Biomedical subjects

Rajeev Dayal

Publications and source records attributed to Rajeev Dayal.

At least 19 recordsLinked to original sources

PubMed2006

The development of endotension is associated with increased transmission of pressure and serous components in porous expanded polytetrafluoroethylene stent-grafts: characterization using a canine model.

OBJECTIVE: This study used a canine model of abdominal aortic aneurysms (AAAs) to compare intra-aneurysmal pressure and thrombus formation after exclusion with Dacron and expanded polytetrafluoroethylene (ePTFE) stent-grafts. METHODS: Prosthetic AAAs with implanted strain-gauge pressure transducers were treated by stent-graft exclusion using Food and Drug Administration-approved devices in 10 mongrel dogs: five Dacron (AneuRx) and five ePTFE (original Excluder). Intra-aneurysmal pressure was measured over 4 weeks after AAA exclusion and indexed to the systemic pressure, represented as a percentage of a simultaneously obtained systemic pressure (value = 1.0). Magnetic resonance imaging (MRI) of the intra-aneurysmal thrombus was performed at 1, 2, and 4 weeks after exclusion and expressed as a signal-to-noise ratio (S:N) to control for background signal intensity. Comparisons of pressures and S:N between the two stent-grafts was analyzed with the Student's t test. Intra-aneurysmal thrombus was characterized histologically. RESULTS: In animals excluded with both Dacron and ePTFE stent-grafts, the intra-aneurysmal pressure was nonpulsatile and reduced to <30% of systemic pressure. Significantly greater pressure transmission was observed after AAA exclusion using ePTFE compared with Dacron stent grafts (systolic pressure: ePTFE, 0.28 +/- 0.12 vs Dacron, 0.11 +/- 0.02, P < .001; mean pressure: ePTFE, 0.16 +/- 0.08 vs Dacron, 0.06 +/- 0.02, P < .001). MRI confirmed the absence of perfusion in all aneurysms. The T1-weighted signal intensity remained persistently elevated (S:N at 1 week, 2.7 +/- 0.4 vs 2 weeks, 4.0 +/- 0.2 vs 4 weeks, 5.4 +/- 1.3) in ePTFE-treated intra-aneurysmal thrombus, suggesting an absence of thrombus organization. In contrast, progressive evolution of T1 signal intensity in aneurysms excluded by Dacron stent-grafts was consistent with maturation from intact red blood cells (S:N at 1 week, 3.3 +/- 0.4) to methemoglobin (S:N at 2 weeks, 6.1 +/- 0.8), and then hemosiderin and ferritin (S:N at 4 weeks, 2.4 +/- 0.5). Histologically, ePTFE-excluded aneurysms contained poorly organized thrombus with red blood cell fragments and haphazardly arranged fibrin deposition indicative of active remodeling and continued influx of transudated serum. In aneurysms excluded by Dacron stent-grafts, dense, mature collagenous connective tissue and organized fibrin were present, indicative of greater thrombus organization. CONCLUSIONS: Stent-graft treatment reduces intra-aneurysmal pressure to <30% of systemic pressure when no endoleak is present; however, significantly greater pressure is present in aneurysms treated with porous ePTFE stent-grafts than Dacron grafts. Histologic and MRI imaging analysis suggest that active transudation of serous blood components may be contributing to this increased intra-aneurysmal pressure.

Animals↗

PubMed2006

Successful percutaneous treatment of gluteal claudication secondary to isolated bilateral hypogastric stenoses.

We report an unusual case of bilateral buttock claudication at ambulation of less than two blocks in a 57-year-old man with normal lower-extremity segmental pressure on noninvasive exercise testing. He was found to have bilateral high-grade internal iliac artery stenoses on arteriography. Both sides were successfully treated in a staged fashion via a contralateral approach with percutaneous transluminal angioplasty and a balloon-expandable stent, with complete symptom resolution. A clinical vascular examination with normal findings of the common iliac, external iliac, and common and superficial femoral arteries eliminates significant vascular obstruction as a cause of claudication. However, internal iliac occlusive disease may be suspected when symptoms are limited to the gluteal musculature and other causes are eliminated. Percutaneous interventions can be of diagnostic and therapeutic value.

Angioplasty, Balloon↗

PubMed2005

Tibial angioplasty as an alternative strategy in patients with limb-threatening ischemia.

The purpose of this study was to assess the technical feasibility and early outcome of tibial angioplasty for a subset of patients with limb-threatening ischemia who were not candidates for bypass grafting. A retrospective analysis was conducted of 19 patients (7 male, 12 female) who underwent crural angioplasty for limb-threatening ischemia using 0.018- or 0.014 inch-based systems. Contraindications to bypass were insufficient conduit in 7 patients and severe comorbid illness in 12. Concurrent treatment of inflow lesions was performed in 12 of 20 limbs via either angioplasty alone (5) or combined with stenting (12). Outcome measures were ankle-brachial indices (ABI), relief of rest pain, and healing or healed wounds. Twenty-three vessels were treated, including 14 tibial occlusions and 9 stenoses. The average length of diseased segment was 11 cm (range, 3-25 cm). Thirteen of 14 occlusions were treated with subintimal recanalization, the remainder with laser recanalization. Technical success was achieved in 22 of 23 treated vessels. Mean preoperative ABI was 0.53 and mean postoperative ABI was 0.85. Palpable pulses were present in 11 of 20 limbs (55%). There was one perioperative mortality (5.2%). Mean follow-up was 3 months. Three failures occurred requiring amputation (15.8%). The remaining 16 patients were improved with healing (8) or healed (4) wounds and relief of rest pain (4). These results indicate that technical success may be achieved with outflow lesion angioplasty in the majority of patients encountered. The durability of this method of therapy is unknown, and our length of follow-up is not sufficient to answer this question. However, an attempt at angioplasty appears justified before primary amputation and before surgical bypass in those patients at high risk for intervention.

Aged↗

PubMed2005

Percutaneous endovascular treatment for chronic limb ischemia.

Percutaneous transluminal methods of revascularization for chronic limb ischemia have traditionally been used as an adjunctive or secondary mode of treatment. This study examines the outcomes of patients treated via endovascular methods as the primary form of treatment. The records of 66 patients (average age, 71.3 years; range, 53 to 92) with chronic limb ischemia treated from November 2000 to January 2002 at a single institution with endovascular methods were retrospectively reviewed. Thirty-one patients had disabling claudication, 15 had rest pain, 17 had minor tissue loss, and 3 had major tissue loss. There were 94 lesions in the 66 limbs: 45 lesions in the superficial femoral artery, 28 lesions in the popliteal artery, and 21 lesions in tibial arteries. Occlusive lesions were treated by subintimal angioplasty. Stenoses were treated by percutaneous transluminal angioplasty (PTA). The median length of the lesions was 12 cm. Forty-six stents were placed in 32 patients; 34 patients did not receive stents. The approach was contralateral in 71% (47/66) and ipsilateral in 29% (19/66) of cases. Patients were followed up with physical exam, anklebrachial index (ABI), and duplex ultrasonography. Post-intervention medical treatment included aspirin and clopidogrel. Long-term patency was correlated with age, comorbidities, risk factors, and the use of stents in addition to angioplasty. Endovascular treatment was technically successful in 65 of 66 patients (98%). Residual stenosis (<30%) was found in three cases, two in patients with PTA alone and one patient with PTA and a stent. Mean length of follow-up was 6.3 months (range, 6 weeks to 15 months). Post-intervention ABI improved from a mean of 0.65 to a mean of 1.01 (p < 30.05). The perioperative complication rate was 9% and included three cases of hematoma and one case each of thrombosis, lymphocele, and rash reaction to medications. Outcome measures included primary patency (89%), assisted primary patency (96%), and limb salvage (97%) at 6 months. Restenosis of >50% occurred in four patients and occlusion occurred in two. At 6 months, patients with one or more stents had a patency rate of 84% (27/32), whereas those without a stent had a patency rate of 94% (32/34) (p = NS). Endovascular treatment is a safe, feasible, and effective method with a high short-term patency rate and may be used as an alternative to bypass for chronic limb ischemia.

Aged↗

PubMed2005

Multimodal percutaneous intervention for critical venous occlusive disease.

Critical deep venous thrombosis and occlusion constitutes a small percentage of patients with venous disease, who exhibit severe symptomatology. This study examined the results of multimodal percutaneous therapy for the treatment of complex critical venous thrombotic and occlusive disease. Twenty-five patients presented with critical venous thromboses or occlusions (11 with debilitating unilateral lower extremity edema causing ambulatory impairment, 2 with debilitating bilateral lower extremity edema, 3 with phlegmasia cerulea dolens, 2 with venous claudication, 2 with superior vena cava (SVS) syndrome with respiratory compromise, 4 with debilitating upper extremity edema, and 1 with renal insufficiency). Therapeutic modalities including thrombolysis, mechanical thrombectomy, percutaneous venoplasty and stent placement, temporary inferior vena cava filtration, and ultrasound guidance were used in all cases in conjunction with long-term systemic anticoagulation. The venous access site was determined by the anatomic location of the lesion and included popliteal, femoral, brachial, and lesser saphenous. Patients were followed with clinical exam and duplex surveillance. Resolution of symptoms was achieved in 18 of 25 patients (72%) and partial resolution occurred in 4 of 25 (16%). Failure of treatment identified as both lack of clinical response and evidence of continued venous thrombosis occurred 3 of 25 patients (12%). Restoration of arterial pulses and limb salvage was achieved in the three patients with phlegmasia cerulea dolens and acute limb-threatening ischemia. Both patients with SVC syndrome experienced resolution of respiratory compromise and facial edema. The mean length of follow-up was 11 +/- 2.7 months. Complications included transfusion requirement (2), hematuria (2), retroperitoneal hematoma (1), and cellulitis (1). Acute critical venous thrombotic and occlusive disease is responsive to multimodal percutaneous treatment. The relief of pain and resolution of acutely life and limb-threatening conditions in this most severely symptomatic subset of patients represents the immediate goal of treatment.

Algorithms↗

PubMed2005

Analysis of anatomic factors and age in patients undergoing carotid angioplasty and stenting.

Recent data suggest that patient age >80 years may be associated with increased risk of periprocedural complications from carotid angioplasty and stenting (CAS). In this study, we analyzed anatomic risk factors in patients undergoing CAS based on age >80 or <80 years. Our hypothesis was that patients >80 would have more challenging anatomy. Between February 2003 and August 2004, 82 patients underwent CAS. Images for 57 lesions were available for review. Eighteen patients were > or =80 years old and 39 were <80. Cerebral protection devices, including EPI Filterwire, Percusurge, Accunet, and Angioguard, were used in all but two cases; and self-expanding stents (Wallstent, NexStent, Acculink, Precise) were placed in all. Arterial anatomic characteristics were assigned a score based on complexity and associated procedural risk. Characteristics evaluated using angiographic images were aortic arch elongation classification, arch calcification, common carotid/innominate stenosis, common carotid tortuosity, internal carotid tortuosity, index lesion length, index lesion calcification, and index lesion stenosis. Statistical analysis was performed using Fisher's exact test. CAS was successfully completed in 98% of cases. The two patients in whom we could not perform CAS were 79 and 83 years old. The anatomic characteristics that were statistically significantly more complex/severe in patients > or =80 were arch calcification (p = 0.045), common carotid/innominate stenosis (p = 0.023), common carotid tortuosity (p = 0.049), and internal carotid tortuosity (p = 0.032). There was no statistically significant difference in arch elongation classification, lesion length, lesion calcification, or stenosis severity (p = nonsignificant). Overall, patients > or =80 years had an increased incidence of complex anatomic risk factors compared to younger patients (p < 0.001). Cerebrovascular accident without residual deficits occurred in two patients; both were >80 years old. Complex arterial anatomy is more often present in patients >80 years and may explain the increased complication rates associated with CAS. Pre- or intraoperative consideration of these characteristics may help provide better risk assessment in candidates for CAS.

Age Factors↗

PubMed2005

A canine model to study the significance and hemodynamics of type II endoleaks.

OBJECTIVE: The clinical significance of Type 2 endoleak after endovascular repair of abdominal aortic aneurysms (AAA) remains incompletely delineated. This study describes the development of a novel canine model that allows for continuous monitoring of intraaneurysmal pressure in the setting of Type 2 endoleak. METHODS: Infrarenal AAA were created in 10 mongrel dogs by implanting a prosthetic aneurysm containing an intraluminal, solid-state, strain gauge pressure transducer which is able to measure pressures in both solid and liquid media. A segment of native aorta with two or more patent side branch vessels was reimplanted into the prosthetic aneurysm using a Carrel patch. Four animals had two lumbar vessels implanted; two had two lumbar vessels and the caudal mesenteric artery implanted, and four control animals had no vessels reimplanted. Retrograde flow in the aneurysmal side branches caused a Type 2 endoleak after the aneurysm was excluded from antegrade flow by deploying a stent graft. Both systemic and intra-sac pressures were measured daily for up to 90 days after endovascular exclusion and indexed to systemic pressure. Endoleak patency and flow were assessed with digital subtraction angiography, duplex ultrasound, and cine-magnetic resonance angiography (MRA). Histological characterization of the intraaneurysmal contents was performed. RESULTS: Before endovascular exclusion, the systolic, mean arterial, and pulse pressure within the aneurysmal sac closely matched that of the systemic circulation (systolic, 0.96 +/- 0.22; mean, 0.94 +/- 0.21; pulse pressure, 0.97 +/- 0.22) (R value, 0.97). Endovascular exclusion in animals with no collateral side branch vessels resulted in no endoleak and significantly reduced intraaneurysmal pressure when compared to systemic pressure, with systolic, mean arterial, and pulse pressure 0.172 +/- 0.05, 0.137 +/- 0.05, and 0.098 +/- 0.02, respectively (P < 0.001). In animals with Type 2 endoleaks, the pressures were lower than systemic pressure, but statistically significant in their difference from the control group. The systolic pressure of those with Type 2 endoleaks was 0.702 +/- 0.048; mean arterial pressure was 0.784 +/- 0.028, and pulse pressure was 0.406 +/- 0.031 when indexed to systemic pressure (P < 0.001). Cine-MRA and Duplex ultrasound documented persistent patency of the Type 2 endoleaks throughout the study period in animals with multiple side branches. CONCLUSION: Intraaneurysmal pressure in the setting of Type 2 endoleaks may be accurately determined using this canine model. Intraaneurysmal pressure is maintained at a significant level in the context of this retrograde collateral perfusion, suggesting that persistent Type 2 endoleaks are of clinical significance. This model may serve to allow further evaluation and characterization of Type 2 endoleaks.

Angiography, Digital Subtraction↗

PubMed2005

Treatment of type II endoleaks with a novel polyurethane thrombogenic foam: induction of endoleak thrombosis and elimination of intra-aneurysmal pressure in the canine model.

OBJECTIVE: The clinical significance and treatment of retrograde collateral arterial perfusion of abdominal aortic aneurysms after endovascular repair (type II endoleak) have not been completely characterized. A canine abdominal aortic aneurysm model of type II endoleak with an implanted pressure transducer was used to evaluate the use of polyurethane foam to induce thrombosis of type II endoleaks. The effect on endoleak patency, intra-aneurysmal pressure, and thrombus histology was studied. METHODS: Prosthetic aneurysms with an intraluminal, solid-state, strain-gauge pressure transducer were created in the infrarenal aorta of 14 mongrel dogs. Aneurysm side-branch vessels were reimplanted into the prosthetic aneurysm of 10 animals by using a Carrel patch. Type II (retrograde) endoleaks were created by excluding the aneurysm from antegrade perfusion with an impermeable stent graft. Thrombosis of the type II endoleak was induced by implantation of polyurethane foam into the prosthetic aneurysm sac of four animals. Six animals with type II endoleaks were not treated. In four control animals, no collateral side branches were reimplanted, and therefore no endoleak was created. Intra-aneurysmal and systemic pressures were measured daily for 60 to 90 days after the implantation of the stent graft. Endoleak patency and flow were assessed during surgery and at the time of death by using angiographic imaging and duplex ultrasonography. Histologic analysis of the intra-aneurysmal thrombus was also performed. RESULTS: Intra-aneurysmal pressure values are indexed to systemic pressure and are represented as a percentage of the simultaneously obtained systemic pressure, which has a value of 1.0. All six animals with untreated type II endoleaks maintained patency of the endoleak and side-branch arteries throughout the study period. Compared with control aneurysms that had no endoleak, animals with patent type II endoleaks exhibited significantly higher intra-aneurysmal pressurization (systolic pressure: patent type II endoleak, 0.702 +/- 0.283; control, 0.172 +/- 0.091; P < .001; mean pressure: endoleak, 0.784 +/- 0.229; control, 0.137 +/- 0.102; P < .001; pulse pressure: endoleak, 0.406 +/- 0.248; control, 0.098 +/- 0.077; P < .001; P < .001 for comparison for all groups by analysis of variance). Treatment of the type II endoleak with polyurethane foam induced thrombosis of the endoleak and feeding side-branch arteries in all four animals with type II endoleaks. This resulted in intra-aneurysmal pressures statistically indistinguishable from the controls (systolic pressure, 0.183 +/- 0.08; mean pressure, 0.142 +/- 0.09; pulse pressure, 0.054 +/- 0.04; not significant). Angiography and histology documented persistent patency up to the time of death (mean, 64 days) for untreated type II endoleaks and confirmed thrombosis of polyurethane foam-treated endoleaks in all cases. CONCLUSIONS: Untreated type II endoleaks were associated with intra-aneurysmal pressures that were 70% to 80% of systemic pressure. Treatment with polyurethane foam resulted in a reduction of intra-aneurysmal pressure to a level that was indistinguishable from control aneurysms that had no endoleak. CLINICAL RELEVANCE: Endovascular repair of abdominal aortic aneurysms is dependent on the successful exclusion of the aneurysm from arterial circulation. Type II endoleaks originate from retrograde flow into the aneurysm sac. This study demonstrates the use of polyurethane foam to induce thrombosis in a canine model of a type II endoleak, thereby reducing intra-aneurysmal pressure to levels similar to levels in animals without endoleaks. This approach may be a strategy for future treatment of type II endoleaks.

Animals↗

PubMed2005

Comparison of results in endovascular interventions for infrainguinal lesions: claudication versus critical limb ischemia.

This study analyzed clinical success, patency, and limb salvage after endovascular repair in patients treated for chronic limb ischemia presenting with claudication versus critical limb ischemia. Between October 2001 and August 2004, 115 patients (mean age 71) underwent endovascular treatment for infrainguinal arterial disease. Techniques included subintimal angioplasty and transluminal angioplasty with or without stents. Lesions were classified according to Transatlantic InterSociety Consensus. Follow-up (mean 11 months) included physical exam, ankle-brachial index, and duplex ultrasound. Patency rates were determined using Kaplan-Meier and compared by log-rank analysis. One hundred ninety-nine lesions were treated in 121 limbs using percutaneous techniques. Comorbidities were similar except higher rates of diabetes mellitus (67% vs 41%, P < 0.001) and chronic renal insufficiency (22% vs 7%, P < 0.05) were found in critical limb ischemia patients. Primary patency for claudicants was 100 per cent, 98 per cent, and 85 per cent at 3, 6, and 12 months and 89 per cent, 80 per cent, and 72 per cent for critical limb ischemia, respectively (P = 0.06). Limb salvage was 91 per cent at 12 months for critical limb ischemia patients. Morbidity was similar between groups, and there was no perioperative mortality. Percutaneous intervention for both claudication and critical limb ischemia provides acceptable 12 month patency with limited morbidity.

Adult↗

PubMed2004

Continuity in the treatment of carotid artery disease: results of a carotid stenting program initiated by vascular surgeons.

The treatment of carotid artery stenosis currently constitutes a major component of vascular surgical practice. Carotid angioplasty and stenting (CAS), however, is mainly performed by nonvascular surgeon interventionalists with cerebral protection devices available only through investigational protocols. This study reports the initial results of a CAS program initiated and performed by vascular surgeons using commercially available cerebral protection devices. Fifty-seven patients were enrolled in the study over a 14-month period. All patients were at high risk for conventional endarterectomy (7 resentosis, 4 irradiation, and 46 medically high-risk ASA III). Mean age was 75.7 years (range, 45-93 years). High-grade stenosis of the carotid artery was present in all cases (mean stenosis, 85%; range, 80-99%). Twenty-four percent of patients were symptomatic. Cerebral protection was performed with an occlusion balloon-wire in 32 cases and with a filter-wire device in 24; no cerebral protection was used in 1 patient with restenosis after endarterectomy. Initially in the study, atropine was administered selectively for the development of bradycardia. Currently atropine is administered routinely prior to the initial balloon angioplasty of the carotid bulb. Clopidogrel (75 mg/day) was administered for 5 days prior to CAS and for 30 days after CAS. All 57 patients underwent successful dilatation of their carotid stenoses without occlusion or dissection. Ten of 32 patients in whom balloon occlusion was used for cerebral protection exhibited transient evidence of cerebral ischemia during protection balloon occlusion. These symptoms resolved completely without permanent neurological deficit in all cases. Development of bradycardia with a heart rate <50 bpm was significantly reduced by routine administration of atropine prior to the initial dilatation within the carotid bulb (p = 0.01). Mean hospital length of stay was 1.33 days (range, 1-5 days). There were two periprocedure myocardial infarctions, two postprocedure transient ischemic attacks, and one reversible ischemic neurologic deficit. There was no 30-day mortality. There have been no instances of hemodynamically significant restenosis during a mean follow-up period of 5.4 months. From these results we have concluded that CAS can be performed effectively and safely using commercially available cerebral protection devices. A program initiated and performed exclusively by vascular surgeons is effective and should be the standard model used in the endovascular treatment of carotid artery stenosis.

Aged↗

PubMed2004

Characterization of retrograde collateral (type II) endoleak using a new canine model.

OBJECTIVE: The clinical significance of retrograde collateral arterial perfusion of abdominal aortic aneurysms after endovascular repair (type II endoleak) has not been completely characterized. In this study a canine model was used to analyze intra-aneurysmal pressure, thrombus histologic characteristics, endoleak patency, and radiographic appearance of type II endoleaks originating from single and multiple aneurysm side branches. METHODS: Prosthetic aneurysms with an intraluminal solid-state strain-gauge pressure transducer were created in the infrarenal aorta of 14 mongrel dogs. A single collateral side branch was reimplanted in 4 animals, multiple side branches were reimplanted in 6 animals, and no side branches were reimplanted in 4 control animals. Intra-aneurysmal and systemic pressure was measured for 60 to 90 days after creation of the type II endoleak. Endoleak patency and flow were assessed with duplex ultrasound scanning and cine-magnetic resonance angiography. Histologic analysis of the intra-aneurysmal thrombus was also performed. RESULTS: Stent-graft exclusion reduced intra-aneurysmal pressure significantly in all animals, as compared with systemic pressure (P < .001). All intra-aneurysmal pressure values are indexed to the systemic pressure, and are represented as a percentage of the simultaneously obtained systemic pressure, which has a value of 1.0. Type II endoleaks originating from multiple side branches exhibited significantly increased intra-aneurysmal systolic pressure, mean pressure, and pulse pressure, as compared with endoleaks derived from either a single side branch (systolic pressure: multiple, 0.70 +/- 0.28 vs single, 0.50 +/- 0.19; P < .001; mean pressure: multiple, 0.78 +/- 0.23 vs single, 0.59 +/- 0.22, P < .001; pulse pressure: multiple, 0.41 +/- 0.25 vs single, 0.17 +/- 0.15, P < .001) or excluded control aneurysms that had no side branches and no endoleak (systolic pressure, 0.17 +/- 0.09; mean pressure, 0.14 +/- 0.10; pulse pressure, 0.098 +/- 0.08; P < .001). Cine-magnetic resonance angiograms and duplex ultrasound scans documented persistent patency of multiple branch endoleaks up to the time of euthanasia. In contrast, single side branch endoleaks thrombosed within 3 days (P < .001). Thrombus in the aneurysm sac in close proximity to the endoleak contained intact red blood cells and limited fibrin. Thrombus distant from the endoleak demonstrated extensive fibrin deposition and degraded red blood cells. CONCLUSION: The canine model may be used to reliably measure intra-aneurysmal pressure in the presence of patent and thrombosed type II endoleaks. In this model 2 or more side branches are necessary to maintain persistent patency of type II endoleaks. These endoleaks are associated with significantly elevated intra-aneurysmal pressure, that is, 70% to 80% of systemic pressure. These results suggest that persistent type II endoleaks have clinical significance. CLINICAL RELEVANCE: Endoleaks originating from retrograde flow in the side branch vessels of the aneurysm generate significant levels of intra-aneurysmal pressure, that is, 70% to 80% of systemic pressure. At least 2 patent side branch vessels appear to be necessary to cause persistent patency of type II endoleak in the canine model. Further studies will be necessary to enable more complete characterization of retrograde endoleaks and to extend these findings to allow clinical application. However, these results suggest that persistently patent type II endoleaks are clinical significance and may require more intensive follow-up intervention.

Anastomosis, Surgical↗

PubMed2004

Computer simulation as a component of catheter-based training.

INTRODUCTION: Computer simulation has been used in a variety of training programs, ranging from airline piloting to general surgery. In this study we evaluate the use of simulation to train novice and advanced interventionalists in catheter-based techniques. METHODS: Twenty-one physicians underwent evaluation in a simulator training program that involved placement of a carotid stent. Five participants were highly experienced in catheter-based techniques (>300 percutaneous cases), including carotid angioplasty and stenting (CAS); the remaining 16 participants were interventional novices (<5 percutaneous cases). The Procedicus VIST simulator, composed of real-time vascular imaging simulation software and a tactile interface coupled to angiographic catheters and guide wires, was used. After didactic instruction regarding CAS and use of the simulator, each participant performed a simulated CAS procedure. The participant's performance was supervised and evaluated by an expert interventionalist on the basis of 50 specific procedural steps with a maximal score of 100. Specific techniques of guide wire and catheter manipulation were subjectively assessed on a scale of 0 to 5 points based on ability. After evaluation of the initial simulated CAS procedure, each participant received a minimum of 2 hours of individualized training by the expert interventionalist, with the VIST simulator. Each participant then performed a second simulated CAS procedure, which was graded with the same scale. After completion, participants assessed the training program and its utility via survey questionnaire. RESULTS: The average simulated score for novice participants after the training program improved significantly from 17.8 +/- 15.6 to 69.8 +/- 9.8 (P < .01), time to complete simulation decreased from 44 +/- 10 minutes to 30 +/- 8 minutes (P < .01), and fluoroscopy time decreased from 31 +/- 7 minutes to 23 +/- 7 minutes ( P < .01). No statistically significant difference in score, total time, or fluoroscopy time was noted for experienced interventionalists. Improvement was noted in guide wire and catheter manipulation skills in novices. Analysis of survey data from experienced interventionalists indicated that the simulated clinical scenarios were realistic and that the simulator could be a valuable tool if clinical and tactile feedback were improved. Novices also thought the simulated training was a valuable experience, and desired further training time. CONCLUSIONS: An endovascular training program using the Procedicus VIST haptic simulator resulted in significant improvement in trainee facility with catheter-based techniques in a simulated clinical setting. Novice participants derived the greatest benefit from simulator training in a mentored program, whereas experienced interventionalists did not seem to derive significant benefit.

Blood Vessel Prosthesis Implantation↗

PubMed2004

Stent graft treatment for abdominal aortic aneurysm repair: recent developments in therapy.

PURPOSE OF REVIEW: Minimally invasive endovascular techniques for the treatment of abdominal aortic aneurysms have significantly reduced the morbidity of these procedures compared with standard surgical repair. In addition, patients with extensive comorbid medical illnesses in whom standard operative repair is contraindicated may be successfully treated using endovascular means. RECENT FINDINGS: Recently, several important developments have significantly advanced this area of treatment. The Food and Drug Administration has approved four endovascular stent grafts for the treatment of abdominal aortic aneurysms: the Medtronic AneuRx, the W.L. Gore Excluder, the Cook Zenith, and the Guidant Ancure. The Zenith received approval for marketing in 2003 and has gained relatively wide use, in part because of its ability to treat aneurysms with relatively large-diameter implantations zones. Also in 2003, Guidant Corporation withdrew the Ancure graft from marketing and distribution. The withdrawal was influenced by difficulties encountered using the graft's delivery system and improper reporting to the Food and Drug Administration. Enrollment has also been recently completed for the phase II Food and Drug Administration trials of the Medtronic Talent graft and the Cordis Fortron graft. These devices have been approved for use in the European Union and are awaiting Food and Drug Administration panel meeting in the United States. Several significant advances have also occurred recently in stent graft research and development. Of particular significance has been the initiation of the phase I trial of the Trivascular Enovus graft. Deployment of the Trivascular graft may be accomplished through a delivery system that is considerably reduced in profile. The potential for percutaneous application of the graft may be available in the future. In selecting the specific stent graft to be used for endovascular abdominal aortic aneurysm repair, the specific graft characteristics must be considered, particularly with regard to the individual patient's anatomic and physiologic characteristics. Comparative analysis of the several of the various stent grafts has been performed. Results have varied with regard to the need for secondary interventions, aneurysm sac size reduction, and the occurrence of continued perfusion of the aneurysm sac. In addition, the indications for use of endovascular grafts compared with standard open surgery have not yet been fully defined. SUMMARY: This article describes the general principles of use for endovascular devices for the repair of abdominal aortic aneurysms. It details the features and results for the devices in current use, and highlights the recent developments in stent graft treatment of abdominal aortic aneurysms.

Aortic Aneurysm, Abdominal↗

PubMedDate not supplied

Rupture of excluded popliteal artery aneurysm: implications for type II endoleaks--a case report.

The fate of popliteal artery aneurysms after ligation and bypass is believed to be relatively innocuous. The patient presented in this report, however, experienced spontaneous rupture of a popliteal aneurysm 11 years after ligation and bypass. Magnetic resonance angiography was used to establish the diagnosis of rupture, which was subsequently confirmed at surgery. Intraoperative arteriography demonstrated persistent collateral arterial perfusion of the excluded popliteal aneurysm sac. The collateral arterial flow originated from the superior and inferior lateral genicular arteries. The persistent arterial perfusion resulted in growth of the aneurysm from 4.2 to 7.0 cm over the 11-year period. The ruptured aneurysm was successfully treated by direct arterial exposure and suture ligation of the collateral vessels performed from within the aneurysm sac. The development of popliteal aneurysm expansion and rupture as a result of collateral arterial perfusion suggests that persistent collateral perfusion of abdominal aortic aneurysms after endovascular repair (type II endoleak) may lead to aneurysm rupture. Therefore, close observation and intervention for aneurysm expansion to prevent rupture of the excluded aneurysm are warranted.

Aged↗

PubMedDate not supplied

Postcarotid endarterectomy pseudoaneurysm treated with combined stent graft and coil embolization--a case report.

Pseudoaneurysm formation is a rare complication following carotid endarterectomy (CEA); however, its occurrence is associated with significant risk of morbidity. The patient in this report presented 2 years following CEA with headache and lateral neck mass. The diagnosis of a 3.5 x 3.0 cm carotid artery bifurcation pseudoaneurysm was made by using magnetic resonance angiography (MRA). Endovascular exclusion of the aneurysm was accomplished with coil embolization of the external carotid artery followed by deployment of a 7 x 50 mm wall stent graft into the common carotid artery-internal carotid artery (CCA-ICA). The patient's symptoms improved and at 6-months postexclusion, duplex ultrasound demonstrated a significant reduction in pseudoaneurysm size. This case highlights the feasibility and safety of using endovascular techniques in the treatment of post-CEA pseudoaneurysm.

Aged↗

PubMedDate not supplied

Endoluminal recanalization in a patient with phlegmasia cerulea dolens using a multimodality approach-a case report.

Phlegmasia cerulea dolens is a limb-threatening form of deep venous thrombosis and should be treated aggressively. The authors report a patient who presented with iliocaval and femoral deep venous thrombosis and posed an additional therapeutic challenge based on a recent history of heparin-induced thrombocytopenia. Catheter-directed pharmacologic thrombolysis and balloon venoplasty were applied in treatment. The direct thrombin inhibitor argatroban was used in place of heparin for concurrent anticoagulation. This multimodality endovascular approach (chemical and mechanical interventions) was successful in relieving the venous occlusion and salvaging the limb, while maintaining appropriate treatment for heparin-induced thrombocytopenia.

Anticoagulants↗

PubMedDate not supplied

Multimodal therapy for acute and chronic venous thrombotic and occlusive disease.

Critical deep venous thrombosis and occlusion constitutes a small percentage of patients with venous disease. However, these patients exhibit severe symptomatology including pain and extensive edema that may progress to limb- or life-threatening complications such as phlegmasia cerulea dolens and superior vena cava syndrome. This paper reviews the different multimodal percutaneous interventions currently available for the treatment of complex critical venous thrombotic and occlusive disease.

Acute Disease↗

PubMedDate not supplied

Embolization of renal artery aneurysm and arteriovenous fistula-a case report.

A renal artery aneurysm with an associated arteriovenous fistula in a native kidney has been reported infrequently in the literature. Management depends on size, location, and the patient's physiological condition. We describe a case in which endovascular therapy was used to successfully exclude both aneurysm and fistula. This report describes a 13-centimeter renal artery aneurysm with arteriovenous fistula originating from an isolated branch of the renal artery. Coil-embolization resulted in thrombosis of the aneurysm and fistula while preserving parenchymal perfusion. Coil embolization is an alternative to surgery for coexistent renal artery aneurysm and arteriovenous fistula arising from a branch of adequate length for placement of embolic coils. Successful treatment is not limited by aneurysm size or presence of arteriovenous connection.

Aneurysm↗