A reappraisal of a modified through-knee amputation in patients with peripheral vascular disease.

BACKGROUND: Through-knee amputation provides a longer lever arm and improved muscle control of the limb compared with above-knee amputation. Through-knee amputation also allows use of a total end-bearing prosthesis, which avoids the ischial pressure and suspension belts required of the above-knee amputation prosthesis. Several reports in the European literature tout the superiority of the through-knee amputation over the above-knee amputation in the patient with vascular disease. Through-knee amputation has received little attention in the United States, however, owing to the belief that the long flaps necessary to close a standard through-knee amputation are associated with an unacceptable rate of wound problems and offer no functional ambulatory advantage to above-knee amputation. We reviewed our experience with a modified technique of through-knee amputation in a group of patients with severe lower extremity ischemia who were not candidates for below-knee amputation to determine the incidence of wound complications and their functional outcome. METHODS: Since 1996, 12 patients with severe lower extremity arterial insufficiency have undergone through-knee amputation utilizing a technique designed to limit flap length and facilitate the fit of a suction prosthesis. Two patients died of myocardial infarction in the immediate postoperative period and were excluded from the study. In the remaining 10 patients (1 man, 9 women; mean age 63 years (range 40 to 86), the below-knee amputation level was precluded because of gangrene or nonhealing wounds of the mid leg in 5 patients, failure of a previous below-knee amputation attempt in 4 patients, and severe ischemia that would compromise below-knee amputation healing in 1 patient. Nine patients had at least one failed vascular reconstruction procedure. RESULTS: Mean follow-up is 25 months (range 6 to 41). Six (60%) patients had primary healing of their amputations. Two (20%) patients had delayed healing (6 weeks and 8 weeks). Two (20%) patients developed wound infections, which required amputation revision to the above-knee level. Seven (70%) patients were fitted with a suction socket prosthesis and are fully ambulatory. One patient healed but has not ambulated because of ischemia and subsequent ulceration of the contralateral limb. CONCLUSIONS: These data show that through-knee amputation is associated with an acceptable primary healing rate (80%) and satisfactory functional outcomes (70% ambulation) in a high-risk vascular population. The functional advantages of through-knee amputation over above-knee amputation make it the preferred alternative for patients with vascular disease.

Isolated arteriovenous dialysis access graft segment infection: the results of segmental bypass and partial graft excision.

Arteriovenous (AV) access graft infection results in disruption of dialysis and usually necessitates graft removal when the entire graft is involved. The management of an isolated infected segment of an otherwise noninfected AV access graft, however, remains controversial. To evaluate the utility of segmental bypass and partial graft excision for the treatment of an isolated infected AV access graft segment, 17 consecutive cases in 12 patients (7 females/5 males; 14 arm grafts/3 leg grafts; median age = 69 years) were analyzed on a vascular teaching service that performed 1244 total access procedures from January 1995 through February 1999. Infections presented as a draining sinus or a sinus with hemorrhage emanating from an area over the graft. At operation, the infected sinus was covered by a transparent occlusive dressing and the graft was explored through clean incisions proximal and distal to the infected segment. If the graft was incorporated and free of infection, a piece of expanded polytetrafluoroethylene (ePTFE) was anastomosed proximally end-to-end and tunneled through noninfected tissues around the infected sinus. After the distal anastomosis was performed, the skin incisions were closed and covered with occlusive dressings. The infected graft segment was then removed through the infected sinus wound. The technique of segmental bypass and partial graft excision results in predictable eradication of infection, graft salvage, and maintenance of uninterrupted dialysis in patients presenting with an isolated AV dialysis access infection.

Dobutamine stress echocardiography prior to aortic surgery: long-term cardiac outcome.

This study was undertaken to evaluate the efficacy of dobutamine stress echocardiography (DSE) in predicting not only perioperative but also long-term cardiac events. One hundred fifty-nine patients who were evaluated for elective abdominal aortic surgery were screened preoperatively with DSE from January 1, 1992 to December 31, 1993. We concluded that DSE is useful for preoperative assessment of cardiac risk prior to elective aortic surgery to minimize the need for cardiac intervention and still maintain acceptable perioperative MI and death rates. A selective approach for coronary revascularization is justified by the higher mortality in the subgroup requiring sequential procedures. DSE also allowed us to identify those high-risk patients who are best excluded from aortic surgery. Patients with abnormal DSE results are at higher risk for late cardiac events, require cardiology follow-up, and may require late coronary intervention.

The matrix metalloproteinase inhibitor BB-94 limits expansion of experimental abdominal aortic aneurysms.

PURPOSE: Matrix metalloproteinases (MMPs) are proteolytic enzymes that can degrade the extracellular matrix of the aortic wall and lead to the formation of abdominal aortic aneurysms (AAAs). MMP inhibitors are a class of drugs that were developed to inhibit the activity of these proteolytic enzymes and are currently being studied as a way to control inflammatory diseases and cancer metastases. In this project, BB-94 (also known as batimastat), a specific inhibitor of MMPs, was evaluated for its ability to control aneurysmal growth in an experimental AAA model. METHODS: Experimental AAAs were created in a standard rat model by perfusing elastase into an isolated segment of aorta. The rats then were randomized to postoperatively undergo treatment daily with the MMP inhibitor BB-94 or the carrier control solution. Measurements of the aortic diameter were made at the time of initial surgery and at the time of death on postoperative day 7. Aortic tissue was obtained for histologic examination, elastin evaluation, and MAC 1-alpha antibody staining to evaluate the inflammatory response. RESULTS: The rats that underwent treatment with BB-94 had significantly less aneurysmal dilatation and a 113% increase in aortic size, as compared with the control rats that had a 157% increase (P =.026). Histologic examination of the harvested aortas and grading of the elastin content showed a significantly greater elastin preservation in those rats that were treated with BB-94 as compared with the control rats (P =.036). MAC 1-alpha antibody staining showed an attenuation of the inflammatory response in the group of rats that underwent treatment with BB-94. Morphologic examination also revealed that the control of the inflammatory response correlated with the areas of elastin preservation. CONCLUSION: MMP inhibition with BB-94 limited the expansion of AAAs in this rat model. BB-94 appears to work not only as a direct pharmacologic inhibitor of MMPs but also as an interference with the inflammatory response seen in AAAs. Control of the inflammatory response was an unexpected result and may be related to the alterations in feedback mechanisms that are related to extracellular matrix degradation. Because this class of drugs is presently being developed to control the MMP inflammatory response seen with arthritis, these drugs also may ultimately serve as a pharmacologic treatment for patients with AAAs.

Normothermia is protective during infrarenal aortic surgery.

PURPOSE: Mild hypothermia has been suggested to be protective against tissue ischemia during aortic operations. However, recent studies have documented detrimental cardiac effects of hypothermia during a variety of operative procedures. The influence of different warming methods and the impact of hypothermia during standard aortic procedures was assessed. METHODS: One hundred patients who underwent repair of infrarenal aortic aneurysms or aortoiliac occlusive disease were prospectively randomized into 2 groups, receiving either a circulating water mattress or a forced air warming blanket. Adjuvant warming methods were standardized. The day before surgery, 48-hour Holter monitors were applied and interpreted by a cardiologist blinded to the treatment. Randomization resulted in equivalent groups with regard to patient history, indications for surgery, body mass index, length of surgery, and fluid requirements. RESULTS: Core temperatures were significantly warmer during surgery (36.3 degrees C +/- 0.7 degrees C vs 35.4 +/- 0.8 degrees C) and after surgery (36.4 degrees C +/- 0.7 degrees C vs 35.6 degrees C +/- 0.9 degrees C) in patients with forced air warming (P <.001). The circulating water mattress group had significantly more metabolic acidosis perioperatively (P =.03). Postoperative length of stay, cardiac complications, and death rates were not significantly different. Subgroup analysis of 83 aneurysm patients comparing normothermia with hypothermia (temperature less than 36 degrees C) on arrival to the recovery room identified decreased cardiac output (P =.02), thrombocytopenia (P =.02), elevated prothrombin time (P =.04), and inferior Acute Physiology and Chronic Health Evaluation (APACHE) II scores (P <.001) in the hypothermic group. Holter analysis revealed more sinus tachycardia (ST) segment changes and ventricular tachycardia in hypothermic aneurysm patients (P =.05). CONCLUSION: Patients treated with forced air blankets had significantly less metabolic acidosis and were kept significantly warmer than those treated with circulating water mattresses. Patients with aneurysms that were kept normothermic had a significantly improved clinical profile, with fewer cardiac events on the Holter recordings. We therefore conclude that (1) normothermia is protective for infrarenal aortic surgical patients; and (2) forced air warming blankets provide improved temperature maintenance compared with circulating water mattresses.

Expression of matrix metalloproteinases and TIMPs in human abdominal aortic aneurysms.

Degradation of extracellular matrix, especially elastin, within the aortic wall is a hallmark of abdominal aortic aneurysms (AAAs). Normal turnover of matrix proteins is mediated by a family of enzymes called matrix metalloproteinases (MMPs). MMP activity is regulated by proteins called tissue inhibitors of metalloproteinases (TIMPs). We analyzed the expression of all known MMPs with established elastolytic activity and TIMPs in human AAA and control tissue. mRNA coding for MMP-9, MMP-2, human macrophage metalloelastase, MMP-7, TIMP-1, and TIMP-2 were amplified by reverse transcriptase-PCR in control and AAA tissue. A Northern blot assay was used to measure the levels of mRNA coding for MMP-2, MMP-9, TIMP-1, and TIMP-2. Control aortic tissue was obtained from patients with occlusive disease and from organ donors. The expression of MMP-7 and human macrophage metalloelastase was not detected in any aortic specimens. By Northern blot analysis the mean level of MMP-2 mRNA was not significantly different between control groups and AAAs (normalized values: occlusive, 1.5 +/- 0.8, n = 3; donor, 4.5 +/- 2.2, n = 6; AAA, 4.0 +/- 0.95, n = 15). There was a significant increase in the level of MMP-9 mRNA in AAA specimens (occlusive, 16.8 +/- 3, n = 3; donor, 5.7 +/- 1.2, n = 6; AAA, 56.7 +/- 11, n = 15, p = 0.0069). The levels of mRNA coding for TIMP-1 were not significantly different. There was a small but statistically significant increase in TIMP-2 mRNA in AAA tissue. These data support the hypothesis that increased activity of MMP-9, but not MMP-2, is an important factor in the etiology of AAAs. This enhanced MMP-9 activity could then result in degradation of the ECM, leading to aneurysmal dilatation.

Carotid endarterectomy: the mandate for high quality duplex.

Excellent correlation between carotid angiography and duplex scanning has made it possible to perform carotid endarterectomy without angiography. The accuracy of scans from practices without a dedicated vascular laboratory must be validated prior to their use for clinical decisions. Seventy six patients had a carotid duplex performed at an outside institution and were referred for vascular surgery. All patients underwent a repeat study at our dedicated vascular lab. The overall accuracy of our lab was 93.8% for all carotid categories as demonstrated by angiography. Outside carotid duplex reports correlated with repeat exams as follows: occlusions: 10/13 carotids (76.9%); 80%-99% stenoses: 15/39 carotids (38.5%); 50%-79% stenoses: 28/44 carotids (63.6%). If a surgeon's practice is to operate for asymptomatic 80%-99% stenoses by report, then unnecessary surgery might have been performed in 61.5% of these carotids and appropriate surgery denied in 3.6%. Outside duplex velocities consistent with a 60%-99% stenosis correlated in 13/17 carotids (76.5%). If a surgeon's practice is to operate for asymptomatic 60%-99% stenoses based on velocity criteria, then unnecessary surgery might have been performed in 23.5% of these carotids, and appropriate surgery denied in 7.6% placing these patients at increased risk of stroke. Outside scans significantly overestimated the severity of carotid disease (p = 0.003). The weighted kappa analysis for agreement between scans was only 60.2%. Failure to have validated high-quality duplex in labs performing carotid studies can lead to unnecessary angiography or surgery. Carotid endarterectomy without angiography should be performed only when duplex accuracy has been previously validated by angiographic correlation studies. Poor agreement with studies from practices without a dedicated vascular lab makes it mandatory to repeat the duplex on all patients prior to clinical decision making. Reimbursement for such repeat studies should not be denied.

Physician work effort and reimbursement for ruptured abdominal aortic aneurysms.

BACKGROUND: Two major flaws have been previously identified in the resource-based relative value scale (RBRVS): (1) inaccurate estimation of physician work effort; and (2) RBRVS compression, which results in undervaluation of major surgical procedures. The impact of RBRVS for physicians treating patients with ruptured abdominal aortic aneurysms (RAAAs) has not been previously reported and is important owing to the severity of the illness, the potential to quantitate actual work effort, and the high percentage of these patients covered by Medicare. PATIENTS AND METHODS: All patients were studied who underwent surgery for RAAAs during a 5-year period encompassing the implementation of RBRVS. Analysis included all physician services including vascular surgeons, anesthesiologists, and all other medical specialists. Total work effort was quantitated for each specialty in minutes/patient. The financial data were obtained by reviewing all professional bills and reimbursements. Cost of service was calculated to include physician compensation, practice overhead costs, and malpractice expenses. RESULTS: In all, 84 patients underwent repair of a RAAA with a mortality rate of 42%. Medicare was the primary insurance for 87% of patients. The cost of service exceeded the reimbursement by 50% for vascular surgeons, resulting in an average loss of $1,593/patient. Actual operative time represented only 24% of total surgical work effort. Early death and a length of stay (LOS) < or = 1 day for 24 patients resulted in a reimbursement rate of $5.98/minute for surgeons. This gain was significantly offset by 30 patients with a LOS > or = 14 days, resulting in a reimbursement rate of $1.94/minute for vascular surgeons. Over the 5-year period there was a trend of decreasing reimbursement for vascular surgeons (P <0.005) but not other physicians. Vascular surgeons incurred a 28% decrease in reimbursement over the study period. CONCLUSIONS: Physician reimbursement under RBRVS for the treatment of patients with RAAAs is inadequate to cover the costs of providing this care. Reimbursement trends and potential changes to the practice component of the RBRVS will further aggravate the losses involved in caring for these very ill patients. Vascular surgeons must continue to provide input to the Health Care Financing Administration to help correct inequities built into RBRVS.

Syndecan-4 is a primary-response gene induced by basic fibroblast growth factor and arterial injury in vascular smooth muscle cells.

Syndecans are a family of transmembrane proteoglycans that have been implicated in cell-extracellular matrix adhesion and growth factor binding. We reported previously that syndecan-1 expression by cultured rate vascular smooth muscle cells (VSMCs) is induced by serum- or platelet-derived growth factor (PDGF). We now report that syndecan-4 mRNA is rapidly induced in cultured VSMCs in response to basic fibroblast growth factor (bFGF) or serum stimulation. In the presence of cycloheximide, induction of syndecan-4 mRNA was enhanced. These characteristics identified syndecan-4 as a primary-response gene product in VSMCs. In contrast, syndecan-1 mRNA expression in response to serum was completely blocked in the presence of cycloheximide. We also examined the expression of syndecan mRNAs in VSMCs in response to balloon catheter injury in vivo. A reverse transcriptase-polymerase chain reaction technique was developed that enabled us to amplify all four syndecan mRNAs in a single reaction tube and determine relative changes in their expression. All four syndecan mRNAs were detected in uninjured rat carotid arteries. In endothelium-denuded arteries, the medial layer (presumably VSMCs) accounted for 70% to 90% of the syndecan mRNAs in the vessel wall. The levels of syndecan-2 and syndecan-3 mRNAs were not altered significantly after balloon injury. In contrast, syndecan-4 mRNA was increased at early times after injury but then decreased to control level by 7 days. Syndecan-1 mRNA levels showed a slower but prolonged increase that reached a maximum at 7 days after injury. Immunostaining with anti-syndecan-4 antibodies demonstrated a rapid increase in syndecan-4 proteoglycan expression in the injured carotid artery.

Carotid duplex overestimation of stenosis due to severe contralateral disease.

BACKGROUND: In the quest to use carotid duplex to assess carotid occlusive disease, it has been reported that the current velocity criteria to calculate stenosis tends to overestimate the severity when there is a contralateral highly stenotic or occluded carotid artery. METHODS: Patient records were reviewed for 592 consecutive carotid endarterectomies performed from 1987 to 1994. Preoperative and postoperative duplex scan results were compared in a subset of patients in whom duplex overestimated the degree of stenosis, as compared to preoperative angiography. RESULTS: A total of 146 patients were identified in whom duplex overestimated the degree of stenosis contralateral to a high grade stenosis or an occlusion. Of 76 arteries, 18 (23.7%) contralateral to an occluded artery were overestimated by duplex, and 128 (27.0%) of 474 arteries contralateral to a high grade stenosis were overestimated. Following endarterectomy 44 (51.8%) of 128 nonoperated contralateral stenoses decreased by at least one duplex category. The average peak systolic frequency (PSF) decreased by 1175 Hz (P = 0.0018), and the average end diastolic frequency (EDF) decreased by 475 Hz (P = 0.011). CONCLUSIONS: Patients with high grade stenosis have a significant decrease in PSF and EDF in the unoperated carotid after endarterectomy, supporting a compensatory flow phenomenon. This often results in a decrease in the postoperative duplex defined stenosis by at least one category. The clinical significance of these findings is of increasing importance as carotid surgery is being performed more frequently without angiography.

Antisense suppresssion of protein kinase C-alpha and -delta in vascular smooth muscle.

Understanding and being able to manipulate intracellular signaling pathways which control VSMC gene expression and proliferation will be important in efforts to control neointimal hyperplastic vascular diseases. Activation of the protein kinase C (PKC) family of enzymes is a central event in growth factor-stimulated cells. PKC activation results in the activation of downstream protein kinases including mitogen activated protein kinase (MAPK). PKC isozymes alpha (alpha) and delta (delta) predominate in cultured rat aortic VSMC and both isozymes are completely downregulated upon prolonged (16-24 hr) stimulation with the PKC activator, phorbol 12,13 dibutyrate (PDBu). At these low levels of PKC, MAPK activation in response to PDBu is nearly abolished. To assess the role of specific PKC isozymes in regulating MAPK, isozyme-specific antisense oligodeoxynucleotides (ODNs) were used to inhibit reexpression of PKC in downregulated cells. ODNs were phosphorothioated to increase stability and contained C-5 propynyl modified pyrimidines which are reported to have increased binding affinity. ODNs were administered in low concentration (400 nM) with a cationic liposome carrier (Lipofectin; GibcoBRL). Optical imaging of cells treated with FITC-labeled ODNs confirmed that virtually all cells took up the ODNs within 2 hr. With this technique, PKCalpha-specific antisense ODNs selectively inhibited PKCalpha recovery compared to cells treated with an equal length nonsense ODN (76 +/- 3.9, P < 0.001), with no effect on recovery of PKCdelta. However, activation of MAPK by PDBu was not significantly inhibited in these PKCalpha downregulated cells. This suggests that only a small amount of the total PKCalpha is required for PDBu induced activation of MAPK and/or that PKCdelta can mediate the response. Manipulation of PKC isozymes using this model system should allow assessment of the roles of specific isozymes in controlling diverse downstream effectors and events related to VSMC growth and proliferation.

Peter B. Samuels Award. Ruptured abdominal aortic aneurysm repair: the financial analysis.

BACKGROUND: Denial of ruptured abdominal aortic aneurysm (RAAA) repair has been advocated based upon historically poor surgical outcome and a perceived lack of cost effectiveness. Although the repair intuitively seems expensive, the actual cost of care, adequacy of reimbursement, and cost per additional life-year gained for RAAA repair are poorly defined. PATIENTS AND METHODS: Retrospective clinical and financial chart review of 119 consecutive patients undergoing operation for RAAA from 1986 to 1993. RESULTS: Overall in-hospital mortality was 45%. Mean institutional charge per patient in 1993 dollars was $40,763 (range $4,473 to $284,374), with an actual mean cost for service of $22,420 and an average reimbursement of $21,360, resulting in a loss of $1,060 per patient. Losses were higher in Medicare patients. Survivors (n = 65) had an average length of stay of 20 days, cost $41,045 each, and incurred an institutional loss of $298,405. Mean cost per additional (adjusted) life-year was $3,953. One-, 3-, and 5-year survival rates following hospital discharge were 97%, 85%, and 77%, respectively. CONCLUSIONS: Emergency repair of RAAA is relatively inexpensive when compared to other commonly used health maintenance protocols and effectively restores survivors to their former health. Since no clinical or physiologic parameter can predict poor outcome, operative intervention should not be denied.

Regulation of MAP kinase activity by growth stimuli in vascular smooth muscle.

Intracellular signaling pathways regulating vascular smooth muscle (VSM) cell growth and hypertrophy can be initiated by activation of receptor tyrosine kinases and/or protein kinase C (PKC). Mitogen-activated protein kinases (MAP kinases) are cytosolic serine/threonine kinases, proposed to act as a point of convergence for diverse growth factors utilizing these signaling pathways. The goals of this study were (1) to determine whether MAP kinase is expressed in cultured rat aortic VSM, (2) to assess the activation of MAP kinase by known proliferative and hypertrophic stimuli, and (3) to determine if stimulation of a PKC-dependent signaling pathway in these cells results in MAP kinase activation. MAP kinase activity was measured in cytosolic extracts of aortic VSM by quantifying myelin basic protein phosphorylation. Three peaks of activity were resolved chromatographically and identified as MAP kinase isoforms (MW 42, 44, and 46 kDa) by immunoblotting with antipeptide antibodies specific for MAP kinase. MAP kinase activity in quiescent growth-arrested cells (157 +/- 19 pmole 32P/min/mg) was markedly stimulated within 15 min by known mitogens (10% serum, 731 +/- 40 pmole 32P/min/mg; 40 ng/ml PDGF, 670 +/- 105 pmole 32P/min/mg; P < 0.01) and partially sustained for at least 90 min (serum, 606 +/- 34 pmole 32P/min/mg; PDGF, 323 +/- 59 pmole 32P/min/mg P < 0.05). Angiotensin II (AII, 0.1 microM) and a pharmacological PKC activator, phorbol 12,13-dibutyrate (PDB, 0.1 microM), are reported to be nonmitogenic hypertrophic stimuli in these cells. These stimuli transiently increased MAP kinase activity with a peak at 5 min (AII, 328 +/- 15 pmole 32P/min/mg; PDB, 592 +/- 41 pmole 32P/min/mg; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Dobutamine stress echocardiography for cardiac risk assessment before aortic surgery.

PURPOSE: This study evaluates dobutamine stress echocardiography (DSE) for perioperative cardiac risk assessment with elective aortic surgery. METHODS: Dobutamine stress echocardiography was used to evaluate 81 patients before infrarenal aortic surgery. Patients were placed into three groups. Group I (n = 31) had normal DSEs. Group II (n = 25) had resting wall motion abnormalities without dobutamine-induced changes of ischemia. Group III (n = 25) had evidence of dobutamine-induced ischemia. Patient analysis revealed that of 46 patients with clinical indicators of coronary artery disease (CAD), only 23 had DSEs with inducible ischemia. Two of 35 patients without clinical indicators of CAD had DSEs with inducible ischemia. RESULTS: The 56 patients in group I and II underwent aortic reconstruction without cardiac complications or death. Of the 25 patients in group III, surgery was deferred in five (two patients with claudication and three with aneurysms < or = 5 cm), and four underwent coronary artery bypass grafting. Outcome after coronary artery bypass grafting included one death from stroke, one aneurysm rupture, and two uncomplicated aortic reconstructions. The remaining 16 patients in group III underwent aortic surgery, with three postoperative myocardial infarctions (MI) and no deaths. CONCLUSIONS: Using DSE for preoperative assessment of cardiac risk allowed us to operate on 74 of 81 patients being considered for elective aortic reconstruction, with no operative deaths and a 4.1% rate of perioperative MI. Dobutamine stress echocardiography has the ability to identify patients with asymptomatic stress-induced ischemic myocardium and its increased risk for perioperative MI (p < 0.001). Equally important, for patients with clinical indicators of CAD but without DSE-inducible ischemia, no further cardiac evaluation is necessary.

Dipyridamole thallium imaging: use in preoperative cardiac risk assessment in vascular surgical patients.

BACKGROUND: The objective of this study was to determine whether routine performance of dipyridamole thallium imaging adds to the power of a careful clinical evaluation in the risk stratification of patients undergoing major vascular surgery. METHODS: In this retrospective study, 115 cases evaluated by dipyridamole thallium imaging before major vascular surgery were reviewed. Patients were assigned to a high-risk cohort if they had a history of congestive heart failure or evidence of previous myocardial infarction. RESULTS: Six (8%) patients from the high-risk cohort developed major cardiovascular complications. Reversible perfusion defects, present in 67% of the high-risk patients, did not predict complications. None of the patients in the low-risk cohort developed complications despite the presence of reversible perfusion defects in 33%. Patients in the high-risk cohort who underwent cardiac catheterization and selective coronary bypass grafting were uniformly free of perioperative complications. The extent and severity of fixed or reversible thallium perfusion did not predict the occurrence of cardiovascular complications. However, three patients were denied surgery following an unacceptable cardiovascular risk assessment based on clinical findings and multiple reversible thallium perfusion defects. CONCLUSION: In low-risk patients, screening with dipyridamole thallium can identify patients with redistribution defects whose risk of perioperative ischemic events can be reduced by intensifying perioperative anti-ischemic management. If the patient is in the high-clinical-risk subgroup, screening with dipyridamole thallium does not identify a cohort with negligible perioperative risk; thus, further evaluation of these patients by cardiac catheterization should be considered.

An algorithm for the surgical management of chronic abdominal aortic occlusion and occluded aortofemoral grafts.

An algorithm for the surgical management of chronic abdominal aortic occlusion is presented based upon experience of treating 60 consecutive patients. Of 33 patients with juxtarenal aortic occlusion, 17 underwent aortofemoral bypass (AFB), 10 descending thoracic aortofemoral (DTAF), 5 axillofemoral (AxF) bypass, and 1 ascending thoracic aortofemoral bypass. Of 11 patients with mid or distal aortic occlusion, 8 underwent AFB, 2 DTAF and 1 AxF. Of 16 patients with aortic graft occlusion, 1 underwent AFB, 10 DTAF and 5 AxF. Acceptable risk patients were selected for AFB (26). DTAF (22) was frequently preferred for patients with occluded aortic grafts or other hazardous intraabdominal pathology. AxF (11) was used for patients with severe cardiopulmonary risk, limited life expectancy from malignancy, or when emergency procedures were required for salvage of severely ischemic limbs in debilitated patients with chronic aortic occlusion. In the AFB, DTAF and AxF groups the perioperative mortality was 8%, 5% and 36% respectively, the late mortality was 15%, 36% and 45%, and the 5-year primary cumulative graft patency was 92%, 89% and 15%.

Long term follow-up of descending thoracic aorto-iliac/femoral bypass.

A prospective study of 26 patients undergoing descending thoracic aorto-iliac/femoral (DTAI/F) bypass was conducted over a 13-year period with an average follow up of 53 months. Reasons for selecting the procedure were occluded aortic bifurcation grafts (9 patients), hostile abdomen (6), infected aortic graft (1), microaorta (10, and surgeons preference in 8 patients who had juxtarenal aortic occlusion. The operative mortality was 3.8% (1 patient). A late mortality of 36% was due to myocardial infarction (1), lung carcinoma (2), renal failure (4), stroke (1) and pulmonary insufficiency (1). Graft failure occurred in 4 patients at 23, 26, 54 and 109 months respectively. Primary cumulative patency was 86% statistically valid at 42 months. DTAI/F bypass is recommended in selected patients when conventional approaches to the aorta are considered unduly hazardous.

Aortocaval fistula and contained rupture of an abdominal aortic aneurysm presenting with pelvic venous congestion.

This case report describes pelvic venous congestion without associated high-output cardiac failure as an unusual presentation of an aortocaval fistula as a complication of a contained rupture of an abdominal aortic aneurysm. Options for caval control and management of perioperative problems unique to this situation are discussed.

Implantation of the distal aorta: a technique for preservation of pelvic blood flow in aortofemoral reconstruction.

We report our initial experience with a previously undescribed variation of aortofemoral bypass. This technique is an alternative to end-to-side aortic anastomosis for preservation of pelvic blood flow. It involves an end-to-end proximal aortic anastomosis with implantation of the distal aorta into the posterior wall of the bifurcation graft. This approach has been used selectively for nine patients. Seven patients operated on using this technique had bilateral external iliac artery disease preventing retrograde perfusion of the pelvis. We used this procedure in two other young patients to preserve large inferior mesenteric and distal aortic lumbar vessels proximal to common iliac artery occlusions. Mean follow-up has been 20 months. There have been no deaths and no major complications. This technique provides the hemodynamic benefit of a proximal end-to-end aortic anastomosis while maintaining patency of the distal aorta and its branches. Additional technical advantages may include better suture line protection from the duodenum and a decreased potential for graft limb kinking. These factors may ultimately result in superior long-term graft patency.

Intraoperative local anesthetic injection of the carotid sinus nerve. A prospective, randomized study.

One hundred patients undergoing carotid endarterectomy under general anesthesia were prospectively randomized to receive either a local anesthetic injection of their carotid sinus nerve with bupivacaine (Marcaine) or no injection. Systolic blood pressure and pulse rate were recorded before injection and at 5 and 30 minutes after injection. The need for intraoperative and postoperative use of systemic vasopressor and vasodilator medications was recorded for each group as was the incidence of arrhythmias, neurologic complications, and myocardial infarctions. Intraoperative local anesthetic injection of the carotid sinus nerve did not significantly influence the intraoperative pulse rate or incidence of hypotension. It did, however, significantly increase the incidence of intraoperative hypertension and the need for systemic vasodilator medications intraoperatively. The incidence of postoperative hypotension (6 percent of patients), hypertension (34 percent), arrhythmias (6 percent), cerebrovascular accidents (1 percent), transient ischemic attacks (3.1 percent), and myocardial infarctions (2 percent) were not significantly influenced by intraoperative local anesthetic injection of the carotid sinus nerve. Intraoperative and postoperative hypotension did not cause morbidity in this series, however, local anesthetic injection was associated with a significant incidence of perioperative hypertension. Routine prophylactic local anesthetic injection of the carotid sinus nerve cannot be recommended in view of its detrimental effects in relation to the development of hypertension.