Coagulation changes during thoracoabdominal aneurysm repair.

PURPOSE: The cause of coagulopathic hemorrhage during thoracoabdominal aneurysm (TAA) repair has not been well defined in human studies. We investigated changes in the coagulation system associated with supraceliac versus infrarenal cross-clamping to address this critical issue. METHODS: Blood levels of fibrinogen, the prothrombin fragment F1.2, D-dimer, and factors II, V, VII, VIII, IX, X, XI, and XII were analyzed in 19 patients with TAAs and four patients with abdominal aortic aneurysms (AAAs) at: (A) induction; (B) 30 minutes into supraceliac (TAA) or infrarenal (AAA) clamping; (C) 30 minutes after release of supraceliac or infrarenal clamps; and (D) immediately after surgery. Preoperative and intraoperative variables, including but not limited to aneurysm type, pathologic findings, comorbid conditions, clamp times, volume and timing of blood products, and clinical outcome, were prospectively recorded. Significance was determined by analysis of variance, Student's t test, and univariate linear regression. RESULTS: Levels of fibrinogen and factors II, V, VIII, VIII, IX, X, XI, and XII decreased (p < 0.05) at time B versus time A and returned to near baseline by time D. D-dimer and F1.2 increased starting at time B and reached significance (p < 0.05) by time D. Data points were compared for the TAA and AAA groups. Although AAA groups demonstrated a trend to factor activity reduction and increased fibrinolysis, the effect was much less pronounced than in TAA and did not approach significance. No correlation of coagulation change with clamping time was present; however, visceral clamping times were all less than 65 minutes (mean, 44 minutes). Blood and factor replacement was initiated after time B. Univariate regression analysis of factor level versus total blood replacement demonstrated a significant (p < 0.04) correlation between the reduction in the levels of factors II, V, VII, VIII, X, and XII, and the increase in the level of D-dimer at time B and subsequent total blood replacement. CONCLUSIONS: Thoracoabdominal aneurysm repair is associated with a reduction in clotting factor activity and an increase in fibrinolytic function, which occurs after placement of the supraceliac clamp. Explanations include visceral ischemia or a greater and longer ischemic tissue burden as the likely cause of coagulation alterations. Total blood replacement during TAA procedures was correlated to the degree of factor reduction and fibrinolysis at the time of visceral cross-clamping. An aggressive approach to early blood component replacement and to coagulation monitoring could lessen blood loss during TAA repair and avoid potentially disastrous bleeding complications.

Simultaneous aortic and renal artery reconstruction: evolution of an eighteen-year experience.

PURPOSE: We reviewed an 18-year experience with combined abdominal aortic and renal artery reconstruction (AOR) with a particular focus on patients' clinical risk profile and surgical results in contemporary practice as compared with earlier experience. METHODS: One hundred seventy patients underwent AOR during the interval January 1, 1976 to June 30, 1994. To examine parameters representative of current practice, the cohort was divided into group I patients (n = 110) treated before 1990 and group II (n = 60) treated between 1990 and 1994. Median follow-up duration for the entire cohort was 8.4 +/- 0.6 years. Renal artery reconstruction patency and patient survival rates were calculated by life-table methods. Logistic and Cox regression analysis were used to determine predictors of perioperative and long-term morbidity/mortality rates. RESULTS: Although demographic features changed little over the review period, the detection (56% vs 73%, p = 0.03) and treatment with percutaneous transluminal coronary angioplasty/coronary artery bypass grafting (11% vs 40%, p = 0.0001) of associated coronary artery disease were more frequent in group I patients. The operative mortality rate for the entire cohort was 6.5% (group I = 9% vs group II = 2%, p = 0.06). Changing trends of surgical techniques over the review period included (group I vs II, respectively) increased use of bilateral simultaneous renal artery repair (12% vs 25%, p < 0.005) and transaortic endarterectomy as the renal artery reconstruction technique (3% vs 25%, p < 0.0001). Favorable response in blood pressure control was noted in 68% of group II patients. The cumulative 5-year survival rate for all patients was 75% with an initial serum creatinine of 2.0 mg/dl or greater being the only negative predictor of late survival after regression analysis. CONCLUSION: The current operative mortality rate for AOR is in the range anticipated for aortic surgery alone, and this appears to be related to improved detection and treatment of associated coronary artery disease and intervention before major deterioration in renal function. These findings coupled with currently available natural history data relative to renovascular disease justify an aggressive approach with AOR when significant renal artery stenosis is detected during evaluation of aortic disease.

Epidural cooling for regional spinal cord hypothermia during thoracoabdominal aneurysm repair.

PURPOSE: We investigated the feasibility of achieving regional hypothermia of the spinal cord with an infusion of iced (4 degrees C) saline solution administered into an epidural catheter while monitoring cerebral spinal fluid (CSF) temperature in eight patients undergoing thoracic or thoracoabdominal aneurysm resection. METHODS: As part of the anesthetic management, an epidural catheter was placed at T11-12, and a subarachnoid thermistor catheter was placed at L3-4. Approximately 30 minutes before aortic cross-clamping, iced (4 degrees C) saline solution was infused into the epidural catheter until CSF temperature decreased to approximately 25 degrees C. The infusion was then adjusted to maintain this temperature until the aorta was unclamped. The subarachnoid catheter was also used to measure CSF pressure and provide for CSF drainage. Surgery was performed in all patients with a clamp-and-sew technique with selective intercostal vessel reattachment. RESULTS: Infusion of a mean volume of 489 ml (range 80 to 1700 ml) of iced saline solution into the epidural space before aortic cross-clamping led to a decrease in mean CSF temperature to 26.9 degrees C (range 25 degrees to 28.8 degrees C) in 15 to 90 minutes. During cross-clamping and aortic replacement the mean CSF temperature was maintained between 25.2 degrees to 27.6 degrees C and, with discontinuation of the infusion, returned to within 1 degrees C of body core temperature by the end of the procedure. Body core temperature was not significantly affected by the epidural infusion. Mean CSF pressure increased during the epidural infusion but could be reduced by removing saline solution from the epidural space. No postoperative neurologic deficits were observed. CONCLUSION: Epidural cooling appears to be a satisfactory method of achieving regional spinal cord hypothermia in patients requiring resection of thoracic or thoracoabdominal aortic aneurysms.

Intraoperative duplex scanning and late carotid artery stenosis.

PURPOSE: The purpose of this study was to assess the effect of intraoperative duplex scanning on early and late results after carotid endarterectomy. METHODS: We reviewed 316 carotid arteries in 283 patients who underwent operation since 1986. The results of intraoperative ultrasonography were normal in 254 (80.4%) and abnormal in 62 (19.6%). We did not reexplore 53 (85.5%) of the abnormalities because the defect was minor, 2 to 3 mm or less. These defects were retained atheroma in the common carotid artery (n = 35), internal carotid artery (ICA) (n = 5), external carotid artery (n = 2), small frond in the bulb (n = 2), thickened wall of the vein patch (n = 2), and ICA kink (n = 7), two of which were associated with retained atheroma. Nine defects (14.5%) were reexplored and repaired; there were seven flaps, one residual plaque, and one case with turbulent flow alone. RESULTS: Patients with a normal examination result had an early ICA occlusion rate of 0.79% (n = 2), an early stroke rate of 1.6% (n = 4), and one death (0.4%). In the unrepaired group these rates were 1.9% (n = 1) and 1.9% (n = 1), respectively. No occlusion occurred in the repaired group, but one preexisting cerebrovascular accident worsened immediately after operation. Frequency analysis and B-mode imaging were performed after operation and every 6 to 12 months in all patients (mean 21.6 months). A greater than 75% area stenosis was found in nine (17%) of the 53 unrepaired carotid arteries, but in only four (4.3%) of the 254 carotid arteries lacking defects and in one of the reopened group (p < 0.001). There have been no late strokes, and only three late transient ischemic attacks overall. CONCLUSIONS: A normal intraoperative scanning result obtained after carotid endarterectomy is associated with improved late patency rates. Even small defects appear to be associated with an increased incidence of late restenosis, reemphasizing the importance of technical perfection.

Long-term results and current indications in femoropopliteal vascular reconstructions.

The current indications to and long-term results of the femoropopliteal by-passes are analysed. The absolute indication is critical ischaemia with rest pain or trophic change i.e. ulcers and gangrene. The most important factor influencing the long-term results is the nature of the graft per se. The indications, arteriographic run-off, site of anastomosis, earlier femoropopliteal operations all exert a major influence on the late results, particularly prosthetic grafts are used. The results indicate the need for more prospective studies with careful monitoring of different variants in order to better understand the role of the femoropopliteal by-pass in the palliation of infra-inguinal atherosclerotic occlusive disease.