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Biomedical subjects

M C Donaldson

Publications and source records attributed to M C Donaldson.

At least 19 recordsLinked to original sources
PubMed1999

Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery.

BACKGROUND: Cardiac complications are important causes of morbidity after noncardiac surgery. The purpose of this prospective cohort study was to develop and validate an index for risk of cardiac complications. METHODS AND RESULTS: We studied 4315 patients aged > or = 50 years undergoing elective major noncardiac procedures in a tertiary-care teaching hospital. The main outcome measures were major cardiac complications. Major cardiac complications occurred in 56 (2%) of 2893 patients assigned to the derivation cohort. Six independent predictors of complications were identified and included in a Revised Cardiac Risk Index: high-risk type of surgery, history of ischemic heart disease, history of congestive heart failure, history of cerebrovascular disease, preoperative treatment with insulin, and preoperative serum creatinine >2.0 mg/dL. Rates of major cardiac complication with 0, 1, 2, or > or = 3 of these factors were 0.5%, 1.3%, 4%, and 9%, respectively, in the derivation cohort and 0.4%, 0.9%, 7%, and 11%, respectively, among 1422 patients in the validation cohort. Receiver operating characteristic curve analysis in the validation cohort indicated that the diagnostic performance of the Revised Cardiac Risk Index was superior to other published risk-prediction indexes. CONCLUSIONS: In stable patients undergoing nonurgent major noncardiac surgery, this index can identify patients at higher risk for complications. This index may be useful for identification of candidates for further risk stratification with noninvasive technologies or other management strategies, as well as low-risk patients in whom additional evaluation is unlikely to be helpful.

Aged↗
PubMed1999

Improved graft patency and altered remodeling in infrainguinal vein graft reconstruction for aneurysmal versus occlusive disease.

PURPOSE: This study attempted to determine whether autogenous vein used for infrainguinal reconstruction in patients with aneurysmal disease might demonstrate an altered adaptive response compared with those patients who underwent reconstructive surgery for occlusive disease, potentially altering graft patency. METHODS: From 1974 to 1997, 43 patients underwent vein grafting for 60 popliteal artery aneurysms (PAA). RESULTS: In an attempt to monitor early vein graft adaptation, serial graft surveillance by Duplex ultrasound scan was performed in a statistically valid subset of age-, sex-, and distal anastomotic site-matched patients with PAA and patients with occlusive disease (OD; n = 8 PAA; n = 8 OD). Compared with an age-matched and sex-matched cohort of patients (n = 60 grafts in each group) with occlusive disease and who had femoral below-knee bypass grafts (FBP) only, patients undergoing infrainguinal reconstruction for PAA had a higher 5-year primary graft patency (92% +/- 4% for PAA vs 66% +/- 7% for FBP; P <.01). Duplex surveillance demonstrated a progressive increase in arterialized vein graft diameter in the PAA group versus the OD group. In univariant analysis, aneurysmal disease was a significant predictor of final follow-up diameter (P =.002). In a linear regression model, controlling for diameter at first follow-up after bypass grafting, first follow-up diameter was also predictive of final follow-up diameter. CONCLUSION: These data suggested altered remodeling of vein grafts in patients with popliteal artery aneurysm, which may have a beneficial effect on patency.

Adult↗
PubMed1998

Early operative intervention after thrombolytic therapy for primary subclavian vein thrombosis: an effective treatment approach.

PURPOSE: Effective treatment of primary subclavian vein thrombosis focuses on restoration of venous patency, relief of intrinsic stenosis, and decompression of the thoracic inlet. The appropriate method and timing for surgery, however, have not been not well defined. We conducted a study to determine an acceptable treatment approach. METHODS: A retrospective review evaluated 11 patients seen at our institution in an 8-year period. Seven patients were male and four were female, with an average age of 30 years (range 15 to 54 years). Two patients who had symptomatic stenosis without occlusion were omitted from the study. All patients with occlusion received urokinase therapy and underwent surgical decompression within 5 days of thrombolytic therapy. Five percutaneous transluminal angioplasties were attempted before operative intervention. Eleven decompressions were performed, including nine first-rib resections and two scalenectomies. Five operative venous procedures, consisting of thrombectomy with patch closure (n = 3) and bypass (n = 2), and seven venolysis procedures were performed. All patients received coumadin for 3 to 6 months after the operation. RESULTS: Urokinase therapy established wide venous patency in nine of the 11 extremities treated, with the remaining two requiring thrombectomy for residual thrombus at the time of operation. One patient who underwent transluminal angioplasty before the operation had rethrombosis, and the remaining four showed no improvement in venous stenosis after the intervention. Eight of nine extremities treated by first-rib resection and one of two treated by scalenectomy were free of residual symptoms at follow-up. CONCLUSIONS: Preoperative use of percutaneous balloon angioplasty is ineffective and should be avoided in this setting. Surgical intervention within days of thrombolysis obviates the need for interim oral anticoagulation and enables patients to return to normal activity sooner.

Adolescent↗
PubMed1998

Cost-identification analysis of revascularization procedures on patients with peripheral arterial occlusive disease.

OBJECTIVE: To determine average total in-hospital costs of various revascularization procedures for peripheral arterial occlusive disease; to examine the effect of procedure-related complications and patient characteristics on these costs; and to examine whether costs have changed over time. METHODS: We collected cost data on all admissions involving one revascularization procedure for peripheral arterial occlusive disease at the Brigham and Women's hospital from 1990 through 1995 (n = 583). The main outcome measures were total costs per admission in 1995 US dollars and length of stay in days. RESULTS: For each of 12 different procedures identified, total costs per admission varied considerably. Multiple linear regression analysis was performed to determine the effect of local and systemic complications and of patient characteristics on total in-hospital costs per admission. The additional cost incurred for fatal systemic complications was $11,675 (P = .004) and for nonfatal systemic complications was $9345 (P < .001). The results demonstrated significant additional costs with management of critical ischemia versus intermittent claudication ($4478, P < .001), presence of coronary artery disease ($1287, P = .05), female sex ($1461, P = .03), and advanced age ($1345, P = .02). No statistically significant changes over time were demonstrated. CONCLUSION: Total in-hospital costs per admission for peripheral revascularization procedures are highly variable and significantly increased by procedure-related complications, advanced age, female sex, management of critical ischemia, and presence of coronary artery disease.

Adult↗
PubMed1998

Contralateral symptoms after unilateral intervention for peripheral occlusive disease.

OBJECTIVE: The objectives of this study were (1) to determine the incidence of contralateral symptoms in patients with a unilateral intervention for peripheral arterial occlusive disease and (2) to identify characteristics that predict these symptoms. SUBJECTS AND SETTING: We included patients who had a unilateral surgical or percutaneous intervention for peripheral arterial occlusive disease at the Brigham and Women's Hospital (Boston) between 1990 and 1995 (n = 532). MAIN OUTCOME MEASURE: The main outcome measure was the first occurrence of contralateral critical ischemia or intermittent claudication. RESULTS: The annual incidence rate of contralateral critical ischemia was considerable, ranging from 3.3% to 8.3% during the first 4 years after the initial ipsilateral intervention. The annual incidence rate of contralateral critical ischemia and claudication combined varied from 7.7% to 21.3%. Cox regression analysis indicated that the initial ipsilateral symptoms and the initial contralateral ankle/brachial index can be used to predict the occurrence of contralateral symptoms. After correction was done for these two variables, we found no statistically significant effects for other factors including age, sex, diabetes, smoking, antihypertensive medication, history of coronary artery disease, the type of intervention, and the arterial level of the intervention. CONCLUSIONS: The results of our analysis emphasize that peripheral arterial occlusive disease is essentially a two-limb problem. Especially patients with previous ipsilateral critical ischemia and patients with a poor initial contralateral ankle/brachial index have a high risk for contralateral critical ischemia.

Adult↗
PubMed1997

Optimal methods for autogenous bypass to the anterior tibial artery.

BACKGROUND: Autogenous bypass to the anterior tibial artery (AT) has been increasingly used for infrageniculate revascularization. The conduit may be routed through the interosseous membrane, a pretibial tunnel, or through a lateral thigh and calf tunnel. This study reviewed results of AT bypass to determine the optimal routing method. METHODS: One hundred thirty consecutive vein grafts to the AT were analyzed retrospectively to compare the experience with the interosseous (group I; n = 50), pretibial (group II; n = 51), and lateral (group III; n = 29) routing alternatives. RESULTS: Indications were claudication in 16 (12.3%) and critical ischemia in 114 (87.8%) procedures with no differences among routing subgroups. Ectopic nonreversed and composite conduits were more common in group III. Major operative morbidity occurred after 7 procedures (5.4%) with no differences in early graft failure (7.7% overall) among the three routing subgroups. Wound infections were more common among group I patients, but without predilection to the interosseous tunnel. During a mean follow-up of 24.9 months (0 to 111.2) overall 5-year secondary patency was 70% with no difference among routing technique. CONCLUSION: Optimal routing choice depends on the location of suitable AT, the length of adequate vein conduit, and the surgeon's preference rather than on factors inherent to the method used.

Aged↗
PubMed1997

Mesenteric revascularization during aneurysmectomy.

The most important association between aortic aneurysm surgery and the mesenteric circulation is the potential for inadvertent compromise to the mesenteric trunks and their end organs. Preservation of visceral blood flow is a critical objective in each case, using methods that have been developed as techniques for suprarenal abdominal and thoracoabdominal aneurysmectomy have evolved. Beyond simply preserving what existed, revascularization by endarterectomy or bypass has a role in selected cases to improve the natural history of advanced mesenteric occlusive disease, although the rationale for such prophylactic surgery must remain relatively weak until more is learned about disease progression in the visceral arteries. Finally, a small number of patients with mesenteric ischemic symptoms at the time of aneurysmectomy clearly benefit from combined surgery.

Aortic Aneurysm, Abdominal↗
PubMed1997

Hemodynamic impact of vein graft stenoses and their prediction in the vascular laboratory.

PURPOSE: We undertook this prospective evaluation to define the direct hemodynamic impact of vein graft stenoses and to correlate intraoperative hemodynamic findings with the preoperative duplex scan. METHODS: Twelve consecutive isolated vein graft stenoses were identified in the vascular laboratory during our routine duplex scanning surveillance protocol over 10 months. Peak systolic flow velocity ratios (PSFVRs; velocity within stenosis/velocity proximal to the stenosis) at the stenoses ranged from 2.7 to 10 (mean, 5.5), and ankle-brachial indexes ranged from 0.47 to 0.94 (mean, 0.68) Preoperative arteriograms were obtained and confirmed the isolated stenoses, which radiographically ranged from 20% to 83% diameter reduction (mean, 64%). At the time of surgery the stenotic graft segment was isolated, and simultaneous pressure measurements proximal and distal to the graft stenosis were measured, along with ultrasound transit-time blood flow measurements. Pressure and flow wave forms were recorded for 10 seconds at 200 Hz and were stored on a personal computer-based digital acquisition system. The graft stenoses were then repaired with either a vein patch or short interposition graft, and the hemodynamic measurements were repeated. Fourier transformation of the pressure and flow curves was performed, and the resistance and longitudinal impedance were calculated for each graft segment. RESULTS: Before repair, mean pressure gradients across the stenotic graft segments (delta P) ranged from 1.0 to 74.6 mm Hg (mean, 20.4 mm Hg), and vein graft flow ranged from 4.9 to 140 ml/min (mean, 45.2 ml/min). After repair of the stenotic segments, the mean pressure gradient was decreased to a mean of 1.3 mm Hg, and vein graft flow increased to a mean of 104.8 ml/min. The PSFVR recorded in the vascular laboratory correlated significantly with delta P (r = 0.71; p = 0.01) and allowed prediction of delta P as: delta P = 7.4 (PSFVR) - 19.8. PSFVR also correlated with measured resistance across the stenosis (r = 0.79; p = 0.004). Conversely, the angiographic measurement of stenosis did not correlate significantly with these parameters. The angiographic measurement of stenosis showed a moderate correlation with the PSFVR (r = 0.58; p = 0.046). CONCLUSIONS: The PSFVR, as measured in the laboratory, is an accurate and useful indicator of the hemodynamic impact of vein graft stenosis. Revision of stenotic vein graft segments resulted in a significant improvement in graft hemodynamics.

Blood Flow Velocity↗
PubMed1997

Validation of a new and specific intraoperative measurement of vein graft resistance.

PURPOSE: Clinical studies have revealed that the most important predictor of successful bypass grafting is the origin and quality of the bypass conduit. Attempts at intraoperative evaluation of the hemodynamic properties of the conduit, including assessment of blood flow (Q), pressure gradients (delta P), and resistance (R), have not been useful. This is because each of these parameters measures the characteristics of the graft plus the outflow bed. To date, no specific measurement of the resistive properties of the conduit only is available. The purpose of this investigation was to evaluate longitudinal impedance (ZL) as a measure of conduit-specific resistance and to evaluate its potential in predicting the outcome of infrainguinal vascular reconstructions. METHODS: ZL was measured during surgery in 73 infrainguinal autologous vein reconstructions performed in 68 patients in two separate institutions over a 21-month period. Vein graft ultrasonic transit time Q and delta P (from proximal to distal anastomosis) were measured at baseline and after maximal peripheral vasodilatation with an intraarterial injection of papaverine 30 mg. Waveforms were recorded for 10 seconds at 200 Hz using a digital acquisition system. R was calculated as proximal mean pressure divided by mean blood flow (Q). After Fourier transformation, ZL was calculated as delta P/Q at each harmonic and total ZL (integral of ZL) was defined as the integral of moduli from 0 to 4 Hz. RESULTS: All hemodynamic variables were significantly affected by papaverine vasodilatation (delta P, 3.9 +/- 0.5 vs 6.3 +/- 0.8 mm Hg; Q, 78.2 +/- 7.0 vs 126 +/- 11 ml/min; R, 134 +/- 17 vs 72.7 +/- 6.2 x 10(3) dyne.sec.cm-5; p < 0.0001), except integral of ZL, which remained constant (31.1 +/- 2.8 vs 30.8 +/- 2.8 x 10(3) dyne.cm-5; p = NS). After follow-up of 1 week to 17 months (median, 5 months), the 1-year primary, primary-assisted, and secondary patency rates were 72% +/- 7%, 77% +/- 6%, and 81% +/- 6%, respectively. Using Cox analysis, primary patency was significantly associated with decreased integral of ZL (p = 0.0001), but not with baseline or papaverine-stimulated delta P, Q, delta P/Q, or R integral of ZL > 47 x 10(3) dyne.cm-5 predicted primary failure with 90% positive and negative predictive value. CONCLUSIONS: Intraoperative measurement of integral of ZL in infrainguinal vein grafts is independent of outflow conditions (that is, does not change with papaverine), and hence describes the resistive properties of the conduit only. In addition, these preliminary data suggest that integral of ZL is predictive of short-term primary patency. integral of ZL is the first available hemodynamic measurement that is conduit-specific and may therefore be a better predictor of graft patency than currently available methods.

Aged↗
PubMed1997

Impact of activated protein C resistance on general vascular surgical patients.

PURPOSE: The prevalence of activated protein C resistance (APCR) and associated thrombotic morbidity among patients who undergo arterial reconstruction were investigated. METHODS: Preoperative assays for functional APCR and factor V (Leiden) mutation were performed on 262 patients who underwent arterial reconstructions that consisted of cerebrovascular surgery (109), aortic or iliofemoral procedures (76), or infrainguinal bypass procedures (77). Patients were monitored for thrombotic complications during the postoperative period. RESULTS: Depending on the stringency of the definition used, functional APCR was detected in 10.6% to 22.0% of patients tested. Factor V (Leiden) was found in 5.3% of patients. Thrombotic morbidity consisting of myocardial infarction, cerebrovascular event, or graft thrombosis occurred in 9.9% of patients, who were followed-up for a mean of 4.8 months. No significant overall correlations were found between APCR and thrombotic morbidity. Subgroup analysis revealed significant associations between functional APCR and total early postoperative thrombotic complications and early graft failure, and between factor V (Leiden) and early cerebrovascular events and late graft thrombosis (p < 0.03). CONCLUSIONS: Functional APCR is somewhat more prevalent among general vascular surgical patients than in the general population, but factor V (Leiden) is no more prevalent. APCR is not a prominent cause of thrombotic morbidity in contemporary vascular surgery. Nonetheless, it is a sufficiently important potential contributor to morbidity among some subgroups to warrant selective testing and directed therapy pending further study.

Factor V↗
PubMed1997

Health-related quality of life after elective surgery: measurement of longitudinal changes.

OBJECTIVE: To examine the responsiveness of the 36-Item Short Form Health Survey (SF-36) to clinical changes in three surgical groups and to study how health-related quality of life (HRQL) changes with time among patients who undergo total hip arthroplasty, thoracic surgery for treatment of non-small-cell lung cancer, or abdominal aortic aneurysm (AAA) repair. DESIGN: Prospective cohort study with serial evaluations of HRQL preoperatively and at 1, 6, and 12 months after surgery. SETTING: University tertiary care hospital. PATIENTS: Of 528 patients, more than 50 years of age, who were admitted for these elective procedures, 454 (86%) provided preoperative health status data and are members of the study cohort. At 12 months after surgery, 439 (93%) of the cohort was successfully contacted and 390 (90%) provided follow-up interviews. MEASUREMENTS AND MAIN RESULTS: The Medical Outcomes Study SF-36, the Specific Activity Scale, five validated health transition questions, and a 0 to 100 scale measure of global health were used to assess changes in health status at 1, 6, and 12 months after surgery. Change in health status as measured by the SF-36 demonstrated that physical function and role limitations due to physical health problems were worse 1 month after these three surgeries. However, by 6 months after surgery, most patients experienced significant gains in the majority of the dimensions of health, and these gains were sustained at 12 months after surgery. Longitudinal changes in the SF-36 were positively associated with responses to the five health transition questions, to changes on the Specific Activity Scale and global health rating question, and to clinical parameters for persons who had AAA repair. These findings indicate that the SF-36 has evidence of validity and is responsive to expected changes in HRQL after elective surgery for these procedures. CONCLUSIONS: For the total hip arthroplasty patients, responsiveness was greatest for the SF-36 scales that measure physical constructs. However, for the two other procedures and at various points of recovery, significant changes were observed for all eight subscales, suggesting that responsiveness was dependent on the type of surgery and the timing of follow-up, and that multidimensional measures are needed to fully capture changes in HRQL after surgery.

Aged↗
PubMed1996

Troponin T as a marker for myocardial ischemia in patients undergoing major noncardiac surgery.

To assess the diagnostic performance of cardiac troponin T as a marker for myocardial injury in patients undergoing major noncardiac surgery, we prospectively collected preoperative and postoperative clinical data, including measurements for creatine kinase (CK), CK-MB, and troponin T for 1,175 patients undergoing major noncardiac surgery. Acute myocardial infarction was diagnosed in 17 patients (1.4%) by a reviewer who was blinded to troponin T data and who used CK-MB and electrocardiographic criteria to define acute myocardial infarction. Other predischarge major cardiac complications were detected for another 17 patients. Troponin T elevations (>0.1 ng/ml) occurred in 87% of patients with and in 16% of patients without myocardial infarction. Among patients without myocardial infarction, troponin T was elevated in 62% of patients with and in 15% of patients without major cardiac complications. Receiver-operating characteristic analysis indicated that troponin T had a performance for the diagnosis of acute myocardial infarction similar to CK-MB, and a significantly better correlation with other major cardiac complications in patients without definitive infarction. Future research should seek to determine the significance of troponin T elevations in patients without complications.

Aged↗
PubMed1996

Thigh ischemia complicating femoral vessel cannulation for cardiopulmonary bypass.

Compartment syndrome of the lower leg is an occasional complication of prolonged ischemia and reperfusion. Compartment syndrome of the thigh is a less well-recognized complication. We present 2 patients with compartment syndrome of the ipsilateral thigh after femoral arterial and venous cannulation for cardiopulmonary bypass. Early diagnosis and urgent decompressive fasciotomy may limit the extent of local tissue damage and subsequent myonephropathic syndrome.

Aged↗
PubMed1996

Infrainguinal arterial reconstruction with nonreversed greater saphenous vein.

PURPOSE: This study was undertaken to examine the effectiveness and the possible advantages of infrainguinal arterial reconstruction with nonreversed greater saphenous vein (NRGSV) grafts. We reviewed the results achieved with 189 consecutive NRGSV bypass procedures from July 1, 1985, to August 31, 1995, and compared them with 568 consecutive in situ greater saphenous vein (INGSV) bypass procedures completed over the same interval. METHODS: NRGSV bypass procedures were performed by selecting the optimum inflow and outflow vessels and then excising the best available appropriate-length segment of greater saphenous vein. The valves were lysed with a Mills valvulotome using gentle antegrade distention with an isotonic electrolyte solution containing heparin (1000 U/500 ml) and papaverine (60 mg/500 ml). The graft was then translocated to the inflow site, where the proximal and distal anastomoses were sequentially completed, followed by a completion arteriography. RESULTS: Demographic and risk factor characteristics did not differ between patients who underwent NRGSV and those who underwent INGSV bypass. Compared with INGSV bypasses, NRGSV bypasses were more commonly secondary procedures (26% vs 8%; p < 0.001) and were more often performed for limb salvage indications (89% vs 68%; p < 0.001). NRGSV bypasses also had more distal inflow vessels (23% superficial femoral artery [SFA] and 28% popliteal artery [POP] vs 10% SFA and 1% POP; p < 0.001) and more distal outflow vessels (52% tibial and 22% pedal artery vs 47% tibial and 3% pedal artery; p < 0.001) than did INGSV bypasses. Despite the higher incidence of secondary bypass procedures and more distal outflow vessels in the NRGSV group, the overall results achieved at 5 years did not differ between the two groups. The 5-year primary patency rates were 65% +/- 5% for NRGSV and 72% +/- 3% for INGSV (p < 0.12), and the 5-year secondary patency rates were 74% +/- 5% and 82% +/- 2% (p < 0.08), respectively. Similarly, the 5-year limb salvage rate among bypass procedures performed for limb salvage indications did not differ for NRGSV (82% +/- 5%) and INGSV (90% +/- 2%; p < 0.06). CONCLUSIONS: The application of the NRGSV bypass graft preserves the INGSV's main advantage of optimal size match between artery and vein at each anastomosis, but facilitaties the tailoring of the procedure to the patients anatomy and the completion of the bypass with the shortest, best-quality conduit available. Our application of the NRGSV in a more challenging series of bypass procedures produced equivalent results to those achieved in a concurrent series of INGSV bypass procedures.

Aged↗
PubMed1996

Improvement in results of repair of type IV thoracoabdominal aortic aneurysms.

PURPOSE: Although management of extensive type I and II thoracoabdominal aortic aneurysms (TAA) remains a formidable challenge, results of repair of TAA originating in the distal thoracic aorta (type IV) appear to have improved significantly. To quantitate this perceived improvement, the following retrospective study was undertaken to examine the results of type IV TAA repair at the Brigham & Women's Hospital over the past 18-year period. METHODS: From July 1977 to September 1994, nonruptured atherosclerotic type IV TAAs were repaired in 58 patients. The mean age was 70 years, and associated risk factors included smoking (91%), hypertension (86%), coronary artery disease (52%), and previous aortic surgery (38%). Mean follow-up was 2.4 years (median 2 years). RESULTS: Overall 30-day mortality was 5.3% (two deaths). Morbidity included stroke (3.5%), paraplegia (1.8%), permanent paraparesis (1.8%), myocardial infarction (7%), pneumonia (8.8%), gastrointestinal bleeding (11%), intestinal ischemia (5.3%), wound infection (7.0%), peripheral ischemia (5.3%), in-hospital dialysis (8.8%), and permanent dialysis (1.9%). Overall 5-year survival was 50%. With univariate analysis, survival was positively correlated with more recent year of operation (p = 0.002), smaller volume of intraoperative blood transfusion (p = 0.02), decreased supraceliac ischemia time (p = 0.04), and the use of the retroperitoneal approach (p = 0.09). Multiple regression analysis revealed that the year of operation was the only independent predictor of survival (p = 0.003). Subgroup analysis of patients who underwent operation between 1977 and 1987 (n = 13) and 1988 and 1994 (n = 45) revealed statistically significant improvements in length of hospital stay (46 +/- 12 vs 21 +/- 4 days, p = 0.02), postoperative dysrhythmia (50% vs 16%, p = 0.03), postoperative maximum serum glutamic oxaloacetic-transaminase (516 +/- 234 vs 319 +/- 139 mg%, p = 0.04), incidence of hemorrhage requiring reexploration (33% vs 0%, p = 0.002), 30-day mortality (23% vs 0%, p = 0.009), and in-hospital mortality (39% vs 2.2%, p = 0.002). CONCLUSIONS: The modern mortality, morbidity, and survival of surgical repair of type IV TAA in our institution approaches that of infrarenal abdominal aortic aneurysm.

Aged↗