LITERATURE REVIEW Linda Shore-Lesserson, MD Section Editor
THORACOABDOMINAL ANEURYSM
Brock MV, Redmond JM, Ishiwa S, et ah Clinical markers in CSF for determining neurologic deficits after thoracoabdominal aortic aneurysm repairs. Ann Thorac Surg 64:999-1003, 1997 Neurologic injury during thoracoabdominal aneurysm (TAA) repair may be a result of excitotoxicity because of elevated amino acid neurotransmitter levels. To evaluate this, excitatory amino acid levels were measured in 18 consecutive patients undergoing repair of TAA by using distal perfusion techniques. Patients were divided into groups based on neurologic outcome. Patients suffering spinal cord injury had significantly longer aortic cross-clamp times and elevated levels of glutamate during aortic cross-clamp, early reperfusion, and late reperfusion (p < 0.05). A similar elevation occurred for glycine levels, but did not reach statistical significance. Efforts to reduce the levels of these excitatory amino acids or to block the channels by which they mediate toxicity may be of value in reducing neurologic morbidity associated with TAA surgery.
Kashyap VS, Cambria RP, Davison JK, L'Italien GJ: Renal failure after thoracoabdominal aortic surgery. J Vasc Surg 26:49-57, 1997 Despite the major advances in the surgical and perioperative management of patients undergoing thoracoabdominal aortic surgery, renal failure remains a common complication leading to increased morbidity and mortality. Additionally, there is continued controversy as to the optimal perioperative management to decrease the risk of this complication. This is a retrospective analysis of 183 patients who underwent thoracoahdominal aortic surgery, that sought to identify perioperative risk factors for renal failure. Univariate analysis showed that factors associated with postoperative renal failure included a preoperative creatinine level greater than 1.5 mg/dL (p = 0.004) and a total cross-clamp time of greater than 100 minutes (p = 0.035). The surgical mortality risk was significantly increased for this group of patients (odds ratio, 9.2; 95% confidence interval, 2.6 to 33;p < 0.005). The data suggest that preoperative renal failure and prolonged crossclamp times are important risk factors for renal failure after thoracoabdominal aortic surgery.
Halpern V J, Kline RG, D'Angelo A J, Cohen JR: Factors that affect survival rate of patients with ruptured abdominal aortic aneurysms. J Vasc Surg 26:939-948, 1997 The mortality rate after ruptured abdominal aortic aneurysm (AAA) remains elevated and has not changed significantly over the past 20 years. For this reason, many suggest rigid patient selection criteria for repair of ruptured AAA. In a retrospective analysis of 96 patients presenting with this condition, preoperative patient-related variables 490
were analyzed for their statistical association with mortality. Preoperative factors, including loss of consciousness, a minimal systolic blood pressure less than 90 mmHg, a hemoglobin level less than 10 g/dL, and a creatinine level greater than 1.5 mg/dL, were predictive of death. The highest predictive power occurred when the above data were associated with refractory intraoperative hypotension (intraoperative blood pressure < 90 mmHg). Thus, risk factors for death in patients with ruptured AAAs are most predictive when accompanied by a hemodynamic shock state.
Meissner MH, Chandler WC, Nicholls SC: Coagulopathy after ruptured abdominal aortic aneurysm. Vasc Surg 31:727-736, 1997 Coagulopathy is often included among the predictors of a poor outcome after raptured abdominal aortic aneurysm (AAA). A retrospective review of 89 patients presenting with ruptured AAA was performed to define the incidence of coagulopathy and to identify the factors contributing to its development. More than 86% of patients had at least one abnormal coagulation variable on admission. In a multivariate analysis, hematocrit predicted elevated INR and hematocrit plus the degree and duration of hypotension predicted elevated partial thromboplastin time (PTT). The amount of fluid resuscitation did not predict an abnormal international normalized ratio (INR) or PTr, but was predictive of a platelet count of 50,000/gL or lower. All coagulation variables showed deterioration after admission, but none were associated with mortality. Only advanced age and the lowest systolic blood pressure were significantly associated with mortality in patients undergoing emergent repair of ruptured AAA. The majority of patients presenting with ruptured AAA have abnormal coagulation parameters that worsen throughout the course of resuscitation, but are not predictive of mortality.
Kang D-H, Song J-K, Song M-G, et ah Clinical and echocardiographic outcomes of aortic intramural hemorrhage compared with acute aortic dissection. Am J Cardiol 81:202-206, 1998 Aortic intramural hemorrhage (IMH) is a form of aortic dissection without intimal tear and flow communication and is difficult to diagnose using standard aortography. The ability to differentiate IMH from aortic dissection by using transesophageal echocardiography (TEE) was studied and the differences in outcome were compared. One hundred patients comprised the study group (dissection plus IMH). In 49 patients who had the diagnosis confirmed surgically, the sensitivity of TEE in detecting IMH was 100% (27 of 27 patients), and the specificity was 91% (20 of 22 patients). The incidence of complications and the mortality rate were significantly lower in IMH than in dissection, and the development of complications was significantly correlated with mortality. TEE was useful in detecting these complications and may prove to be an important diagnostic technique for distinguishing causes of aortic pathology.
Journal o f Cardiothoracic and Vascular Anesthesia, Vo112, No 4 (August), 1998: pp 490-492