Myocardial revascularization before abdominal aortic aneurysmorrhaphy: effect of coronary angioplasty.

Percutaneous transluminal coronary angioplasty (PTCA) has assumed an increasing role in the preoperative preparation of patients with an abdominal aortic aneurysm (AAA). The influence of this modality on perioperative morbidity and long-term outcome has not been substantiated. To determine the effect of PTCA, we analyzed a cohort of 2,452 patients who underwent repair of an AAA between 1980 and 1990 at our institution. We compared the cardiac morbidity, mortality, and survival of patients who had preoperative coronary revascularization by PTCA or coronary artery bypass grafting (CABG). The overall perioperative mortality for the 2,452 patients was 2.9%. Preoperative coronary revascularization was necessary in 100 patients (4.1%)--86 had CABG and 14 had PTCA. Of these 100 patients, 95% had cardiac symptoms. Patients selected for PTCA, in comparison with CABG, had significantly less three-vessel disease but not significant differences in cardiac history or ejection fraction. During the study period, the use of PTCA increased significantly. The perioperative rate of myocardial infarction for patients with prior CABG was 5.8% in comparison with 0% for those with prior PTCA. No hospital deaths occurred in either group. The median interval between coronary revascularization and repair of an AAA was 10 days for PTCA and 68 days for CABG. The 3-year survival was not statistically different between CABG (82.8%) and PTCA (92.3%) groups. The rate of late cardiac events (at 3 years) was 56.5% in the PTCA group and 27.3% in the CABG group. We conclude that PTCA as part of a highly selective approach to coronary revascularization before repair of an AAA minimizes cardiac-related events and death.(ABSTRACT TRUNCATED AT 250 WORDS)

The treatment of complicated appendicitis in children. What is the gold standard?

From 1976 to 1985, 233 consecutive children were treated for appendicitis by a standardized protocol. Forty-nine percent of these cases were complicated: 11% by gangrene, 33% by perforation, and 4% by perforations with well-developed abscesses. Treatment of gangrenous and perforated appendicitis consisted of administration of ampicillin sodium, gentamicin sulfate, and clindamycin phosphate; appendectomy; and saline peritoneal irrigation. Transperitoneal drainage was not used. Skin and subcutaneous tissues were left open for delayed primary wound closure. Perforations with well-developed abscesses were treated with triple antibiotic therapy and interval appendectomy. The only infectious complication was one intra-abdominal abscess. There were no wound infections or deaths. The rate of infectious complications was 0.9%, and the overall morbidity was 4.4%. This standardized treatment of complicated appendicitis in children prevents wound infection and significantly decreases the incidence of intra-abdominal abscess formation and mortality.

Renal failure and advanced atherosclerotic lesions. Salvage by vascular reconstruction.

Occlusive renal artery lesions and progressive renal failure have a dismal prognosis if not treated. We analyzed our results to determine if the risks of renal vascularization were justified based on the final outcome in such patients. Inclusion criteria were a creatinine concentration of at least 160 mumol/L (1.8 mg/dL) and one of the following angiographic findings: (1) severe (greater than or equal to 75%) bilateral occlusions, (2) total occlusion with severe (greater than or equal to 75%) contralateral occlusion, or (3) solitary kidney with severe (greater than or equal to 75%) occlusion. Thirty patients met these criteria and underwent revascularization. Six required simultaneous aortic reconstruction. The average creatinine concentration on admission was 310 mumol/L (3.55 mg/dL); this had a statistically significant improvement to 210 mumol/L (2.41 mg/dL) at discharge. There was one perioperative death (3.3%). Initially, 22 patients had improved function (creatinine concentrations 20% lower), and seven patients had stable creatinine values. Eight patients ultimately required long-term dialysis. In the remaining 21 patients, with an average follow-up of 32 months, the average creatinine concentration was 220 mumol/L (2.51 mg/dL), still a significant improvement. Thus, we have demonstrated the relative safety and benefit of operating on these high-risk patients.

Selective nonoperative management of blunt splenic trauma in adults.

The use of selective nonoperative management of blunt splenic trauma in adults is based on the undeniable benefits of this approach in children. Proper patient selection requires hemodynamic stability, lack of generalized peritoneal irritation, and minimal blood transfusion needs. Computed tomography is now used to make the diagnosis, but the decision for laparotomy is based on clinical grounds. Forty-one (87%) of 47 patients selected for nonoperative management were treated successfully without laparotomy, while the remaining 6 patients underwent delayed operations for persistent splenic bleeding. Blood transfusion requirements were significantly less in the observed group than in the operative group for patients with isolated trauma and for patients with polytrauma. There were no known missed intra-abdominal injuries and no deaths with the nonoperative approach. Analysis of our results has confirmed that nonoperative management is a safe and effective alternative to immediate laparotomy in properly selected patients and it can result in splenic salvage without the need for an operation.

Computerized topographic brain mapping during carotid endarterectomy.

Computerized topographic brain mapping processes standard electroencephalographic data and displays it in a color map, thus simplifying interpretation. During a 2-year period, 65 carotid endarterectomies were performed with the use of brain mapping as the sole criterion for shunt replacement. Forty-three patients (66%) were found to have abnormal brain maps preoperatively. Ten patients (15%) developed ischemic changes after cross-clamping (all resolved after shunt placement). Postoperative brain maps were unchanged in 54 patients (83%) and improved in 7 patients (11%). A new, small focal abnormality was identified in 4 patients without shunts (6%), none of whom had a change in neurologic status. The overall major morbidity and mortality was 1.5%. Computerized brain mapping is a sensitive and readily interpretable means of monitoring cerebral perfusion during carotid surgery. We found the computerized electroencephalographic data to be a dependable criterion for selective shunting and for confirmation of shunt patency during carotid endarterectomy.

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.

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.

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.

Use of limited color-flow duplex for a carotid screening project.

BACKGROUND: Although the efficacy of carotid endarterectomy for asymptomatic carotid stenosis has been established, no cost-effective approach for identification of these patients has yet been devised. The purpose of this study was to develop a limited carotid duplex screening examination to be utilized for the detection of asymptomatic carotid stenoses. METHODS: Carotid screening examinations employed rapid identification of the carotid bifurcation using color-flow duplex imaging and an immediate Doppler-derived velocity of the segment of the internal carotid artery with the most turbulent flow. Complete examinations were then finished using well-established protocols in our accredited vascular laboratory. A total of 512 patients were referred for complete studies based upon standard indications. Criteria for at least a 50% internal carotid artery stenosis on the complete examination was defined as a peak systolic velocity (PSV) of at least 125 cm/sec. Receiver operator characteristic (ROC) curves were then constructed to identify the optimal screening velocity criteria as compared with the final results on the complete examination. RESULTS: Five screening examinations were technically limited yielding a total of 507 patients with 1,014 carotid arteries available for analysis. Comparison of screening examinations versus complete examinations for a PSV of 125 cm/sec yielded sensitivity 86%, specificity 98%, positive predictive value (PPV) 95%, and a negative predictive value (NPV) 93%. ROC analysis identified a "cut point" of 115 cm/sec on the screening examinations to achieve sensitivity 91%, specificity 95%, PPV 89%, and NPV 96%. Time to perform screening examinations averaged 3.2 minutes per patient. Three patients had common carotid lesions not identified on the limited internal carotid screening examinations. CONCLUSIONS: Screening carotid examinations are a rapid, reliable, and relatively inexpensive method for detection of patients with asymptomatic internal carotid artery stenosis. Limited screening examinations should be developed in each vascular laboratory and utilized in high-risk patients.

Functional changes in canine saphenous veins after cryopreservation.

This study was designed to determine the functional characteristics of the endothelium, smooth muscle and nerve terminals of cryopreserved veins. Freshly harvested and cryopreserved canine saphenous veins were cut into rings. In some rings, the endothelium was removed. Cryopreserved veins were stored at -196 degrees C for at least 3 weeks prior to use. All rings contracted in a concentration-dependent manner to depolarization with KCl and to alpha-adrenergic stimulation; the maximal tensions were significantly less in cryopreserved than in freshly harvested veins. Calcium ionophore A23187 caused greater relaxations in rings with than without endothelium in freshly harvested and cryopreserved veins. These relaxations were reduced significantly by methylene blue and NG-monomethyl-L-arginine (L-NMMA) only in fresh veins. Cocaine-sensitive uptake of H3-norepinephrine was reduced following cryopreservation. Immediately after cryopreservation, the production of prostacyclin was elevated. The calcium ionophore A23187 stimulated production of prostacyclin only in freshly harvested veins. Tissue content of endothelin did not change following cryopreservation. These results suggest that cryopreservation of canine saphenous veins alters nerve terminals and decreases the ability of the smooth muscle to contract. The endothelium releases an endothelium-derived relaxing factor and prostanoids following cryopreservation but the ability to synthesize nitric oxide is probably reduced. These changes following cryopreservation may affect patency of the veins when used as arterial grafts.

Femoral artery infections associated with percutaneous arterial closure devices.

Hemostasis obtained by manual compression after femoral artery catheterization results in consistently low rates of major complications. A rare complication of femoral artery catheterization is arterial infection. Its occurrence after diagnostic angiography using manual compression has not been reported. We report two cases of femoral arterial infection after uneventful diagnostic catheterization in nonimmunocompromised patients using the Perclose percutaneous arterial closure device. Our cases are representative of Perclose associated infections, with delayed presentation of a staphylococcal arterial infection requiring arterial debridement and reconstruction. This article indicates that Perclose use carries a risk of severe arterial infection. Surgeons should be aware of the potential infectious complications associated with Perclose use and the need for aggressive treatment.

Cryopreservation affects endothelial and smooth muscle function of canine autogenous saphenous vein grafts.

Cryopreserved veins used as arterial grafts may be affected by both rejection and the cryopreservation process. Experiments were designed to study changes in endothelial and smooth muscle function after cryopreservation but independent of rejection. One saphenous vein from each of eight dogs was cryopreserved for subsequent use as autografts. After 3 weeks one cryopreserved and one freshly harvested autogenous saphenous vein were implanted as bilateral femoral arterial interposition grafts. Platelet deposition was studied in vivo with indium 111-labeled platelets. At 4 weeks the autografts were removed, and the functional characteristics of the grafts were studied in organ chambers; and the ability of nerve terminals to uptake transmitter was studied with 3H-norepinephrine. Neither patency rates, blood flows, nor platelet deposition were significantly different between freshly harvested and cryopreserved grafts. Uptake of 3H-norepinephrine was significantly reduced in both grafts as compared to unoperated veins. The smooth muscle of the cryopreserved and fresh grafts contracted comparably to alpha-adrenergic agonists and endothelin. In cryopreserved grafts, the maximal tensions that developed to KCl, prostaglandin F2 alpha, and endothelin were greater when the endothelium was present compared to that developed by the smooth muscle alone. Calcium ionophore A23187 caused relaxations only in rings with endothelium; these were not significantly different between graft types. However, relaxations of the smooth muscle to nitric oxide were decreased in the cryopreserved grafts.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrasound-guided thrombin injection is a safe and durable treatment for femoral pseudoaneurysms.

Ultrasound-guided percutaneous thrombin injection has recently been described as a treatment for postcatheterization femoral pseudoaneurysms. Although ultrasound guided compression offers another nonoperative treatment option, thrombin injection has shown superior initial success rates. Reports of follow-up for thrombin injection longer than 30 days are currently lacking. The authors reviewed their initial experience with thrombin injection and prospectively evaluated patients for occult late recurrences of pseudoaneurysm and for distal circulatory complications. Records and vascular laboratory data for all patients treated with ultrasound-guided thrombin injection were reviewed for an 18-month period. Tibial vessel Doppler waveforms and ankle/brachial indices were routinely obtained before and after thrombin injection. Follow-up duplex examinations were performed within 24 hours of initial treatment. In the prospective portion of the study, successfully treated patients underwent a repeat femoral duplex scan and lower extremity arterial examination for comparison with the pretreatment studies. Forty-nine of 52 femoral pseudoaneurysms (94%) were successfully treated with ultrasound guided thrombin injection. One immediate failure and 2 early recurrences were treated surgically. There was 1 thrombotic complication of the native circulation identified at the time of injection. Follow-up studies were obtained in 32 of 46 available patients with a mean length of follow-up of 9 months (range 3-17 months). No late recurrences of the pseudoaneurysms or arterial-venous fistulas were observed. No distal circulatory complications were detected by arterial waveform analysis. Three deaths occurred in the interim (cardiac related). Two patients were lost to follow-up. The remaining 12 patients reported no additional limb complications but declined to be restudied. Ultrasound-guided thrombin injection is a safe, effective, and durable treatment for iatrogenic pseudoaneurysms. Thrombin injection should be the therapy of choice for catheter-related femoral false aneurysms.

Carotid endarterectomy: the financial impact of practice changes.

PURPOSE: New techniques in the management of extracranial carotid occlusive disease have focused attention on the outcome and economics of carotid endarterectomy (CEA). Changing practice patterns for CEA must be assessed to allow accurate comparisons. The purpose of this study was to evaluate the effect of practice modifications related to CEA on patient outcome and cost data. METHODS: Data on patients undergoing CEAs at a single institution from fiscal year 1992 to 1998 were prospectively collected and entered into a computerized database. Records were reviewed for patient demographics and outcome with regard to stroke and death. Selected years that corresponded to transitions in perioperative management were audited for complete hospital financial information from. RESULTS: We performed 960 CEAs during the study period, with a combined stroke and death rate of 1.1%. Inflation-adjusted hospital costs per patient in 1998 dollars for the years 1992, 1996, and 1998 were $5494, $4476, and $3350, respectively. In 1998, costs for patients who required arteriography were $1825 greater than those operated on during duplex scan examination alone in 1998. Statistically significant differences occurred in the year-to-year comparisons in the use of arteriography, intensive care unit monitoring, same day admissions, and length of stay. There were no statistically significant differences in the stroke and death rate between years. CONCLUSION: Practice changes related to CEA have resulted in significant savings without detriment in patient outcome. Comparisons between CEA and endovascular techniques will need to be evaluated within this context. Given these advances in perioperative management, it will be difficult to justify carotid stenting on the basis of current economic considerations.

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.

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.

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.

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.

Inhibition of inducible nitric oxide synthase limits nitric oxide production and experimental aneurysm expansion.

PURPOSE: Nitric oxide (NO), frequently cited for its protective role, can also generate toxic metabolites known to degrade elastin. Both abdominal aortic aneurysms (AAAs) and inducible nitric oxide synthase (iNOS) are associated with inflammatory states, yet the relationship between NO production by iNOS and AAA development is unknown. The current study examines iNOS expression, NO production, and the effects of selective inhibition of iNOS by aminoguanidine in experimental AAA. METHODS: An intra-aortic elastase infusion model was used. Control rats received intra-aortic saline infusion and postoperative intraperitoneal saline injections (Group 1). In the remaining groups, intra-aortic elastase infusion was used to induce aneurysm formation. These rats were treated with intraperitoneal injections of saline postoperatively (Group 2), aminoguanidine postoperatively (Group 3), or aminoguanidine preoperatively and postoperatively (Group 4). Aortic diameter and plasma nitrite/nitrate levels were measured on the day of surgery and postoperative day 7. Aortas were harvested for biochemical and histologic analysis on postoperative day 7. RESULTS: Infusion of elastase produced AAAs (P <.001) with significant production of iNOS (P <.05) and nitrite/nitrate (P <.003) compared with controls. Selective inhibition of iNOS with aminoguanidine in elastase-infused aortas significantly reduced aneurysm size (P <.01) compared with elastase infusion alone. Aminoguanidine-treated rats displayed suppression of iNOS expression and plasma nitrite/nitrate production not significantly different from the control group. Histologic evaluation revealed equivalent inflammatory infiltrates in elastase-infused groups. CONCLUSION: Expression of iNOS is induced and plasma nitrite/nitrate levels are increased in experimental AAA. Inhibition of iNOS limits NO production and iNOS expression, resulting in smaller aneurysm size. NO production by iNOS plays an important role with detrimental effects during experimental aneurysm development.