Distal Aortic Perfusion Research Articles

Combined distal aortic perfusion and balloon occlusion to facilitate the repair of complex thoracic and thoracoabdominal aortic aneurysms

We investigated a unique method utilising a Heartport bifurcated arterial cannula and an aortic occlusion balloon to provide both distal perfusion and bloodless, distal arterial exposure during repair of thoracic and thoracoabdominal aortic pathology. Between February 2002 and September 2008, 21 patients underwent thoracic or thoracoabdominal aortic repair with this method. Because of an inability or potential difficulty in achieving distal aortic control secondary to anatomic or technical challenges, a compliant balloon was passed through the accessory arterial channel using fluoroscopic guidance. Adjunctive cerebrospinal drainage was used in all cases. Ballon deployment and satisfactory occlusion was attained in all cases. The overall 30-day mortality rate was 4.75% (1 of 21 patients). Renal failure occurred in one patient (4.75%) and heart failure occurred in two patients (9.5%). Six patients (29%) had pulmonary complications. Transient encephalopathy occurred in two patients (9.5%). Spinal cord neurologic deficit and stroke were avoided in all patients. We recommend the application of this simple method to obtain a bloodless anastomotic field and maintain ongoing distal aortic perfusion in instances where distal control with a clamp is challenging, not feasible or presents the potential for catastrophic intra-operative bleeding.

Postoperative renal function preservation with nonischemic femoral arterial cannulation for thoracoabdominal aortic repair

Renal failure after thoracoabdominal aortic repair is a significant clinical problem. Distal aortic perfusion for organ and spinal cord protection requires cannulation of the left femoral artery. In 2006, we reported the finding that direct cannulation led to leg ischemia in some patients and was associated with increased renal failure. After this finding, we modified our perfusion technique to eliminate leg ischemia from cannulation. In this article, we present the effects of this change on postoperative renal function. Between February 1991 and July 2008, we repaired 1464 thoracoabdominal aortic aneurysms. Distal aortic perfusion was used in 1088, and these were studied. Median patient age was 68 years, and 378 (35%) were women. In September 2006, we began to adopt a sidearm femoral cannulation technique that provides distal aortic perfusion while maintaining downstream flow to the leg. This was used in 167 patients (15%). We measured the joint effects of preoperative glomerular filtration rate (GFR) and cannulation technique on the highest postoperative creatinine level, postoperative renal failure, and death. Analysis was by multiple linear or logistic regression with interaction. The preoperative GFR was the strongest predictor of postoperative renal dysfunction and death. No significant main effects of sidearm cannulation were noted. For peak creatinine level and postoperative renal failure, however, strong interactions between preoperative GFR and sidearm cannulation were present, resulting in reductions of postoperative renal complications of 15% to 20% when GFR was <60 mL/min/1.73 m(2). For normal GFR, the effect was negated or even reversed at very high levels of GFR. Mortality, although not significantly affected by sidearm cannulation, showed a similar trend to the renal outcomes. Use of sidearm cannulation is associated with a clinically important and highly statistically significant reduction in postoperative renal complications in patients with a low GFR. Reduced renal effect of skeletal muscle ischemia is the proposed mechanism. Effects among patients with good preoperative renal function are less clear. A randomized trial is needed.

Anatomical Pattern of Feeding Artery and Mechanism of Intraoperative Spinal Cord Ischemia

We evaluated correlation between anatomical pattern of the spinal cord feeding artery, detected by preoperative multidetector row computed tomography, and the mechanism of spinal cord ischemia during aortic surgery. One hundred sixteen patients underwent multidetector row computed tomography before descending or thoracoabdominal replacement. Segmental arteries feeding the spinal cord were detected in 92 patients (79%), and were classified into "critical" (isolated hairpin shaped) or "supplemental" (confluence-shaped or multiple). Spinal cord ischemia was monitored together with distal aortic perfusion in 53 of them by motor-evoked potentials, evoked spinal cord potentials, or both. The relationship between monitoring results and operative management to the detected feeding arteries was analyzed. When no feeding segmental artery was involved in the extent of replacement (n = 18), spinal cord ischemia was detected in 1 (6%), which was due to cross-clamping the subclavian artery. When a supplemental feeding artery was involved (n = 15), ischemia was detected in 7 patients (47%), and was reversed by stopping back-bleeding. When a critical feeding artery was involved (n = 20), ischemia was detected in 6 (30%). In 3 of them, ischemia was reversed by stopping back-bleeding, whereas it was reversed only after reconstruction of the critical feeder in the remaining 3. Paraparesis occurred in 1 of the latter 3, and the incidence of spinal cord injury was 2% (1 of 53). When the involved feeding artery is a supplemental one, the steal phenomenon is the predominant mechanism of ischemia. Conversely, blood flow interruption to the critical feeding artery may cause spinal cord ischemia without steal phenomenon.

Cerebrospinal Fluid Drainage During Thoracic Aortic Repair: Safety and Current Management

The benefit of cerebrospinal fluid (CSF) drainage during thoracic aortic repair has been established. Few studies, however, report management and safety of CSF drainage. Between September 1992 and August 2007, 1,353 repairs of the thoracic aorta were performed, with 82% using CSF drainage. The CSF drainage was not used in cases of rupture, acute trauma, infection, or prior paraplegia. Thirty-one percent (76 of 246) of patients without CSF drainage were repaired prior to standardized use. All drains were inserted by cardiovascular anesthesia staff. Repairs were performed using distal aortic perfusion with heparinization. Early management involved free drainage to maintain CSF pressure less than 10 mm Hg, but was later modified to limit CSF drainage unless neurologic deficit occurred. Cerebrospinal fluid drainage was technically achieved in 99.8% (1,105 of 1,107) of cases. The CSF catheter-related complications occurred in 1.5% (17 of 1,107) of patients. No spinal hematomas were observed. The CSF leaks with spinal headache, CSF leak without spinal headache, spinal headache, intracranial hemorrhage, catheter fracture, and meningitis occurred in 6 (0.54%), 1 (0.1%), 2 (0.2%), 5 (0.45%), 1 (0.1%), and 2 (0.2%) cases, respectively. Mortality from subdural hematoma was 40% (2 of 5), and from meningitis was 50% (1 of 2). Spinal headaches resolved with conservative management. All CSF leaks resolved, but 71% (5/7) required blood patches. Since implementation of a limited CSF drainage protocol, no subdural hematomas have been observed. Cerebrospinal fluid drainage for thoracic aortic repairs can be performed safely with excellent technical success. Perioperative management of CSF drains requires diligent monitoring and judicious drainage. Standardizing CSF management may be beneficial.

Long-Term Durability of Open Thoracic and Thoracoabdominal Aneurysm Repair

Results of open surgical repair of descending and thoracoabdominal aortic aneurysms have improved dramatically over the years. Nevertheless, while adjunctive protective strategies, such as spinal cord drainage and distal aortic perfusion, have improved outcomes, clinical challenges remain. In the current era, thoracic aortic surgeons must possess both open and endovascular stent-graft capabilities to offer these complex patients the most optimal and individualized treatment approach. Herein we summarize the contemporary outcomes of open surgical repair of patients with either descending thoracic or thoracoabdominal aortic aneurysms, focusing on the risk of complications and means for preventing their occurrence.

Technique for repair of suprarenal and thoracoabdominal aortic aneurysms

Suprarenal and thoracoabdominal aortic aneurysms represent significant surgical challenges. For patients with associated aortic dissections, current endovascular technology has not been matured to address branch reconstructions that derive from separate lumens, making open surgical reconstruction the only proven method for repair. The required exposures of the thoracoabdominal aorta are expansive, and the extent of aortic replacement mandates efficient technique. Furthermore, a well-orchestrated team of surgeons, nurses, anesthesiologists, and perfusionists are all integral to achieving good outcomes and keeping operative courses tightly managed. Techniques to address extensive aneurysms of the thoracoabdominal aorta are reviewed in detail here, and videos are provided on The Journal website to show relevant anatomical features.

RR33. Postoperative Creatinine Reduction with Non-Ischemic Femoral Arterial Cannulation for Thoracoabdominal Aortic Repair

Renal failure after thoracoabdominal aortic (TAAA) repair is a significant clinical problem. Distal aortic perfusion for organ and spinal cord protection requires cannulation of the left femoral artery. In 2006 we discovered that direct cannulation led to leg ischemia in some patients, and that this was associated with increased renal failure. Following this finding, we modified our perfusion technique to eliminate leg ischemia from cannulation. Here we present the effects of this change on postoperative renal function. Between February 1991 and July 2008, we repaired 1443 TAAA, 1067 using distal aortic perfusion, and only those receiving distal perfusion were studied. Median age was 68 years and 373/1067 (35%) were female. In September 2006 we adopted a sidearm femoral cannulation technique that provides distal aortic perfusion while maintaining downstream flow to the leg. This was used in 135 (12%) patients. We measured the joint effects of preoperative glomerular filtration rate (GFR) and cannulation technique on highest postoperative creatinine. Analysis was by multiple linear regression with interaction and log transformation of creatinine. Median postoperative creatinine was 1.6 mg/dl, with an interquartile range of 1.0 - 3.4. The highest observed postoperative creatinine was 12.3. Although crude mean postoperative creatinine did not differ between the direct and sidearm cannulation groups, a strong interaction with preoperative GFR was present. Regression model terms were GFR x −0.006 (p<0.0001), sidearm x −0.27 (p<0.02) and GFR x sidearm x 0.004 (p<0.0001). For preoperative GFR below 70, sidearm cannulation was associated with an approximate 50% reduction in peak postoperative creatinine. Use of sidearm cannulation is associated with a clinically important and highly statistically significant reduction in postoperative creatinine in patients with low GFR. Reduced renal effect of skeletal muscle ischemia is the proposed mechanism.

PP71. A Reappraisal of Extent IV Thoracoabdominal Aortic Aneurysms

Extent IV aneurysms have long been viewed as low risk members of the thoracoabdominal aortic aneurysm (TAAA) family. This perception is based largely on old data in which extent I and II aneurysms carried extremely high morbidity (paraplegia / paraparesis) and mortality risk relative to extent IV aneurysms. More recently, we have shown that preoperative renal function as measured by glomerular filtration rate (GFR) is worse with more extensive abdominal / visceral aortic involvement. Here we revisit the risk factors and outcomes of open repair of extent IV TAAA. Between February 1991 and July 2008, we repaired 231 Crawford extent IV TAAA. Median age of the population was 70 (range 37-86) and 77/231 (33%) patients were female. All repairs were performed using open technique with graft replacement using distal aortic perfusion and cerebrospinal fluid drainage. Median baseline GFR was 59.6 (interquartile range 42-80) ml/min/1.73m2. When GFR is below the median, 30-day mortality is 30/111 (27%) vs 10/120 (8%), odds ratio 4.1, p <0.0002. Three immediate neurologic deficits occurred in the population (3/231 = 1%), and all of these were in the lowest quartile of GFR (GFR < 42). Mortality following extent IV TAAA repair is strongly correlated with preoperative GFR. Neurologic deficit rates are very low in this population (1%) and in our experience occur exclusively in the setting of very low GFR. Risk stratification based on preoperative GFR is helpful in evaluating the outcome of different treatment modalities for patients with extent IV TAAA.

Response to Letter Regarding Article, “Continuous Aortic Flow Augmentation: Not Enough MOMENTUM”

I agree with the objection raised by Dr Greenberg about my comment1 that implied that the continuous aortic flow augmentation system had a primary or direct effect on increasing cardiac output. Clearly, any increase in cardiac output would be secondary to a decrease in peripheral resistance associated with the distal aortic perfusion. The study design used in the Multicenter Trial of the Orqis Medical Cancion System for the Enhanced Treatment of Heart Failure Unresponsive to Medical Therapy (MOMENTUM) did in fact include a paired analysis, as noted by Dr Greenberg. The population of patients who develop worsening heart failure and become progressively unresponsive …

Brain and spinal cord protection during simultaneous aortic arch and thoracoabdominal aneurysm repair

We assessed the surgical and neurological outcome of patients undergoing simultaneous repair of aortic arch and descending thoracic aortic aneurysms (DTAA) or thoracoabdominal aortic aneurysms (TAAA) via left thoracotomy or thoracolaparotomy. During a 6-year period, we performed 32 procedures in 23 male and 9 female patients with DTAA or TAAA with concomitant aortic arch aneurysms. The mean age of the patients was 50.9 years (range, 18-75 years). Twenty-two patients suffered from DTAA, 4 had type-I TAAA, and 6 had type-II TAAA. The entire aortic arch was involved in 12 patients and the distal hemi-arch in 20 patients. The mean diameter of the aneurysms was 6 cm (range, 4.9-7.6 cm). All patients were operated on according to the protocol with cerebrospinal fluid drainage, distal aortic and selective organ perfusion, as well as antegrade brain perfusion. Neuromonitoring was performed by means of motor evoked potentials (MEPs), transcranial Doppler (TCD), and electroencephalography (EEG). All patients survived the surgical procedure and 30-day mortality did not occur. At the end of the procedure, all patients had adequate MEPs, TCD, and EEG. One patient died 47 days after operation due to gastrointestinal bleeding and therapy-resistant coagulopathy. Major postoperative complications like paraplegia or paraparesis, renal failure, and myocardial infarction were not encountered. One patient had a stroke but neurological deficits were irrelevant. Mean preoperative creatinine level was 125 mmol/L, which peaked to a mean maximal level of 130 and returned to 92 mmol/L at discharge. Other complications included bleeding requiring surgical intervention (n = 4), arrhythmia (n = 1), pneumonia (n = 5), and respiratory distress syndrome (n = 2). At a median follow-up of 38 months, all but 1 patient was alive and free of re-intervention. Single-stage repair of aortic arch and concomitant thoracic and thoracoabdominal aortic aneurysms via left-sided thoracotomy or thoraco-laparotomy yields excellent short- and midterm outcomes. Monitoring of cerebral and spinal cord function contributes to improved neurologic outcome.

Assessment of hepatosplanchnic pathophysiology during thoracoabdominal aortic aneurysm repair using visceral perfusion and shunt☆

Despite the recognition of importance to avoid visceral ischemia during thoracoabdominal aortic aneurysm (TAAA) repair, the methodology of visceral perfusion seems still controversial and its pathophysiology has not been clearly understood. We investigated hepatosplanchnic metabolism during visceral perfusion/shunt in TAAA repair. Seventeen patients (10 male, 64+/-15 years old) who underwent elective TAAA repair using visceral perfusion/shunt under mild hypothermic distal aortic perfusion were retrospectively enrolled. Their aneurysm extension was type I and II in eight patients. In seven patients, four visceral arteries were perfused through a side-arm of distal aortic perfusion, while they were perfused by an independent pump in another five patients. In four of these 12 (two in each technique), visceral perfusion was converted into selective shunt after completion of aortic anastomosis. In the remaining five patients, four branches were initially perfused through a side-arm of distal aortic perfusion, and aortic perfusion was subsequently stopped after completion of aortic anastomosis. Hepatic venous oxygen saturation (ShO(2)), oxygen and lactate extraction ratio (OER, LER), and arterial ketone body ratio (AKBR) were measured at six time points. There was no mortality, liver/renal dysfunction, or spinal cord injury. Two patients required re-exploration for bleeding. Fourteen patients were extubated within 24h postoperatively. Mean intensive care unit stay was 2.3+/-1.7 days. During visceral perfusion, OER raised (31+/-13% to 68+/-21%, p=0.0012) and ShO(2) decreased (67+/-12% to 34+/-24%, p=0.0026) significantly. They recovered to baseline at skin closure. During the same period, LER (41+/-22% to -1+/-34%, p=0.0035) and AKBR (0.47+/-0.13 to 0.20+/-0.08, p=0.0012) significantly decreased. AKBR recovered to baseline at skin closure, but LER did not. ShO(2) (R(2)=0.483, p=0.0257) and LER (R(2)=0.774, p=0.0018) at skin closure and LER after initiation of partial cardiopulmonary bypass (R(2)=0.427, p=0.0211) had significant correlation with postoperative peak serum bilirubin level. AKBR after initiation of partial cardiopulmonary bypass had significant correlation with postoperative peak serum alanine aminotransferase level (R(2)=0.289, p=0.0476). Visceral perfusion/shunt in TAAA repair may avoid critical irreversible hepatosplanchnic ischemia but provide unphysiological blood flow to the liver and thus should be shortened.

Visceral Injury and Systemic Inflammation in Patients Undergoing Extracorporeal Circulation During Aortic Surgery

Visceral injury and inflammation are evaluated in patients undergoing extracorporeal circulation (ECC) either with distal aortic perfusion (DAP) during thoracic aortic aneurysm (TAA) repair or DAP and selective organ perfusion (DAP and SP) during thoracoabdominal aortic aneurysm (TAAA) repair. Visceral hypoperfusion and subsequent visceral injury, mainly to the gut, have been implicated as central events in the development of systemic inflammatory response syndrome (SIRS) and organ dysfunction after major surgery. Patients undergoing DAP or DAP and SP are exposed to artificial visceral perfusion, potentially leading to the development of intestinal injury and systemic inflammation. To assess visceral injury arteriovenous differences of fatty acid binding proteins were measured for the gut (I-FABP and L-FABP) and left kidney (L-FABP) along with systemic plasma concentrations. Systemic ALT was used as liver injury marker. Plasma IL-6 and IL-8 denoted systemic inflammation. During ECC systemic I-FABP and L-FABP levels increased in both groups, representing intestinal injury. Significantly elevated levels of I-FABP (P < 0.001) and L-FABP (P < 0.001) were found in the DAP and SP group, after ECC was stopped and normal circulation restored. Liver and renal tubular cell injury was not detected. Significant increases in systemic IL-6 and IL-8 values were measured only in patients undergoing DAP and SP. Additionally, the extent of intestinal injury correlated positively with systemic inflammation. This study shows the development of intestinal mucosal injury during ECC with DAP or DAP and SP, indicative of insufficient intestinal perfusion. Intestinal injury was associated with a systemic pro-inflammatory response.

Intraoperative skeletal muscle ischemia contributes to risk of renal dysfunction following thoracoabdominal aortic repair☆☆☆

Renal dysfunction is among the most commonly occurring morbidities following descending thoracic and thoracoabdominal aortic repair. We hypothesized that myoglobin nephrotoxicity might arise from leg ischemia caused by femoral artery cannulation, which is required for distal aortic perfusion. Lacking complete historical laboratory data on myoglobinemia, we studied somatosensory evoked potential (SSEP) changes in the leg (a functional marker of leg ischemia), as a surrogate predictor of acute postoperative renal failure. Intraoperative leg SSEP function and preoperative glomerular filtration rate (GFR - an essential covariate) were available for 299 patients. Change in SSEP was defined as 10% increase in latency or 50% decrease in amplitude. Postoperative renal dysfunction was 1mg/dl/day increase in creatinine for 2 days, clinical diagnosis of ARF or need for dialysis postoperatively. Change in SSEP in the cannulated leg occurred in 108/299 (36%) of cases intraoperatively. All recovered normal SSEP function at decannulation. Patients with SSEP changes had 41/108 (38%) postoperative renal failure compared to 49/191 (26%) without (odds ratio 1.8, p<0.03). Modeled with GFR, aneurysm extent, and chronic obstructive pulmonary disease (COPD), SSEP changes had an adjusted odds ratio of 1.9, p<0.03. Pre-op GFR was also a highly significant predictor of postoperative renal failure (OR 0.98/ml; p<0.0001). This is the first study to show a relationship between intraoperative leg ischemia and postoperative renal failure. It provides epidemiological evidence that the ischemic leg may be an important contributor to rhabdomyolysis-like renal morbidity after thoracoabdominal aortic surgery.

Thoracoabdominal Aortic Aneurysm Repair in Patients with Marfan Syndrome

We assessed the surgical outcome of descending thoracic aortic aneurysm repair (DTAA) and thoracoabdominal aortic aneurym (TAAA) repair in patients with Marfan syndrome. During a six year period, 206 patients underwent DTAA and TAAA repair. In 22 patients, Marfan syndrome was confirmed. The median age was 40 years with a range between 18 and 57 years. The extend of the aneurysms included 6 DTAA (1 with total arch, 2 with distal hemi-arch), 11 type II TAAA (2 with total arch, 3 with distal hemi-arch), 4 type III and one type IV TAAA. All patients suffered from previous type A (n=6) or type B (n=16) aortic dissection and 15 already underwent aortic procedures like Bentall (n=7) and ascending aortic replacement (n=8). All patients were operated on according to the standard protocol with cerebrospinal fluid drainage, distal aortic and selective organ perfusion and monitoring motor evoked potentials. In patients undergoing simultaneous arch replacement (via left thoracotomy), transcranial Doppler and EEG assessed cerebral physiology during antegrade brain perfusion. In four patients circulatory arrest under moderate hypothermia was required. In-hospital mortality did not occur. Major postoperative complications like paraplegia, renal failure, stroke and myocardial infarction were not encountered. Mean pre-operative creatinine level was 125mmol/L, which peaked to a mean maximal level of 130 and returned to 92mmol/L at discharge. Median intubation time was 1.5 days (range 0.33-30 days). Other complications included bleeding requiring surgical intervention (n=1), arrhythmia (n=2), pneumonia (n=2) and respiratory distress syndrome (n=1). At a median follow-up of 38 months all patients were alive. Using CT surveillance, new or false aneurysms were not detected, except in one patient who developed a visceral patch aneurysm six years after open type II repair. Surgical repair of descending and thoracoabdominal aortic aneurysms provides excellent short- and mid-term results in patients with Marfan syndrome. In this series, a surgical protocol with cerebrospinal fluid drainage, distal aortic and selective organ perfusion and monitoring motor evoked potentials resulted in low morbidity and absent mortality. These outcomes of open surgery should be considered when discussing endovascular aneurysm repair in Marfan patients.

Is Distal Aortic Perfusion in Traumatic Thoracic Aortic Injuries Necessary to Avoid Paraplegic Postoperative Outcomes?

Traumatic thoracic aorta injuries account for nearly 8,000 deaths annually in the United States. Clamp-and-sew techniques can lead to high rates of paraplegia. Use of distal aortic perfusion can lead to heparin-related complications, particularly with associated head trauma. Our objective was to evaluate whether or not an individualized approach to operative management provides acceptable neurologic outcomes. A retrospective review (1991-2004) of patients with a traumatic thoracic aortic injury at a Level I trauma center was performed. A total of 67 patients fit the study criteria. Ninety-one percent of patients had concomitant injuries. Median time from injury to evaluation was 38.0 minutes and from evaluation to operating room (OR) 111.0 minutes. Fifty-three percent of patients died before definitive repair could be undertaken; 29% were in the emergency department and 24% were in the OR. When definitive repair occurred, distal aortic perfusion was used in 81% of cases (75% left heart bypass, 6% cardiopulmonary bypass). The remaining 19% underwent clamp-and-sew technique without heparinization. There were no spinal cord deficits or adverse cerebral events related to repair. If definitive repair was completed, the mortality was 16%. Male sex and increasing time, both to evaluation and to OR, were the only risk factors associated with increased mortality. Judicious use of clamp-and-sew techniques can achieve excellent neurologic outcomes, equivalent to distal aortic perfusion. Prompt evaluation leads to improved survival. Factors such as age, mechanism of injury, site of aortic injury, or operative technique did not affect mortality.

Hypothermic circulatory arrest with 'low flow' lower body perfusion: An experimental study of microcirculatory parameters

Objective: Cerebral perfusion seems to be an adequate tool for neuroprotection under hypothermic circulatory arrest (HCA). To avoid extended cardiopulmonary bypass (CPB) times, moderate temperatures are applied for body arrest, jeopardizing optimal organ protection, especially if prolonged HCA times are anticipated. Therefore, distal aortic perfusion might become an alternative, but experimental data are missing.

Multilevel somatosensory evoked potentials and cerebrospinal proteins: indicators of spinal cord injury in thoracoabdominal aortic aneurysm surgery

Multilevel somatosensory evoked potentials (SSEP) and the release of biochemical markers in cerebrospinal fluid (CSF) were investigated to identify patients with spinal cord ischemia during thoracoabdominal aortic repair and/or a vulnerable spinal cord during the postoperative period. Thirty-nine consecutive patients undergoing elective aneurysm repair using distal aortic perfusion and cerebrospinal fluid drainage were studied. Continuous SSEP were monitored using nerve stimulation of the right and left posterior tibial nerves with signal recording at the level of both common peroneal nerves, the cervical cord and at the cortical level. CSF concentrations of the markers glial fibrillary acidic protein (GFAp), the light subunit of neurofilament triplet protein (NFL), and S100B were determined at different time points from before surgery until 3 days postoperatively. SSEP indicated spinal cord ischemia in two patients leading to additional intercostal artery reattachments. In one of them the signal loss was permanent and the patient woke up with paraplegia. In the other the signal returned but the patient later developed delayed paraplegia. Three patients without SSEP indications of spinal cord ischemia during surgery later developed delayed paraplegia. The patients with spinal cord symptoms had significant increases, during the postoperative period of CSF biomarkers GFAp (571-fold), NFL (14-fold) and S100B (18-fold) compared to asymptomatic patients. GFAp increased before or in parallel to onset of symptoms in the patients with delayed paraplegia. Peroperative multilevel SSEP has a high specificity in detecting spinal cord ischemia but does not identify all patients with a postoperative vulnerable spinal cord. Biochemical markers in CSF increase too late for intraoperative monitoring but GFAp is promising for identifying patients at risk for postoperative delayed paraplegia.

Pulmonary Complications After Descending Thoracic and Thoracoabdominal Aortic Aneurysm Repair: Predictors, Prevention, and Treatment

Although recent advances in surgical techniques have improved outcomes of descending thoracic (DTA) and thoracoabdominal aortic aneurysm (TAAA) repair, significant mortality and morbidity still occur. The aim of the current retrospective study is to determine predictors of postoperative pulmonary complications and prolonged hospital stay. Two hundred nineteen patients (median age, 66 years; range, 18 to 88; 112 male) underwent DTA (n = 79 [36%; 23 elephant trunk completions]) or TAAA (n = 140 [64%; Crawford I (52%), II (10%), III (11%), IV (7%); 31 elephant trunk completions]) between June 2002 and June 2005. Forty-one patients presented with ruptured aneurysms. Left atrial-to-femoral bypass was utilized in 51% of the patients. Femorofemoral bypass and distal aortic perfusion were used in 41% of the patients, deep hypothermic circulatory arrest (DHCA) was used in 43 patients (mean duration: 31 +/- 9 minutes); 8% were done with clamp-and-sew technique. Adverse outcomes were seen in 21 patients (9.5%); hospital death in 13 (5.9%), and stroke in 13 (5 of whom died; 5.9%). Sixty patients (27%) experienced respiratory complications with prolonged postoperative ventilation (longer than 48 hours); 24 required tracheostomy (11%). Independent predictors of pulmonary complications after DTA/TAAA were TAAA (p = 0.03), preoperative blood urea nitrogen greater than 24 mg/dL (p = 0.03) and rupture (p = 0.09). The median hospital stay was 11 days (interquartile range, 6 to 35). Independent predictors of length of hospital stay were preoperative blood urea nitrogen (p = 0.045), postoperative bleeding (p < 0.005), reintubation (p = 0.001), tracheostomy (p < 0.0005), and transfusion of platelets (p = 0.008). This contemporary experience demonstrates that preoperative renal insufficiency and extensive aneurysm are important predictors of respiratory complications after aortic aneurysm surgery.

Heparin reduction with the use of cardiotomy suction is associated with hyperfibrinolysis during distal aortic perfusion with a heparin-coated semi-closed cardiopulmonary bypass system

We sought to elucidate the effects of different anticoagulation levels and the use of cardiotomy suction on the postoperative coagulatory and fibrinolytic systems in patients undergoing distal aortic perfusion using a fully heparin-coated (semi-)closed cardiopulmonary bypass (CPB) system incorporating a soft reservoir bag. Thirty-two patients were divided into two groups: those who underwent cardiotomy suction (S group, 18 patients) and those who did not (N group, 14 patients). We administered 1-2 mg/kg heparin in the S group, which achieved an activated clotting time (ACT) of 345 +/- 71 s. In the N group, we administered 0.7-1 mg/kg heparin, which achieved an ACT of 297 +/- 52 s. Data on platelet counts and serum levels of fibrinogen, antithrombin III, D-dimer, and fibrin degradation products (FDP) were collected, and factors influencing these variables were analyzed by multiple regression analysis. Both the patient group and the initial ACT level were independent factors influencing postoperative levels of FDP and D-dimer, whereas peak ACT level and the use of selective visceral/renal shunt/perfusion, but not the patient group, were independent factors influencing the postoperative platelet counts. In the S group, a significant inverse correlation was found between the ACT and levels of FDP or D-dimer, whereas no correlation was found in the N group. The use of cardiotomy suction was associated with elevated FDP and D-dimer levels even when a fully heparin-coated semi-closed CPB system was used. Lower ACT levels with the use of cardiotomy suction were associated with higher FDP and D-dimer levels, whereas such a relationship did not exist when cardiotomy suction was not used.

Perioperative Management to Improve Neurologic Outcome in Thoracic or Thoracoabdominal Aortic Stent-Grafting

Thoracic or thoracoabdominal aortic stent-graft repair has shown a reduction in morbidity and mortality rates due to the procedure's advantages (no aortic cross-clamping, continuous distal aortic perfusion, no reperfusion injury). However, 3% to 12% of the patients are at risk of spinal cord ischemia. We investigated spinal cord protective measures with evoked potentials, cerebrospinal fluid drainage, and prevention of hypotension to minimize postoperative neurologic deficit. Between November 2000 and July 2005, vital parameters and spinal cord function were monitored, including cerebrospinal fluid pressure and transcranial motor-evoked and somatosensory-evoked potentials in 36 stent-graft procedures (31 patients) on the thoracic or thoracoabdominal aorta. Stent-graft placement was technically successful in all patients. We achieved a survival rate of 100% without neurologic deficit after fast-track extubation. Eleven of 31 patients exhibited changes in evoked potentials during stent-graft deployment. In 12 of 31 patients (including the 11 with evoked potential alterations), cerebrospinal fluid pressure exceeded 15 mm Hg. Cerebrospinal fluid drainage and vital parameter adjustment were executed in those instances. We observed intraoperative evoked potential total recovery in 10 of 11 patients after these interventions. Interventions to improve spinal cord perfusion led to total recovery of spinal function in most patients (10/11). Therefore, spinal cord protective measures with motor- and somatosensory-evoked potential monitoring, cerebrospinal fluid drainage, and prevention of hypotension can reduce the incidence of spinal cord ischemia and improve the neurologic outcome of patients undergoing endovascular thoracic or thoracoabdominal aortic repair.