Costs of open versus endovascular abdominal aortic aneurysm repair.
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Aortic Aneurysm, Abdominal↗
Biomedical subjects
Thomas L Forbes
Publications and source records attributed to Thomas L Forbes.
Cumulative sum failure analysis of the learning curve with endovascular abdominal aortic aneurysm repair.
PURPOSE: The purpose of this study was to evaluate the importance of experience and the learning curve with endovascular abdominal aortic aneurysm (AAA) repair. METHODS: A retrospective analysis was performed of all elective endovascular AAA repairs attempted by an individual surgeon and radiologist over a 4-year period. The primary outcome variable was achievement and 30-day maintenance of initial clinical success as defined by the Society for Vascular Surgery/American Association of Vascular Surgery reporting standards. Following standard statistical analysis, the cumulative sum (CUSUM) method was used to analyze the learning curve, with a predetermined acceptable failure rate of 10% and calculated 80% alert and 95% alarm lines. RESULTS: Ninety-six elective endovascular AAA repairs were attempted by this team between 1998 and 2002 (mean age 74 +/- 0.8 years; mean aneurysm diameter 5.98 +/- 0.8 cm). Initial clinical success was achieved and maintained in 85 of 96 patients (88.5%). Although results were acceptable throughout the study period, improved results with respect to the target failure rate (10%) were not achieved until 60 patients were treated. The learning or CUSUM curves did not differ for different device manufacturers, with improved results being achieved following 20 implantations of each device. The results did differ when comparing aortouniiliac grafts (n = 27) and bifurcated grafts (n = 64). Results with bifurcated grafts remained consistent throughout the study period, whereas with aortouniiliac grafts, results improved after only a few procedures in comparison with the target failure rate. CONCLUSION: Success rates with endovascular aneurysm repair will improve with an individual's experience. The CUSUM method is a valuable tool in the evaluation of this learning curve, which has credentialing and training implications. Although acceptable results were obtained throughout the study period, this analysis indicates that 60 endovascular aneurysm repairs, or 20 with an individual device, are necessary before optimal rates of initial clinical success can be achieved. These results can be achieved more readily with aortouniiliac grafts than with bifurcated grafts.
Aged↗
Management of blunt thoracic aortic injuries: endovascular stents versus open repair.
BACKGROUND: Endovascular stent graft (EV) technology has been successfully adapted to the repair of blunt traumatic aortic injuries. The purpose of this study was to compare the outcomes of patients treated with EV repair and open repair after blunt thoracic aortic trauma. METHODS: A review of a tertiary trauma center's prospective trauma registry identified all patients who suffered a blunt traumatic thoracic aortic injury over an 11-year period (1991-2002). Operative interventions and outcomes were then compared. RESULTS: Over an 11-year period, 18 patients underwent repair of a blunt thoracic aortic injury (EV, 6; open, 12). There were no significant differences in demographics, injury, or crash statistics between groups. The open group had a 17% early mortality rate (n = 2), a paraplegia rate of 16% (n = 2), and an 8.3% incidence of recurrent laryngeal nerve injury (n = 1). This is in contrast to a 0% rate of mortality, paraplegia, and recurrent laryngeal nerve injury in the EV group. A definite trend toward decreased morbidity, mortality, intensive care unit length of stay, and number of ventilator-dependent days was seen with EV repair. CONCLUSION: We observed a clear trend toward improved outcomes after EV repair of thoracic aortic injuries compared with standard open repair. EV repair is emerging as the preferred method of repairing blunt thoracic aortic injuries in trauma patients with multiple injuries.
Adult↗
Chronic lower extremity ischemia: a human model of ischemic tolerance.
BACKGROUND: Ischemic preconditioning (IPC) has been found in animals to have a protective effect against future ischemic injury to muscle tissue. Such injury is unavoidable during some surgical procedures. To determine whether chronic ischemia in the lower extremities would imitate IPC and reduce ischemic injury during vascular surgery, we designed a controlled clinical study. PATIENTS AND METHODS: Two groups of patients at a university-affiliated medical centre with chronic lower-extremity ischemia served as models of IPC: 6 patients awaiting femoral distal bypass (FDB) and 4 scheduled for aortobifemoral (ABF) bypass grafting for aortoiliac occlusive disease. Seven patients undergoing elective open repair of an infrarenal abdominal aortic aneurysm (AAA) were chosen as non-IPC controls. Three hematologic indicators of skeletal-muscle injury, lactate dehydrogenase (LDH), creatine kinase (CK) and myoglobin, were measured before placement of the proximal clamp, during surgical ischemia, immediately upon reperfusion, 15 minutes after and 1 hour after reperfusion, and during the first, second and third postoperative days. RESULTS: Baseline markers of skeletal-muscle injury were similar in all groups. In postreperfusion samples, concentrations of muscle-injury markers were significantly lower in the 2 PC groups than in the control group. For example, at day 2, LDH levels were increased by about 30% over baseline measures in the elective AAA (control) group, whereas levels in the FDB and ABF groups remained statistically unchanged from baseline. Myoglobin in controls had increased by 977%, but only by 160% in the FDB and 528% in the ABF groups. CK levels, in a similar trend, were 1432% higher in the control group and only 111% (FDB) and 1029% (ABF) in the study groups. Taken together, these data represent a significant level of protection. CONCLUSIONS: Patients with chronic lower-extremity ischemia suffered less severe ischemic injury after a period of acute ischemia than those with acute ischemia alone. Ischemic preconditioning is one proposed mechanism to help explain this protective effect.
Aged↗
Is intensive care necessary after elective abdominal aortic aneurysm repair?
BACKGROUND: To review morbidity and mortality of patients undergoing elective, open repair of infra-renal abdominal aortic aneurysms and were admitted postoperatively to a surgical stepdown unit rather than routinely to the intensive care unit (ICU), we carried out a retrospective review. METHODS: All patients undergoing this type of repair in our centre, a division of vascular surgery in a tertiary-care teaching hospital in Ontario, over a 27-month period were reviewed. A consecutive 230 patients who underwent aneurysm repair from September 1999 through November 2001 were routinely admitted to a surgical stepdown unit postoperatively, with only a minority of patients requiring admission to ICU. We reviewed the rate of initial ICU admission and that of subsequent ICU admission after stepdown-unit admission. We also assessed morbidity, mortality and length of hospital stay for patients admitted to ICU as well as those admitted to the stepdown unit. RESULTS: ICU admission was avoided in 204 (89%) of these patients. The remaining 26 patients (11%) required ICU admission at some point during their hospital stay. Only 3 patients (1%) originally admitted to the stepdown unit subsequently required postoperative admission to ICU. CONCLUSIONS: Our experience demonstrates that proper preoperative assessment and selection allows the majority of elective infra-renal aneurysm repairs to be safely cared for postoperatively in a stepdown unit, and that subsequent ICU admissions are rare.
Aged↗
Combined trauma laparotomy and endovascular repair of thoracic aortic injury.
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Accidents, Traffic↗
Limitations of ischemic tolerance in oxidative skeletal muscle: perfusion vs tissue protection.
OBJECTIVES: This study determined if ischemic tolerance occurs in oxidative skeletal muscle following a severe ischemia/reperfusion (I/R) insult and if such protection involves the induction of nitric oxide synthase (NOS). METHODS: The soleus muscle of male Wistar rats (250-350 g) was preconditioned (PC + I/R) using five cycles of ischemia (10 min) and reperfusion (10 min) or had no PC (I/R) and 24 h later 2 h no-flow ischemia was induced. Calcium dependent (cNOS) and independent (iNOS) NOS activities were determined from PC (n = 5), or sham (n = 5) and the role of iNOS was tested by application of aminoguanidine (AMG) (100 microM; n = 4) to the muscle bath. Direct measures of the number of perfused capillaries (Npc; #/mm) during 90-min reperfusion were obtained using intravital microscopy. Tissue injury was estimated using the fluorescent vital dyes ethidium bromide (E; labels injured cells) and bisbenzimide (B; labels all cells) and expressed as the ratio E/B. RESULTS: PC prevented microvascular flow deficits (Npc:I/R = 23.4 +/- 1.3 vs PC + I/R = 29.9 +/- 1.1) and resulted in a modest, but significant reduction (21%) in tissue injury (I/R = 0.82 +/- 0.03 vs PC + I/R = 0.64 +/- 0.04). PC led to a nine fold increase in iNOS activity, but decreased cNOS activity by 94% compared to sham. AMG prevented the parenchymal protection following PC, but had no effect on microvascular perfusion. CONCLUSIONS: Ischemic tolerance, 24 h following PC, preserved microvascular perfusion, but only modestly improved tissue viability in the soleus muscle.
Animals↗
Synchronous fluorescence spectrometry of 1-hydroxypyrene: a rapid screening method for identification of PAH exposure in tissue from marine polychaetes.
The uptake of polycyclic aromatic hydrocarbons (PAHs) by marine deposit-feeding invertebrates can be determined by screening for PAH-derived metabolites. We identified 1-hydroxypyrene as the only intermediate metabolite in tissue of four species of deposit-feeding polychaetes, Nereis diversicolor, Nereis virens, Arenicola marina, and Capitella sp. I exposed to pyrene spiked sediment. Synchronous fluorescence spectroscopy (SFS) provides a fast and simple method for both qualitative and quantitative analysis of 1-hydroxypyrene in all four species. The SFS assay was validated using HPLC with ultraviolet detection. A good correlation between 1-hydroxypyrene concentrations determined by the two methods was observed. We used HPLC with fluorescence detection combined with enzymatic hydrolysis of conjugated metabolites to investigate species specific metabolite patterns. A tentative aqueous metabolite identification scheme indicates that Nereid polychaetes predominately make use of glucuronide conjugation whereas Capitella sp. I. and Arenicola marina appear to utilize predominantly sulfate and/or glucoside conjugation. The usefulness of 1-hydroxypyrene as a biomarker for PAH exposure in deposit-feeding invertebrates is discussed.
Animals↗
1-Hydroxypyrene glucuronide as the major aqueous pyrene metabolite in tissue and gut fluid from the marine deposit-feeding polychaete Nereis diversicolor.
Both 1-hydroxypyrene and 1-hydroxypyrene glucuronide are identified as the primary phase I and phase II metabolites of the four-ringed polycyclic aromatic hydrocarbon (PAH) pyrene in the marine deposit-feeding polychaete Nereis diversicolor. Identification of pyrene and primary metabolites was performed using high-pressure liquid chromatography (HPLC) with diode-array detection and fluorescence detection (HPLC/DAD/F) and an ion-trap mass spectrometer for positive identification of 1-hydroxypyrene glucuronide. Besides 1-hydroxypyrene and 1-hydroxypyrene glucuronide, the HPLC/F trace of tissue samples from pyrene-exposed worms showed three additional low-intensity peaks that may be related to pyrene metabolism based on similar excitation/emission wavelengths. The peaks were all too low in intensity to be positively identified. Of the total PAH in tissue, 1-hydroxypyrene glucuronide, 1-hydroxypyrene, and pyrene constituted 73%, 2%, and 25% respectively. Gut elimination of metabolic products is supported by the identification of 1-hydroxypyrene and 1-hydroxypyrene glucuronide in both gut fluid and defecation water. Being the only phase I metabolite of pyrene, 1-hydroxypyrene becomes a useful marker for PAH exposure, and it may serve as a valuable model compound for assessing species-specific PAH metabolic capabilities.
Animals↗
A CUSUM analysis of ruptured abdominal aortic aneurysm repair.
Studies have investigated the role of hospital and surgeon case volume in outcome after ruptured abdominal aortic aneurysm repair (rAAA). Few have analyzed the learning curve of an individual surgeon. The purpose of this study was to analyze this learning curve in reducing morbidity and mortality after rAAA repair. Thirty-two consecutive patients who underwent rAAA repair during the initial 2.5 years of a vascular surgeon's career were reviewed retrospectively. They were divided temporally into two groups of 16 patients (groups 1 and 2). Outcome measures included mortality, postoperative myocardial infarction, stroke, and renal and respiratory failure. Perioperative variables previously associated with increased mortality were analyzed. The cumulative sum (CUSUM) method was used to analyze the learning curve with respect to published acceptable event rates and predetermined 80% alert and 95% alarm boundary lines. Groups 1 and 2 did not differ statistically in age, preoperative blood pressure, hemoglobin or creatinine. There was no difference in transfusion requirements (6.8 +/- 1.2 units vs. 6.4 +/- 1.0 units; p = 0.78), urine output (340 +/- 65 mL vs. 389 +/- 94 mL; p = 0.72) or clamp position. There was no difference in the incidence of postoperative myocardial infarction, stroke, or respiratory or renal failure. Thirty-day mortality in group 2 was 12% as compared to 50% in Group 1 (p = 0.03). On CUSUM analysis, the cumulative failure rate in group 2 progressed lower than the 80% reassurance line, indicating improved results with time. Mortality after rAAA repair decreased over time during an early period of an individual surgeon's career. The CUSUM method is a valuable tool in analyzing an individual surgeon's experience and shows promise in quality control in vascular surgery.
Aged↗
Acute aortic thrombosis following incorrect application of the Heimlich maneuver.
The Heimlich maneuver has been widely accepted as a safe and effective method of relieving life-threatening foreign-body upper airway obstruction. When applied incorrectly, however, it may result in direct trauma to the intraabdominal viscera. Only two cases of major aortic complications have been reported. Both have involved thrombosis of an abdominal aortic aneurysm. We report two further instances of aortic thrombotic complications due to the incorrect application of the Heimlich maneuver. The first case resulted in thrombosis of an abdominal aortic aneurysm. In the second case the abdominal thrusts caused dislodgement of thrombus from an atherosclerotic nonaneurysmal aorta, which resulted in thromboembolic occlusion of both lower extremities. In both cases, as with the two previously reported instances, massive reperfusion injury resulted, which eventually proved fatal. When applied incorrectly, the Heimlich maneuver may result in direct trauma to the abdominalaorta and is an unusual cause of acute aortic thrombosis.
Acute Disease↗
Glomus vagale: paraganglioma of the vagus nerve.
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Aged↗
Popliteal artery false aneurysm secondary to tibial osteochondroma.
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Adult↗
Is long-term anticoagulation after acute thromboembolic limb ischemia always necessary?
OBJECTIVE: After thromboembolectomy, patients with acute limb ischemia often receive anticoagulant therapy to prevent recurrent events. Patients with atrial fibrillation or cardiac thrombus have a higher risk of recurrent emboli than those without these risk factors. This study examines the importance of long-term anticoagulation in these 2 groups. DESIGN: A review of patients presenting with acute limb ischemia over a 5-year period (1994-1999). SETTING: A university-affiliated medical centre. PATIENTS: Fifty patients divided into 2 groups: 19 (38%) patients with atrial fibrillation (group 1) and 31 (62%) patients with no atrial fibrillation or cardiac thrombus (group 2) as confirmed by transthoracic echocardiography. INTERVENTION: All patients underwent surgical thromboembolectomy and received postoperative anticoagulant therapy. OUTCOME MEASURES: Mortality, limb loss, further thromboembolic events and bleeding complications as determined by telephone survey. RESULTS: There was a significant difference in 5-year survival (group 1, 84%; group 2, 64%) and early limb loss (group 1, 0%; group 2, 13%). Further thromboembolic events and bleeding complications were rare but were more common in group 1. In group 2 there were no instances of recurrent thromboemboli and no bleeding complications although only 39% of patients in this group were taking angicoagulants at the end of the study period. CONCLUSIONS: Patients with extremity thromboemboli without atrial fibrillation or cardiac thrombus may not be at the same risk for recurrent events as those with these risk factors, and long-term anticoagulant therapy may not be as necessary in this group.
Adult↗
A cost-effectiveness analysis of standard versus endovascular abdominal aortic aneurysm repair.
OBJECTIVE: To compare endovascular and standard open repair of abdominal aortic aneurysms in terms of initial in-hospital costs and the costs of secondary interventions and surveillance. DESIGN: A retrospective study. SETTING: A university-affiliated tertiary care medical centre. PATIENTS: Seven patients who underwent elective endovascular (EV) repair of an abdominal aortic aneurysm in 1998 and 31 patients anatomically suitable for endovascular repair who underwent standard (STAN) elective repair. Follow-up ranged from 2 to 14 months. INTERVENTIONS: Elective repair of an abdominal aortic aneurysm with use of the standard technique or endovascular technology. OUTCOME MEASURES: Costs common to both groups were not determined. Costs were determined for total hospital stay, preoperative or postoperative embolization, grafts, additional endovascular equipment, and follow-up computed tomography. RESULTS: Groups were similar with respect to demographic data and aneurysm size (EV = 6.23 cm v. STAN = 6.05 cm). All patients were in American Society of Anesthesiologists class III or IV. Vanguar bifurcated grafts and extensions were used in the EV group. The total cost for both groups in Canadian dollars included: cost of stay (EV, 5.6 d, $2092.63 v. STAN, 10.7 d, $4449.19; p = 0.009); cost of embolization (EV, n = 3; $900/procedure); cost of follow-up CT (EV, 5.4 per patient; $450/CT); cost of grafts (EV = $8571.43, STAN = $374); additional radiologic equipment costs (EV = $1475). The mean total cost differed significantly between the 2 groups (EV = $14,967.63 v. STAN = $4823.19; p = 0.004). The additional cost associated with a reduction in hospital stay was calculated by determining the incremental cost-effectiveness ratio (ICER, difference in mean costs/difference in mean length of stay = $1604.51). CONCLUSIONS: Endovascular repair continues to be more expensive than standard open repair determined according to procedural and follow-up costs. The technology is still in the developmental stage, but as it evolves and follow-up protocols are streamlined, it is hoped that there will be an eventual reduction in the costs associated with the endovascular procedure.
Aortic Aneurysm, Abdominal↗
Tuberculous aneurysm of the supraceliac aorta--a case report.
Significant vascular complications are rare following systemic infections with Mycobacterium tuberculosis (TB). This report describes a 33-year-old man who presented with a short history of abdominal discomfort and febrile episodes with no prior history of infection with TB. Ultrasound, CT scan, and aortography confirmed the presence of a pseudoaneurysm originating from the posterior aspect of the supraceliac aorta at the level of the diaphragm. Via a full thoracoabdominal approach, periaortic inflammatory tissue and the aortic wall itself were debrided, and repair of the pseudoaneurysm was achieved with a synthetic patch. Mycobacterium tuberculosis was isolated from the aortic wall, and anti-TB medications were instituted. Postoperatively the patient did well and was discharged after 14 days. As illustrated by this case, tuberculous mycotic aneurysms of the aorta are optimally treated with a combination of medical and surgical therapy, and early diagnosis is essential to ensure survival.
Adult↗
Abdominal aortic aneurysms following orthotopic heart transplantation.
The purpose of these authors' study was to analyze their center's experience with orthotopic heart transplantation (OHT) and abdominal aortic aneurysms (AAA) with particular attention to corticosteroid dosing, hemodynamic parameters, and aneurysm growth rate. A retrospective review of all patients (453) who underwent OHT at their university-affiliated medical center over an 18-year period (1981-1999) was undertaken. Nine (2%) patients who developed AAAs were identified and aneurysm growth was correlated with corticosteroid immunosuppression and hemodynamic parameters. The mean age of OHT patients was 44.5 +/-15 years and the majority were males (371 males, 82%). Median follow-up was 5.7 years. Ischemic cardiomyopathy (IC) was the most common indication for transplantation (45.5% of patients). All AAA patients were male (p=0.157), with a mean age of 58.4 +/-4.8 years (p=0.001), and had undergone OHT for IC (p=0.001). Mean arterial blood pressure and ejection fraction in the AAA patients had increased from pretransplant values of 107 mm Hg and 14.3 +/-5.7% to 142 mm Hg (p=0.017) and 54.1 +/-14.1% (p<0.001), respectively, before aneurysm repair. Mean aneurysm diameter at the time of repair was 6.0 +/-0.8 cm, and the average growth rate was 1.2 +/-0.4 cm/year in the 4 patients in whom it could be measured. Aneurysm repair was performed urgently in 2 patients and electively in 7 patients with 1 early postoperative death (11%). The extent of corticosteroid immunosuppression, corticosteroid pulses, and total corticosteroid dosing did not correlate with the rate of aneurysm growth. Improved hemodynamics and progressive posttransplant hypertension may contribute to aneurysm formation and growth in this group of patients.
Adrenal Cortex Hormones↗
Outcomes of hemodialysis-dependent patients following elective abdominal aortic aneurysm repair.
As hemodialysis-dependent patients have a shorter life expectancy it has been recently questioned whether they benefit from procedures such as abdominal aortic aneurysm (AAA) repair. The purpose of this study was to review our results with elective AAA repair in hemodialysis-dependent patients. During a recent 6-year period (1998-2003), 7 such patients underwent elective repair of their infrarenal aortic aneurysms. Mean age and aneurysm diameter were 71 years and 69 mm, respectively. Mean length of stay was 28.6 days including routine intensive care unit admission. Three patients underwent standard open repair, and 3 underwent endovascular repair. In the seventh patient iliac calcification precluded endograft delivery and resulted in conversion to open repair. Another endovascular patient suffered from perforation of her sigmoid colon. One- and 3-year survival rates in the entire cohort were 100% and 75%, respectively. The authors conclude that aneurysm repair in hemodialysis patients is warranted and life prolonging in appropriate risk patients, despite lengthy hospital stays. However, successful endovascular repair may be prevented by the severe arterial calcification in these patients.
Aged↗