Distal Aortic Perfusion Research Articles

Open repair of chronic complicated type B aortic dissection using the open distal technique.

The present study aimed to analyze early and late outcomes after open repair of chronic type B aortic dissection. We retrospectively reviewed our cases of open descending thoracic aortic aneurysm (DTAA) with chronic dissection from 1991-2013. Long-term survival and aortic reinterventions were analyzed and patient comorbidities were evaluated in order to determine the risk of adverse outcomes. Furthermore, the technique for "distal first approach" is described. Between 1991 and 2013, 240 (40%) descending thoracic aortic repairs with associated chronic dissection were performed. Mean age is 59 years and 178 (74%) are men. The majority of patients (218, 91%) underwent repair using the adjunct of distal aortic perfusion with cerebral spinal fluid drainage. Early mortality was 8.3% (20/240). Permanent neurologic deficit occurred in 1.3% (3/240). Stroke occurred in 2.9% (7/240), and dialysis on discharge in 6% (12/240). 5-, 10-, 15-, and 20-year survival was 72%, 60%, 45%, and 39%, respectively. Freedom from reoperation on the operated segment was 97%, 94%, 94% and 94% at 5, 10, 15 and 20 years. Open repairs of chronic descending thoracic dissections can be performed with respectable morbidity and mortality. Risk of neurologic deficit remains low with use of adjuncts, and risk of reintervention on the involved aortic segment is also low. These results allow comparison with endovascular repair for chronic aortic dissection.

Commentary on “Temporary Aneurysm Sac Perfusion as an Adjunct for Prevention of Spinal Cord Ischaemia After Branched Endovascular Repair of Thoracoabdominal Aneurysms”

The pathogenesis of spinal cord ischaemia following open surgical repair of thoracoabdominal aortic aneurysms (TAAAs) has been established over many years and includes spinal cord ischaemia during aortic clamping, haemodynamic instability, ischaemiaereperfusion injury, and reduced intercostal and lumbar perfusion. To reduce the incidence of spinal cord ischaemia, surgical techniques have evolved to combat each of these pathological mechanisms. Open repair of TAAA is now commonly performed on left heart bypass with distal aortic perfusion, sequential aortic clamping, intercostal reimplantation, visceral perfusion, cerebrospinal fluid (CSF) drainage, and the utilisation of evoked potential monitoring to guide surgical strategies. 1 However, the advent of endovascular repair of TAAA has posed a different set of challenges. While spinal cord injury remains a significant complication, 2 the pathogenesis has not been so extensively studied, and strategies to reduce the incidence of neurological complications are still being formulated. Fundamentally, spinal cord ischaemia after endovascular repair of TAAA appears to be primarily caused by coverage of the thoracoabdominal aorta with an endograft that reduces or abolishes flow through the intercostal and lumbar arteries. Therefore, the causative mechanism would appear to be primarily ischaemic, although embolisation has been implicated in some cases of immediate postoperative paraplegia. As a consequence, endovascular strategies have evolved in an attempt to reduce spinal cord injury, although there is no absolute consensus around a “gold standard” set of procedural and adjunctive preventive measures. The primary management strategy for preventing and treating spinal cord ischaemia is achieving an effective spinal cord perfusion pressure. The principle determinants of spinal cord perfusion pressure are the mean arterial pressure (MAP) and CSF pressure. Most experts would agree than an effective MAP is essential to prevent spinal cord ischaemia. The place of CSF drainage (whether routine or selective) is more controversial, although it appears to be of benefit in symptomatic patients, and has become extensively utilised. In light of the ischaemic aetiology of spinal cord injury, maintenance of existing collateral perfusion to the spinal cord would appear to be important in preventing neurological complications. The spinal cord vascular plexus receives important contributions from the vertebral and hypogastric arteries, and maintaining perfusion through these vascular beds is likely to influence favourably spinal cord perfusion. 3 Recently, several authors have suggested that staging endovascular TAAA procedures may deliver benefits regarding the prevention of spinal cord ischaemia. Staging these procedures maintains a degree of aneurysm sac perfusion through not attempting to obtain complete aneurysm exclusion during the primary procedure. Staging may be achieved in one of several ways, including staging the thoracic and abdominal components; leaving an anatomical branch unstented (e.g., coeliac or iliac); or incorporating a dedicated perfusion branch. In between the procedural stages, the spinal cord is theoretically exposed to a relative degree of ischaemia, which may then stimulate collateral formation. 4 The endovascular reconstruction may then be completed at a later date. The second procedure is usually of a smaller magnitude than the primary procedure and may be performed under local anaesthesia with evoked potential monitoring. In the preceding article, Kasprczak et al. 5 describe their

Microcirculatory perfusion shift in the gut wall layers induced by extracorporeal circulation

Extracorporeal circulation (ECC) is regularly applied to maintain organ perfusion during major aortic and cardiovascular surgery. During thoracoabdominal aortic repair, ECC-driven selective visceral arterial perfusion (SVP) results in changed microcirculatory perfusion (shift from the muscularis toward the mucosal small intestinal layer) in conjunction with macrohemodynamic hypoperfusion. The underlying mechanism, however, is unclear. Therefore, the aim of this study was to assess in a porcine model whether ECC itself or the hypoperfusion induced by SVP is responsible for the mucosal/muscular shift in the small intestinal wall. A thoracoabdominal aortic approach was performed in 15 healthy pigs divided equally into three groups: group I, control; group II, thoracic aortic cross-clamping with distal aortic perfusion; and group III, thoracic aortic cross-clamping with distal aortic perfusion and SVP. Macrocirculatory and microcirculatory blood flow was assessed by transit time ultrasound volume flow measurement and fluorescent microspheres. In addition, markers for metabolism and intestinal ischemia-reperfusion injury were determined. ECC with a roller pump induced a significant switch from the muscularis and mucosal layer of the small intestine, even with adequate macrocirculation (mucosal/muscular perfusion ratio: group I vs II, P = .005; group I vs III, P = .0018). Furthermore, the oxygen extraction ratio increased significantly in groups II (>30%) and III (>40%) in the beginning of the ECC compared with the control (group I vs II, P = .0037; group I vs III, P = .0062). Lactate concentrations and pH values did not differ between groups I and II; but group III demonstrated a significant shifting toward a lactate-associated acidosis (lactate: group I vs III, P = .0031; pH: group I vs III, P = .0001). We demonstrated a significant shifting between the small intestinal gut wall layers induced by roller pump-driven ECC. The shift occurs independently of macrohemodynamics, with a significant effect on aerobic metabolism in the gut wall. Consequently, an optimal intestinal perfusion cannot be guaranteed by a roller pump; therefore, perfusion techniques need to be optimized.

Further experience with distal aortic perfusion and motor-evoked potential monitoring in the management of extent I-III thoracoabdominal aortic anuerysms

Prior studies indicated improved early mortality and paraplegia rates in a small cohort of patients with type I-III thoracoabdominal aortic aneurysms (TAAs) treated with atriofemoral bypass (AFB) and motor-evoked potentials (MEVPs) when compared with a propensity-matched cohort of patients treated with the clamp and sew (CS) method, wherein epidural cooling was the principal spinal cord protective adjunct. The use of AFB/MEVP increases the complexity of TAA repair and in this study, we address whether the early benefits will be sustained when this is applied to a general population with type I-III TAAs. Consecutive patients undergoing repair of nonruptured Crawford extent I-III TAAs from 1/1987 to 12/2011 were identified. Patients were stratified according to operative approach (AFB/MEVP vs CS). Endpoints included long-term survival, and the composite outcome of perioperative death and paraplegia. A multivariate, risk-adjusted model was then created to determine if operative approach independently influenced outcome. There were 485 patients (CS = 385 [79%]; AFB/MEVP = 100 [21%]). The cohorts differed in that the AFB/MEVP group was younger (65.8 ± 12.5 years vs 70.9 ± 9.7 years; P < .001), had more extent I/II aneurysms (66% vs 50.1%; P = .005), and had more chronic dissections (30.3% vs 18.9%; P = .018). Operative variables differed in that the AFB/MEVP cohort had longer operative times (434 ± 112 minutes vs 324 ± 98 minutes; P < .001) and higher blood turnover (6028 ± 3473 mL vs 3581 ± 3111 mL; P < .0001). There was no difference in the rate of intraoperative death (AFB/MEVP = 1.0% vs CS = 0.5%; P = .50), length of intensive care unit stay (AFB/MEVP = 9.6 ± 8.6 days vs CS = 9.5 ± 12.3 days; P = .95) or hospital length of stay (AFB/MEVP = 19.9 ± 12.6 days vs CS = 21.6 ± 23.5 days; P = .49). The composite perioperative death and paraplegia rate was lower in the AFB/MEVP cohort (7% vs 19%; P = .004). The multivariate model for predictors of the composite outcome showed that AFB/MEVP was protective (odds ratio, 0.39; 95% confidence interval, 0.17-0.9; P = .028). Long-term (4-year) survival was improved in the AFB/MEVP group as well (73 ± 6% vs 60 ± 3%; P = .004). AFB/MEVP is an independent predictor of improved perioperative death and paraplegia rates as well as long-term survival in patients undergoing repair of type I-III TAAs and is the preferred operative strategy.

Aortic arch/elephant trunk procedure with Sienna(TM) graft and endovascular stenting of thoraco-abdominal aorta for treatment of complex chronic dissection.

Aneurismal dilatation of the remaining thoracic aorta after ascending aortic interposition grafting for type 'A' aortic dissection is not uncommon. For such complex cases, one treatment option is total arch replacement and elephant trunk procedure with the Sienna(TM) collared graft (Vascutek, Inchinnan, UK) technique followed by a staged thoracic endovascular aortic repair (TEVAR). The video illustrates our technique in a 56-year-old man with an extensive aortic arch and descending thoracic aortic dissecting aneurysm. For the 'open' procedure femoral arterial and venous cannulation was used along with systemic cooling and circulatory arrest at 22 °C. Upon circulatory arrest, the aortic arch was incised and antegrade cerebral perfusion achieved via selective cannulation to the right brachiocephalic and left common carotid artery, keeping flow rates at 10-15 mL/kg/min and perfusion pressure at 50-60 mmHg. Arch replacement with an elephant trunk component was then performed and after completion of the distal aortic anastomosis antegrade perfusion via a side-arm in the graft was started and the operation completed using a variation of the 'sequential' clamping technique to maximize cerebral perfusion. The second endovascular stage was performed two weeks after discharge. Two covered stents were landing from the elephant trunk to the distal descending thoracic aorta, to secure the distal landing a bare stent of was placed to cover the aorta just distal to the origin of the celiac axis. The left subclavian artery was embolised with fibre coils. Post TEVAR angiogram showed no endoleak Although re-operative total arch replacement and elephant trunk procedure and subsequent TEVAR remained a challenging procedure, we believe excellent surgical outcome can be achieved with carefully planned operative strategy.

Reversal of acute monoparesis following thoracoabdominal aortic aneurysm repair

A 67-year-old man underwent surgical repair for a Crawford extent V thoracoabdominal aortic aneurysm under cerebrospinal fluid drainage and motor evoked potential monitor on distal aortic perfusion. Postoperatively, weakness of right-sided leg graded 2/5 and bladder disorder were recognized. Magnetic resonance imaging revealed hyperintensity between Th11 and L1 on T2-weighted image. Intravenous glycerin and edaravone for spinal cord ischemia had been administered. The strength of right leg resolved completely with disappearance of hyperintensity on magnetic resonance image. Finally, he could walk on foot with bladder disorder.

Descending Thoracic and Thoracoabdominal Aortic Aneurysms: Open and Endovascular Repair

The prevalence of descending thoracic aortic aneurysms (DTAs) and thoracoabdominal aortic aneurysms (TAAAs) are described. Imaging techniques and classification is given. Preoperative evaluation is described in detail, as prior to proceeding with repair of a DTA or a TAAA, patients must be thoroughly evaluated medically to determine if they are physiologically fit enough for repair. Indications for repair, primarily relating to size of aneurysm, are listed for both DTAs and TAAAs. Repair options and management for DTAs now includes thoracic endovascular aortic repair (TEVAR); its outcomes, benefits, and drawbacks are discussed in detail. The discussion of TAAAs is similar, with indications for repair and surgical management options given: direct open repair; a debranching procedure with subsequent endograft repair; and branched or fenestrated endograft repair. A table lists the symptoms attributable to thoracic and thoracoabdominal aortic aneurysms. Figures show the classification of DTAs; the evaluation of a patient with a thoracic aortic aneurysm; available thoracic endografts; anatomic restrictions for TEVAR; evaluation of a patient with a thoracoabdominal aneurysm; regional spinal cord hypothermic protection; distal aortic perfusion; visceral artery bypass; and a branched endograft. This review contains 8 figures, 3 tables, and 125 references.

Anestesia en la cirugía del aneurisma toracoabdominal: 17 años de experiencia

ObjectiveTo review the results after thoracoabdominal aortic aneurysms repair performed by the same team of surgeons and anesthesiologists over a 17 year period. Material and methodsA prospective and observational study carried out on 65 patients (97% male) who were operated on from 1995 until July 2011 for thoracoabdominal aneurysm, Crawford type i 5 (7.6%), ii 22 (33.8%), iii 17 (26.11%) and iv 21 (32.31%). ResultsThe 30-day mortality was 9.2% (6/65 patients), which was the same as the incidence of paraplegia. This complication only occurred in the Crawford types ii and iii aneurysms. Paraplegia was present in 4.5% (1/22) of patients in whom “left bypass” was used, compared with 29% (5/17) in which the intervention was performed by cross-clamping without distal aortic perfusion (P=.068).The most frequent complication was respiratory, with prolonged mechanical ventilation (>48h) in 20% (13 patients) of cases. The mean hospital stay was 28 days (7-92). DiscussionThe average mortality in referral centers is 9.7%, ranging between 5% and 16%. In other centres the mortality at 30 days is between 19% and 31% per year. Our group had a 9.2% of mortality rate at 30 days. The incidence of paraplegia in hospitals with greater experience ranges between 2.7% and 16%. Nowadays, an incidence of less than 10% is accepted as good. We had 9.2%. The use of CSF drainage in these patients, as well as the use of left bypass and moderate hypothermia in the Crawford types i, ii and iii appear to be acceptable for prophylaxis of paraplegia.

Early and Late Results of Graft Replacement for Dissecting Aneurysm of Thoracoabdominal Aorta in Patients With Marfan Syndrome

When treating dissecting aneurysm of the thoracoabdominal aorta surgically in patients with Marfan syndrome, we have usually performed graft replacement- including the entire thoracoabdominal aorta and reconstruction of all visceral branches, even if dilatation is mild in some segments-to avoid further aortic operations in the follow-up period. From October 1999 through July 2011, 20 consecutive patients with Marfan syndrome underwent repair of dissecting aneurysm of the thoracoabdominal aorta (median age, 45 years; range, 19-65 years). All patients underwent surgical intervention with cerebrospinal fluid (CSF) drainage and distal aortic and selective organ perfusion. Deep hypothermia was used in 13 patients for spinal cord protection. No in-hospital mortality was observed. One patient had temporary spinal cord ischemia but was fully recovered by discharge. Other complications included exploration for bleeding (n=1), prolonged ventilation (n=1), and graft infection (n=1). At a mean follow-up of 54 months (range, 9-129 months), 1 patient had died of interstitial pneumonia at 38 months postoperatively. Survival at 8% years was 91.2±9.0%. Two patients required additional aortic procedures (total arch replacement and aortic valve-sparing surgery). Actuarial rate of freedom from aortic operations at 8 years was 83.9%±10.5%, but no patient needed required repeated thoracotomy for an aortic procedure. Neither false nor patch aneurysms were observed using computed tomography (CT) during follow-up surveillance. Graft replacement for dissecting aneurysm of the thoracoabdominal aorta in Marfan syndrome offers good early and long-term results. We believe total aortic replacement including the entire thoracoabdominal aorta and reconstruction of all visceral arteries should be recommended for selected patients with Marfan syndrome.

Invited Commentary

Invited Commentary

The impact of selective visceral perfusion on intestinal macrohemodynamics and microhemodynamics in a porcine model of thoracic aortic cross-clamping

Despite its presumed effectiveness and clinical use, the physiology of selective visceral perfusion combined with distal aortic perfusion during open thoracoabdominal aortic surgery has not been characterized. Thus, the aim of this study was to establish a translatable model of thoracic aortic-clamping to assess the effect of selective visceral perfusion with added distal aortic perfusion on local intestinal macrohemodynamics and microhemodynamics, intestinal histopathology, and markers of inflammation and intestinal damage. A thoracolaparotomy was performed in 15 pigs, and the aorta was exposed, including the origins of celiac trunk and superior mesenteric artery. The animals were divided into three cohorts: control (I), thoracic aortic cross-clamping (II), and thoracic aortic cross-clamping with selective visceral perfusion plus distal aortic perfusion using extracorporeal circulation (III). Macrocirculatory and microcirculatory blood flow was assessed by transit time ultrasound volume flow measurements and fluorescent microspheres. Intestinal ischemia-reperfusion injury was determined by the analysis of perioperative intestinal fatty acid-binding protein (IFABP) and interleukin-8 (IL-8) levels and correlated with histopathologic changes. Severe intestinal tissue injury and an inflammatory response were observed in cohort II compared with cohort III for IL-8 (38.2 vs 3.56 pg/mL; P = .04). The procedure in cohort III resulted in a flow and pressure-associated intestinal hypoperfusion compared with cohort I in the superior mesenteric artery (mean blood pressure, 24.1 ± 10.4 vs 67.2 ± 7.4 mm Hg; P < .0001; mean flow rates: 353.3 ± 133.8 vs 961.7 ± 310.8 mL/min; P < .0001). This was paralleled in cohort III vs cohort I by a significant mucosal injury (IFABP, 713 ± 307.1 vs 170 ± 115.4 pg/mL; P = .014) despite a profound recruitment of intestinal microcirculation (338% ± 206.7% vs 135% ± 123.7%; P = .05). This study reports a novel large-animal model of thoracic aortic cross-clamping that allows the study of visceral perfusion strategies. However, we demonstrated with IL-8 and IFABP measurements that thoracoabdominal aortic aneurysm surgery with selective visceral perfusion and distal aortic perfusion is superior to the clamp-and-sew technique, even though small intestinal tissue damage cannot be completely avoided by selective visceral perfusion and distal aortic perfusion. In any case, this model seems to be a platform to evaluate and optimize measures for gut wall protection.

Open surgical repair of thoracoabdominal aneurysms - the Massachusetts General Hospital experience.

The modern era of surgical management of thoracoabdominal aneurysms (TAA) began with the pioneering work of E. Stanley Crawford (1); this benchmark series reported an operative mortality of 10% with an incidence of spinal cord ischemia (SCI) of 16%, some 50% of which were total paraplegia. Over a 20 year period until 2006, TAA repair at our institution (2) was predominantly performed using a simplified clamp and sew approach in accordance with Dr. Crawford’s teachings which emphasized operative expediency and technical efficiency (2). Management of TAA during this time was typically performed without use of distal perfusion techniques. Adjunct use included routine cerebrospinal fluid (CSF) drainage (3,4), aggressive intercostal re-implantation (3,5,6), regional hypothermia for spinal cord protection (7,8), infusion of hypothermic renal preservation fluid for prevention of renal failure, and in-line mesenteric shunting (9) to reduce complications resulting from visceral ischemia. Using this approach we achieved favorable results with an overall operative mortality of 8% (6% elective and 13% urgent) with significant SCI in 8% of patients (2). Largely driven by the apparent failure of epidural cooling to drive SCI to less than 5%, we modified operative management of TAA in recent years in an effort to further reduce spinal cord complications. As our experience has shown (10) that patients with type IV TAA can safely be managed with a simplified clamp/sew approach with favorable results, this evolution in operative strategy has been exclusively implemented in management of patients with extents I-III TAA. In essence the rationale exploited the collateral network concept (11-13): we adopted routine use of distal aortic perfusion (DAP) via left atrial to femoral bypass to support the collateral circulation to the spinal cord during the period of aortic cross clamp application. Additionally, intra-operative motor evoked potential (MEP) monitoring (14,15) has afforded the ability to dynamically assess spinal cord ischemia during aneurysm reconstruction. As a result, we have abandoned aggressive intercostal re-implantation in favor of a selective MEP driven re-implantation strategy. Clinical outcomes resulting from this evolution in operative strategy for extents I-III TAA have recently been published and are further highlighted herein (16).

Distal aortic perfusion during thoracoabdominal aneurysm repair for prevention of paraplegia.

During thoracoabdominal aortic aneurysm (TAAA) surgery, decreased spinal cord perfusion can result in neurological deficits such as paraplegia and paraparesis. Distal aortic perfusion, alone or in combination with other adjuncts, may counter the decrease in spinal cord perfusion and hence reduce the risk of spinal cord injury. To determine the effectiveness of distal aortic perfusion with or without other adjuncts against other adjuncts without use of distal perfusion during TAAA surgery in reducing the risk of developing paraplegia and paraparesis. The Cochrane Peripheral Vascular Diseases Group Specialised Register (last searched 5 January 2012) and CENTRAL (Issue 4, 2011) were searched for publications describing randomised controlled trials of distal aortic perfusion during thoracoabdominal aortic aneurysm surgery. Reference lists of relevant studies were checked. Randomised or quasi-randomised controlled clinical trials of distal aortic perfusion during TAAA repair. Studies identified for potential inclusion were independently assessed for inclusion by at least two authors, with excluded trials arbitrated by the third author. There were no randomised controlled trials identified. Currently, there are no randomised controlled trials to support the role of distal aortic perfusion in TAAA surgery for prevention of neurological injury. However, randomised controlled trials are not always feasible based on ethical grounds. Observational studies suggest that distal aortic perfusion alone or in combination with other adjuncts, that is cerebrospinal fluid (CSF) drainage, reduces the rate of neurologic deficit across all types of TAAA; in particular making a striking difference in the rate of neurologic deficit following type II TAAA repair. In the absence of randomised controlled trials, we recommend a standardised approach to reporting through registry studies to strengthen the evidence base for distal aortic perfusion.

Spinal cord protective strategies during descending and thoracoabdominal aortic aneurysm repair in the modern era: The role of intrathecal papaverine

An array of neuroprotective strategies has evolved to limit spinal cord injury during descending thoracic aneurysm and thoracoabdominal aortic aneurysm repair. This study prospectively assessed the neuroprotective impact of intrathecal papaverine added to other techniques in aortic aneurysm repairs. From January 2002 to January 2010, 398 consecutive patients underwent descending thoracic aneurysm and thoracoabdominal aortic aneurysm repairs at Cleveland Clinic, 68 under hypothermic circulatory arrest. We focused on the remaining 330, in whom a combination of neuroprotective adjuncts was used intraoperatively to mitigate spinal cord ischemia. These included distal aortic perfusion with moderate hypothermia, cerebrospinal fluid drainage, and intrathecal papaverine. Two patient groups were discriminated according to whether intrathecal papaverine was (n = 250) or was not (n = 80) administered. Postoperative outcomes were analyzed from a prospectively maintained clinical database. Preoperative patient characteristics and comorbidities were similar between groups. Extent of aortic disease was also similar: descending thoracic aneurysm (34% with papaverine vs 28%) and Crawford types I (25% vs 34%), II (27% vs 24%), III (13% vs 13%), and IV (2% vs 2.5%). Groups had similar in-hospital mortality (6.4% vs 11%; P = .11) and permanent stroke (4.4% vs 7.5%; P = .3). Permanent paraplegia (3.6% vs 7.5%; P = .01) and paraparesis (1.6% vs 6.3%; P = .01) were significantly lower in the intrathecal papaverine group. Adding intrathecal papaverine to the neuroprotective protocol for descending thoracic aneurysm and thoracoabdominal aortic aneurysm repairs may enhance spinal cord perfusion and provide additional spinal cord protection.

Cytokine balance in hepatosplanchnic system during thoracoabdominal aortic aneurysm repair

While prolonged visceral ischemia seems to be a potential source of elevated proinflammatory cytokines during thoracoabdominal aortic aneurysm (TAAA) repair, the underlying mechanisms are unclear. We have investigated the production of cytokines and fatty acid binding proteins (FABPs) in the hepatosplanchnic system during TAAA repair. Arterial and hepatic venous levels of tumor necrosis factor-alpha (TNF-α), interleukin (IL) -6, -8, and -10, and liver- and intestinal-type FABPs (L-FABP, I-FABP) were measured at four time points in ten patients undergoing TAAA repair. Visceral arteries were perfused through either a side-arm of distal aortic perfusion or an individual circuit using an independent pump, or both, without measuring perfusion pressure or blood flow. The postoperative courses of all patients were uneventful. During visceral perfusion, the levels of arterial IL-6, -8, and -10, and L-FABP elevated significantly (P=0.0077, 0.0051, 0.0077, 0.0077, respectively), and these elevated levels persisted up to skin closure, with the exception of L-FABP (P=0.0051 each). In contrast, there were only subtle increases in TNF-α and I-FABP levels. The production ratio through the hepatosplanchnic system of TNF-α, L-FABP, and I-FABP showed a pronounced peak during visceral perfusion, but only the peak of L-FABP was significant compared with baseline (P=0.0077). All production ratios returned to baseline level at skin closure. The production ratio of IL-6 was negative throughout the operation and that of IL-8 and IL-10 remained at baseline during visceral perfusion. In conclusion, a portion of the TNF-α, L-FABP, and I-FABP might be produced temporarily in the hepatosplanchnic system during TAAA repair. Systemic elevation of IL-6, IL-8, and IL-10 might be modulated by inflammatory response to extracorporeal circulation or surgical stress. Thus, our simple visceral perfusion techniques may indeed be justified.

Hypothermic Circulatory Arrest with “Low Flow” Lower Body Perfusion: An Experimental Feasibility Study of Microcirculatory Parameters

To avoid extended cardiopulmonary bypass (CPB), moderate temperatures are commonly accepted for hypothermic circulatory arrest (HCA), thereby jeopardizing organ protection. Distal aortic perfusion may be an option, but supportive experimental data is missing. Eight juvenile pigs (36 ± 2 kg) were cooled to 30 °C followed by 60 min of HCA with 50 min of low flow (LF) lower body perfusion. Multimodal monitoring was used to measure overall metabolism, hemodynamics and microcirculation of the terminal ileum. The animals were observed for four hours following reperfusion. Organs were harvested for histopathological evaluation. During LF perfusion, initially elevated l-lactate levels decreased subsequently ( P < 0.05). Capillary blood flow decreased during cooling to 50 % baseline levels ( P = 0.03), but remained stable under LF conditions. Parameters indicative of reduced liver and kidney function were slightly elevated at the end of the experiment, but still within normal ranges. Under moderate hypothermia, low flow perfusion seems to provide adequate protection for the lower body organs. Microcirculatory parameters during perfusion as well as lactate levels within normal ranges throughout the experiments further confirm the concept.

Open Repair of Extensive Thoracoabdominal and Thoracic Aneurysm: A Preliminary Single-Center Experience With Femorofemoral Distal Aortic Perfusion With Oxygenator and Without Cerebrospinal Fluid Drainage

Thoracoabdominal aortic aneurysms (TAAA) and extensive thoracic descending aortic aneurysms (TDA) are not accessible through standard endovascular treatment. Fenestrated and branched endograft technology was developed rapidly without widespread application. The aim of this study was to review our open repair (OR) experience of TAAA and TDA. A total of 28 patients who underwent elective OR of TAAA or TDA between January 2001 and January 2009 were analyzed retrospectively. The mean age of the patients was 65.5 years (three women). The anatomic locations of the aneurysms were as follows: six in thoracic descending aorta and 22 in thoracoabdominal aorta (14 TAAA I, two TAAA II, six TAAA III). TDA (40 patients) available for ordinary endovascular treatment and TAAA IV (35 patients) were excluded from this study. To focus on spinal cord vascularization, 25 patients were submitted for angiography. Three patients suffering from back pain required quick treatment and were excluded from angiographic investigations. Angiography procedures were contributive in 23 patients (92%). Surgical repairs were driven through left thoraco-phreno-laparotomy, with the adjunct of distal aortic perfusion (femorofemoral bypass) including the use of an oxygenator and sequential aortic cross-clamping. Cerebrospinal fluid drainage was not used in this experience. The 30-day mortality rate was 14.3% (four of 28 patients): one multiorgan failure and three pulmonary sepsis. An immediate postoperative paraplegia occurred, affecting a patient with TDA who was previously submitted for infrarenal aorta replacement, despite angiographic identification and revascularization of intercostal artery destined to spinal artery. The 1-year survival rate was 82.1% (23 of 28 patients). In the preliminary experience of this study, OR of extensive TAAA and TDA with distal aortic perfusion and an oxygenator without use of cerebrospinal fluid drainage was associated with a significant perioperative mortality rate (14.2%), a reasonable rate of paraplegia (3%), and 1-year survival rate of 82.1%.

Evolution of operative strategies in open thoracoabdominal aneurysm repair

During a 24-year interval, we managed >90% of thoracoabdominal aortic aneurysm (TAA) repairs with a clamp-and-sew (clamp/sew) approach supplemented with protective adjuncts, including renal hypothermia and epidural cooling with aggressive intercostal reconstruction for spinal cord protection. A finite paraplegia rate led to operative modifications using distal aortic perfusion (DAP) through atriofemoral bypass to support cord collateral circulation and selective intercostal reconstruction based on motor evoked potential (MEP) monitoring. This study evaluated the effect of DAP/MEP on perioperative outcomes. Consecutive patients undergoing repair of nonruptured Crawford extent I-III TAA using DAP/MEP were compared with propensity-matched patients treated with the clamp/sew technique. Outcomes included 30-day mortality and paraplegia. There were 52 patients in the DAP cohort vs 127 undergoing clamp/sew. The DAP and clamp/sew cohorts differed in age (62.6 vs 69.5 years, P = .0003), presence of Marfan disease (10% vs 2%, P = .01), and chronic dissection (37% vs 8%, P = .001). Operative mortality was low (DAP, 2%; clamp/sew, 5%; P = .38). Postoperative renal insufficiency, although doubled in clamp/sew (17%) vs DAP (8%; P = .10), was not significant. DAP patients had a significantly lower incidence of intercostal reconstruction than the clamp/sew group (10% vs 34%, P < .0001), yet there was no paraplegia in the DAP cohort vs 5% in clamp/sew (P = .11). The composite death/paraplegia rate was decreased with DAP at 1 of 52 (2%) vs clamp/sew at 11 of 127 (9%; P = .01). Paraparesis with complete recovery occurred in 5 of 52 (10%) of the DAP group. Elective TAA repair was accomplished with a low mortality in the DAP and clamp/sew cohorts. The use of MEP in the DAP cohort (despite a higher spinal cord ischemic risk due to the number of chronic dissection patients) decreased the need for intercostal reconstruction, with no paraplegia to date. DAP with MEP is the preferred operative strategy for extent I to III TAA repair.

Progress in the Treatment of Blunt Thoracic Aortic Injury: 12-Year Single-Institution Experience

Recent advancements in the diagnosis and management of blunt thoracic aortic injury have improved outcomes after operative repair. With consideration of these advancements, we analyzed our level 1 trauma experience with blunt traumatic aortic injury. Between January 1997 and March 2009, 255 patients with blunt traumatic aortic injury were entered into the Utah Trauma Registry-Trauma Center Registry. Of these, 145 (58%) patients underwent thoracic aortic repair, with 12 (5%) undergoing aortic exploration without repair. Median age was 32 years (range, 13 to 87), with 43 (30%) women. Repair approach included open repair without adjunct (clamp), open with distal aortic perfusion, open with cardiopulmonary bypass, and thoracic endovascular aortic repair. The affect of management modifications, which included use of distal aortic perfusion (1999), delayed repair (2002), and use of thoracic endovascular aortic repair (2005) was analyzed. We used multiple logistic regression to evaluate the changes in morbidity (paraplegia and stroke) and mortality attributable to changes in surgical practice, adjusted for calendar time and injury severity score. Mortality from operative aortic intervention for blunt thoracic aortic injury (BTAI) was 17% (24 of 145). Delayed repair, used in 41% (59 of 145) of repairs, was associated with only 1 death (2%), which was significantly lower than immediate repair 28% (23 of 86) mortality (p < 0.002). Mean injury severity score was 39 +/- 11. Adjusted for injury severity score and calendar time, delayed repair resulted in a greater than tenfold reduction in mortality compared with immediate open intervention (odds ratio 0.07, p < 0.02). Use of thoracic endovascular aortic repair was associated with zero mortality (p < 0.03 versus other treatments). Mortality with open repair with and without distal aortic perfusion was 14% and 31%, respectively, p < 0.02. Paraplegia occurred in 10% with open repair without distal aortic perfusion, and in no cases in open with distal aortic perfusion and thoracic endovascular aortic repair. Although thoracic aortic injury still accounts for significant mortality during blunt trauma, patients reaching specialized trauma centers can achieve good results with thoracic aortic repair. Improved early outcomes have been observed with delayed selective management and thoracic endovascular repair. Long-term results of thoracic endovascular aortic repair, however, need further study.

Is hypothermia a reliable adjunct for spinal cord protection in descending and thoracoabdominal aortic repair with regional or systemic cooling?

1multidisciplinary approaches have been directed toward minimizing spinal cord ischemic injury during surgery of the descending thoracic and thoracoabdominal aorta. The principal modality has been distal aortic perfusion during the aortic crossclamping, which was passive in the past with a temporary shunt tube or bypass and that currently has been active with a left heart bypass or a cardiopulmonary bypass (CPB). Other approaches include the following: intraoperative monitoring of spinal cord ischemia with somatosensory evoked potentials and transcranial motor evoked potentials; reattaching the responsible intercostal artery; increasing collateral fl ow by controlling the back-bleeding of the patent intercostal arteries with high cardiac output and arterial pressures with cerebrospinal fl uid (CSF) drainage; increasing ischemic tolerance with pharmacological adjuncts including naloxane, steroid, barbiturates, and with hypothermia; reducing excitotocixity from neuronal ischemia with hypothermia, naloxane, and steroid; and attenuating reperfusion injury with steroid, hypothermia, and free radical scavengers. Particularly, in Japan, with recent great advances in diagnostic imaging modalities, preoperative demonstration of the arteria radicularis magna (Adamkiewicz artery) by magnetic resonance imaging (MRI) or computed tomography (CT) scans has been highlighted as a reliable guide for reattachment or preservation of the responsible intercostal arteries including the collaterals. Since the 1950s hypothermia has been proven effective for protecting organs, including the central nervous system, in the cardiovascular surgical fi eld. 2–5 When focusing on milestones of aortic surgery, systemic profound hypothermia at 12°–15°C was applied to aortic arch surgery for brain protection in 1975. 6