Aortic Arch Reconstruction: Safety of Moderate Hypothermia and Antegrade Cerebral Perfusion During Systemic Circulatory Arrest

Validation of a new model of selective antegrade cerebral perfusion with circulatory arrest in rats

BACKGROUND

Selective antegrade cerebral perfusion (SACP) is adopted as an alternative to deep hypothermic circulatory arrest (DHCA) during aortic arch surgery. However, there is still no preclinical evidence to support the use of SACP associated with moderate hypothermia (28-30°C) instead of DHCA (18-20°C). The present study aims to develop a reliable and reproducible preclinical model of cardiopulmonary bypass (CPB) with SACP applicable for assessing the best temperature management.

MATERIALS AND METHODS

A central cannulation through the right jugular vein and the left carotid artery was performed, and CPB was instituted.Animals were randomized into two groups: normothermic circulatory arrest without or with cerebral perfusion (NCA vs SACP). EEG monitoring was maintained during CPB. After 10 min of circulatory arrest, rats underwent 60 min of reperfusion. After that, animals were sacrificed, and brains were collected for histology and molecular biology analysis.

RESULTS

Power spectral analysis of the EEG signal showed decreased activity in both cortical regions and lateral thalamus in all rats during the circulatory arrest. Only SACP determined complete recovery of brain activity and higher power spectral signal compared to NCA (p < 0.05). Histological damage scores and western blot analysis of inflammatory and apoptotic proteins like caspase-3 and Poly-ADP ribose polymerase (PARP) were significantly lower in SACP compared to NCA. Vascular endothelial growth factor (VEGF) and RNA binding protein 3 (RBM3) involved in cell-protection mechanisms were higher in SACP, showing better neuroprotection (p < 0.05).

CONCLUSIONS

SACP by cannulation of the left carotid artery guarantees good perfusion of the whole brain in this rat model of CPB with circulatory arrest. The present model of SACP is reliable, repeatable, and not expensive, and it could be used in the future to achieve preclinical evidence for the best temperature management and to define the best cerebral protection strategy during circulatory arrest.

Comparative effectiveness and safety of open triple-branched stent graft technique with stented elephant trunk implantation in treating Stanford type A aortic dissection: A trial sequential meta-analysis

BACKGROUND

The optimal surgical intervention for Stanford type A aortic dissection is controversial. The aim of this trial sequential meta-analysis was to investigate the comparative effectiveness and safety of open triple-branched stent graft and stent elephant trunk implantation for total aortic arch reconstruction in Sandford type A aortic dissection.

METHODS

PubMed, Embase, Cochrane library, Chinese Biomedical Literature database (CBM), and China National Knowledge Infrastructure (CNKI) were searched for retrieving relevant studies from inception to February 28, 2022. We evaluated 30-day mortality, procedure-related time including cardiopulmonary bypass (CPB), aortic cross-clamp (ACC), and selective cerebral perfusion (SCP), the incidence of postoperative complications including paralysis, cerebral embolism, and acute renal failure, intensive care unit (ICU) time, and medical expenditure. Statistical analysis was performed by RevMan 5.4 and trial sequential analysis (TSA) software.

RESULTS

Six studies involving 260 dissection cases were included eventually. Total aortic arch reconstruction with open triple-branched stent graft was comparable to the stented elephant trunk implantation in 30-day mortality, incidence of postoperative complications, ICU time, and medical expenditure, but open triple-branched stent graft was related to shorter procedure-related time including CPB (mean difference [MD] = -46.11, 95% confidence interval [CI] = -67.24 to -24.98, p < .001), ACC (MD = -42.82, 95% CI = -66.74 to -18.90, p < .001), and SCP (MD = -17.88, 95% CI = -33.36 to -2.39, p = .02). TSA confirmed robustness of findings.

CONCLUSIONS

Our analysis suggested that total aortic arch reconstruction with open triple-branched stent graft may be an effective and simplified procedure than the stented elephant trunk implantation.

Neuroprotective strategies with circulatory arrest in open aortic surgery - A meta-analysis

Objective

Deep hypothermic circulatory arrest (DHCA) in aortic surgery is associated with morbidity and mortality despite evolving strategies. With the advent of antegrade cerebral perfusion (ACP), moderate hypothermic circulatory arrest (MHCA) was reported to have better outcomes than DHCA. There is no standardised guideline or consensus regarding the hypothermic strategies to be employed in open aortic surgery. Meta-analysis was performed comparing DHCA with MHCA + ACP in patients having aortic surgery.

Methods

A systematic review of the literature was undertaken. Any studies with DHCA versus MHCA + ACP in aortic surgeries were selected according to specific inclusion criteria and analysed to generate summative data. Statistical analysis was performed using STATS Direct. The primary outcomes were hospital mortality and post-operative stroke. Secondary outcomes were cardiopulmonary bypass time (CPB), post-operative blood transfusion, length of ICU stay, respiratory complications, renal failure and length of hospital stay. Subgroup analysis of primary outcomes for Arch surgery alone was also performed.

Results

Fifteen studies were included with a total of 5869 patients. There was significantly reduced mortality (Pooled OR = +0.64, 95% CI = +0.49 to +0.83; p = 0.0006) and stroke rate (Pooled OR = +0.62, 95% CI = +0.49 to +0.79; p < 0.001) in the MHCA group. MHCA was associated significantly with shorter CPB times, shorter duration in ICU, less pulmonary complications, and reduced rates of sepsis. There was no statistical difference between the two groups in terms of circulatory arrest times, X-Clamp times, total operation duration, transfusion requirements, renal failure and post-op hospital stay.

Conclusion

MHCA + ACP are associated with significantly better post-operative outcomes compared with DHCA for both mortality and stroke and majority of the secondary outcomes.

Quality of life: modified triple-branched stent graft implantation versus frozen elephant trunk technique

Objective

To compare the effects of modified triple-branched stent implantation and frozen elephant trunk technique on the quality of life (QoL) of acute Stanford Type A aortic dissection (AAAD) patients at different follow-up times.

Methods

Data from 175 AAAD survivors was collected which were divided into two groups according to different surgical techniques: (group A): modified triple-branched stent graft implantation; (group B): frozen elephant trunk. The SF-36 were used to assess the QoL at discharge (AD), the third postoperative month (POM3), and the twelfth postoperative month (POM12).

Results

(1) The total scores at each time of both groups showed lower than the normal level; Group A scored higher than group B at some time points in terms of some items (role physical, role emotion and mental health; all P = 0.000), and some items at POM3 or POM12 scored higher than at discharge (role physical, social function; both P = 0.000). (2) There were less patients with heavy self-perceived burden in group A than group B at discharge (P = 0.032) and patients with heavy self-perceived burden decreased over time. (3) Young postoperative AAD patients (P = 0.002) in group B (P = 0.005) with heavy self-perceived burden (P = 0.000), acute renal failure (P = 0.008), long LOS (P = 0.026) and blood loss (> 1000 mL/24 h) (P = 0.039) seemed to get a worse QoL.

Conclusion

The impact on QoL of the modified triple-branched stent graft implantation technique seemed to be better than those of frozen elephant trunk surgery in role physical, role emotion and mental health.

Physiological Impact of Hypothermia: The Good, the Bad and the Ugly

Hypothermia is defined as a core body temperature of < 35°C, and as body temperature is reduced the impact on physiological processes can be beneficial or detrimental. The beneficial effect of hypothermia enables circulation of cooled experimental animals to be interrupted for 1-2 h without creating harmful effects, while tolerance of circulation arrest in normothermia is between 4 and 5 min. This striking difference has attracted so many investigators, experimental as well as clinical, to this field, and this discovery was fundamental for introducing therapeutic hypothermia in modern clinical medicine in the 1950's. Together with the introduction of cardiopulmonary bypass, therapeutic hypothermia has been the cornerstone in the development of modern cardiac surgery. Therapeutic hypothermia also has an undisputed role as a protective agent in organ transplantation and as a therapeutic adjuvant for cerebral protection in neonatal encephalopathy. However, the introduction of therapeutic hypothermia for organ protection during neurosurgical procedures or as a scavenger after brain and spinal trauma has been less successful. In general, the best neuroprotection seems to be obtained by avoiding hyperthermia in injured patients. Accidental hypothermia occurs when endogenous temperature control mechanisms are incapable of maintaining core body temperature within physiologic limits and core temperature becomes dependent on ambient temperature. During hypothermia spontaneous circulation is considerably reduced and with deep and/or prolonged cooling, circulatory failure may occur, which may limit safe survival of the cooled patient. Challenges that limit safe rewarming of accidental hypothermia patients include cardiac arrhythmias, uncontrolled bleeding, and "rewarming shock".

Temperature Selection in Antegrade Cerebral Perfusion for Aortic Arch Surgery: A Meta-Analysis

BACKGROUND

The increasing use of antegrade cerebral perfusion (ACP) during aortic arch surgery has corresponded with a trend toward warmer target temperatures for hypothermic circulatory arrest. This meta-analysis examined the clinical outcomes using colder or warmer circulatory arrest targets with ACP.

METHODS

Electronic searches were performed using four databases from their inception to February 2017. Comparative studies of adult patients who underwent aortic arch operations using ACP at different circulatory arrest temperatures were included. Data were extracted by 2 independent researchers and analyzed according to predefined end points using a random-effects model.

RESULTS

The literature search identified 18 comparative studies, with 1,215 patients in the "cold" cohort and 1,417 in the "warm" cohort. Mean hypothermic circulatory arrest temperatures were 20.3°C and 26.5°C in the cold and warm groups, respectively. A trend existed for increased permanent neurologic deficit overall when colder targets were used (odds ratio, 1.45; 95% confidence interval, 0.98 to 2.13; p = 0.06); this became significant when adjusted estimates were aggregated (odds ratio, 1.65; 95% confidence interval, 1.06 to 2.55; p = 0.03). No difference in the mortality rate was seen when adjusted effects were aggregated. Temporary neurologic deficit, postoperative dialysis, ventilator time, and intensive care unit stay were significantly reduced in the warm cohort overall. No significant differences in reexploration for bleeding were found.

CONCLUSIONS

ACP with warmer circulatory arrest temperatures may reduce the incidence of permanent neurologic deficit as well as potentially other clinical outcomes. Further studies are required to determine the safe circulatory arrest durations for visceral organs at warmer temperatures.

Neuro-protection in open arch surgery

Although antegrade cerebral perfusion (ACP) is the predominant method of protecting the brain in patients undergoing total arch replacement, both deep hypothermic circulatory arrest and ACP provide excellent and comparable clinical outcomes with regard to mortality, stroke, and temporary neurological deficit rates.

Right axillary and femoral artery perfusion with mild hypothermia for aortic arch replacement

Objectives

Aortic arch replacement is associated with increased mortality and morbidity especially in acute type-A aortic dissection. Although hypothermic circulatory arrest with selective antegrade cerebral perfusion has been widely used because of its excellent cerebral protection, its optimal perfusion characteristics are unknown. The present study investigates clinical results obtained after perfusion method modification and temperature management during cardiopulmonary bypass (CPB).

Methods

Between July 2010 and August 2012, 16 consecutive adult patients (mean age 50.0 yr ± 14.1 yr, range 25 yr to 73 yr, 12 males, 4 females) who presented with acute Stanford type-A aortic dissection underwent aortic arch replacement (total arch, n = 11; hemiarch, n = 5) under mild hypothermia (31.1°C ± 1.5°C) with right axillary and femoral artery perfusion.

Results

The mean CPB time was 201 min ± 53 min, and the mean myocardial ischemic time was 140 min ± 42 min. The mean selective cerebral perfusion time was 80 min ± 16 min, and the mean lower-body circulatory arrest time was 20 min ± 13 min. No patient death occurred within 30 post-operative days. The following details were observed: new post-operative permanent neurologic deficit in 1 patient (6.3%), temporary neurologic deficit in 2 patients (12.5%), acute renal dysfunction (creatinine level > 230 umol/L) in 3 patients (18.8%) and mechanical ventilation > 72 h in 5 patients (31.2%).

Conclusions

Aortic arch replacement for acute type-A aortic dissection under mild hypothermia with right axillary and femoral artery perfusion could be safely performed in the patient cohort.

Modern temperature management in aortic arch surgery: the dilemma of moderate hypothermia

Arch surgery is undoubtedly among the most technically and strategically challenging endeavours in aortic surgery, requiring thorough understanding not only of cardiovascular physiology, but also in particular, of neurophysiology (cerebral and spinal cord), and is still associated with significant mortality and morbidity. In the late 1980s, when deep hypothermic circulatory arrest (HCA) had gained widespread acceptance as the standard approach for arch surgery, antegrade selective cerebral perfusion (SCP), as an adjunct to deep HCA, began its triumphal march, offering excellent neuroprotection and improved overall outcome. This encouraged the use of antegrade SCP in combination with steadily increasing body core temperatures--a trend culminating in the progressive advocation of moderate-to-mild temperatures up to 35 °C, and even normothermia. The impetus for progressive temperature elevation was the limitation of adverse effects of profound hypothermia and the most welcome side effect of significantly shorter cooling and rewarming periods on cardiopulmonary bypass (CPB), and thereby, potentially, the alleviation of the systemic inflammatory response and, in particular, the risk of severe postoperative bleeding (and other organ dysfunctions). The safe limits of prolonged distal circulatory arrest, particularly with regard to the ischaemic tolerance of the viscera and the spinal cord, have not yet been clearly defined. Adverse outcomes due to inappropriate temperature management (core temperatures too high for the required duration of distal arrest) are probably highly underreported. Complications historically associated with hypothermia, namely excessive bleeding, are possibly overestimated. Trading effective neuroprotection and excellent outcomes for the risk of prolonged 'warm' distal ischaemia might constitute a significant step back, jeopardizing visceral and, in particular, spinal cord integrity, with unpredictable consequences for long-term outcome and quality of life, particularly affecting those in need of more complex surgery or with previous neurological deficits.

Acute aortic dissection: an update

The aorta, which has a complex intrinsic biology and sophisticated mechanical properties for conducting the blood ejected from the left ventricle to the rest of the systemic arterial bed, is the largest and strongest artery in the body. It carries roughly 200 million liters of blood in an average lifetime. Any process that undermines the architecture threatens the structure, stability, and functionality of the aorta. In this regard, acute aortic dissection (AAD) requires special attention because it is the most catastrophic acute illness of the aorta; it has high morbidity and mortality because of potentially fatal complications. AAD has, therefore, become an important topic of recent research, and knowledge about this disease has improved during the past few years. Up-to-date knowledge about the natural history, epidemiology, presentation, physiopathology, evolution, management, follow-up, and long-term outcomes of AAD are summarized in this review.

Results of Proximal Arch Replacement Using Deep Hypothermia for Circulatory Arrest: Is Moderate Hypothermia Really Justifiable?

The use of selective cerebral perfusion with warmer temperatures during circulatory arrest has been increasingly used for arch replacement over concerns regarding the safety of deep hypothermic circulatory arrest (DHCA). However, little data actually exist on outcomes after arch replacement and DHCA. This study examines modern results with DHCA for proximal arch replacement to provide a benchmark for comparison against outcomes with lesser degrees of hypothermia. Between July 2005 and June 2010, 245 proximal arch replacements (“hemiarch”) were performed using deep hypothermia; mean minimum core and nasopharyngeal temperatures were 18.0 ± 2.1°C and 14.1 ± 1.6°C, respectively. Adjunctive cerebral perfusion was used in all cases. Concomitant ascending aortic replacement was performed in 41 per cent, ascending plus aortic valve replacement in 23 per cent, and aortic root replacement in 32 per cent. Mean age was 58 ± 14 years; 36 per cent procedures were urgent/emergent. Mean duration of DHCA was 20.4 ± 6.2 minutes. Thirty-day/in-hospital mortality was 2.9 per cent. Rates of stroke, renal failure, and respiratory failure were 4.1 per cent (0.8% for elective cases), 1.2 per cent, and 0.4 per cent, respectively. Deep hypothermia with adjunctive cerebral perfusion for circulatory arrest during proximal arch replacement affords excellent neurologic as well as nonneurologic outcomes. Centers using lesser degrees of hypothermia for arch surgery, the safety of which remains unproven, should ensure comparable results.

Deep hypothermic circulatory arrest: Alternative strategies for cerebral perfusion. A review article

Deep hypothermic circulatory arrest is an essential tool in the surgeon’s armamentarium. There are essentially three strategies to address cerebral ischemia during arrest periods. Early surgical case series pioneered the option of complete anoxia with deep hypothermia. Subsequent innovators introduced the concept of retrograde perfusion of the cerebral vessels through the venous system, and others have advocated the use of selective and non-selective antegrade perfusion of the cerebral arteries. Clinical studies assessing outcomes of the three approaches are compromised by small patient numbers, retrospective design and surgeon bias.

In this review, the authors will briefly discuss the conceptual basis of these strategies and the literature comparing these approaches in terms of key neurologic outcomes. The importance of this topic will emphasize the key role the perfusion community plays in establishing guidelines for best practice in circulatory arrest to go forward with education and research in this area.

Clinical Results of Ascending Aorta and Aortic Arch Replacement under Moderate Hypothermia with Right Brachial and Femoral Artery Perfusion

Background

Selective antegrade perfusion via axillary artery cannulation along with circulatory arrest under deep hypothermia has became a recent trend for performing surgery on the ascending aorta and aortic arch and when direct aortic cannulation is not feasible. The authors of this study tried using moderate hypothermia with right brachial and femoral artery perfusion to complement the pitfalls of single axillary artery cannulation and deep hypothermia.

Materials and Methods

A retrospective analysis was performed on 36 patients who received ascending aorta or aortic arch replacement between July 2005 and May 2010. The adverse outcomes included operative mortality, permanent neurologic dysfunction and temporary neurologic dysfunction.

Results

Of these 36 patients, 32 (88%) were treated as emergencies. The mean age of the patients was 61.9 years (ranging from 29 to 79 years) and there were 19 males and 17 females. The principal diagnoses for the operation were acute type A aortic dissection (31, 86%) and aneurysmal disease without aortic dissection (5, 14%). The performed operations were ascending aorta replacement (9, 25%), ascending aorta and hemiarch replacement (13, 36%), ascending aorta and total arch replacement (13, 36%) and total arch replacement only (1, 3%). The mean cardiopulmonary bypass time was 209.4±85.1 minutes, and the circulatory arrest with selective antegrade perfusion time was 36.1±24.2 minutes. The lowest core temperature was 24±2.1℃. There were five deaths within 30 post-op days (mortality: 13.8%). Two patients (5.5%) had minor neurologic dysfunction and six patients, including three patients who had preoperative cerebral infarction or unconsciousness, had major neurologic dysfunction (16.6%).

Conclusion

When direct aortic cannulation is not feasible for ascending aorta and aortic arch replacement, the right brachial and femoral artery can be used as arterial perfusion routes with the patient under moderate hypothermia. This technique resulted in acceptable outcomes.

Tepid hypothermic (32° C) circulatory arrest for total aortic arch replacement: a paradigm shift from profound hypothermic surgery

In total aortic arch replacement (TARCH) using hypothermic circulatory arrest (HCA) and selective cerebral perfusion (SCP), postoperative cerebral complications, including metabolic abnormalities, are by no means rare. Furthermore, there is a lack of international guidelines for the optimal perfusion temperature and flow for SCP. Starting in 2008, TARCH was performed using tepid HCA at 32 °C. In the present study, 27 patients (group C) who underwent TARCH with deep hypothermia at the lowest rectal temperatures of 20-25 °C were retrospectively reviewed and compared with 23 patients (group W) who underwent TARCH with 32 °C tepid hypothermia. Preoperative patient characteristics and intraoperative and postoperative parameters were compared. Preoperative patient characteristics did not differ significantly between the two groups. Circulatory arrest time, cardiopulmonary bypass time, operating time, amount of blood transfused and postoperative neurological complications were significantly reduced in group W compared with group C. Our procedure of TARCH using tepid hypothermia at 32 °C was safe, and it significantly reduced all parameters of extracorporeal circulation time. However, this study has several limitations. To indicate the safety and usefulness of tepid HCA for TARCH, a further multifaceted study should be performed with a greater number of patients.

Central Nervous System Protection in Cardiac Surgery

Neurological dysfunction and stroke following cardiac surgery and thoracic surgery requiring hypothermic circulatory arrest is a well-defined problem. The original studies in CABG patients identified risk factors, such as prior stroke and lower educational level. There is older evidence suggesting that higher perfusion pressures during cardiopulmonary bypass are helpful. Hyperthermia during rewarming on cardiopulmonary bypass and postoperative hyperthermia have been associated with adverse cognitive outcomes. Glucose management intraoperatively remains controversial, but most now advocate for moderate glucose control using insulin, if required. The subset of patients having thoracic aortic surgery requiring periods of aortic discontinuity are particularly problematic. A cerebral protection strategy should be determined, and this may include hypothermic circulatory arrest, selective cerebral perfusion, or retrograde cerebral perfusion. All of these techniques have been associated with good surgical outcomes, but there is little information on cognitive outcomes of thoracic aortic surgery.

Analysis of the risk factors of postoperative respiratory dysfunction of type A aortic dissection and lung protection

AIM

Retrospectively to analyze the risk factors of postoperative respiratory dysfunction (RD) in 196 patients with type A dissection operated on with cerebral perfusion and a lower body hypothermia circulatory arrest (HCA) and to investigate the method of the lung protection.

METHODS

From January 2005 to April 2008, 196 patients with type A dissection underwent surgical repair with cerebral perfusion and HCA. There were 142 male patients and 54 female patients, with ages from 17 to 78 years. Antegrade selective cerebral perfusion (SCP) through the axillary artery was performed for 168 patients and retrograde cerebral perfusion (RCP) from the superior vena cava for 28 patients. All the factors underwent univariate and multivariate analysis.

RESULTS

Mean cardiopulmonary bypass (CPB) duration was (186+/-56) minutes and mean cerebral perfusion time was (35+/-15) minutes; mean HCA time was (39+/-14) minutes. Postoperative RD was detected in 26 patients (13.3%). Multivariate analysis showed that the longer duration of circulatory arrest (CA), P=0.008, OR=1.048, and the higher temperature in the bladder during CA, P=0.002, OR=1.614, were independent risk factors of postoperative RD. There was a higher mortality (23.1%, P=0.025) in patients with postoperative RD when compared with the other patients.

CONCLUSION

The longer duration of CA and the higher temperature in the bladder during CA were found to be the independent risk factors of postoperative RD after type A aortic dissection surgery. Attention should be paid to lung protection for these patients and the adjunct of continuing descending aortic perfusion and cerebral perfusion should be a safe and feasible procedure and it would be valuable to perform a prospective trial.

Cerebrovascular response to continuous cold perfusion and hypothermic circulatory arrest

OBJECTIVE

Clinical and laboratory studies have documented changes in cerebrovascular resistance after hypothermic circulatory arrest, both with and without adjunctive cerebral perfusion modalities. This study was designed to clarify whether these changes are due to cerebral edema, resistance vessel abnormalities, or alterations in the cerebral microcirculation.

METHODS

Four mature swine underwent hypothermic circulatory arrest for 60 minutes, and 7 mature swine underwent cold cerebral perfusion for 60 minutes to simulate antegrade selective perfusion. All were rewarmed and weaned from cardiopulmonary bypass. Pial vascular diameter and reactivity were measured in vivo through a cranial window and ex vivo in an organ chamber; cerebral microvascular endothelium was studied in culture for release of vasoactive mediators. Cerebral water content was recorded.

RESULTS

Cold perfusion caused pial arteriole and venule constriction, whereas hypothermic circulatory arrest alone caused pial arteriole and venule dilatation. Cold perfusion caused a temporal loss of endothelium-dependent vasodilatation, most notably to bradykinin. Hypothermic circulatory arrest caused a loss of nitric oxide-mediated endothelium-dependent vasodilatation. Endothelium-independent vasoreactivity remained intact in both groups. Endothelial cells from the cold group had a vasoconstrictive secretory phenotype, whereas endothelial cells from the hypothermic circulatory arrest group had a vasodilatory phenotype. Cerebral water content was the same in both groups.

CONCLUSION

The increase in cerebrovascular resistance observed after cold cerebral perfusion is caused by resistance vessel constriction and may be promoted by an altered microcirculation. Hypothermic circulatory arrest alone is associated with endothelium-dependent vasoparesis. Both could contribute to cerebral injury in the early hours after operation.

Antegrade selective cerebral perfusion in thoracic aorta surgery: safety of moderate hypothermia

OBJECTIVE

Although antegrade selective cerebral perfusion (ASCP) has been demonstrated to be the best method of protection of brain ischemia during aortic arch surgery, there is no consensus regarding optimal temperature during ASCP. The study analyzed the outcomes of aortic surgery using ASCP at different degree of systemic hypothermia.

METHODS

Between November 1996 and November 2005, 305 patients underwent thoracic aorta surgery using ASCP. Patients were divided into two groups according to the lowest systemic temperature: moderate systemic hypothermia (> or =25 degrees C) was used in 189 patients (group A), and a deeper hypothermia (<25 degrees C) in 116 patients (group B). One hundred and five patients suffered from acute type A aortic dissection.

RESULTS

The extension of aortic replacement was significantly larger in group A, while the average ASCP time was not different between groups (63+/-37.7min group A, 58.6+/-35.6min group B; p=0.314). The 30-day mortality rate was 12.7% in group A and 13.8% in group B (p=0.862). Permanent neurologic deficits occurred in eight patients (2.6%) without significant differences between groups (3.1% group A vs 1.7% group B; p=0.715). Twenty-five patients (8.2%) suffered from temporary neurologic dysfunction (7.9% group A vs 8.6% group B; p=0.833).

CONCLUSIONS

In our experience, ASCP was a safe technique for thoracic aorta surgery allowing complex aortic repairs to be performed with good results in terms of hospital mortality and neurologic outcomes. The fact that there was no difference between the two groups suggests that moderate systemic hypothermia (26 degrees C) appears to be a safe and sufficient tool for brain protection. Moreover, the well known hypothermia-related side effects may be avoided.

Axillary Versus Femoral Cannulation for Aortic Surgery: Enough Evidence for a General Recommendation?

There is a trend towards cannulation of the axillary artery for extracorporeal circulation in patients requiring aortic arch surgery. We analyzed the published data comparing axillary and femoral cannulation for safety and outcome. End points were death; stroke, neurologic, and vascular complications; and malperfusion. Femoral cannulation is safe for extracorporeal circulation in patients without aortic arch surgery. In patients with type A dissections, malperfusion may occur owing to retrograde perfusion of the false lumen and subsequent occlusion of the origin of the supra aortic vessels. Cannulation of the axillary/subclavian artery results in antegrade flow, at least in the right carotid artery, with the possibility of antegrade cerebral perfusion during aortic arch repair. There was a trend towards improved neurologic outcome when the axillary artery was used for extracorporeal circulation in such patients. When different techniques were compared, the use of a side graft for axillary cannulation reduced the complication rate. The lack of randomized trials and the high variety of inclusion criteria in the different studies do not allow a general recommendation for the use of the axillary artery as cannulation site.

Whole-Body Perfusion under Moderate-Degree Hypothermia during Aortic Arch Repair

INTRODUCTION

There continue to be some controversies concerning aortic arch reconstruction, especially the cerebral protection methods. We report our operative and postoperative outcomes for cases of aortic arch replacement using whole-body perfusion during aortic reconstruction under 28 degrees C moderate hypothermia.

MATERIALS AND METHODS

A total of 12 patients were operated on between March 2003 and November 2005. Two of the patients were female. The mean age of the patients was 53.5 x 7.3 years (range, 42-65 years). We cannulated the right axillary artery for cerebral perfusion and the right femoral artery for body perfusion. Arch replacement was done under continuous antegrade cerebral perfusion through the right axillary artery and continuous body perfusion through the right femoral artery via intra-aortic occlusion of the proximal descending aorta with an intra-aortic occlusion catheter. Perioperative data and postoperative outcomes, blood urea nitrogen, serum creatinine, and alanin aminotransferase values were evaluated retrospectively in the patients.

RESULTS

There was only 1 hospital mortality. There were no neurologic complications. Postoperative levels of blood urea nitrogen and creatinin did not show significant difference but the alanin aminotransferase levels were significantly higher in the postoperative period, which was within the normal ranges of cardiopulmonary bypass effect.

DISCUSSION

Whole-body perfusion through the axillary and femoral arteries may provide more time for the surgeon and good cerebral and visceral protection, which are especially important for surgical teams in the learning curve.