Adequate Collateral Flow Research Articles

Tailoring Management of May-Thurner Syndrome : Case Comparison

Background: May-Thurner syndrome (MTS) is a post-thrombosis syndrome (PTS) of the lower extremity. This disorder results from compression and/or irritation from adjacent crossing the right common iliac artery to the left iliac venous. In this report, we present two management comparisons of patients with left lower DVT with consideration of MTS. Case Illustration: The first patient is a 49-year-old male soldier presented with chronic unilateral left leg edema and a mild clinical presentation for 9 months. Previous Doppler ultrasonography (DUS) revealed a thrombus in the left venous femoralis. Anticoagulant was given for six months. DUS and CT venography following anticoagulant treatment revealed a thrombus in the left venous femoralis. Venography revealed entire blockage of the left common femoral and left iliac veins, with adequate collateral flow. PTV was attempted twice and failed both times. The patient was following a conservative therapy (walking exercise and stocking compression) that yielded positive outcomes. The second patient is a 53-year-old male soldier has had unilateral left leg edema for three years, which has increased during the previous three months with ulceration and active bleeding. Previous Doppler ultrasonography revealed a thrombus in the left iliac externa. Anticoagulants and compression stockings were given for eight months, but the symptoms persisted. CT and venography revealed a complete blockage from the left popliteal vein to the iliac vein. Femoral crossover bypass surgery yielded favorable results. Conclusion: Clinically moderate MTS demonstrated fair results with conservative treatment, whereas clinically severe MTS showed superior results with bypass surgery. Keyword: Anticoagulant, May-Thurner Syndrome, Palma Procedure.

Large-Vessel Occlusion Stroke: Effect of Recanalization on Outcome Depends on the National Institutes of Health Stroke Scale Score

Arterial recanalization is currently considered the main standard of successful early management of acute ischemic stroke. Intravenous (IV) thrombolysis with tissue plasminogen activator (tPa) is the only Food and Drug Administration-approved medical treatment. Large-vessel occlusion, estimated to account for up to 40% of all acute ischemic strokes, is often refractory to IV thrombolysis and is associated with a poor patient outcome. Mechanical recanalization procedures are therefore increasingly used in the treatment of large-vessel occlusion refractory to, or presenting outside the accepted time window for, IV thrombolysis. The aim of this study was to investigate the effect of early vessel recanalization on clinical outcome in patients with large-vessel occlusion stroke. This is a single-center cohort study, analyzing prospectively collected data on 152 patients with large-vessel occlusion and acute ischemic stroke. Seventy-one patients received endovascular treatment (of whom 57.7% also received IV tPA), and 81 (55.6% of whom also received IV tPa) were not treated with endovascular therapy. Clinical outcome was compared for 2 cohorts: patients who recanalized (n = 46) and patients with persisting large-vessel occlusion (n = 106). Early recanalization was an independent predictor of a good clinical outcome in only those patients who presented with a severe ischemic stroke (National Institutes of Health Stroke Scale [NIHSS] score >15; P = .017). This was not the case for less severe strokes (NIHSS score ≤ 15) where recanalization did not lead to more patients with functional independence at 90-day follow-up (P = .21). In this study of acute large-vessel occlusion stroke, we found that clinical outcome following early recanalization was dependent on the patient's pretreatment NIHSS score. A non-negligible proportion of patients with milder strokes did well despite persistent large-vessel occlusion. These results may suggest that in patients who are able to maintain adequate collateral flow despite proximal arterial occlusion, effective adaptive mechanisms are present, which for some patients are long-lasting. This may influence the process of appropriate patient selection for endovascular therapy.

Collaterals in endovascular therapy for stroke.

Endovascular therapy is a promising aspect of acute ischemic stroke treatment. The ideal population of patients who benefit from treatment remains undefined, and the status of collateral circulation at presentation may be a key feature in their identification. Adequate collateral flow has been recently demonstrated to be associated with improved clinical status on presentation, increased likelihood of recanalization with endovascular therapy, and better functional outcome at 3 months. In this review, we define the collateral circulation, review methods of its measurement, and present recent clinical data on its impact in endovascular therapy for acute ischemic stroke. We outline our current understandings and discuss their relevance in future directions with clinical stroke management.

Balloon Test Occlusion of the Internal Carotid Artery with Stump Pressure Ratio and Venous Phase Delay Technique

Balloon test occlusion (BTO) is crucial before sacrificing parent arteries. We proposed a simple paradigm combining clinical tolerance with venous phase technique and stump pressure ratio as a criterion for sufficient collateral flow. Internal carotid artery (ICA) occlusion was considered safe for asymptomatic patients who exhibited less than 2seconds of venous phase delay or had a stump pressure ratio greater than 60%. A total of 37 BTO procedures were performed on 31 patients. Twenty-three patients were monitored clinically and 3 were symptomatic. Venous phase comparison was performed on 27 patients, and 5 failed the test. The stump pressure was measured in all patients, and 7 patients failed the test. In summary, 7 patients failed the BTO, of which 6 received high-flow bypass and 1 of these 6 were symptomatic and exhibited stump pressure ratios less than 60% in the second BTO procedure. Occlusion of the ICA was performed on 29 patients. Only 1 patient developed delayed vasospasm and brain infarction. Adequate collateral flow may be indicated by a stump ratio of 60% or greater with or without a high-flow bypass. Combined with clinical assessment and venous phase technique, ICA occlusion may be a safe option that does not result in delayed ischemic complications.

Radial Artery Cannulation: A Comprehensive Review of Recent Anatomic and Physiologic Investigations

Consistent anatomic accessibility, ease of cannulation, and a low rate of complications have made the radial artery the preferred site for arterial cannulation. Radial artery catheterization is a relatively safe procedure with an incidence of permanent ischemic complications of 0.09%. Although its anatomy in the forearm and the hand is variable, adequate collateral flow in the event of radial artery thrombosis is present in most patients. Harvesting of the radial artery as a conduit for coronary artery bypass grafting, advances in plastic and reconstructive surgery of the hand, and its use as an entry site for cardiac catheterization has provided new insight into the collateral blood flow to the hand and the impact of radial arterial instrumentation. The Modified Allen's Test has been the most frequently used method to clinically assess adequacy of ulnar artery collateral flow despite the lack of evidence that it can predict ischemic complications in the setting of radial artery occlusion. Doppler ultrasound can be used to evaluate collateral hand perfusion in an effort to stratify risk of potential ischemic injury from cannulation. Limited research has demonstrated a beneficial effect of heparinized flush solutions on arterial catheter patency but only in patients with prolonged monitoring (>24 h). Conservative management may be equally as effective as surgical intervention in treating ischemic complications resulting from radial artery cannulation. Limited clinical experience with the ultrasound-guided arterial cannulation method suggests that this technique is associated with increased success of cannulation with fewer attempts. Whether use of the latter technique is associated with a decrease in complications has not yet been verified in prospective studies. Research is needed to assess the safety of using the ulnar artery as an alternative to radial artery cannulation because the proximity and attachments of the ulnar artery to the ulnar nerve may potentially expose it to a higher risk of injury.

Bailout Percutaneous External Shunt to Restore Carotid Flow in a Patient With Acute Type A Aortic Dissection and Carotid Occlusion

To report the use of an external common femoral to carotid artery shunt in the setting of acute type A aortic dissection associated with carotid occlusion and stroke. The procedure is illustrated in a 52-year-old man who presented with a type A dissection extending into the innominate trunk, with associated occlusion of the right common carotid artery (CCA). Angiography showed no collateral circulation to the right cerebral hemisphere. To re-establish brain perfusion in this setting, a percutaneous external shunt was installed from the common femoral artery to the right CCA. The 5-F femoral sheath used during diagnostic angiography was replaced by an 8-F femoral introducer securely fixed to the skin with silk sutures. Ultrasound-guided percutaneous CCA access was obtained using an 18-G needle and a 6-F introducer, also sutured to the skin. The ICA and intracranial branches showed no evidence of thrombosis at this level. A plastic tube was used to connect the femoral and carotid sheath side arms to restore ICA flow. Transcranial Doppler showed normal flow at the right middle cerebral artery after shunt placement. The patient was immediately transferred to the operating room for aortic surgery, during which an intrapericardially ruptured aorta was found. The ascending aorta and proximal arch were replaced under cardiopulmonary bypass and circulatory arrest, but the patient died during the procedure due to uncontrolled bleeding. A temporary percutaneous external femoral-carotid shunt can restore blood flow to the brain whenever the carotid artery is occluded by the dissection flap and adequate collateral flow is absent.

One Patent Intracranial Collateral Predicts Tolerance of Flow Reversal during Carotid Angioplasty and Stenting

Internal carotid artery (ICA) flow reversal is an effective means of cerebral protection during carotid stenting. Its main limitation is that in the absence of adequate collateral flow it may not be tolerated by the patient. The purpose of this study was to determine if preoperative identification of intracranial collaterals with computerized tomographic (CTA) or magnetic resonance (MRA) angiography can predict adequate collateral flow and neurological tolerance of ICA flow reversal for embolic protection. This was a study of patients undergoing transcervical carotid angioplasty and stenting. Neuroprotection was established by ICA flow reversal. All patients underwent preoperative cervical and cerebral noninvasive angiography with CTA or MRA and had at least one patent intracranial collateral. Mean carotid artery back pressure was measured. Neurological changes during carotid clamping and flow reversal were continuously monitored with electroencephalography (EEG). Thirty-seven patients with at least one patent intracranial collateral on brain imaging with CTA or MRA were included. Mean carotid artery back pressure was 58 mm Hg. All procedures were technically successful. No EEG changes were present with common carotid artery occlusion and ICA flow reversal. One patent intracranial collateral provides sufficient cerebral perfusion to perform carotid occlusion and flow reversal with absence of EEG changes. Continued progress in noninvasive imaging modalities is becoming increasingly helpful in our understanding of cerebral physiology and selection of patients for invasive carotid procedures.

Use of radial artery grafts in extracranial–intracranial revascularization procedures

Cerebral revascularization procedures have been used in the clinical management of actual or threatened cerebral ischemic states and unclippable cerebral aneurysms. An alternative to a low-flow bypass graft (for example, with the superficial temporal artery) is the use of high-flow grafts created using the saphenous vein (SV) or radial artery (RA). These high-flow grafts are particularly useful when otherwise adequate collateral flow is insufficient to enable sacrifice of the parent vessel without the risk of cerebral ischemia. In their clinical series of 13 patients who underwent high-flow bypass with an RA graft, the authors describe 8 women and 5 men whose ages ranged from 44 to 69 years (mean 57.84 +/- 9.05 years). Indications for RA graft bypass were unclippable aneurysms in 10 patients and occlusive cerebrovascular disease in 3 patients. The authors review the properties of the 2 most common conduits, the SV and RA grafts. They present the technique of high-flow extracranial-intracranial bypass produced using RA grafts in the management of occlusive atherosclerotic disease and complex intracranial aneurysms that are not otherwise amenable to either clip ligation or coil occlusion.

Brachial Artery Thrombosis in Infants: An Algorithm for Limb Salvage

Arterial occlusion in infants, although uncommon, is usually an iatrogenic event associated with arterial vascular access. Most common in the upper limb, the consequences of iatrogenic arterial occlusion may be gangrene and limb loss. Even if there is adequate collateral flow and limb loss is avoided, long-term growth disturbances may be seen. There are few published data to guide the management of arterial occlusion in premature or sick infants. In general, there is agreement regarding the importance of early diagnosis and the reestablishment of limb perfusion with the fewest risks, but the optimal choice and timing of treatment modalities remain unknown. This article examines the authors' experiences at the Royal Children's Hospital, Melbourne, and provides their algorithm for the management of this complex iatrogenic disease. The management algorithm has successfully treated 11 limbs in 11 patients with arterial vascular access-associated thrombosis over the period 1995 to 2003, with no instances of limb loss. Five of these patients required surgical intervention. The authors recommend a multidisciplinary approach involving plastic surgeons and hematologists for all cases of suspected or confirmed arterial thrombosis. A consensus algorithm that determines the role of heparin, thrombolysis, and acute surgical interventions, and the sequence of such interventions, is useful in providing the framework of therapy. The early recognition of the limb at risk is a key factor in obtaining a successful outcome.

Endovaskulärer Verschluss der A. basilaris zur Behandlung dissektionsbedingter und dysplastischer fusiformer Aneurysmen

Dissecting aneurysms of the basilar artery trunk frequently affect young adults. Fusiform shape and narrowing of the proximal parent artery are typical features. Changes in aneurysm size and geometry may be observed more rapidly than in atherosclerotic or dysplastic aneurysms. Dissecting aneurysms carry a significant risk of rupture. Thrombotic or embolic occlusion of small pontine branches may cause ischemic symptoms. Sufficiently large aneurysms compress the adjacent brainstem. The operative treatment of these aneurysms is associated with unacceptable risks. At least one posterior communicating artery with normal calibre together with the ipsilateral P1 segment needs to provide adequate collateral flow to the upper basilar artery to allow endovascular coil occlusion of the segment that is affected by the dissection and/or fusiform aneurysmal dilatation. Four illustrative cases of endovascular coil occlusion of the basilar artery for the treatment of fusiform aneurysms are presented and discussed.

Ruptured Popliteal Artery Aneurysm

A high index of suspicion for popliteal aneurysms must be present when evaluating a popliteal mass. Though typically pulsatile, in the presence of chronic thrombosis, the absence of a pulse may make the diagnosis even more difficult. A case is presented that illustrates this point, where an 83-year-old man presents following the biopsy of what turned out to be a very large popliteal aneurysm. In the presence of chronic thrombosis and adequate collateral flow, decompression and ligation of any feeding vessels is typically sufficient. These patients must be followed lifelong for the development of other associated aneurysms.

Initial experience with an endoscopic radial artery harvesting technique

ObjectiveThe purpose of the study was to investigate the feasibility of an endoscopic radial artery harvesting technique to improve esthetic results and possibly reduce the incidence of neurologic complications observed with the open method. MethodsBetween July 1, 2002, and October 1, 2003, a total of 54 patients underwent endoscopic radial artery harvesting at our institution. Standard endoscopic equipment and a Harmonic Scalpel (Ethicon Endo-Surgery, Inc, Cincinnati, Ohio) were used. Mean age of the patients was 63 ± 8.1 years, and 16% were female. All patients underwent a preoperative Allen test and duplex ultrasonography to demonstrate adequate ulnar collateral flow. The nondominant arm was used for radial artery harvesting. Mean clinical follow-up was 13 ± 4.6 months. ResultsThe artery was harvested through a 3-cm incision at the wrist and was divided at the elbow either through a small counterincision (n = 16) or endoscopically with the use of clips, Endoloop, and endoscopic scissors (n = 38). Mean harvest time was 42.2 ± 16.9 minutes but decreased from 85 minutes for the first cases to 25 minutes for the last 5 cases. Mean harvested length was 19.6 ± 1.7 cm. Harvesting complications included 1 conversion, 2 postoperative hematomas, 1 injury, 8 endoscopically controlled bleedings, and 15 cases of at least some superficial radial nerve paresthesia at 6 weeks (clinically relevant in 4 cases). Selective postoperative angiography revealed 1 occluded graft and 1 stenotic graft requiring percutaneous transluminal coronary angioplasty of the native vessel. Eighty-seven percent of the patients were enthusiastic about this new procedure. ConclusionsEndoscopic radial artery harvesting is a feasible procedure that requires a definite learning curve. Although nerve paresthesias were not completely eliminated in our experience, the technique provided ample patient satisfaction. Further clinical follow-up is required to determine long-term patency rates.

Complete vasomotor collapse: an unusual manifestation of the carotid sinus reflex.

Complete vasomotor collapse: an unusual manifestation of the carotid sinus reflex.

Gadolinium-enhanced elliptically reordered three-dimensional MR angiography in the assessment of hand vascularization before radial artery harvest for coronary artery bypass grafting: first experience.

To assess the suitability of contrast-enhanced magnetic resonance angiography (MRA) in the preoperative evaluation of hand vasculature in potential candidates for radial artery bypass grafting. In 21 patients, gadobenate dimeglumine-enhanced, three-dimensional gradient-echo sequences of both hands were performed, as well as a Doppler ultrasound study with radial artery compression. Doppler findings were correlated with MRA, focusing on the assessment of anastomoses between the vascular bed of the ulnar and radial arteries. One individual had to be excluded because of accidentally disclosed metal foreign bodies. Sufficient depiction of the hand vasculature was achieved in the remainder. Seventeen patients had evidence of adequate collateral flow between the ulnar and radial artery supply on Doppler ultrasound. Three patients exhibited inadequate collateral flow, with angiographic signs of vessel occlusion or missing collaterals between the palmar arches. Two patients presented with stenosis or occlusion of the radial artery. Magnetic resonance angiograms displayed great variations in hand vasculature and collateral formation, with no mismatch compared with Doppler ultrasound results. Contrast-enhanced MRA displays vascularization of the hand in detail and supplies ultrasound flow measurements for radial artery harvest, with high-resolution angiographic data about possible vessel variations and the presence of anastomoses between the radial or ulnar artery supply.

The Use of Preoperative Transcranial Doppler Variables to Predict Which Patients do Not Need a Shunt During Carotid Endarterectomy

Objectives: to analyse whether preoperative transcranial Doppler (TCD) variables can predict intraoperative shunt requirement. Design and methods: the blood-flow velocity (BFV) in the major basal cerebral arteries was measured preoperatively with TCD, in 178 patients scheduled for CEA. Carotid artery compression and CO2 reactivity tests were also performed. Intraoperative electroencephalography was used to decide whether a shunt was needed. Differences in the probability of shunt requirement between the categories of variables were assessed with crosstabs statistics. Results: preoperative TCD criteria clearly identified a subgroup of 59 patients (33%) who did not require a shunt. In general, these patients appeared to have adequate collateral flow through the anterior communicating artery. In contrast, prediction of the need for a shunt was less reliable. TCD variables could predict the need for a shunt with a probability of only 60%.Conclusions: preoperative TCD can be used to identify patients who do not require a shunt during carotid endarterectomy.

Pseudoaneurysm after penetrating trauma in children and adolescents

Background: Although skin lacerations are common in children and adolescents, the complication of pseudoaneurysm (PA) has rarely been reported. Methods: The author reports a series of four cases of patients in whom PA developed after lacerations. The diagnosis was made on the basis of the history and clinical findings in all cases. Doppler ultrasound confirmed the diagnosis in two cases. Resection of the aneurysm was the treatment in each. Results: Each of the patients had successful removal of his lesion. One patient with a radial artery PA underwent resection without reconstruction; he remains free of claudication and has symmetrical upper extremities. Conclusions: Pseudoaneurysms are uncommon sequella of lacerations. In children, resection is satisfactory treatment when adequate collateral flow can be demonstrated.

Transcranial Doppler correlation with angiography in detection of intracranial stenosis.

The purpose of this study was to evaluate the use of velocity criteria applied to transcranial Doppler (TCD) signals in the detection of stenosis of the middle cerebral (MCA), distal vertebral, and basilar arteries. Sixty-five patients who underwent both cerebral angiography and transcranial Doppler examinations in the workup of acute cerebral ischemia were reviewed. Angiography was performed a mean of 7 +/- 5 days (range, 1 to 28 days) after TCD. Interpretation of the angiogram was performed without input regarding the TCD findings. TCD interpretation was performed according to standard criteria. When we used a mean velocity (MV) cutoff of > or = 80 cm/s in the MCA as the criterion for stenosis, 10 of 12 stenoses of any degree were detected by TCD, with 11 of 87 false-positives. Nine of 12 MCA stem (M1) stenoses were detected when a cutoff of > or = 90 cm/s was used, with 7 of 87 false-positives. When we used an MV cutoff of > or = 70 cm/s as the criterion for > or = 50% stenosis of the vertebrobasilar system, 5 of 6 stenoses were detected, with 15 of 85 false-positives. The most important confounding factor was the presence of > or = 75% stenosis of the extracranial internal carotid artery, resulting in both false-positive (from collateral flow) and false-negative (decreased volume flow from the proximal stenosis without adequate collateral flow) errors in TCD interpretation. When patients with > or = 75% stenosis of the cervical internal carotid artery were excluded from analysis, a TCD MV cutoff of > or = 80 cm/s identified 9 of 10 M1 lesions with 7 of 61 false-positives, and an MV of > or = 70 cm/s identified 3 of 4 vertebrobasilar lesions causing > or = 50% stenosis with 7 of 56 false-positives. TCD may be an effective screening test for M1 stenosis when velocity criteria alone are used. TCD may less reliably detect intracranial vertebral and basilar artery stenosis.

Complete occlusion of the left main coronary artery: clinical and angiographic observations in five cases.

Involvement of the left main coronary artery is observed in approximately 5 to 8% of patients with coronary artery lesions detected by coronary angiography, but occlusion of the left main artery is a very infrequent finding. Out of approximately 4000 patients undergoing coronary angiography, four men and one woman, 37 to 60 years old, showed total occlusion of this vessel. Four of them had angina pectoris and three had had a myocardial infarction. All five showed deep ST depression in V 2(or 3)-6 during bicycle exercise testing. Apart from the left main artery occlusion, all had significant obstructive lesions in other coronary vessels, including the right coronary artery or its major branches. There was collateral circulation from the right coronary artery in all patients. Left ventricular function was well preserved in three patients and markedly impaired in two. Four patients underwent bypass surgery and they have been followed for 10 to 28 months. Three are free of angina and one has only minimal angina. One patient refused surgery and he continued to have severe angina despite intense medical treatment. He died suddenly after 30 months follow-up. In patients with complete occlusion of the left main coronary artery, development of adequate collateral flow seems important in preserving left ventricular function, but collaterals are usually insufficient to prevent angina. Moreover, associated obstructive lesions in other coronary arteries constitute a potential threat to the collateral circulation. Effective symptomatic relief is obtained by coronary bypass grafting, and revascularization may also improve prognosis in this subset of patients with coronary heart disease.

Cerebral blood flow measured by xenon-enhanced computed tomography as a guide to management of patients with cerebrovascular disease

CT scanning performed before and sequentially during the inhalation of stable xenon (32%), coupled with end-tidal xenon measurements, has made possible the routine construction of regional cerebral blood flow (rCBF) maps with resolution that approximates that of the CT scanner. The capability of obtaining quantitative flow maps with direct anatomic correlation is now available with a commercial package of hardware and software adapted to the General Electric 9800 scanner. The ability to distinguish between normal and reduced rCBF in specific vascular territories has proved useful in the management of cerebrovascular disease. Specific clinical dilemmas that have been addressed with rCBF information from xenon-enhanced CT scanning include the following: (1) In the patient with asymptomatic occlusive disease, is normal rCBF preserved? Is there adequate collateral flow? (2) Are cerebrovascular symptoms a result of emboli or chronic regional low flow? (3) In the patient with complex multivessel occlusive disease, which revascularization procedure is indicated first? Did operation improve rCBF? Should a further procedure be added? (4) May a diffusely diseased but patent artery, which is the source of emboli, be sacrificed safely without compromising rCBF? On the basis of experience with 155 patients, the management and understanding of cerebrovascular disease has been aided substantially by the incorporation of rCBF mapping by xenon-enhanced CT scan in the evaluation of these patients.

Carotid Artery Thrombosis after Elective Mandibular and Maxillary Osteotomies

This is believed to be the first reported case of carotid artery thrombosis after elective maxillary or mandibular osteotomy. The most likely cause was a sudden, sharp blow to the right carotid artery region either when the mandibular split was completed or when the maxillary tuberosity was separated. The blow was associated with neck hyperextension and some lateral flexion. In a patient with tight, underdeveloped soft tissue, the resultant intimal tear caused thrombosis of the artery. Although this event is associated with a 40% mortality and further 52% serious morbidity our patient has regained nearly full neurological function—probably thanks to a competent circle of Willis that allowed adequate collateral flow to the brain.