Endovascular treatment of renal artery thrombosis caused by umbilical artery catheterization

AbstractRenal arterial thrombosis, usually in association with aortic thrombosis, has been reported as a result of prolonged neonatal umbilical artery catheterization. A case of renal artery thrombosis attributable to umbilical artery catheterization, resulting in malignant renovascular hypertension, in a 15-day-old neonate, treated by catheter-directed thrombolysis through the involuting umbilical artery, was studied. Resolution of systemic hypertension and partial return of right renal function followed rapid thrombus dissolution. (J Vasc Surg 1998;28:949-53.

A volumetric index for the quantification of deep venous thrombosis

AbstractPurpose: The evaluation of treatment strategies for deep venous thrombosis (DVT) is assessed through the use of a reliable method of quantifying the extent of the thrombotic process. Previous indices of thrombus burden have suffered from various limitations, including lack of clinical relevance, poor correlation with actual thrombus mass, and failure to include important venous segments in the methodology. The use of a novel scheme of quantifying venous thrombus was evaluated as an alternative method that would avoid some of the drawbacks of existing indices. Methods: The volumes of 14 venous segments (infrarenal inferior vena cava, common iliac, hypogastric, external iliac, common femoral, profunda, superficial femoral, and popliteal and six tibial veins) were calculated from computed tomography (pelvic vein diameter), duplex ultrasound scan (infrainguinal vein diameter), and contrast venography (length of all segments) measurements. A venous volumetric index (VVI) was assigned with the normalization of the values to the volume of a single calf vein. The VVI was validated with the assessment of the ability to discriminate between asymptomatic and symptomatic DVT and between those DVT that were associated with pulmonary emboli and those that were not. Results: With the imaging data, the VVI ranged from 1 for a single calf vein thrombus to 26 for the infrarenal inferior vena cava. Each VVI unit represented 2.3 mL of thrombus, with a maximum possible score of 63 representing a thrombus burden of 145 mL for a single extremity, including the infrarenal inferior vena cava. In 885 patients with DVT, the VVI ranged from 1 to 56, averaging 3.9 ± 0.2 in patients who were asymptomatic and 8.7 ± 0.3 in patients who were symptomatic (P < .001). The VVI was similar in the patients with pulmonary emboli as compared with those without (9.6 ± 1.2 vs 7.7 ± 0.2, respectively). In comparison with the three existing methods of quantifying venous thrombus burden, the receiver operating characteristic curve analysis results suggested that the VVI and the Venous Registry index were better than the other two indices in the discrimination of patients with symptomatic and asymptomatic DVT (P < .001). Conclusion: A novel index of venous thrombus burden, on the basis of actual venous volume measurements, was more accurate than present indices in the differentiation between clinical categories of patients with DVT. As such, it offers an acceptable alternative to current scoring systems. (J Vasc Surg 1999;30:1060-6.

Safety and efficacy of limited-dose tissue plasminogen activator in acute vascular occlusion

AbstractObjective: The purposes of this study were to evaluate the safety and efficacy of limited-dose tissue plasminogen activator (t-PA) in patients with acute vascular occlusion and to compare these results with those obtained in equivalent patients receiving urokinase. Methods: We compared the results of 60 patients receiving catheter-directed urokinase from November 1997 to November 1998 (240,000 units/h × 4 h, 120,000 units/h thereafter for a maximum of 48 h) with those of 45 patients receiving catheter-directed t-PA from November 1998 to August 2000 (2 mg/h, total dose ≤100 mg) for acute arterial occlusion (AAO) and acute venous occlusion (AVO). Interventional approaches such as cross-catheter and coaxial techniques were used to reduce the dose of lytic agent needed to achieve pre–lysis-treatment goals (eg, complete lysis of all thrombus/unmasking graft stenosis or establishing outflow target). Statistical analysis was performed using Student t test and Fisher exact test. Results: The urokinase and t-PA groups were comparable with regard to age, comorbidities (coronary artery disease, hypertension, diabetes, renal insufficiency, smoking), duration of ischemic or occlusive symptoms, location of occlusive process, pretreatment with warfarin, and thrombotic versus embolic and native versus graft occlusion in patients with AAO. In patients with AAO and in those with AVO, t-PA was equivalent to or better than urokinase with regard to percent of clot lysis, incidence of major bleeding complications, limb salvage, and mortality. Achievement of pretreatment goals (arterial patients only) was 50% for urokinase patients and 76% for t-PA patients (P =.02). Analysis of success in individual pretreatment-goal achievement showed urokinase and t-PA to be equivalent in unmasking stenoses (85% and 84%, respectively; P = NS), whereas t-PA was superior to urokinase in the more critical task of establishing run-off (39% versus 81% for urokinase and t-PA, respectively; P =.001). Additional interventions, either endovascular or surgical, were required in 60% and 51% (P = NS) of patients receiving urokinase and t-PA, respectively, for AAO, and in 54% and 62% (P = NS) of patients receiving urokinase and t-PA, respectively, for AVO. Conclusions: Limited-dose t-PA is a safe and effective therapy for AAO and AVO when administered by experienced teams using innovative but well-established interventional techniques. (J Vasc Surg 2001;34:854-9.

Explant analysis of AneuRx stent grafts: relationship between structural findings and clinical outcome

AbstractObjectiveWe reviewed the structural findings of explanted AneuRx stent grafts used to treat abdominal aortic aneurysms, and relate the findings to clinical outcome measures.MethodsWe reviewed data for all bifurcated AneuRx stent grafts explanted at surgery or autopsy and returned to the manufacturer from the US clinical trial and worldwide experience of more than 33,000 implants from 1996 to 2003. Devices implanted for more than 1 month with structural analysis are included in this article. Explant results were analyzed in relation to cause of explantation and pre-explant evidence of endoleak, enlargement, or device migration.ResultsOne hundred twenty explanted stent grafts, including 37 from the US clinical trial, were analyzed. Mean implant duration was 22 ± 13 months (range, 1-61 months). Structural abnormalities included stent fatigue fractures, fabric abrasion holes, and suture breaks. The mean number of nitinol stent strut fractures per explanted device was 3 ± 4, which represents less than 0.2% of the total number of stent struts in each device. The mean number of fabric holes per explanted device was 2 ± 3, with a median hole size of 0.5 mm2. Suture breaks were seen in most explanted devices, but composed less than 1.5% of the total number of sutures per device. “For cause” explants (n = 104) had a 10-month longer implant duration (P = .007) compared with “incidental” explants (n = 16). “For cause” explants had more fractures (3 ± 5; P = .005) and fabric holes (2 ± 3; P = .008) per device compared with “incidental” explants, but these differences were not significant (P = .3) when adjusted for duration of device implantation. Among clinical trial explants the number of fabric holes in grafts in patients with endoleak (2 ± 3 per device) was no different from those without endoleak (3 ± 4 per device; P = NS). The number of fatigue fractures or fabric holes was no different in grafts in clinical trial patients with pre-explant aneurysm enlargement compared with those without enlargement. Pre-explant stent-graft migration was associated with a greater number of stent strut fractures (5 ± 7 per device; P = .04) and fabric holes (3 ± 3 per bifurcation; P = .03) compared with explants without migration. Serial imaging studies revealed inadequate proximal, distal, or junctional device fixation as the probable cause of rupture or need for conversion to open surgery in 86% of “for cause” explants. Structural device abnormalities were usually remote from fixation sites, and no causal relationship between device findings and clinical outcome could be established.ConclusionsNitinol stent fatigue fractures, fabric holes, and suture breaks found in explanted AneuRx stent grafts do not appear to be related to clinical outcome measures. Longer term studies are needed to confirm these observations

Systematic review and meta-analysis of the diagnostic accuracy of ultrasonography for deep vein thrombosis

Background Ultrasound (US) has largely replaced contrast venography as the definitive diagnostic test for deep vein thrombosis (DVT). We aimed to derive a definitive estimate of the diagnostic accuracy of US for clinically suspected DVT and identify study-level factors that might predict accuracy. Methods We undertook a systematic review, meta-analysis and meta-regression of diagnostic cohort studies that compared US to contrast venography in patients with suspected DVT. We searched Medline, EMBASE, CINAHL, Web of Science, Cochrane Database of Systematic Reviews, Cochrane Controlled Trials Register, Database of Reviews of Effectiveness, the ACP Journal Club, and citation lists (1966 to April 2004). Random effects meta-analysis was used to derive pooled estimates of sensitivity and specificity. Random effects meta-regression was used to identify study-level covariates that predicted diagnostic performance. Results We identified 100 cohorts comparing US to venography in patients with suspected DVT. Overall sensitivity for proximal DVT (95% confidence interval) was 94.2% (93.2 to 95.0), for distal DVT was 63.5% (59.8 to 67.0), and specificity was 93.8% (93.1 to 94.4). Duplex US had pooled sensitivity of 96.5% (95.1 to 97.6) for proximal DVT, 71.2% (64.6 to 77.2) for distal DVT and specificity of 94.0% (92.8 to 95.1). Triplex US had pooled sensitivity of 96.4% (94.4 to 97.1%) for proximal DVT, 75.2% (67.7 to 81.6) for distal DVT and specificity of 94.3% (92.5 to 95.8). Compression US alone had pooled sensitivity of 93.8 % (92.0 to 95.3%) for proximal DVT, 56.8% (49.0 to 66.4) for distal DVT and specificity of 97.8% (97.0 to 98.4). Sensitivity was higher in more recently published studies and in cohorts with higher prevalence of DVT and more proximal DVT, and was lower in cohorts that reported interpretation by a radiologist. Specificity was higher in cohorts that excluded patients with previous DVT. No studies were identified that compared repeat US to venography in all patients. Repeat US appears to have a positive yield of 1.3%, with 89% of these being confirmed by venography. Conclusion Combined colour-doppler US techniques have optimal sensitivity, while compression US has optimal specificity for DVT. However, all estimates are subject to substantial unexplained heterogeneity. The role of repeat scanning is very uncertain and based upon limited data

Analysis and computer program for rupture-risk prediction of abdominal aortic aneurysms

BACKGROUND: Ruptured abdominal aortic aneurysms (AAAs) are the 13(th )leading cause of death in the United States. While AAA rupture may occur without significant warning, its risk assessment is generally based on critical values of the maximum AAA diameter (>5 cm) and AAA-growth rate (>0.5 cm/year). These criteria may be insufficient for reliable AAA-rupture risk assessment especially when predicting possible rupture of smaller AAAs. METHODS: Based on clinical evidence, eight biomechanical factors with associated weighting coefficients were determined and summed up in terms of a dimensionless, time-dependent severity parameter, SP(t). The most important factor is the maximum wall stress for which a semi-empirical correlation has been developed. RESULTS: The patient-specific SP(t) indicates the risk level of AAA rupture and provides a threshold value when surgical intervention becomes necessary. The severity parameter was validated with four clinical cases and its application is demonstrated for two AAA cases. CONCLUSION: As part of computational AAA-risk assessment and medical management, a patient-specific severity parameter 0 < SP(t) < 1.0 has been developed. The time-dependent, normalized SP(t) depends on eight biomechanical factors, to be obtained via a patient's pressure and AAA-geometry measurements. The resulting program is an easy-to-use tool which allows medical practitioners to make scientific diagnoses, which may save lives and should lead to an improved quality of life

Predictors of adverse events after endovascular abdominal aortic aneurysm repair: A meta-analysis of case reports

Introduction: Endovascular abdominal aortic aneurysm repair is a life-saving intervention. Nevertheless, complications have a major impact. We review the evidence from case reports for risk factors of complications after endovascular abdominal aortic aneurysm repair. Case presentation: We selected case reports from PubMed reporting original data on adverse events after endovascular abdominal aortic aneurysm repair. Extracted risk factors were: age, sex, aneurysm diameter, comorbidities, re-interventions, at least one follow-up visit being missed or refusal of a re-intervention by the patient. Extracted outcomes were: death, rupture and (non-)device-related complications. In total 113 relevant articles were selected. These reported on 173 patients. A fatal outcome was reported in 15% (N = 26) of which 50% came after an aneurysm rupture (N = 13). Non-fatal aneurysm rupture occurred in 15% (N = 25). Endoleaks were reported in 52% of the patients (N = 90). In half of the patients with a rupture no prior endoleak was discovered during follow-up. In 83% of the patients one or more re-interventions were performed (N = 143). Mortality was higher among women (risk ratio 2.9; 95% confidence interval 1.4 to 6.0), while the presence of comorbidities was strongly associated with both ruptures (risk ratio 1.6; 95% confidence interval 0.9 to 2.9) and mortality (risk ratio 2.1; 95% confidence interval 1.0 to 4.7). Missing one or more follow-up visits (≥1) or refusal of a re-intervention by the patient was strongly related to both ruptures (risk ratio 4.7; 95% confidence interval 3.1 to 7.0) and mortality (risk ratio 3.8; 95% confidence interval 1.7 to 8.3). Conclusion: Female gender, the presence of comorbidities and at least one follow-up visit being missed or refusal of a re-intervention by the patient appear to increase the risk for mortality after endovascular abdominal aortic aneurysm repair. Larger aneurysm diameter, higher age and multimorbidity at the time of surgery appear to increase the risk for rupture and other complications after endovascular abdominal aortic aneurysm repair. These risk factors deserve further attention in future studies