Natural history of the residual infrarenal aorta after infrarenal abdominal aortic aneurysm repair.

PURPOSE: We determined the natural history of the residual native infrarenal aortic segment after conventional abdominal aortic aneurysm (AAA) repair. METHODS: For the retrospective arteriographic case series, 800 hundred translumbar aortograms (TLAs) were obtained for 272 patients, before and after conventional AAA repair. The main outcome measures were changes in the aortographic diameter and the length of the infrarenal aortic segment, corrected and uncorrected for magnification by normalization to the first lumbar vertebral body height. RESULTS: The mean follow-up time from the preoperative TLA to the most recent postoperative TLA was 42 months (range, 1 to 257 months). Vertebral body height did not change (p = 0.35). The length of the native infrarenal aorta cephalad to the proximal anastomosis increased a mean of 3 mm, from 23 to 26 mm (p = 0.001). However, in 115 patients (43%), this aortic segment elongated more than 5 mm, and in 63 patients (24%), it elongated more than 10 mm. The native residual infrarenal aorta above the proximal anastomosis dilated a mean of 1 mm, from 23 to 24 mm (p = 0.001), but in 21 patients (8%), it dilated more than 5 mm. There was a weak positive correlation between the increase in residual native aortic diameter and duration of follow-up. There was a negative correlation between this increase and the initial size. The diameters of the proximal anastomosis and proximal graft did not change. Marked variability in the changes in aortic dimensions was observed. CONCLUSIONS: A mean period of 42 months after conventional AAA repair, the native infrarenal aortic segment elongates and dilates. Although such enlargement is statistically significant, the average increase appears to be small. However, residual aortic cuff diameter increased more than 5 mm and neck length more than 10 mm in a significant number of patients, with potentially serious implications for endovascular treatment of AAA.

Noninvasive venous testing in the diagnosis of pulmonary embolism: the impact on decisionmaking.

PURPOSE: To characterize the use and utility of lower extremity noninvasive venous testing (NIVT) in the diagnosis of pulmonary embolism (PE). METHODS: The study is a retrospective case series of consecutive patients in whom PE was suspected who were referred to a large, urban tertiary care center for NIVT. The main outcome measures of the study were the rate of positive results of NIVT, the amount of new information provided by NIVT, and the frequency of management changes that were attributable to NIVT. RESULTS: Forty-one of 450 patients (9%) had deep venous thrombosis (DVT) by NIVT. The prevalence of DVT by NIVT among patients not evaluated by ventilation/perfusion (V/Q) scanning was 8%. The prevalence of DVT by NIVT among patients with a high-probability V/Q scan result before NIVT was 39%, but no management decisions in this group were based on a positive NIVT result and only two decisions were based on negative NIVT results. The prevalence of DVT according to NIVT among patients who had a negative "diagnostic" (low, or very low probability, or normal) result of V/Q scan before NIVT was 2%. The overall frequency of management changes attributed to NIVT was only 2.5%. In the remaining 97% of patients, management was determined by the result of V/Q scanning or of subsequent pulmonary arteriography. CONCLUSIONS: In patients in whom PE is suspected, results of NIVT are usually negative for acute DVT. Management decisions are almost always based on V/Q scan or results of pulmonary arteriography and not on NIVT. The utility of NIVT to identify DVT in these patients appears limited, and a more selective approach to its application for the diagnosis of PE should be considered.

Protective effect of hypothermia and left heart bypass on spinal ischemia in the dog.

OBJECTIVE: To test the hypothesis that systemic hypothermia (SH) to 30 degrees C in combination with partial left heart bypass (PLHB) at either a high or low distal arterial perfusion pressure (DAPP) following 45 minutes of cross-clamp (XC) occlusion of the thoracic aorta will protect against clinical and histological spinal cord ischemia in the dog. DESIGN: A blinded, prospective, randomized, and controlled experimental trial. SETTING: Tertiary care center animal laboratory. PARTICIPANTS: Seventeen adult mongrel dogs. INTERVENTIONS: The animals were randomized into 5 groups: control group 1: XC plus no protection (n = 3); control group 2; XC plus systemic normothermia plus PLHB, with a DAPP less than 20 mm Hg (n = 3); treatment group 1: XC plus systemic normothermia plus PLHB, with a DAPP greater than 20 mm Hg (n = 3); treatment group 2: XC plus SH plus PLHB, with a DAPP greater than 20 mm Hg (n = 3); treatment group 3: XC plus SH plus PLHB, with a DAPP less than 20 mm Hg (n = 5). MAIN OUTCOME MEASURES: Clinical and histological neurological injury evaluation by separate blinded observers. RESULTS: Control animals were neurologically and histologically ischemic. Treatment animals were neurologically and histologically normal. Partial left heart bypass with a DAPP greater than 20 mm Hg prevented paraplegia, with either systemic normothermia or SH. Systemic hypothermia plus PLHB, even with a DAPP less than 20 mm Hg, protected against spinal cord ischemia during thoracic aortic occlusion. CONCLUSION: Systemic hypothermia to 30 degrees C combined with PLHB at either a high or low DAPP prevented spinal cord ischemia following thoracic aortic XC occlusion in our canine model and merits clinical trial in patients.

An analysis of perioperative surgical mortality and morbidity in the asymptomatic carotid atherosclerosis study. ACAS Investigators. Asymptomatic Carotid Atherosclerosis Study.

BACKGROUND AND PURPOSE: Our aim was to determine the perioperative morbidity and mortality rates of patients in the surgical arm of the multi-institutional, prospective, randomized Asymptomatic Carotid Atherosclerosis Study (ACAS). METHODS: Of 828 patients with carotid stenosis of 60% or more randomized to the surgical arm of ACAS, 721 underwent carotid endarterectomy (CEA). To qualify for participation, surgeons were required to have performed at least 12 CEAs per year with a combined neurological morbidity and mortality rate no greater than 3% for asymptomatic patients and 5% for symptomatic patients. Clinical centers had to demonstrate arteriographic morbidity less than 1% and mortality less than 0.1% per year. Primary events were stroke and death in the period between randomization and 30 days after surgery; secondary events were transient ischemic attack and myocardial infarction occurring in the same period. RESULTS: Of the 721 patients who underwent CEA, 1 died and 10 others had strokes within 30 days (1.5%). Of the 415 who underwent arteriography after randomization but before CEA, 5 (1.2%) suffered transient ischemic attack or stroke caused by arteriography. Thus, a nearly equal risk of stroke was associated with both CEA and carotid arteriography. In addition, 6 transient ischemic attacks and 3 myocardial infarctions could be directly linked to CEA, for a total CEA event rate of 2.6%. CONCLUSIONS: Patients with asymptomatic internal carotid artery stenosis exceeding 60% reduction in diameter who are acceptable candidates for elective operation may be considered for CEA if the combined arteriographic and surgical complication rates are 3% or less.

Vascular surgical training of general and vascular surgery residents.

OBJECTIVE: The opinions of general surgery program directors (SPDs) and vascular surgery program directors (VPDs) regarding vascular surgery training of general surgery residents and the construct of the vascular surgery residency were compared. METHODS: Questionnaires were mailed to 55 VPDs and 290 SPDs in 1987 and 1988, and to 80 VPDs and 277 SPDs in 1995. Both questionnaires included questions regarding attitudes about vascular surgical competence, operative experience, future vascular practice opportunities of general surgery residents, and the impact of a vascular surgery residency on general surgery resident education. In addition, the 1995 survey included questions regarding the duration, content, and prerequisite versus requisite experience for the vascular surgery residency. RESULTS: Significant differences in opinions between SPDs and VPDs persisted regarding vascular surgery training of general surgery residents. SPDs were more likely to feel that general surgery graduates are fully competent in vascular surgery, should be exposed to more complex vascular surgery during training, and should be granted unlimited vascular surgical privileges on entering practice. Most VPDs felt that general surgery graduates lack competence in vascular surgery, should be exposed to less complex vascular surgery during training, and should have limited vascular surgery privileges in practice. Both groups of program directors agreed about the construct of vascular surgery residencies and that such residencies have had a favorable impact on general surgery resident education. Both SPDs and VPDs were willing to consider creative restructuring of vascular surgery residencies to accommodate governmental restrictions on funding of graduate medical education. CONCLUSIONS: External pressures forcing residency reform may provide an opportunity for SPDs and VPDs to creatively work with regulatory bodies to resolve differences in expectations of vascular surgery education and practice.

Role of nitric oxide in the effect of blood flow on neointima formation.

PURPOSE: Neointima formation after arterial injury is inhibited by increased blood flow. The object of this study was to determine whether nitric oxide mediates the effect of increased blood flow on neointima formation. METHOD: Balloon catheter-denuded rat carotid arteries were exposed to increased blood flow or control blood flow by ligation of the contralateral carotid artery. Beginning 2 days before balloon denudation, rats were given either saline vehicle alone or the nitric oxide synthase inhibitor N-nitro-L-arginine-methyl ester (L-NAME) at a dose of 10 mg/kg/day or 2 mg/kg/day intraperitoneally. The normalized neointima area was measured 14 days after denudation. RESULTS: Blood flow was significantly increased by ligation of the contralateral carotid artery for all drug treatments (p<0.008). In rats given saline vehicle only, normalized neointima area was significantly reduced after increased blood flow compared with control blood flow (0.33+/-0.04 compared with 0.48+/-0.03; p=0.006). Systolic blood pressure was significantly elevated by treatment with high-dose L-NAME (p=0.002 compared with vehicle), but was not altered by low-dose L-NAME (p=NS compared with vehicle). Normalized neointima area was not significantly reduced after increased carotid blood flow for rats treated with either dose of L-NAME (p=NS). CONCLUSION: The inhibition of neointima formation by increased blood flow was abolished with hypertensive and nonhypertensive doses of the nitric oxide synthase inhibitor L-NAME, which suggests that the L-NAME effects are independent of systemic hemodynamic alterations. It is concluded that flow-induced inhibition of neointima formation is mediated in part by nitric oxide.

Vascular surgery in the United States: workforce issues. Report of the Society for Vascular Surgery and the International Society for Cardiovascular Surgery, North American Chapter, Committee on Workforce Issues.

The Committee on Workforce Issues of the Society for Vascular Surgery (SVS) and the North American Chapter, International Society for Cardiovascular Surgery (NA-ISCVS) generated data on the numbers and trends of operations performed and workforce requirements to provide surgical care of patients with vascular disease. Data for analysis were obtained from The National Center for Health Statistics-National Hospital Discharge Survey and questionnaires sent to 2732 vascular surgeons. The data showed that SVS/NA-ISCVS and regional vascular society (RVS) surgeons performed 51% of 583,000 vascular procedures undertaken in the United States in 1992. This represents a 24% increase over the 41% reported in 1985 by similarly defined surgeons. Analysis of 1992 index cases documented that SVS/NA-ISCVS and RVS surgeons accounted for 80% of 31,000 aortoiliofemoral bypasses, 68% of 46,000 aortic aneurysmectomies, 64% of 91,000 carotid endarterectomies, and 72% of 98,000 angioaccess procedures. The mean numbers of vascular operations performed in 1992 by SVS/NA-ISCVS and RVS surgeons were 144 and 100, respectively. These procedures represented 64% and 39% of the total surgical caseload of SVS/NA-ISCVS and RVS surgeons, respectively. American Board of Surgery (ABS)-certified vascular surgeons performed a mean of 171 vascular operations in 1992. Other surgeons, including ABS-certified general surgeons, appear to be performing fewer vascular operations. The latter fact and the increasing incidence of vascular disease in an expanding elderly population supports a continued need for vascular surgery specialists. Evolving technology and new health care delivery systems, however, may lessen the need for surgical care of these patients. Continued assessments of workforce activity will allow better definition of changing vascular surgery needs.

Results of lower extremity amputations in patients with end-stage renal disease.

PURPOSE: The purpose of this study was to determine the impact of end-stage renal disease (ESRD) on the outcome of patients undergoing lower extremity (LE) amputation. METHODS: Hospital charts and vascular surgery registry data were reviewed for all patients who underwent LE amputation over a consecutive 56-month period. The results of 84 patients with ESRD (137 amputations) were compared with 375 patients (442 amputations) without ESRD. RESULTS: Hospital mortality rate was significantly greater in patients with ESRD than patients without ESRD, 24% versus 7% (p = 0.001). Patients with ESRD undergoing minor amputations had mortality rates three times greater than patients without ESRD undergoing major LE amputations. In patients with ESRD requiring bilateral or unilateral above-knee amputation hospital mortality rates were 43% and 38%, respectively. In addition, patients with ESRD were seven times more likely to undergo bilateral amputation than patients without ESRD over a mean follow-up period of 17 months. No kidney transplant patients died after amputation. CONCLUSION: ESRD has a profound negative impact on morbidity, mortality, and survival rates after LE amputation. Attempts at prevention of amputation with aggressive foot care and patient education in this high-risk group should be the focus of therapy.

Acute aortic occlusion. A 40-year experience.

OBJECTIVE: To review a large experience with acute aortic occlusion (AAO) to better define the cause, clinical presentation, treatment, prognostic variables, and outcome. DESIGN: Retrospective review of 46 consecutive patients with AAO during a 40-year period. SETTING: A large urban tertiary care referral center in Detroit, Mich. PATIENTS: Adult patients with arteriographic and/or operative confirmation of acute occlusion of the abdominal aorta plus signs and symptoms of acute ischemia. INTERVENTION: Operative and nonoperative treatment of AAO. MAIN OUTCOME MEASURES: Mortality, morbidity, and long-term survival. Other variables measured included cause, risk factors, and effects of duration and severity of ischemia and treatment methods on outcome. RESULTS: Two primary causes were identified--embolism (65%) and thrombosis (35%). Heart disease and female gender were risk factors for embolism, while smoking and diabetes were risk factors for thrombosis. Severity of ischemia on presentation correlated better with outcome than duration of ischemia. The hospital mortality rate was 35% and morbidity, 74%, with no difference between the two groups. Recurrent arterial embolism occurred in 43% of patients with embolic AAO. Seventy-two percent of AAO survivors were alive 5 years after therapy. CONCLUSIONS: Acute aortic occlusion remains a serious vascular surgical emergency with significant morbidity and mortality, even when recognized promptly and treated appropriately. Nevertheless, survivors have a reasonable long-term outcome. Permanent anticoagulation is suggested in patients with embolic AAO to minimize a high incidence of recurrent arterial embolism.

Groin lymphatic complications after arterial reconstruction.

PURPOSE: The purpose of this study was to better define the associated risks and optimal management of groin lymphatic complications (GLC) after femoral artery reconstructive operations. METHODS: Retrospective review of a vascular surgery registry for the last 15 years identified 2679 arterial operations requiring a groin incision. Forty-one GLC were recognized, 28 lymphocutaneous fistulas (LF) and 13 lymphoceles. RESULTS: The incidence of GLC was 1.5% per patient or 1.2% per incision. The highest incidence of GLC was in patients having an aortobifemoral bypass for aneurysmal disease in a previously operated groin (8.1% per patient) and in those undergoing an isolated femoral procedure in a previously operated groin (5.3%). The lowest frequency of GLC was after femoropopliteal/tibial bypasses (0.5%). Twenty-nine patients (71%) were treated without operation with bedrest, intravenous antibiotics, and aggressive local wound care. Operative therapy with wound reexploration attempted identification and control of the leak site, and meticulous wound closure was used in 12 patients (29%). Lymph fistulas in patients undergoing reoperation (10/28) resolved sooner than in patients treated without operation (18/28) (9 +/- 3 days vs 24 +/- 3 days). Infectious wound complications with one resultant graft infection developed in five of 18 patients with LF who did not undergo reoperation. There were no wound or graft infections in the patients in the LF group treated with operation. Operative exploration of lymphoceles did not reduce hospital stay or infectious wound complications. Repetitive lymphocele aspiration did not affect rapidity of resolution or increase the infectious complications. CONCLUSION: GLC remain a troublesome complication of femoral arterial reconstruction. Early reoperation should be performed once a LF is diagnosed. Treatment for lymphoceles should be individualized, with neither operative nor nonoperative management showing clear superiority.