Myocardial injury in major aortic surgery

PURPOSE: The purpose of this study was to examine the effects of major aortic surgery and its associated oxidative stress and injury on the myocardium. METHODS: Plasma from 27 patients who underwent thoracoabdominal aortic aneurysm (TAAA) repair and 17 patients who underwent infrarenal aortic aneurysm (AAA) repair was collected at incision, aortic crossclamping, and reperfusion and 1, 8, and 24 hours thereafter. Samples were assayed for the myocardial specific protein troponin-T, total antioxidant status, and lipid hydroperoxides. RESULTS: Ten patients experienced cardiac dysfunction in the first 24 hours after surgery (eight patients in the TAAA group and two patients in the AAA group). Immediately after reperfusion, total antioxidant status levels dropped in all patients with TAAA and with AAA; this was more marked in patients with TAAA, leading to a significant difference between the two groups at this time point and for up to 1 hour thereafter (P <.01). Patients with TAAA showed a sharp rise in lipid hydroperoxide levels immediately after reperfusion, and levels were significantly higher than in patients with AAA (P =.0007). In patients with AAA, no significant change in troponin-T was observed throughout the study period; whereas in patients with TAAA, levels were significantly elevated at 8 and 24 hours after reperfusion (P <.01). Troponin-T levels significantly correlated with total antioxidant status (r = -0.5) and lipid hydroperoxides (r = 0.78) but not with systolic blood pressure. CONCLUSION: Supracoeliac aortic crossclamping is associated with a significant release of the myocardial injury marker troponin-T. This seems to correlate with the severity of oxidative rather than hemodynamic stresses. Ameliorating oxidative injury during TAAA surgery may therefore have a cardioprotective effect.     

Thoracoabdominal aortic aneurysm repair after prior aortic surgery

PURPOSE: The purpose of this study was to determine whether the morbidity and mortality of surgery for thoracoabdominal aortic aneurysm (TAAA) in patients with prior aortic surgery are increased. METHODS: The results for all patients undergoing operation for TAAA at a single institution were reviewed. RESULTS: Over a 10-year interval, 279 patients (136 women and 143 men) underwent aortic replacement for TAAA. The mean patient age was 68 years (range, 34-90). The extent of aortic replacement was relatively evenly distributed: type I (91), type II (54), type III (78), or type IV (56). Of these 279 patients, 76 (27%) had undergone prior aortic surgery. Prior infrarenal AAA was the most common prior procedure (56, 20%). Reoperation for prior failed TAAA repair was performed in 20 (7%) patients. A history of Marfan syndrome was highly associated with the need for remedial TAAA procedures (P <.0001). Overall 30-day mortality was 11.4% (32). Mortality was independent of prior aortic surgery (P =.98), prior AAA (P =.84), prior TAAA (P =.61), and gender (P =.18). Postoperative complications were seen in 67 (24%) patients and were more likely in patients who had undergone prior AAA surgery (P =.008). TAAA repair in patients with recurrent TAAA was not associated with higher morbidity (P =.33). Paraplegia (10) occurred in type I (3), type II (2), and type III (5) aneurysms but not in type IV (0), and its development was associated with higher mortality (P =.01). Prior aortic surgery was not found to be predictive of paraplegia (P =.90), although 30% of patients who developed paraplegia had a history of prior AAA repair. CONCLUSIONS: Aortic reoperation for TAAA is required in a significant number of patients, particularly those with Marfan syndrome. Therefore, ongoing surveillance of the residual aorta is mandatory. Postoperative complications are more likely to occur in patients after prior infrarenal aortic replacement, but mortality is not significantly increased. Special technical considerations exist for remedial procedures after failed TAAA repair to provide protection for the spinal cord, kidneys, and viscera. Patients with failed TAAA procedures or progression of aneurysmal extent should be offered reoperation when indicated.     

Suprarenal clamping is a safe method of aortic control when infrarenal clamping is not desirable

We evaluated the safety of suprarenal aortic clamping in patients with abdominal aortic aneurysm (AAA) treated by open aortic replacement by retrospectively reviewing all patients who underwent elective AAA replacement at a university hospital from 1993 until 2003. We reviewed 249 patient charts and divided them into three groups according to the clamp location during aortic replacement: group 1, infrarenal clamp group (n = 185); group 2, suprarenal clamp group (n = 52); and group 3, supraceliac clamp group (n = 12). Groups 1 and 2 were compared with respect to risk factors, intraoperative events, and postoperative events. Statistical analysis was done using Wilcoxon's rank-sum test, chi-squared test, and Fisher's exact test. Risk factors were comparable in groups 1 and 2 except for weight, which was higher in group 1. Intraoperative urine output, hypotensive episodes, and use of renal protective drugs were comparable in the two groups. Operation time, blood loss, and use of IV fluids were all significantly higher in group 2, while total aortic clamp time was higher in group 1. Postoperative events were comparable except for postoperative peak creatinine, intensive care unit length of stay, and postoperative length of stay, which were higher in group 2; however, discharge creatinine was comparable without a significant difference. Suprarenal clamping is a safe method of aortic control during open AAA replacement surgery. The selection of clamping site should be individualized according to the intraoperative anatomy. Supraceliac clamping is not necessarily the preferable method of aortic control when the infrarenal location is not suitable for clamping.     

Renal Artery Endarterectomy for Treatment of Renovascular Hypertension Combined with Infrarenal Aortic Reconstruction: Analysis of Surgical Results

From June 1995 to February 2000, 16 patients with renovascular hypertension had bilateral transaortic renal artery endarterectomy (RA TEA) combined with either infrarenal aortic aneurysm repair (8 patients) or infrarenal aortodistal bypass for occlusive disease (8 patients). Aortic clamp level for RA TEA was supraceliac in eight patients and suprarenal in eight patients with a mean clamp time of 19 min (range 14 to 25 min). Perioperative complications occurred in four patients. These included respiratory insufficiency with prolonged intubation (1 patient), prolonged intubation with transient renal failure requiring temporary dialysis (1 patient), acute thrombosis of right limb of aortofemoral bypass graft (1 patient) and major left hemispheric cerebrovascular accident (1 patient). Results from this contemporary patient series demonstrate acceptable perioperative morbidity and mortality when RA TEA for treatment of renovascular hypertension is combined with infrarenal aortic reconstruction. In this setting, either supraceliac or suprarenal aortic clamping for short time periods appears to be well tolerated. Clinical outcome is enhanced by salvage of renal function, decrease in medication requirement, and improvement in blood pressure control.     

Case report of a hybrid endovascular approach to an abdominal aortic dissection with retrograde thoracic extension and infrarenal aneurysm

Spontaneous abdominal aortic dissection (AAD) with retrograde thoracic extension is an extremely rare occurrence with a high mortality. Abdominal aortic dissection can be associated with an abdominal aortic aneurysm (AAA) and the presence of an AAD with an AAA mandates surgical intervention because of a high rate of rupture. We present the case of a 53-year-old woman with a spontaneous AAD that extended retrograde into the thoracic aorta with a concomitant supraceliac intimal tear and an infrarenal AAA repaired electively with a hybrid approach using a supraceliac stent graft and an open infrarenal aortobiiliac graft. This hybrid approach provided an excellent outcome of this rare and complex vascular pathology.     

Consumption of mannan-binding lectin during abdominal aortic aneurysm repair.

OBJECTIVE: Patients undergoing abdominal aortic aneurysm (AAA) repair are exposed to an ischaemia-reperfusion injury (IRI), which is in part mediated by complement activation. We investigated the role of the novel lectin pathway of complement during IRI in patients undergoing AAA repair. METHODS: Patients undergoing elective open infrarenal AAA repair had systemic blood samples taken at induction of anaesthesia, prior to aortic clamping, prior to aortic declamping and at reperfusion. Control patients undergoing major abdominal surgery were also included. Plasma was assayed for levels of mannan-binding lectin (MBL) using ELISA techniques. Consumption of plasma MBL was used as a measure of lectin pathway activation. RESULTS: Twenty-three patients undergoing AAA repair and eight control patients were recruited. No lectin pathway activation could be demonstrated in the control patients. AAA patients experienced a mean decrease in plasma MBL levels of 41% representing significant lectin pathway activation (p = 0.003). CONCLUSION: Consumption of MBL occurs during AAA repair, suggesting an important role for the lectin pathway in IRI. Specific transient inhibition of lectin pathway activity could be of significant therapeutic value in patients undergoing open surgical AAA repair.     

Midline retroperitoneal versus midline transperitoneal approach for abdominal aortic aneurysm repair

PURPOSE: The purpose of this study was to compare the midline retroperitoneal approach with the midline transperitoneal approach for abdominal aortic aneurysm (AAA) repair with respect to operative details, gastrointestinal complications, and wound complications. METHODS: From January 1990 through January 1998, 128 patients underwent elective aortic reconstruction for infrarenal AAA. Of these, 64 patients (the transperitoneal group) underwent conventional transperitoneal midline aortic exposure, whereas the remaining 64 patients (the retroperitoneal group) underwent retroperitoneal midline exposure of the aneurysm. RESULTS: Preclamp time, that is, the time from skin incision to aortic clamping, was significantly shorter in the transperitoneal group than in the retroperitoneal group (P <.001). However, the midline retroperitoneal approach was associated with decreased incidence of ileus (P <.01), earlier resumption of oral intake (P <.01), and decreased wound pain (P <.01), in comparison with the transperitoneal approach. Furthermore, there was no incidence of wound complications such as abdominal bulge or wound pain in any of the patients in the postoperative period or over the long term. CONCLUSIONS: The midline retroperitoneal approach for AAA was associated with fewer postoperative gastrointestinal and wound complications than the midline transperitoneal approach. Over the long term, there was no wound complication such as abdominal bulge and wound pain in any of the patients.     

Visceral and renal tissue oxygenation during supraceliac aortic crossclamping and left heart bypass with selective organ perfusion.

INTRODUCTION: Left-heart bypass (LHB) and selective organ perfusion (SOP) are used during thoracoabdominal aortic surgery to prevent ischemic damage to the kidneys and visceral organs after supraceliac aortic crossclamping. We studied the hypothesis, in a porcine model, that despite LHB and maximal SOP, visceral and renal ischemia still occurred during surgery. MATERIAL AND METHODS: Eleven pigs (54-70 kg) were coupled to a non-pulsatile LHB with inflow and outflow at the lower thoracic and distal infrarenal aorta, respectively. After supracoeliac and infrarenal aortic crossclamping, SOP was started using perfusion catheters. The proximal and distal mean aortic blood pressures were kept above 70 and 50 mmHg, respectively, while the mean blood pressure within the SOP system was above 60 mmHg. The visceral and renal tissue oxygenation was measured by intermittent blood gas analysis, from the portal and both renal veins. The jejunal mucosal oxygenation was measured by tonometric measurement of the luminal pCO2. RESULTS: Measured median blood blood flow through the LHB and the SOP system were 800 and 1140 ml/min, respectively. Median blood flow prior to, and during LHB and SOP through the celiac artery, superior mesenteric artery, and left renal artery were 300 and 240, 762 and 295, and 235 and 235 ml/min, respectively. During 3 h of LHB and SOP no significant changes in the renal tissue oxygenation were noted compared with the physiological situation prior to supracoeliac aortic crossclamping and cannulation. However, in the visceral vascular bed median mixed venous oxygen saturation dropped from 79 to 63% (p<0.001), and median oxygen extraction ratio increased from 26 to 41% (p<0.001). Median tonometric measured intraluminal jejunal pCO2 increased from 9.9 to 12.15 kPa (p>0.05). During 3 h of LHB and SOP no hemolysis was detected, as there was no rise in serum LDH. CONCLUSION: LHB and SOP preserves renal but not visceral tissue oxygenation during supraceliac aortic crossclamping and does not induce hemolysis.     

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. (J Vasc Surg 1996;24;936-45.)     

Oxygen uptake and mixed venous oxygen saturation during aortic surgery and the first three postoperative hours

This study was designed to determine the significance of changes in mixed venous oxygen saturation (SVO2) associated with aortic surgery. In 12 patients undergoing aortic aneurysm repair, SVO2 was monitored using a fiberoptic pulmonary arterial catheter, and oxygen uptake (VO2) was measured at 2-min intervals by a mass-spectrometer system. Excluding the phase of aortic clamping, VO2, hemoglobin, and arterial oxygen saturation were moderately stable during anesthesia, and changes in SVO2 were correlated with changes in cardiac output (CO). SVO2 remained stable during infrarenal aortic clamping, but increased during supraceliac aortic clamping. During the first three postoperative hours, changes in SVO2 were opposite to changes in VO2 and CO. They were especially marked in the patients whose preoperative left ventricular ejection fraction was less than 50%. We conclude that SVO2 changes are an indicator of same-direction changes in CO during general anesthesia except during periods of aortic clamping. The interpretation of SVO2 changes is more complex during aortic clamping and during the immediate postoperative period, two critical periods during which simultaneous changes in VO2 and CO occur.     

Supraceliac clamping: An underused alternative in aortic surgery

In the majority of patients undergoing abdominal aortic surgery, proximal clamping can be readily achieved below the renal vessels. In some situations however, this may be difficult, impossible or ill advised, and an alternative method of control must be sought. We describe the technique and report our personal experience with supraceliac clamping, a maneuver which merits more widespread use in emergency and difficult infrarenal aortic surgery.     

Interleukin-10 appearance following thoraco-abdominal and abdominal aortic aneurysm repair is associated with the duration of visceral ischaemia.

OBJECTIVES: to evaluate the plasma IL-10 levels during elective operative repair of thoraco-abdominal and abdominal aortic aneurysm repair. To study whether IL-10 plasma levels are associated with the duration of cross-clamping (ischaemia) and clinical outcome. MATERIALS: fifteen consecutive patients undergoing surgery for TAAA and 10 consecutive patients undergoing surgical repair of AAA were included. METHODS: plasma concentrations of IL-10 were measured by ELISA technique. Clinical outcome of the TAAA patients was prospectively analysed. RESULTS: during aortic clamping IL-10 was produced in both populations. The plasma IL-10 peak (934+/-172 pg/ml) of the TAAA group was seen at 4 h after declamping and remained detectable after 48 h. The plasma IL-10 peak (212+/-32 pg/ml) of the AAA group was seen 30 min after declamping and fell to undetectable levels by 24 h. These data show that the peak IL-10 plasma levels in TAAA repair are significantly (p<0.05) higher compared to the peak IL-10 plasma levels as seen during AAA repair. A positive correlation was seen between cross-clamping and peak plasma IL-10 and organ dysfunction. CONCLUSIONS: IL-10 plasma concentrations appear higher, later and are longer detectable in patients undergoing TAAA. Correlations were seen with duration of cross-clamping and MSOD.     

Assessment of spinal cord integrity during thoracoabdominal aortic aneurysm repair

BACKGROUND: Monitoring motor-evoked potentials (MEPs) is an accurate technique to assess spinal cord integrity during thoracoabdominal aortic aneurysm (TAAA) repair, guiding surgical strategies to prevent paraplegia. METHODS: In 210 consecutive patients with type I (n = 75), type II (n = 103), and type III (n = 32) TAAA surgical repair was performed using left heart bypass, cerebrospinal fluid drainage, and MEPs monitoring. RESULTS: Reliable MEPs were registered in all patients. The median total number of patent intercostal and lumbar arteries was five. After proximal aortic crossclamping, MEP decreased below 25% of base line in 72 patients (34%) indicating critical spinal cord ischemia, which could be corrected by increasing distal aortic pressure. By using sequential clamping it appeared that in 43% of type I and II cases spinal cord circulation was supplied between T5 and L1, and 57% between L1 and L5. In type II and III cases cord perfusion was dependent upon lower lumbar arteries in 16% and pelvic circulation in 8%, necessitating reattachment of these segmental arteries. In 9% of patients critical ischemic MEP changes occurred without visible arteries, requiring aortic endarterectomy and selective grafting. One patient suffered early paraplegia and 2 delayed, and 2 patients had temporary neurologic deficit (5 of 210; 2.4%). CONCLUSIONS: In patients with TAAA, blood supply to the spinal cord depends upon a highly variable collateral system. Monitoring MEPs is an accurate technique for detecting cord ischemia, guiding surgical tactics to reduce neurologic deficit (2.4%).     

Conformational changes associated with proximal seal zone failure in abdominal aortic endografts

OBJECTIVE: Endovascular aneurysm repair (EVAR) has become a popular treatment for abdominal aortic aneurysm (AAA). This study examines conformational changes in the infrarenal aortas of patients in whom proximal seal zone failures (PSF) developed after EVAR. METHODS: All 189 patients with aortic endograft underwent routine post-EVAR computed tomographic scan surveillance. Patients identified with proximal type I endoleaks, type III endoleaks, or proximal component separation without demonstrable endoleak underwent three-dimensional reconstruction of the computed tomographic scans from which measurements of the migration, length, volume, and angulation of the infrarenal aorta were made. RESULTS: Five patients (3%) had PSF develop, four of whom had aortic extender cuffs. Although changes in the AAA volume and aortic neck angle were slight or variable, the mean AAA length increased 34 mm and the mean aortic body angulation increased 17 degrees (P =.03 and.01, respectively). Lengthening and migration caused proximal component separation in four patients, with concomitant migration in two patients. Two patients underwent endovascular repair, two patients needed explantation of the endograft, and one patient awaits endovascular repair. Proximal component separation and type III endoleak recurred in one patient and were repaired with a custom-fitted graft. CONCLUSION: PSF of aortic endografts is associated with proximal angulation and lengthening of the infrarenal aorta. These findings reinforce the importance of proper initial deployment to minimize the need for aortic extender cuffs, which pose a risk of late endoleak development.     

Renal artery clamping and left renal vein division during abdominal aortic aneurysm repair.

OBJECTIVES: To determine whether renal artery clamping and division of the left renal vein affects renal function in the patients who undergo repair of infrarenal abdominal aortic aneurysm (AAA). METHODS: Between 1992 and 2000, 267 patients had open surgery for infrarenal AAA. Of these, 22 (8%) required temporary bilateral (15) or unilateral (7) renal artery clamping. 8 also had the left renal vein divided, three of which were re-anastomosed. RESULTS: Renal artery clamping and/or renal vein divisions did not affect the incidence of complications and long term renal failure. CONCLUSIONS: Clamping of the renal arteries and/or renal vein division during AAA surgery does not in itself compromise short or long term renal function.     

Analysis of coagulation changes associated with supraceliac aortic crossclamping using thromboelastography

INTRODUCTION: The etiology of the coagulation changes seen with supraceliac (SC) aortic crossclamping (AXC) remains controversial; both primary fibrinolysis and clotting factor consumption have been implicated. The cause of these changes was investigated with thromboelastography (TEG), a test that measures the viscoelastic properties of thrombus to dynamically assess coagulation and fibrinolysis. METHODS: Eight pigs underwent SC AXC for 30 min; 5 pigs undergoing 30 min of infrarenal (IR) aortic clamping served as controls. Blood was drawn before AXC, before unclamping, and 5 and 60 min after unclamping. Thromboelastography and standard coagulation tests [prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen, and platelet count] were performed. Measured TEG parameters included fibrinolytic index (a measure of fibrinolysis), r value (a reflection of intrinsic coagulation cascade activity), and the alpha angle and K values (measures of the speed of solid clot formation). Repeated measures ANOVA and t test were used for statistical analysis. RESULTS: There was no difference in the fibrinolytic index at any time point between the two groups. Increased activity of the intrinsic coagulation cascade during SC clamping was reflected by a lower R value just before unclamping (12.6 +/- 3.0 vs 20.0 +/- 3.0, P = 0.048) compared to IR AXC. Decreased speed of solid clot formation was noted 5 min after unclamping in the SC group but not the IR group [as defined by an increased K value (ANOVA, P = 0.010) and a decreased alpha angle value (ANOVA, P = 0.005)]. Fibrinogen levels were lower in the SC than in the IR group 5 (P = 0.013) and 60 min after unclamping (P = 0.02), but PT, PTT, and platelets did not differ between the groups at any time points. CONCLUSIONS: Thirty minutes of SC AXC does not result in fibrinolysis. There is increased clotting activity during SC clamping followed by decreased speed of clot formation and decreased fibrinogen levels after unclamping. These changes are consistent with clotting factor consumption.     

Alterations in carbon dioxide release during abdominal aortic clamping for aneurysmal or occlusive repair.

BACKGROUND: Application and removal of an infrarenal aortic clamp is associated with changes in oxygen consumption, especially when collateral perfusion is limited. Carbon dioxide production during abdominal aortic clamping is expected also to change. The aim of this study was to evaluate the alterations of CO2 release during abdominal aortic surgery. METHODS: DESIGN: prospective study. SETTING: University Hospital, Greece. PATIENTS: 17 patients undergoing abdominal aortic aneurismal (AAA) repair and 8 patients undergoing repair of aortoiliac occlusive disease. Intervention: intraoperative record or calculation of PaCO2, PetCO2, PECO2, VD, VDalv, and VCO2. Patients with aneurysms were randomly divided to have constant ventilation (group AA) or modified ventilation to preserve normocapnia (group AB) during clamping. Ventilation was kept constant in the occlusive patients group (group OD). RESULTS: Patients with AAA showed a significant decrease of VCO2 during clamping and an elevation after unclamping in both groups (AA and AB), with no difference of statistical importance between them. During clamping, PetCO2/ PaCO2 ratio was decreased and VDalv was increased especially in group AA, while unclamping produced the opposite effect. Occlusive patients showed insignificant alterations. CONCLUSIONS: Our results suggest that, the calculated alveolar dead space is only an indicator of the true V/Q in patients with AAA, because it is strongly dependent on the CO2 load to the lungs, which is markedly altered in the same period. The modification of ventilation during clamping based only on PetCO2 and not on arterial sampling, could possibly lead to hypercarbia in these patients.     

Aortenzentren

The ideal aortic center is a maximum care center which treats all pathologies from the aortic root downwards, including the side branches and target organs. Furthermore, it offers the best quality of all treatment modalities round the clock. Should aortic surgery only be performed at ideal aortic centers? Meta-analyses, which investigated the volume-outcome relationship for abdominal aortic aneurysm (AAA) surgery identified a hospital and/or surgeon low annual operation volume as being a significant mortality predictor. Data from these studies suggested that AAA surgery should be performed only at high-volume centers but there is no evidence to centralize patients with infrarenal, juxtarenal and suprarenal AAA in maximum care aortic centers as defined above. However, absolutely safe AAA surgery requires a competent and experienced team, a minimal annual case volume and an adequate infrastructure. These conditions are more or less applicable to thoracic endovascular aortic repair (TEVAR). In contrast thoracic aortic aneurysm (TAA) open repair and all thoracic abdominal aortic aneurysms (TAAA) should be treated in specialized aortic centers because TAA(A) surgery requires high expertise and vast experience as well as extensive technical equipment to provide extracorporeal circulation and neuromonitoring.     

Strategies to prevent neurologic deficit based on motor-evoked potentials in type I and II thoracoabdominal aortic aneurysm repair

Purpose: Motor-evoked potentials (MEPs) were monitored during thoracoabdominal aortic aneurysm (TAAA) repair to assess spinal cord ischemia and evaluate the subsequent protective strategies to prevent neurologic deficit. Methods: Between January 1996 and December 1997, 52 consecutive patients with type I (n = 24) and type II (n = 28) TAAA underwent surgery (mean patient age, 60 years; range, 21–78 years). The surgical protocol included left heart bypass, cerebrospinal fluid drainage, and monitoring transcranial myogenic MEPs. When spinal cord ischemia was detected, distal aortic pressure and mean arterial pressure were increased. By means of sequential crossclamping, MEPs were used to identify critical intercostal or lumbar arteries. Results: Reproducible MEPs could be recorded in all patients, and spinal cord ischemia was detected within 2 minutes. During distal aortic perfusion, 14 patients (27%) showed rapid decrease in the amplitude of MEPs to less than 25% of baseline, indicating spinal cord ischemia, which could be corrected by increasing distal aortic pressure. The mean distal aortic pressure to maintain adequate cord perfusion was 66 mm Hg; however, it varied among individuals between 48 and 110 mm Hg. In 24 patients (46%), MEPs disappeared after segmental clamping and returned after reattachment of intercostal arteries. In 9 patients (17%), MEPs disappeared completely, but no intercostal arteries were found. After aortic endarterectomy, 6 or 8 mm Dacron grafts were anastomosed to intercostal arteries, and MEPs returned after reperfusion. Using this aggressive surgical approach based on MEPs, no early or late paraplegia occurred in this series. Conclusion: Monitoring of MEPs is an effective technique to assess spinal cord ischemia. Operative strategies based on MEPs prevented neurologic deficits in patients treated for type I and II TAAA. (J Vasc Surg 1999;29:48-59.)     

Results of supraceliac aortic clamping in the difficult elective resection of infrarenal abdominal aortic aneurysm

We have used clamping of the aorta above the celiac axis (SC) in 30 of 431 elective resections of infrainguinal abdominal aortic aneurysms (AAA) during the past five years as an alternative to a difficult aortic cuff dissection. The results of SC clamping in these 30 patients are compared with the results of 379 routine aneurysm resections with infrarenal (IR) clamping and 22 additional aneurysm resections where the clamp was placed immediately above the renal arteries. These difficult cuff dissections occurred in 12 patients with inflammatory AAA, in 11 patients with juxtarenal AAA, and in seven patients with recurrent or noninfected false AAA of the proximal cuff. Patients with ruptured or suprarenal aneurysms and those undergoing combined operation for a visceral ischemic syndrome and an aneurysm were excluded from this study. Patients with SC clamping had similar operative mortality rates, comparable renal function, and frequency of cardiac events as patients with IR clamping. Blood loss was slightly higher in the SC group (p = 0.07) and serum aspartate amino transferase (AST) levels were three times higher than in the IR group; however, this was of no clinical significance. In contrast, those 22 patients whose aortas were clamped immediately above the renal arteries (AR) had higher perioperative mortality rates (2% IR, 3% SC vs 32% AR) and a higher incidence of kidney failure requiring dialysis (1% IR, 3% SC vs 23% AR). The mean values of serum creatinine and blood urea nitrogen were also significantly higher in the AR group when compared with both the IR and the SC groups (IR: 25 and 1.5 mg/dl, respectively; SC: 27 and 1.8 mg/dl; AR: 41 and 3.5 mg/dl). The single most important risk factor accounting for the differences between clamping above the celiac artery and clamping above the renal arteries was the presence of atherosclerotic debris in the nonaneurysmal, juxtarenal aortic segment. Clamping the aorta with juxtarenal atherosclerosis caused either atheroembolization to kidneys, legs, and intestine or injury to the aorta, renal arteries, or both; it was the cause of morbidity in all five cases of kidney failure requiring dialysis and accounted for all seven of the deaths in the AR group. SC clamping does not add risk to the patient undergoing resection of an infrarenal AAA and is the preferred method of achieving proximal control of the infrarenal aorta when a a hazardous cuff dissection is likely.(ABSTRACT TRUNCATED AT 400 WORDS)