alternative for the conventional coil embolization.

Quantitative biomechanical comparison of ankle fracture casting methods.

The incidence of ankle fractures is increasing rapidly due to the ageing demographic. In older patients with compromised distal circulation, conservative treatment of fractures may be indicated. High rates of malunion and complications due to skin fragility motivate the design of novel casting systems, but biomechanical stability requirements are poorly defined. This article presents the first quantitative study of ankle cast stability and hypothesises that a newly proposed close contact cast (CCC) system provides similar biomechanical stability to standard casts (SC). Two adult mannequin legs transected at the malleoli, one incorporating an inflatable model of tissue swelling, were stabilised with casts applied by an experienced surgeon. They were cyclically loaded in torsion, measuring applied rotation angle and resulting torque. CCC stiffness was equal to or greater than that of SC in two measures of ankle cast resistance to torsion. The effect of swelling reduction at the ankle site was significantly greater on CCC than on SC. The data support the hypothesis that CCC provides similar biomechanical stability to SC and therefore also the clinical use of CCC. They suggest that more frequent re-application of CCC is likely required to maintain stability following resolution of swelling at the injury site.

Finger necrosis after accidental radial artery puncture.

Radial artery puncture, an invasive procedure, is frequently used for critical patients. Although considered safe, severe complications such as finger necrosis can occur. Herein, we review the clinical course of finger necrosis after accidental radial artery puncture. A 63-year-old woman visited the emergency department (ED) with left second and third finger pain after undergoing intravenous (IV) access in her wrist for procedural sedation. During the IV access, she experienced wrist pain, which increased during the 12 hours prior to her ED presentation. Emergency angiography revealed a pseudoaneurysm in her left radial artery and absence of blood flow to the proper palmar digital artery. Subsequent angiointervention and urokinase thrombolysis failed. The second finger was eventually amputated owing to gangrene. Radial artery puncture can occur accidentally during IV wrist access, resulting in severe morbidity. Providers should carefully examine the puncture site and collateral flow, followed by multiple examinations to ensure distal circulation.

Sublingual nitroglycerin in patients with heart failure and preserved ejection fraction: Impact on central and regional carotid and radial input impedance and hemodynamics

Background: The systolic blood pressure lowering effect of sublingual nitroglycerin (NTG) administration is generally thought to primarily arise from its action on wave reflection, although recent invasive data indicate that at least part of the blood pressure reduction can be ascribed to an effect on left ventricular dynamics. Methods: Carotid and radial pressure waveforms and aortic, carotid and radial flow were measured in 19 HFpEF patients using applanation tonometry and pulsed Doppler ultrasound, respectively. Signals were time-aligned and global systemic as well as regional impedance and wave reflection analysis was applied. Results: NTG lowered carotid systolic (130.8±26 at baseline vs. 110.4±18.4mmHg after NTG, P<0.01) and mean (92.5±18.4 vs.85.4±14.3) blood pressure. Global systemic effects included a decrease in systemic vascular resistance (1.00±0.32 vs. 0.88±0.28 mmHg.ml-1.s, P<0.05), characteristic impedance (0.133±0.089 vs. 0.089±0.034 mmHg.ml-1.s, P<0.05) and an increase in total arterial compliance (1.20±0.58 vs. 1.52±0.53 ml.mmHg-1, P<0.01).NTG had a major impact on the amplitude of the forward pressure wave (58±24.3 vs. 40.6±13.3 mmHg, P<0.01), with no significant change in reflection magnitude. Regional analysis demonstrated a large effect of NTG on carotid input impedance, lowering impedance over the entire frequency spectrum, with radial artery input impedance did not demonstrate any significant changes (despite large effects on pressure and flow waveform morphology). Conclusions: Our data in HFpEF confirm the absence of impact of NTG on reflection magnitude, and demonstrate large effects of NTG on the input impedance of the cerebral vascular district, with little effect on the distal forearm circulation.

Vascular geometry and oxygen diffusion in the vicinity of artery-vein pairs in the kidney.

Renal arterial-to-venous (AV) oxygen shunting limits oxygen delivery to renal tissue. To better understand how oxygen in arterial blood can bypass renal tissue, we quantified the radial geometry of AV pairs and how it differs according to arterial diameter and anatomic location. We then estimated diffusion of oxygen in the vicinity of arteries of typical geometry using a computational model. The kidneys of six rats were perfusion fixed, and the vasculature was filled with silicone rubber (Microfil). A single section was chosen from each kidney, and all arteries (n = 1,628) were identified. Intrarenal arteries were largely divisible into two "types," characterized by the presence or absence of a close physical relationship with a paired vein. Arteries with a close physical relationship with a paired vein were more likely to have a larger rather than smaller diameter, and more likely to be in the inner-cortex than the mid- or outer cortex. Computational simulations indicated that direct diffusion of oxygen from an artery to a paired vein can only occur when the two vessels have a close physical relationship. However, even in the absence of this close relationship oxygen can diffuse from an artery to periarteriolar capillaries and venules. Thus AV oxygen shunting in the proximal preglomerular circulation is dominated by direct diffusion of oxygen to a paired vein. In the distal preglomerular circulation, it may be sustained by diffusion of oxygen from arteries to capillaries and venules close to the artery wall, which is subsequently transported to renal veins by convection.

Treatment Strategies for Management of MCA-M1 Spontaneous Dissecting Aneurysms

Perforators along the middle cerebral artery (MCA) M1 territory increase the difficulty of treating dissecting aneurysms. Such lesions may only require observation or complex staged procedures requiring augmentation techniques which reverse flow from the dissecting segment while preserving parent vessel lumen and distal perfusion. A neurovascular registry containing nearly 900 patient admissions from October 2008 through February 2013 comprised 18 patients with fusiform MCA-M1 aneurysms; their records were analyzed to assess demographics, presenting symptoms, co-morbidities, treatments, and outcomes. Patient ages ranged from 22 to 73 years, averaging at 56. The population was predominately female (69%). Unruptured aneurysm was the most frequent presentation (69%), followed by subarachnoid hemorrhage (22%), and stroke (11%). Subarachnoid hemorrhage patients were Hunt Hess grade III (n=1) and IV (n=1). Co-morbidities included hypertension (77%), smoking (62%), and hyperlipidaemia (46%). Two patients (15%) experienced regrowth after initial treatment requiring further intervention. Treatment was most often surgical (85%) and varied among four categories: observation only; simple surgical, including occlusion without parent vessel compromise; transitional, characterized by flow reversal using proximal occlusion or trapping; and maximal combined, defined as flow reversal with bypass to augment MCA distal circulation. Aneurysm management included wraps (47%), bypass with stent, clip or occlusion (27%), coil and stent (13%), bypass with coil (7%), and observation (7%). Seven treatments (47%) were staged procedures. Post-procedure complications included hydrocephalus (27%), vasospasm (20%), and seizures (20%). The 30-day mortality rate was 15% (n=2). The sample size precludes statistical analysis the relationship between treatment type and complications or mortality.

How does Adamkiewicz artery influence blood supply to the fetal spinal cord?

Adamkiewicz artery became important in clinical practice since it was noticed that its damage during aorta aneurysm repair surgery can sometimes lead to distal spinal cord ischemia. The complexity of anatomical variations can be related to the development of spinal cord arteries. The aim was to describe topography of Adamkiewicz artery and its relations to the anterior spinal artery in fetuses. The study was carried on 4 Batson's resin corrosion casts and 24 formalin-fixed fetuses injected with dyed gelatin or latex aged 15-24 weeks gestational age. In fixed specimens vertebral canals were dissected, the anterior spinal artery was traced and Adamkiewicz artery localized. Arteries were photographed and digitally measured. Data were afterwards statistically analyzed. Anterior spinal artery was duplicated in 3/28 cases. There were from 1 to 3 Adamkiewicz arteries per specimen, mean 1.71. No relation was found between the number of Adamkiewicz artery and age. In 37/48 cases Adamkiewicz artery emptied into the anterior spinal artery on the left side. Mean degree of narrowing in anterior spinal artery (diameter of the anterior spinal artery above junction with Adamkiewicz artery divided by its diameter under that junction) was 76.74%. The diameter of Adamkiewicz artery was also correlated linearly with the degree of narrowing of anterior spinal artery (r=0.68; p<0.05). The arteries of the anterior aspect of thoracolumbar spinal cord in the 2nd trimester of pregnancy represent the adult pattern. A potentially great impact of Adamkiewicz artery on the distal spinal cord circulation may be postulated on the basis of these morphological data.

Spontaneous vertebral arteriovenous fistula causing cervical myelopathy and acute ischemic strokes treated by endovascular balloon–assisted coiling and Onyx embolization

Vertebral arteriovenous fistulas (VAVF) are infrequent lesions characterized by abnormal communication of the extracranial vertebral artery or one of its branches to the surrounding venous plexuses, without the presence of any intervening vessels. We describe a rare occurrence of a patient with VAVF presenting with acute ischemic stroke, encephalomalacia from multiple prior embolic events, and cervical myelopathy, which was successfully treated by coil-assisted Onyx embolization (ev3 Endovascular, Plymouth, MN, USA) with balloon for flow arrest. Our patient demonstrates that point occlusion with embolization for VAVF can be a feasible, safe, and effective treatment option for complete obliteration of the fistula, with subsequent reduction in the volume of the intra-spinal canal venous plexus. Although it is postulated that thromboembolism is less common because of redirection of flow to the venous side of the fistula, our patient also illustrates the potential for to–fro flow in such a fistula to result in embolic injury to the distal circulation.

Initial experience with proximal ligation for profunda femoris artery aneurysms: report of three cases

Profunda femoris artery aneurysms (PFAAs) are rare and difficult to diagnose in the early stage. They are often found due to the presence of complicated conditions, such as rapid expansion, rupture, or acute lower limb ischemia. Surgical procedures such as aneurysmectomy and endoaneurysmorrhaphy tend to be technically challenging because of the patient status and the extent of the aneurysm. We experienced three cases of PFAAs that were treated by proximal ligation (PL) without complete control of the distal branches. The exclusion of PFAAs was confirmed by duplex ultrasound or angiography at the end of the operation. There was no mortality in the perioperative period. During a 12-month follow-up, all cases exhibited complete exclusion of aneurysms with marked size reduction. Based on these findings, we propose that PL, with a careful follow-up for PFAA exclusion and distal limb circulation, could be an alternative treatment for complicated PFAAs.

Hemodynamic Instability Increases New Ischemic Brain Lesions on Diffusion-Weighted Imaging After Carotid Artery Stenting

Hemodynamic instability (HI) may impair the washout of debris during distal intracranial circulation and increase the risk of clinically evident cerebral ischemia. However, the interaction between HI and new ischemic brain lesions detected on diffusion-weighted imaging (DWI) has not been examined. This study evaluated whether HI was significantly associated with the incidence of new ischemic brain lesions on DWI. Data on 128 patients who underwent carotid artery stenting (CAS) with the same devices and procedures between January 2005 and May 2010 were retrospectively analyzed. HI was noted in 31 (24.2%) patients. New ischemic brain lesions were detected on DWI in 25 (19.5%) patients. Ten of 31 (32.2%) patients with HI showed new ischemic brain lesions on DWI. Fifteen of 97 (15.5%) patients without HI showed new lesions. Univariate analysis showed that patients with HI had a significantly higher incidence of new ischemic brain lesions than patients without HI (p = 0.04). A multivariable model showed that age and HI were significantly associated with the incidence of new ischemic brain lesions. In patients with carotid artery stenosis, decreased blood pressure produced no active vascular response, but reduced the cerebral blood volume and velocity due to impaired dynamic cerebral autoregulation. The results of this study suggest that HI with CAS induces impaired clearance of microembolisms and causes an increased number of new ischemic brain lesions detected on DWI.

Ulnar Tunnel Syndrome Due to Ulnar Artery Aneurysm: A Case Report

Aims: To report of a case with non-traumatic distal ulnar artery aneurism leading to ulnar nerve neuropathy at level of wrist in the ulnar tunnel. Ulnar nerve impingement has been mostly reported to be a result of posttraumatic false aneurysms, thrombosis, or anomalies distal ulnar artery in ulnar tunnel (Guyon’s canal). Methods: A 33 year-old woman with sever continuous pain which was gradual in onset over the last 9 months associated with intermittent burning sensation and continuous numbness on the ulnar side of her left hand was presented to causality unit. EMG examination showed an ulnar neuropathy in the ulnar tunnel and an ipsilateral carpal tunnel syndrome. Results: An operation was performed and exploration of the right ulnar nerve in the ulnar tunnel at the wrist showed that an ulnar artery aneurysm had pulsatile pressure like effect on the ulnar nerve. Ulnar nerve decompression by ulnar artery ligation was performed after ensuring of distal circulation, the carpal ligament was excised at the same session. After the operation, pain was improved completely in the first day postoperatively but numbness lasted for about 6 months post operatively. Conclusion: Peripheral nerve neuropathies are results of a variety of causes most of which are post traumatic, non-traumatic peripheral artery aneurism are very unlikely seen to be a leading cause to the neuropathy. Although the exact etiology is unknown but mostly it might be the pulsatile pressure like affect that predispose to the upcoming neuropathy which explains the disappearance of the pain first day postoperatively after the ligation of the aneurysm was performed.

Differential diagnosis of multiple sclerosis, is Moyamoya in?

Background and purposeThe pleomorphic presentation of multiple sclerosis underscores the importance of the differential diagnosis with several other pathologies, namely cerebral vascular disease. Summary of caseA 37-year-old woman without any previous relevant pathology presented 3 years ago with two episodes of motor deficit. The first on the right upper extremity with improvement following rehabilitation and a second with left hemiparesis also with improvement in less than a week. After routine etiological investigation and with a brain MRI suggestive of multiple sclerosis the patient initiated β-interferon remaining symptom free.Present day examination revealed bilateral loss of hand dexterity, decreased paleasthesia on the inferior limbs and hyperactive reflexes on the left with a left Babinski response.MRI of the brain showed multiple bilateral T2 lesions in the periventricular white matter. Significantly, there was no infra-tentorial or corpus callosum involvement. There was also no associated restricted diffusion. CSF analysis was normal.Based on this findings and with positive familiar history for Moyamoya the patient underwent a four-vessel angiogram that demonstrated bilateral ICA occlusion with formation of distal collateral circulation through extra-cranial and posterior circulation, consistent with Moyamoya disease. ConclusionMoyamoya disease should be considered in multiple sclerosis differential especially with atypical imaging findings on MRI. Also, the improvement experienced with imunomodulatory treatment highlights the need to better understand the pathophysiology of Moyamoya disease.

Traumatic Pseudoaneurysm of the Posterior Tibial Artery Treated by Endovascular Coil Embolization

Pseudoaneurysms of the posterior tibial artery are rare, but a high index of suspicion should be maintained in evaluating patients who present with a painful swelling after arterial trauma. We report a case of a posterior tibial artery pseudoaneurysm in a young patient sustained from a laceration and associated profuse arterial bleeding. Because of the risk of rupture and the presence of an infection and high venous flow, an embolization of the aneurysm proximally and distally was carried out after verifying that distal collateral circulation ensured foot vascularization. Endovascular treatment of a pseudoaneurysm seems to be a safe therapeutic and noninvasive choice, particularly in young patients in whom the presence of collaterals guarantees distal vascularization and in whom the procedure can be safely performed in the presence of a superficial wound infection.

A Systematic Review of the Outcomes of Distal Upper Extremity Bypass Surgery With Arterial and Venous Conduits

To conduct a systematic review of literature evaluating efficacy of venous and arterial grafts for distal upper extremity bypass surgery. A PubMed search using MeSH terms "veins/surgery" OR "arteries/surgery" AND "radial artery/surgery" OR "ulnar artery/surgery" yielded 794 studies. Manual review produced 42 studies based on inclusion criteria of reported distal upper extremity bypass surgery, complete information on graft type used, examined patency of reconstruction, and described method for determining patency. Studies meeting inclusion criteria underwent data extraction focusing on demographics, revascularization site, conduit type, microsurgical technique, subjective/objective outcomes, and postoperative anticoagulation regimens. Sixteen studies met the inclusion criteria. In 145 patients, 152 grafts were performed for upper extremity revascularization, including 120 grafts for revascularization of distal ulnar artery circulation, 31 for distal radial artery circulation, and 1 for both distal ulnar and radial artery occlusions. Overall patency rate was 87% at an average follow-up of 34 months. Of 152 bypass grafts, 19 were arterial conduits. Donor sites included the deep inferior epigastric artery, subscapular artery, thoracodorsal artery, and descending branch of the lateral femoral circumflex artery. At a mean follow-up of 18 months, arterial conduit patency was 100%. The remaining 133 bypass procedures used vein grafts from various donor sites, including the saphenous, cephalic, and basilic veins. At an average follow-up of 37 months, overall vein graft patency rate was 85%. There was a statistically significant difference between patency rates of arterial conduits compared with venous conduits. All studies reported improved ischemic symptoms including reduction of cold sensitivity, pain, and digital ulceration. This review showed a high patency rate and clinical efficacy of distal upper extremity bypass surgery with a mean follow-up of almost 3 years. There may be a benefit of using arterial versus venous conduits, although further examination is needed given the small number of arterial reconstructions reported.

Multi-scale computational model of three-dimensional hemodynamics within a deformable full-body arterial network

In this article, we present a computational multi-scale model of fully three-dimensional and unsteady hemodynamics within the primary large arteries in the human. Computed tomography image data from two different patients were used to reconstruct a nearly complete network of the major arteries from head to foot. A linearized coupled-momentum method for fluid–structure-interaction was used to describe vessel wall deformability and a multi-domain method for outflow boundary condition specification was used to account for the distal circulation. We demonstrated that physiologically realistic results can be obtained from the model by comparing simulated quantities such as regional blood flow, pressure and flow waveforms, and pulse wave velocities to known values in the literature. We also simulated the impact of age-related arterial stiffening on wave propagation phenomena by progressively increasing the stiffness of the central arteries and found that the predicted effects on pressure amplification and pulse wave velocity are in agreement with findings in the clinical literature. This work demonstrates the feasibility of three-dimensional techniques for simulating hemodynamics in a full-body compliant arterial network.

Arterial injuries at the elbow carry a high risk of muscle necrosis and warrant urgent revascularisation

Revascularisation following axial arterial system injury is effective in upper limb salvage but necrosis of muscle, the tissue most sensitive to ischaemia, may still occur. We examined the frequency of necrosis, its related factors and its functional significance. The clinical findings and operative management of 13 patients with injuries at the elbow referred to 2 plastic surgical hand surgery units over a 30-month period were reviewed. Good outcome was defined as minimal impairment with return to previous occupation, intermediate outcome as moderate impairment with change in occupation and poor outcome as major functional loss preventing work. Seven patients injured the brachial and six injured both the radial and ulnar arteries. Concomitant injuries were severe with nerve injuries in 11 and muscle damage in 12 patients. Functional outcome was good in four cases, intermediate in four and poor in five. Muscle necrosis developed in four brachial artery injuries. In all four cases, initial successful revascularisation failed post-operatively. Case review revealed delayed recognition in three cases where pain heralded ischaemia but distal skin circulation and pulses were adequate. Of patients with necrosis, three had a poor outcome and one had an intermediate outcome. The risk of muscle necrosis must be considered when managing these injuries, particularly if initial revascularisation is unsuccessful. Every effort should be made to optimise repair technique and post-operative monitoring. Limb salvage is no longer enough. Fully viable muscle is necessary to restore function and livelihoods.

The Suitability of End-to-Side Microvascular Anastomosis in Free Flap Transfer for Limb Reconstruction

End-to-end (ETE) microvascular anastomosis used in free flap transfer for limb reconstruction often requires the sacrifice of a major artery, which may aggravate distal circulation of the limb. The purpose of this study is to investigate the relationship between the type of microvascular anastomosis and the survival of free flaps, and to highlight the end-to-side (ETS) anastomotic technique when facing vascular anatomic variations. Between 1999 and 2008, a retrospective review was conducted by a single microsurgeon on 203 patients who underwent free flap reconstruction for limb reconstruction. We examined the clinical course of 209 arterial and 308 venous anastomoses. ETS anastomoses were performed for 99 vessels, whereas ETE anastomoses for 418 vessels. The distribution and outcome of ETS and ETE anastomoses were compared. One arterial thrombosis (1.15%, 1/87) was recorded in ETS anastomosis group, whereas none (0%, 0/122) was recorded in ETE anastomosis group (P = 0.419). Four venous thromboses (1.35%, 4/296) were found in ETE group, whereas none was found in ETS group (0%, 0/12). There was no statistically significant difference between the 2 anastomotic techniques. Six cases with double pedicles needed ETS anastomosis for 2 arterial and 2 venous reconstructions. Flap survival rate in ETS arterial group was 98.8%, whereas in ETE arterial group, it was 100%. ETS microvascular anastomosis has an equivalent flap survival rate as compared with ETE microvascular anastomosis. ETS anastomosis should be considered first when facing vessel size discrepancy and for preserving the major arteries of limbs.

Dysplasie fibromusculaire cervicale et intracrânienne

Fibromuscular dysplasia (FMD) is an uncommon, segmental, nonatherosclerotic arterial disease of unknown etiology, involving intermediate-sized arteries in many areas of the body. It affects primarily women. FMD is often asymptomatic and discovered as an incidental finding. It can, however, be associated with ischemic stroke spontaneous dissection, intracranial aneurysm, and hemodynamic compromise of the distal circulation, and therefore can be a cause of cerebral ischemic symptoms or subarachnoid hemorrhage in some patients.