Blunt Traumatic Innominate Artery Pseudoaneurysm Endografting without Heparin Due to Severe Brain Injury.

Blunt traumatic innominate artery injuries occur in polytrauma victims who have suffered high-speed motor vehicle collisions. Their associated injuries may preclude the use of heparin and affect surgical management and perioperative neurological risk. The uniqueness of this case is combining the arterial injury repair with a severe progressive neurological injury that prohibited standard perioperative antiplatelet or anticoagulent use.

Staged Endovascular Repair of Aortic Coarctation followed by Double Valve Surgery.

We present a unique case of late diagnosis of coarctation of the aorta in an adult, presenting with congestive heart failure associated with severe aortic and mitral valve insufficiency. To minimize operative risk, staged endovascular repair of the coarctation was initially performed, followed by aortic valve replacement and mitral valve repair. Six months postoperatively, the 41-year-old patient remains completely asymptomatic.

Two-stage hybrid repair of a complex symptomatic celiac aneurysm.

We report the case of a novel 2-stage hybrid repair of a complex celiac artery aneurysm. The patient was a 42-year-old man with a proximal celiac artery aneurysm giving rise to distinct right and left hepatic arterial branches. Repair was performed using a staged approach. First, a bifurcated aortohepatic bypass was constructed to the common and left hepatic arteries. After recovering from surgery, he underwent percutaneous embolization of the aneurysm. Completion angiograms demonstrated flow into all celiac branches with successful thrombosis of the aneurysm. At 12-month follow-up, the patient had remained symptom-free with patent bypass grafts and complete aneurysm exclusion. We describe the treatment option we used, which involves repair of a complex celiac aneurysm using a 2-stage, open, endovascular approach.

Dynamic diffuse optical tomography imaging of peripheral arterial disease.

Peripheral arterial disease (PAD) is the narrowing of arteries due to plaque accumulation in the vascular walls. This leads to insufficient blood supply to the extremities and can ultimately cause cell death. Currently available methods are ineffective in diagnosing PAD in patients with calcified arteries, such as those with diabetes. In this paper we investigate the potential of dynamic diffuse optical tomography (DDOT) as an alternative way to assess PAD in the lower extremities. DDOT is a non-invasive, non-ionizing imaging modality that uses near-infrared light to create spatio-temporal maps of oxy- and deoxy-hemoglobin in tissue. We present three case studies in which we used DDOT to visualize vascular perfusion of a healthy volunteer, a PAD patient and a diabetic PAD patient with calcified arteries. These preliminary results show significant differences in DDOT time-traces and images between all three cases, underscoring the potential of DDOT as a new diagnostic tool.

Midterm outcomes after treatment of type II endoleaks associated with aneurysm sac expansion.

PURPOSE: To examine the outcomes following interventions for type II endoleaks in patients with aneurysm sac expansion after endovascular aneurysm repair (EVAR). METHODS: A retrospective review was conducted of all patients who underwent treatment for type II endoleak from July 2001 to September 2010 in a single center. In this time period, 29 (4.7%) patients (22 men; mean age 78.6 years, range 54-87) were identified as having a type II endoleak and enlargement of the aneurysm sac, meeting the criterion for treatment. All patients had at least one attempted percutaneous intervention. Patients were followed both clinically and radiographically, with computed tomographic angiography every 3 to 12 months, over a follow-up period that ranged from 1 to 10 years (mean 3.5). RESULTS: Forty-eight interventions were performed on the 29 patients. Of these, 15 (56%) patients underwent multiple (2-4) procedures. Of the 11 endoleaks with an isolated inferior mesenteric artery identified as the source, initial success for transarterial embolization at 2 years was 72%, with 2 of the failures having successful secondary interventions. For the 18 endoleaks with a lumbar source, the success of the initial intervention was 17% at 2 years; repeated embolization attempts produced a 40% secondary success rate. Seven (24%) patients had continued endoleak despite multiple treatment attempts; 3 ultimately required elective aortic graft explantation. There were no ruptures or deaths during the study period. In a comparison of type II endoleak patients who had stable aneurysm sacs and those who had persistent sac expansion, the only significant differences in preoperative anatomical characteristics were a lower prevalence of mural thrombus (p = 0.036) and longer right iliac arteries (p = 0.012) in the group with sac expansion. Independent predictors of type II endoleak were mural thrombus (p<0.001), patent lumbar arteries (p = 0.004), aneurysm length (p = 0.011), and iliac artery length (p = 0.004). CONCLUSION: This study demonstrates that most patients require multiple reinterventions to treat type II endoleaks; specifically, lumbar artery embolization carries a low midterm success rate.

Utility of duplex ultrasound in detecting and grading de novo femoropopliteal lesions.

BACKGROUND: Digital subtraction angiography (DSA) is the gold standard for diagnosing lower extremity (LE) arterial lesions. However, duplex ultrasound (DUS) is a widely used, safe, and noninvasive method of detecting LE lesions. The purpose of this study was to establish DUS criteria for detecting and grading de novo stenotic lesions in the femoropopliteal arterial segment. METHODS: A prospective database was established including all patients who underwent LE endovascular interventions between 2004 and 2009. Patients with de novo stenotic lesions in the femoropopliteal segment were selected. DUS and DSA data pairs ≤30 days apart were analyzed. Peak systolic velocity (PSV; cm/s), velocity ratio (Vr), and DSA stenosis were noted. Linear regression and receiver operator characteristic (ROC) curves were used. RESULTS: Two hundred seventy-five lesions in 200 patients were analyzed. Indications were claudication (50.5%), rest pain (12.5%), and tissue loss (37.0%). Mean time interval between DUS and DSA was 24 days. Both PSV (R = .80, R(2) = .641; P < .001) and Vr (R = .73, R(2) = .546; P < .001) showed strong correlation with the degree of angiographic stenosis. ROC analysis showed that to detect ≥70% stenosis, a PSV of 200 cm/s had 89.2% sensitivity and 89.7% specificity, and a Vr of 2.0 had 88.7% sensitivity and 90.2% specificity. Similarly, to differentiate between <50% and ≥50% stenosis, PSV of 150 cm/s and Vr of 1.5 were highly specific and predictive. Combining PSV 200 cm/s and Vr 2.0 for ≥70% stenosis gave 79.0% sensitivity, 99.0% specificity, 99.0% positive predictive value, and 85.0% negative predictive value. CONCLUSION: DUS shows a strong agreement with angiography and has good accuracy in detecting femoropopliteal lesions. We propose DUS criteria of PSV 200 cm/s and Vr 2.0 to differentiate between <70% and ≥70% de novo stenosis in the femoropopliteal arterial segment.

Endovascular management as first therapy for chronic total occlusion of the lower extremity arteries: comparison of balloon angioplasty, stenting, and directional atherectomy.

PURPOSE: To evaluate the role of endovascular therapy in the management of infrainguinal arterial chronic total occlusions (CTOs). METHODS: Data on all patients with CTOs treated at a single center from 2004 to 2010 were extracted from a prospectively maintained database for retrospective analysis. Patient demographics, angiographic studies, noninvasive vascular test results, and clinical outcomes were evaluated. In this time frame, 481 patients (283 men; mean age 71.7±11.5 years, range 52-85) with claudication (n = 177) or critical limb ischemia (CLI, n = 304) were treated for 688 CTOs. Lesions were segregated according to location [SFA (n = 193), popliteal (n = 67), tibial (n = 217), and multilevel (n = 211)] and analyzed based on treatment mode (angioplasty, angioplasty with stenting, or atherectomy) and clinical indication. Primary patency, assisted primary patency, and secondary patency, as well as limb salvage rates for CLI patients, were calculated. RESULTS: At 2 years in claudicants with CTOs confined to the SFA, primary patency ranged from 44% to 58% and secondary patency to 92% depending on treatment type; there were no significant differences among the treatments. However, in CLI patients with SFA CTOs, atherectomy produced better outcomes at 2 years (p = 0.002 for primary and p = 0.012 for secondary patency) than angioplasty alone. The limb salvage rates ranged from 73% to 91% (no differences among treatment types). In diabetics, CTOs treated with angioplasty and stent had improved secondary patency rates over angioplasty alone. CONCLUSION: The endovascular management of CTO results in reasonable primary patency; moreover, secondary patency at 2 years is excellent. Endovascular therapy should be the first-line option for many patients with peripheral artery disease, including those with CLI, claudicants with poor bypass conduit, or patients at high medical risk for surgery. The presence of CTOs does not appear to change these recommendations. Although multiple reinterventions may be required, endovascular therapies can be considered a primary therapy for many patients with CTO.

Development and implementation of an introductory endovascular training course for medical students.

BACKGROUND: Endovascular simulation has been promoted as an educational tool for trainees to practice procedures in a safe environment and improve basic technical skills. We sought to determine whether an established endovascular training course for medical students could increase technical proficiency, enhance interest in vascular surgery, and be implemented at another academic institution. METHODS: At Center A, medical students participated in an eight-week elective course with a structured curriculum comprised of weekly mentored simulator sessions and didactic teachings. A similar course was developed at Center B to train a similar cohort of students using the same high-fidelity simulator. Demographics and survey data, including interest in vascular surgery, were obtained, and pre- and postcourse graded simulator sessions on renal stent or iliac/superficial femoral artery stent modules were conducted. Performance was assessed by expert observers using a standardized global endovascular rating scale and objective procedural metrics collected from the simulator. RESULTS: Seventy-seven medical students (41 at Center A and 36 at Center B; 56 men and 21 women) completed the course from 2007 to 2009. Parameters measured on the standardized global endovascular rating scale, including angiography skills, wire handling, and interventional criteria as well as simulator-generated metrics, significantly improved from pre- to postcourse values for both groups of medical students at the two institutions (p < 0.05). More than 94% of the students agreed or strongly agreed that the simulation course increased their interest in vascular surgery. CONCLUSION: A simulation-based endovascular course provides an educational tool that improves basic technical performance and increases interest in vascular surgery among medical students. This simple educational module appears to be transferable and adaptable at another institution with minimal modification to produce similar results.

Determining criteria for predicting stenosis with ultrasound duplex after endovascular intervention in infrainguinal lesions.

BACKGROUND: Studies examining duplex surveillance of lower extremity bypass grafts have defined a role for guiding graft re-intervention. The goal of this study is to determine the utility of duplex scanning to detect angiographic restenosis after endovascular therapy in patients with infrainguinal arterial disease. METHODS: A prospective registry including all patients treated for lower extremity atherosclerotic disease between February 2004 and September 2008 was established. Patients were followed up with duplex ultrasound at 1, 3, 6, 12 months, and then annually. Patients receiving repeat angiograms were identified and angiogram and duplex data were abstracted. Velocity ratios (Vr) were calculated for each lesion by dividing the peak velocity within the lesion by the peak velocity proximal to the lesion. Logarithmic regression and receiver operator characteristic (ROC) curve analyses were used. RESULTS: Repeat angiograms were performed on 345 lesions in 143 patients, and 254 lesions in 103 patients had a corresponding duplex ultrasound. Indications for the initial intervention were claudication (n = 62, 43.4%), rest pain (n = 23, 16.1%), and tissue loss (n = 58, 40.5%). A total of 178 superficial femoral artery (SFA) lesions, 59 popliteal lesions, and 17 tibial lesions were identified by surveillance duplex in 103 patients. In all, 70.5% of the intervened vessels that were studied were nonstented and the remaining 29.5% were stented. A total of 65% of the patients had diabetes. On determining correlations for peak systolic velocity (PSV) as measured by duplex ultrasound with degree of angiographic stenosis, strong correlation coefficients for SFA disease (R² = 0.84) and popliteal disease (R² = 0.88) were found. However, poor correlation was found in patients with tibial disease. When analyzing the lesions on the basis of Vr < 2.0, 11 of 86 (12.8%) had >70% angiographic stenosis. In lesions with ratios from 2 to 2.5, 12 of 13 (92.3%) had >70% angiographic stenosis and in lesions with ratios >2.5, 69 of 75 (92.0%) had >70% angiographic stenosis. ROC curve analysis showed that to detect ≥ 70% stenosis in the SFA, a PSV ≥ 204 cm/sec had a sensitivity of 97.6% and specificity of 94.7%. To detect ≥ 70% stenosis in the overall femoropopliteal region, a PSV ≥ 223 cm/sec had a sensitivity of 94.1% and specificity of 95.2%. CONCLUSIONS: Duplex ultrasound surveillance correlates to the degree of angiographic stenosis on the basis of PSV in the SFA and popliteal region. Correlation in the tibial vessels is poor. Vr > 2.0 appear to correlate to angiographic stenosis of > 70%. ROC analysis shows that PSV can have sufficiently high sensitivity and specificity to predict angiographic stenosis in the femoropopliteal region.

The use of gadolinium for arterial interventions.

BACKGROUND: Gadolinium (Gd) has been traditionally used as a non-nephrotoxic alternative to iodinated contrast for digital subtraction angiography (DSA) in patients with chronic renal insufficiency. However, its use has been questioned on the basis of reports of nephrotoxicity and its recent association with nephrogenic systemic fibrosis (NSF), a potentially lethal complication. Recently available data are conflicting with respect to the true safety profile of intra-arterial Gd. The purpose of this study was to examine the risk of contrast nephropathy and NSF after Gd exposure in a large population of azotemic patients undergoing DSA. METHODS: A comprehensive database encompassing data on all patients who underwent DSA between June 2003 and December 2007 at the New York Presbyterian Hospital was retrospectively reviewed. Patients receiving Gd either alone or in combination with iodinated contrast during DSA were identified and further analyzed. Acute renal failure (ARF) was defined as an elevation in serum creatinine (Cr) by >0.5 mg/dL within 48 hours of exposure. Clinical follow-up was conducted through chart reviewing as well as telephonic interviews with patients and their primary care physicians. RESULTS: A total of 153 patients underwent 179 exposures to Gd either alone (33%) or in combination (67%) with iodinated contrast. Mean follow-up duration was 27.1 months. The mean Cr level was 1.94 ± 0.78 mg/dL and 1.96 ± 1.1 mg/dL before and after DSA, respectively. There were 20 (11.2%) instances of ARF. The mean Cr level before DSA was higher in patients who developed ARF versus those in the non-ARF group (2.7 ± 1.1 mg/dL vs. 1.9 ± 0.7 mg/dL, p = 0.004). In the ARF group, 12 patients had a return to baseline renal function, four experienced irreversible renal deterioration, and four needed dialysis (4.5% incidence of irreversible renal failure). There were 19 deaths at the time of this study (12.4%). The highest risk for the development of ARF after Gd exposure occurred in patients with Cr levels of >3.0 mg/dL before DSA and in those receiving >0.4 mmol/kg of Gd. For patients who received iodinated contrast in combination with Gd, there was a trend toward a higher risk for developing ARF as compared with those receiving only Gd. Finally, there were no instances of NSF identified in any of the patients who received intra-arterial Gd. CONCLUSIONS: Although Gd has the potential to cause kidney injury similar to iodinated contrast, the risk of irreversible renal failure and the requirement for dialysis is low. Life- or limb-threatening interventions should not be avoided in this patient cohort because of preexisting elevations in Cr. These data should help guide the use of Gd in patients with chronic renal insufficiency.

Closed-cell stents present with higher velocities on duplex ultrasound compared with open-cell stents after carotid intervention: short- and mid-term results.

BACKGROUND: The purpose of this study was to evaluate the effect of carotid cell design on duplex ultrasound velocity readings in the immediate postoperative period and over time. METHODS: A prospective database encompassing all patients treated with carotid artery stents between 2003 and 2008 was established and analyzed for stent type (closed-cell vs. open-cell), indications, and comorbidities. Patients were followed up clinically and with duplex ultrasound immediately after surgery, and every 6 months thereafter. Peak systolic velocities (PSV), end diastolic velocities (EDV), and internal carotid artery (ICA) to common carotid artery (CCA) ratios of PSV were recorded. RESULTS: A total of 214 interventions with 157 (73.3%) open-cell and 57 (26.7%) closed-cell types of carotid stents were performed in 205 patients. Two groups were similar regarding demographics, comorbidities, lesions characteristics, and stent length and diameter. The only difference was a significantly higher mean age (74.4 ± 10.1 vs. 70.9 ± 9.7 years; p = 0.027) and a history of myocardial infarction (34.5% vs. 15.6%; p = 0.004) in the closed-cell group versus open-cell group. Immediately after surgery PSV (115.9 ± 66.1 vs. 93.1 ± 38.7 cm/s; p = 0.003) and ICA/CCA ratio (2.08 ± 1.66 vs. 1.45 ± 0.52; p = 0.001) were significantly higher in closed-cell compared with open-cell group. This difference persisted during the follow-up period of 20.2 +/- 16.4 months; PSV (147.2 ± 108.8 vs. 110.0 ± 51.9; p = 0.003) and ICA/CCA ratio (2.61 ± 2.31 vs. 1.76 ± 0.81; p = 0.001). Patients with diabetes and calcified lesions had higher PSV and ICA/CCA ratio immediately after surgery (p > 0.05 and p < 0.05 for those with diabetes and calcified lesions, respectively) and over time. The number of readings showing significant restenosis (PSV >300 cm/s) over time were significantly higher in closed-cell 5 (8.7%) versus open-cell 1 (0.06%). EDV was not statistically different in the two groups (p > 0.05). CONCLUSION: Our study suggests that duplex criteria to screen for poststent restenosis may require modification according to stent-type. However, long-term effect of stent design on restenosis is still to be established.

Lesion types and device characteristics that predict distal embolization during percutaneous lower extremity interventions.

OBJECTIVE: Distal embolization (DE) during percutaneous lower extremity revascularization (LER) may cause severe clinical sequelae. To better define DE, we investigated which lesion types and treatment modalities increase the risk for embolization. METHODS: A prospective registry of LER from 2004 to 2009 was reviewed. All cases with runoff evaluated before and after intervention were included. Angiograms and operative reports were reviewed for evidence of DE. Interventions included percutaneous transluminal angioplasty (PTA), with or without stent placement, and atherectomy with four different devices. Chi-square analysis and Fisher's exact test were used to assess significance. Patency rates were calculated using Kaplan-Meier analysis and compared using log-rank analysis. RESULTS: There were 2137 lesions treated in 1029 patients. The embolization rate was 1.6% (34 events). Jetstream (Pathway, Kirkland, Wash) and DiamondBack 360 (Cardiovascular Systems Inc, St Paul Minn) devices had a combined embolization rate of 22% (8 of 36), 4 of 18 (22%) in each group, which was significantly higher than with PTA alone (5 of 570, 0.9%), PTA and stent (5 of 740, 0.7%), SilverHawk (ev3, Plymouth, Minn) atherectomy (14 of 736, 1.9%), and laser atherectomy (2 of 55, 3.6%; P < .001). There was a significantly higher rate of embolization for in-stent restenosis (6 of 188, 3.2%) and chronic total occlusions (15 of 615, 2.4%) compared with stenotic lesions (13 of 1334, 0.9%; P = .01). The embolization rate was significantly higher in Transatlantic Inter-Society Consensus (TASC) II C and D lesions compared with TASC A and B lesions (P = .018). DE rates were not affected by preoperative runoff status (P = .152). Patency was restored at the completion of the procedure in 32 of 34 cases of DE. The 24-month primary patency, assisted primary patency, and secondary patency in the DE group was 54.0% ± 11.9%, 70.0% ± 10.3%, and 73.2% ± 10.3%, respectively, and was 44.4% ± 1.7%, 61.5% ± 1.7%, and 68.2% ± 1.6%, respectively, when embolization did not occur (P > .05). Limb salvage was 72.6% ± 3.1% in lesions in which no DE occurred vs 83.3% ± 15.2% in lesions in which DE occurred (P = .699). CONCLUSIONS: DE is a rare event that occurs more often with the Jetstream and DiamondBack 360 devices. In-stent and complex native lesions are at higher risk for DE. DE is typically reversible with endovascular techniques and has no effect on patency rates and limb salvage.

Outcomes of carotid stenting compared with endarterectomy are equivalent in asymptomatic patients and inferior in symptomatic patients.

BACKGROUND: Despite the current Centers for Medicare and Medicaid Services coverage criteria for carotid artery stenting (CAS), consensus regarding its appropriateness in patients with carotid artery stenosis has not been reached. This is one of the first population-based studies to use a dedicated administrative convention for the endovascular procedure to address whether there is a cohort of patients in whom CAS is more beneficial than carotid endarterectomy (CEA). METHODS: We analyzed in-hospital mortality, postoperative stroke, and combined postoperative stoke/mortality in 47,752 CAS or CEA hospitalizations, matched by propensity score, in discharge data sets obtained from the states of New York and California for the years 2005 to 2007. Other outcomes included postoperative complications, length of stay, and volume-outcome relationships. RESULTS: For symptomatic patients undergoing CAS, rates were significantly higher for in-hospital mortality (3.7% vs 1.3%) and combined stroke/mortality (8.3% vs 4.6%) compared with CEA. For asymptomatic patients, there was no statistical difference between mortality (0.6% vs 0.4%), stroke (2.0% vs 1.8%), or combined stroke/mortality (2.4% vs 1.9%) across the endovascular and open procedures, respectively. Postoperative respiratory and urinary complications as well as cranial neuropathy were more common after CEA, whereas postoperative complications, including device malfunction and hypotension, were more frequent after CAS. We did not find a volume-outcome relationship for CEA, but one did exist for CAS. CONCLUSIONS: In symptomatic patients with carotid artery stenosis, the most appropriate procedure appears to be CEA, whereas CAS appears to be a suitable minimally invasive approach for asymptomatic patients. On the basis of these results and data from recent multicenter randomized trials, the use of CAS in symptomatic patients should be approached with caution.

Retroperitoneal hematoma with abdominal compartment syndrome during minimally invasive mitral valve replacement.

Although retroperitoneal hematomas most often occur secondary to trauma, they are a reported complication of ruptured aneurysms, anticoagulation therapy, and femoral vascular access. In the cardiovascular literature, retroperitoneal hematomas have occurred after percutaneous coronary interventions; however, these hematomas rarely bleed to the extent that they cause abdominal compartment syndrome. The present report describes the case of an adult patient who had a retroperitoneal hematoma develop during minimally invasive mitral valve replacement with intraoperative abdominal compartment syndrome requiring emergent surgical decompression.

An analysis of the outcomes of a decade of experience with lower extremity revascularization including limb salvage, lengths of stay, and safety.

BACKGROUND: Demographic and practice modality changes during the past decade have led to a substantial shift in the management of peripheral vascular disease. This study examined the effect of these changes using large national and regional data sets on procedure type, indications, morbidity, and on the primary target outcome: limb salvage. METHODS: National Inpatient Sample (NIS) data sets and New York (NY) State inpatient hospitalizations and outpatient surgeries discharge databases from 1998 through 2007 were used to identify hospitalizations for lower extremity revascularization (LER) and major amputations. Patients were selected by cross-referencing diagnostic and procedural codes. Proportions were analyzed by chi(2) analysis, continuous variables by t test, and trends by the Poisson regression. RESULTS: The national per capita (100,000 population, age >40 years) volume of major amputations decreased by 38%. The volume for national and regional use of endovascular LER doubled. The volume of open LER decreased by 67% from 1998 through 2007. Ambulatory endovascular LER grew in NY State from 7 per capita in 1998 to 22 in 2007. Interventions declined by 20% (93 to 75) for critical limb ischemia (CLI) but increased by nearly 50% for claudication. Outpatient data analysis revealed a fivefold increase in vascular interventions for CLI and claudication. Nationally, endovascular LER interventions quadrupled (8% to 32%) for CLI and doubled (26% to 61%) for claudication. A parallel reduction occurred in major amputations for patients with CLI (42% to 30%), for other PAD diagnoses (18% to 14%), and for claudication (0.9% to 0.3%). Although surgical interventions for CLI declined significantly for octogenarians from 317 to 240, outpatient interventions increased for CLI, claudication, and other diagnoses in all age groups. Comorbidities for patients treated in 2006 were substantially greater than those of a decade ago. For most procedures, cardiac and bleeding complications have significantly decreased during the last decade. Length of stay (LOS) declined from 9.5 to 7.6 days and the percentage of short (1-2 day) hospitalizations increased from 16% to 35%. CONCLUSION: Although patients today, whether treated for claudication or CLI, have more comorbidities, the rates of amputation, the procedural morbidity and mortality, and LOS have all significantly decreased. Other variables, including changes in medical management and wound care, undoubtedly are important, but this change appears to be largely due to the widespread and successful use of endovascular LER or to earlier intervention, or both, driven by the safety of these techniques.

Aortic debranching for descending thoracic aortic aneurysm repair by stent grafts.

Endovascular repair of a descending thoracic aortic aneurysm may result in covering the ostia of the left carotid or left subclavian artery for proper proximal landing zones, and the celiac artery or superior mesenteric artery ostia in the abdomen for distal landing zones. To prevent possible complications of occluding the ostia of these vessels, the authors performed an innominate to left common carotid and left subclavian artery bypass as the first procedure in one patient. In the second patient they performed an aortoceliac and aortomesenteric bypass before stent graft placement. The stent graft repair of the descending thoracic aortic aneurysm was performed subsequently in both patients. This aortic debranching provides subsequent proper placement of thoracic stent grafts.

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.