Cerebral Perfusion

Innominate Artery Graft Cannulation for Selective Antegrade Cerebral Perfusion in Aortic Surgery: Clinical Findings and Feasibility

Background: Cerebral protection during aortic surgery is crucial for improving surgical outcomes and reducing neurological complications. Selective antegrade cerebral perfusion (SACP) is increasingly used, and innominate artery (IA) side graft cannulation presents an innovative alternative to conventional axillary artery cannulation, with the potential to reduce complications associated with the latter. Methods: In this retrospective study, 196 patients who underwent proximal aortic surgery with IA graft cannulation for SACP between January 2021 and June 2024 were analyzed. Demographic data, intraoperative parameters, and postoperative outcomes were evaluated. Complications such as new stroke, postoperative delirium, mortality, and acute renal failure (ARF) were assessed. Results: The median age of the patients was 63 years, and 18.37% underwent emergency surgery for Type A acute aortic dissection (TAAAD). The most frequently performed surgical procedure was ascending aorta and hemiarch replacement (36.74%). The median cardiopulmonary bypass, cross-clamp, and SACP durations were 120.5, 93, and 23 min, respectively. The postoperative mortality rate was 3.06%, stroke rate was 2.04%, delirium rate was 9.18%, and ARF rate was 3.06%. All cases of delirium resolved spontaneously within 2-3 days. The mortality rate among Marfan syndrome (MFS) patients was 4.35%, with no reported stroke cases in this group. Conclusions: IA graft cannulation is a safe and effective method for providing SACP in aortic surgery, particularly in high-risk patient groups such as those with TAAAD and MFS. This technique ensures optimal cerebral perfusion, minimizes neurological and systemic complications, and enhances surgical efficiency by reducing operative duration. However, large-scale, multicenter, and prospective studies are needed to evaluate its long-term efficacy and safety.

Impact of mild hypothermic circulatory arrest on surgical outcomes in acute type a aortic dissection patients: a single-centre study

BACKGROUND

As hypothermic circulatory arrest (HCA) is being more frequently induced in patients undergoing aortic arch surgery, its safety at different degrees has become a crucial area of study. The aim of this study was to assess the surgical outcomes of mild hypothermic circulatory arrest (MI-HCA) during aortic arch surgery.

METHODS

Acute type A aortic dissection (ATAAD) patients who underwent total arch replacement (TAR) and frozen elephant trunk (FET) surgery between January 2014 and December 2023 were enrolled in this study. The patients were divided into two groups according to the minimum nasopharyngeal temperature: the moderate hypothermic circulatory arrest (MHCA) group (20-28 °C) and the MI-HCA group (> 28 °C). The inverse probability of treatment weighting (IPTW) was used to balance differences in the baseline characteristics. Perioperative variables were analysed via pairwise comparisons, multivariable logistic regression, and subgroup forest plots to assess the impact of MI-HCA on surgical outcomes.

RESULTS

A total of 447 patients were included in this study, and the mean minimum nasopharyngeal temperature was 24.80 (23.98, 27.30) °C in the MHCA group and 30.10 (29.80, 30.70) °C in the MI-HCA group. The incidence of acute kidney injury (AKI) in the MI-HCA group was lower than that in the MHCA group (52% vs. 78%, p < 0.01). In the multivariable logistic regression analysis, MI-HCA was identified as an independent protective factor for AKI (OR = 0.354, 95% CI 0.177-0.689; p = 0.003). Additionally, compared with MHCA, MI-HCA was not associated with an increased incidence of stroke, spinal cord injury, or in-hospital mortality. After IPTW, the preoperative and intraoperative data of the patients were balanced, and the incidence of AKI in the MI-HCA group was still lower than that in the MHCA group (83.26% vs. 53.61%, p = 0.004). The subgroup forest plot also demonstrated that MI-HCA was a protective factor for postoperative AKI.

CONCLUSIONS

The surgical outcomes of MI-HCA in ATAAD patients were satisfactory. Compared with MHCA, MI-HCA provided sufficient protection for distal organs, the brain, and the spinal cord, with a significantly lower incidence of AKI. These results indicate that MI-HCA could be a better approach for ATAAD surgery.

Cerebral hypoperfusion resulting from improper cannulation positioning during aortic dissection surgery: a case report

BACKGROUND

Selective antegrade cerebral perfusion (sACP) is a crucial cerebral protection technique employed during aortic dissection surgeries involving cardiopulmonary bypass. However, postoperative neurological complications, particularly those related to cannulation issues and perfusion problems, remain a significant concern.

CASE PRESENTATION

This case report details an unusual instance where a 38-year-old male patient with Marfan syndrome experienced cerebral hypoperfusion during emergency surgery for Stanford Type A aortic dissection. Despite following standard protocols, a significant drop in regional cerebral oxygen saturation (rSO2) and abnormal blood pressure fluctuations were observed shortly after initiating sACP via the innominate artery. After initial attempts to optimize perfusion flow proved ineffective, the cannulation position was adjusted, leading to improvements. Nevertheless, the patient subsequently exhibited signs of cerebral hypoperfusion and was found to have suffered a new cerebral infarction.

CONCLUSIONS

This case report underscores the importance of precise cannula placement during sACP procedures and the dire consequences that can arise from improper positioning. It emphasizes the need for continuous monitoring and prompt intervention in cases of abnormal cerebral oxygenation and blood pressure, as well as the value of considering cannulation-related issues as potential causes of postoperative neurological complications.

Effect of Asymptomatic Common Carotid Artery Dissection on the Prognosis of Patients With Acute Type A Aortic Dissection

BACKGROUND

Acute type A aortic dissection can extend upwards to involve the common carotid artery. However, whether asymptomatic common carotid artery dissection (CCAD) requires surgical repair remains controversial. This study aimed to explore the effect of asymptomatic CCAD without surgical intervention on the prognosis of patients who underwent surgery for acute type A aortic dissection.

METHODS AND RESULTS

Between January 2015 and December 2017, 485 patients with no neurological symptoms who underwent surgery for acute type A aortic dissection were enrolled in this retrospective cohort study. The patients were divided into 2 groups based on the exposure factor of CCAD. CCAD was detected in 111 patients (22.9%), and after adjusting baseline data (standardized mean difference <0.1), the 30-day mortality (17.1% versus 6.0%, P<0.001) and incidence of fatal stroke (7.7% versus 1.6%, P=0.001) were significantly higher in the group with CCAD. Univariable and multivariable Cox regression analyses found CCAD as an independent risk factor for 30-day mortality (hazard ratio [HR], 2.8 [95% CI, 1.5-5.2]; P=0.001). At a median follow-up of 6.2 years (interquartile range, 5.6-6.9 years), landmark analysis with a cutoff value of 1 month postoperatively showed a significant increase in mortality in the group with CCAD, especially in the first month (log-rank P=0.002) and no significant difference in survival after the first month postoperatively between the 2 groups (log-rank P=0.955).

CONCLUSIONS

Asymptomatic CCAD increased the risk of early fatal stroke and death in patients with acute type A aortic dissection after surgery but did not affect midterm survival in patients who survived the early postoperative period.

Neuroprotection during Open Aortic Arch Surgery: Cerebral Perfusion Methods and Temperature

Neuroprotection is important in open aortic arch surgery because of the dependence of brain tissues on cerebral perfusion. Therefore, several techniques have been developed to reduce cerebral ischemia and improve outcomes in open aortic arch surgery. In this review, I describe various neuroprotective strategies, such as profound and deep hypothermic circulatory arrest, selective antegrade cerebral perfusion, retrograde cerebral perfusion, and lower body circulatory arrest; compare their advantages and disadvantages, and discuss their evolution and current status by reviewing relevant literature.

Efficacy of pump-controlled selective antegrade cerebral perfusion in total arch replacement: A propensity-matched analysis

Background

Pump-controlled selective antegrade cerebral perfusion (PC-SACP) in total arch replacement (TAR) can regulate cerebral flow accurately, which might be beneficial for cerebral protection. However, the safety of PC-SACP for TAR combined with frozen elephant trunk implantation (FET) in patients with acute Type A dissections (ATAAD) is ambiguous.

Methods

A total of 192 patients with ATAAD underwent TAR at our institution from October 2019 to July 2021. The patients were divided into two groups based on PC-SACP used: PC group (SACP carried out by using a separate pump, n = 35) and Control group (SACP carried out as a traditional method, n = 157). Patients under PC-SACP were propensity-score matched to patients without PC-SACP, resulting in 35 pairs of patients.

Results

Preoperative characteristics, including age, gender, weight, and preoperative creatinine level, were similar between the two groups. Cardiopulmonary bypass time, cross-clamp time, circulatory arrest time, and minimum nasopharyngeal temperature did not differ between the two groups. However, SACP time (54 versus 40, P = 0.001) in the PC group was significantly longer than that in the Control group. The incidence of temporary neurologic dysfunction (5.7% versus 8.6, P = 0.643) showed a no significantly lower trend in the PC group compared with the Control group. Other clinical outcomes showed no significant intergroup differences.

Conclusions

PC-SACP in TAR is safe and feasible and might be beneficial for avoiding brain injury caused by “luxury” perfusion.

Application of Three-Dimensional Arterial Spin Labeling Technique in the Assessment of Cerebral Blood Perfusion in Patients with Middle Cerebral Artery Occlusion: Analysis of Clinical Implications and Prognostic Factors

Objective. To explore the value of three-dimensional- (3D-) arterial spin labeling (ASL) technique in evaluating cerebral perfusion in patients with unilateral middle cerebral artery occlusion (MCAO) and to observe the influencing factors of poor prognosis via long-term follow-up of patients who survived the disease. Methods. The clinical data of 60 patients with unilateral middle cerebral artery (MCA) M1 segment occlusion diagnosed by magnetic resonance angiography (MRA) from January 2018 to January 2022 were retrospectively analyzed. All patients were examined by routine MRI, MRA, and 3D-ASL, in which two postlabeling delays (PLDs; 1525 ms and 2525 ms) were used in 3D-ASL. Cerebral blood flow (CBF) in the regions of interest (ROIs) of MCA on the affected side and the mirror side was measured. The clinical data and laboratory indexes of patients were collected and evaluated by clinical scales. With the modified Rankin Score (mRS) as the outcome indicator, patients were assigned to either the poor or the good prognosis group to analyze the factors influencing patient prognosis via univariate and multivariate analyses. Results. Among unilateral MCAO patients, there was a significant difference in the CBF of the affected side between the PLD 1525 ms and 2525 ms groups ( $P<0.05$ ), but there was no significant difference in the CBF of the mirror side ( $P>0.05$ ). Compared with the mirror side, 43 cases (71.7%) of the affected CBF presented with hypoperfusion, 9 cases (15.0%) with normal perfusion, and 8 cases (13.3%) with hyperperfusion. Age, NIHSS score, collateral circulation, and homocysteine (Hcy) were identified by multivariate Logistic regression analysis as independent risk factors for adverse outcomes. Conclusion. MCAO can lead to cerebral blood perfusion decline, and 3D-ASL technique can evaluate the post-MCAO cerebral blood perfusion level. Old age, high NIHSS scores, poor collateral circulation, and high Hcy levels are associated with poor clinical outcomes.

Elective aortic arch surgery: cerebral perfusion flows and transient neurological dysfunctions

AIMS

Selective antegrade cerebral perfusion technique is a method of cerebral protection used worldwide during aortic arch surgery. This study was designed to identify a potential correlation between perfusion flows and the development of postoperative transient neurological dysfunctions.

METHODS

From January 2015 to May 2020, 175 patients underwent elective surgical replacement of the aortic arch using selective antegrade cerebral perfusion at the Cardiac Surgery Unit of Sant'Orsola Hospital in Bologna. Considering that patients who developed a permanent neurological dysfunction and those who died before a possible evaluation of neurological status were excluded, the study population included 160 patients. The perfusion flows were collected and analyzed. Univariate and multivariate analyses were performed to identify the statistical risk factors involved in the onset of transient neurological dysfunctions.

RESULTS

The study population was divided into two groups: 138 patients (86.3%) without and 22 (13.8%) with postoperative transient neurological complications. Among the intra-operative parameters collected in the study, the univariate analysis showed that the indexed medium perfusion flow of selective antegrade cerebral perfusion was significantly lower in the transient neurological dysfunctions group (11.63 ± 2.41 ml/kg/min vs 12.62 ± 2.39 ml/kg/min, P -value = 0.03). The multivariate logistic regression analysis showed that the female gender ( P  = 0.004, OR = 4.816, IC = 1.636-14.174) was predictor of transient neurological dysfunctions.

CONCLUSION

The results of the study showed that lower perfusion flows seem to be related to a higher probability of developing transient neurological dysfunctions. However, the analysis of a wider population is required to confirm these preliminary data.

Innominate artery direct cannulation provides brain protection during total arch replacement for acute type A aortic dissection

Background

This study aimed to investigate the safety of direct innominate arterial (IA) cannulation using a pediatric arterial cannula to establish selective antegrade cerebral perfusion (ACP) during total arch replacement (TAR) for acute Stanford type A aortic dissection (ATAAD).

Methods

This retrospective study included patients with ATAAD who underwent TAR with the frozen elephant trunk (FET) technique between October 2020 and November 2021. Patients treated with direct IA cannulation using a pediatric arterial cannula for selective anterograde cerebral perfusion were included in the study.

Results

Of the 29 patients, 24 (82.8%) were male. The average age was 50.9 ± 9.47 years. Proximal repair included aortic root plasty (27 patients, [93.1%]) and Bentall surgery (2 patients, [6.9%]). Perioperative mortality and stroke rates were 3.4% and 6.9%, respectively. The mean lowest core temperature was 23.8 ± 0.74 °C and the mean ACP time was 25 ± 6.4 min. The aortic cross-clamp and cardiopulmonary bypass times were 141 ± 28 and 202 ± 29 min, respectively. There were no cases of IA injuries.

Conclusion

Direct IA cannulation using a pediatric arterial cannula is a simple, safe, and effective technique for establishing ACP during TAR with the FET technique for ATAAD and can avoid the potential complications of axillary artery cannulation.

The Role of Deep Hypothermia in Cardiac Surgery

Hypothermia is defined as a decrease in body core temperature to below 35 °C. In cardiac surgery, four stages of hypothermia are distinguished: mild, moderate, deep, and profound. The organ protection offered by deep hypothermia (DH) enables safe circulatory arrest as a prerequisite to carrying out cardiac surgical intervention. In adult cardiac surgery, DH is mainly used in aortic arch surgery, surgical treatment of pulmonary embolism, and acute type-A aortic dissection interventions. In surgery treating congenital defects, DH is used to assist aortic arch reconstructions, hypoplastic left heart syndrome interventions, and for multi-stage treatment of infants with a single heart ventricle during the neonatal period. However, it should be noted that a safe duration of circulatory arrest in DH for the central nervous system is 30 to 40 min at most and should not be exceeded to prevent severe neurological adverse events. Personalized therapy for the patient and adequate blood temperature monitoring, glycemia, hematocrit, pH, and cerebral oxygenation is a prerequisite and indispensable part of DH.

Type A aortic dissection: involvement of carotid artery and impact on cerebral malperfusion

Acute type A aortic dissection is a surgical emergency and management of such pathology can be complex with poor outcomes when there is organ malperfusion. Carotid artery involvement is present in 30% of patients diagnosed with acute type A aortic dissection, and given its emergency and complex nature, there is much controversy regarding the approach, extent of treatment, and timing of the intervention. It is clear that the occurrence of cerebral malperfusion adds an extra layer of complexity to the decision-making framework for treatment. Standardization and validation of the optimal management approach is required, and this should ideally be addressed with large-scale studies. Nonetheless, current literature supports the need for rapid recognition and diagnosis of acute type A aortic dissection with cerebral malperfusion, immediate and extensive surgical repair, and the appropriate use of cerebral perfusion techniques. This paper aims to discuss the current evidence regarding the impact of carotid artery involvement in both the management and outcomes of acute type A aortic dissection.

A simple method to establish antegrade cerebral perfusion during hemiarch reconstruction

Objective

We describe a novel and safe technique using a 12F-14F pediatric arterial cannula to establish unilateral, selective, antegrade cerebral perfusion (ACP) during open hemiarch reconstruction.

Methods

Between January 2015 and September 2018, 42 patients underwent elective aortic aneurysm repair requiring an open distal anastomosis and at least a hemiarch replacement via hypothermic circulatory arrest by 2 surgeons. All distal reconstructions were performed at moderate hypothermia (22°C-26°C) with direct cannulation of the innominate artery (IA) using a pediatric arterial cannula to allow ACP at 10-15 mL/kg/min. Data were collected by retrospective chart review.

Results

Thirty-one of the 42 patients (74%) were male. The mean patient age was 65 ± 13 years, and the mean body surface area was 2.1 ± 0.3 m². Proximal repairs included a modified Bentall with a valve-graft composite (n = 17), valve-sparing root replacement (n = 2), and aortic valve replacement (n = 15). Perioperative mortality was 2% (n = 1), and the incidence of stroke was 0%. The mean lowest core body temperature reached during circulatory arrest was 23.8 ± 2.7°C with a mean ACP time of 21.8 ± 3.6 minutes. The mean aortic cross-clamp and cardiopulmonary bypass times were 160.6 ± 55.5 minutes and 204.7 ± 57.5 minutes, respectively. There were no cases of IA injury.

Conclusions

Direct IA cannulation with a pediatric arterial cannula is a safe and efficient method to allow ACP in aortic surgery requiring hypothermic circulatory arrest and may circumvent the potential complications of axillary cannulation.

Role of Moderate Hypothermia and Antegrade Cerebral Perfusion during Repair of Type A Aortic Dissection

The goal of this study was to compare early postoperative outcomes and actuarial survival between patients who underwent repair of acute type A aortic dissection with deep or moderate hypothermia. A total of 132 consecutive patients from a single academic medical center underwent repair of acute type A aortic dissection between January 2000 and June 2014. Of those, 105 patients were repaired under deep hypothermia (< 24 C°), while 27 patients were repaired under moderate hypothermia (≥24 C°). Median ages were 62 years (range: 27-86) and 59 years (range: 35-83) for patients repaired under deep hypothermia compared with patients repaired under moderate hypothermia, respectively ( p  = 0.451). Major morbidity, operative mortality, and 10-year actuarial survival were compared between groups. Operative mortality was 17.1 and 7.4% in the deep and moderate hypothermia groups, respectively ( p  = 0.208). Incidence of permanent stroke was 12.4% in the deep hypothermic circulatory arrest group and 0% in the moderate hypothermia group ( p  = 0.054). Actuarial 5- and 10-year survival demonstrated a trend for lower long-term mortality with moderate hypothermia compared with deep hypothermia (69% 5-year and 54% 10-year for deep hypothermia vs. 79% 5-year and 10-year for moderate hypothermia, log-rank p  = 0.161). Moderate hypothermia is a safe and efficient alternative to deep hypothermia and may have protective benefits. Stroke rate was lower with moderate hypothermia.

Neuroprotective Strategies in Repair and Replacement of the Aortic Arch

Aortic arch surgery is a technical challenge, and cerebral protection during distal anastomosis is a continued topic of controversy and discussion. The physiologic effects of hypothermic arrest and adjunctive cerebral perfusion have yet to be fully defined, and the optimal strategies are still undetermined. This review highlights the historical context, physiological rationale, and clinical efficacy of various neuroprotective strategies during arch operations.

Neuroprotective effect of selective antegrade cerebral perfusion during prolonged deep hypothermic circulatory arrest: Cerebral metabolism evidence in a pig model

Objective:

The aim of this study was to elucidate the mechanism of cerebral injury and to evaluate selective antegrade cerebral perfusion (SACP) as a superior neuroprotective strategy for prolonged deep hypothermic circulatory arrest (DHCA).

Methods:

Twelve pigs (6–8-week old) were randomly assigned to DHCA alone (n=6) and DHCA with SACP (n=6) at 18°C for 80 min groups. Serum S100 was determined using an immunoassay analyzer. The concentrations of cerebral dialysate glucose, lactate, pyruvate, glycerol, and glutamate were measured using a microdialysis analyzer.

Results:

Compared with a peak at T4 (after 60 min of rewarming) in the DHCA group, the serum S100 in the SACP group was significantly lower throughout the study. The DHCA group was susceptible to significant increases in the levels of lactate, glycerol, and glutamate and the ratio of lactate/pyruvate as well as decreases in the level of glucose. These microdialysis variables showed only minor changes in the SACP group. There was a positive correlation between cerebral lactate and intracranial pressure during reperfusion in the DHCA group. However, the apoptosis index and C-FOS protein levels were lower in the SACP group.

Conclusion:

Metabolic dysfunction is involved in the mechanism of cerebral injury. SACP is a superior neuroprotective strategy for both mild and prolonged DHCA.

Brain protection in aortic arch aneurysm: antegrade or retrograde?

During open aortic arch repair, there is an interruption of cerebral perfusion and to prevent neurological sequelae, the hypothermic circulatory arrest has been established to provide sufficient brain protection coupled with adjuncts including retrograde and antegrade cerebral perfusion. To date, brain protection during open aortic arch repair is a contested topic as to which provides superior brain protection with little evidence existing to suggest supremacy of one modality over the other. This article reviews current literature reflecting on key and emerging studies in brain protection and their associated outcomes in patients undergoing open aortic arch surgery.

Spatially extended versus frontal cerebral near-infrared spectroscopy during cardiac surgery: a case series identifying potential advantages

Stroke due to hypoperfusion or emboli is a devastating adverse event of cardiac surgery, but early detection and treatment could protect patients from an unfavorable postoperative course. Hypoperfusion and emboli can be detected with transcranial Doppler of the middle cerebral artery (MCA). The measured blood flow velocity correlates with cerebral oxygenation determined clinically by near-infrared spectroscopy (NIRS) of the frontal cortex. We tested the potential advantage of a spatially extended NIRS in detecting critical events in three cardiac surgery patients with a whole-head fiber holder of the FOIRE-3000 continuous-wave NIRS system. Principle components analysis was performed to differentiate between global and localized hypoperfusion or ischemic territories of the middle and anterior cerebral arteries. In one patient, we detected a critical hypoperfusion of the right MCA, which was not apparent in the frontal channels but was accompanied by intra- and postoperative neurological correlates of ischemia. We conclude that spatially extended NIRS of temporal and parietal vascular territories could improve the detection of critically low cerebral perfusion. Even in severe hemispheric stroke, NIRS of the frontal lobe may remain normal because the anterior cerebral artery can be supplied by the contralateral side directly or via the anterior communicating artery.

Association Between Optic Nerve Head Blood Flow Measured Using Laser Speckle Flowgraphy and Radial Arterial Pressure During Aortic Arch Surgery

OBJECTIVE

This study was designed to investigate the association between ocular blood flow measured using laser speckle flowgraphy (LSFG) and radial arterial pressure during aortic arch surgery.

DESIGN

A prospective study.

SETTING

A single university hospital.

PARTICIPANTS

This study included 24 patients undergoing aortic arch surgery with cardiopulmonary bypass (CPB) using antegrade selective cerebral perfusion (SCP).

INTERVENTIONS

Measurement of optic nerve head blood flow using LSFG and radial arterial pressure via a catheter in the radial artery METHODS AND MAIN RESULTS: Antegrade SCP was managed with 24℃ and 40-to-60 mmHg at the right radial artery, which usually corresponds to a flow rate of 10 mL/kg/min. Optic nerve head blood flow using LSFG and radial arterial blood pressure were evaluated simultaneously at the right side and recorded at the following 4 points: after the induction of anesthesia (phase 1), after the beginning of CPB (phase 2), after the beginning of antegrade SCP (phase 3), and after cessation of CPB (phase 4). A moderate positive correlation between %change of mean blur rate in the optic nerve head measured using LSFG and %change of radial mean arterial pressure was identified (r = 0.604, p < 0.001). Bland-Altman analysis showed that the bias (mean difference) was -1.2% (95% limits of agreement -47.4% to 45.0%), indicating good agreement between %changes of the values recorded using the 2 measurements.

CONCLUSIONS

Intraoperative monitoring of optic nerve head blood flow using LSFG can be used as an additional cerebral perfusion parameter during aortic arch surgery with CPB using antegrade SCP.

Safe Reentry for False Aneurysm Operations in High-Risk Patients

BACKGROUND

In the absence of a standardized safe surgical reentry strategy for high-risk patients with large or anterior postoperative aortic false aneurysm (PAFA), we aimed to describe an effective and safe approach for such patients.

METHODS

We prospectively analyzed patients treated for PAFA between 2006 and 2015. According to the preoperative computed tomography scan examination, patients were divided into two groups according to the anatomy and extension of PAFA: in group A, high-risk PAFA (diameter ≥3 cm) developed in the anterior mediastinum; in group B, low-risk PAFA (diameter <3 cm) was situated posteriorly. For group A, a safe surgical strategy, including continuous cerebral, visceral, and coronary perfusion was adopted before resternotomy; group B patients underwent conventional surgery.

RESULTS

We treated 27 patients (safe reentry, n = 13; standard approach, n = 14). Mean age was 60 years (range, 29 to 80); 17 patients were male. Mean interval between the first operation and the last procedure was 4.3 years. Overall 30-day mortality rate was 7.4% (1 patient in each group). No aorta-related mortality was observed at 1 and 5 years in either group. The Kaplan-Meier overall survival estimates at 1 and 5 years were, respectively, 92.3% ± 7.4% and 73.4% ± 13.4% in group A, and 92.9% ± 6.9% and 72.2% ± 13.9% in group B (log rank test, p = 0.830). Freedom from reoperation for recurrent aortic disease was 100% at 1 year and 88% at 5 years.

CONCLUSIONS

The safe reentry technique with continuous cerebral, visceral, and coronary perfusion for high-risk patients resulted in early and midterm outcomes similar to those observed for low-risk patients undergoing conventional surgery.

How to Perfuse: Concepts of Cerebral Protection during Arch Replacement

Arch surgery remains undoubtedly among the most technically and strategically challenging endeavors in cardiovascular surgery. Surgical interventions of thoracic aneurysms involving the aortic arch require complete circulatory arrest in deep hypothermia (DHCA) or elaborate cerebral perfusion strategies with varying degrees of hypothermia to achieve satisfactory protection of the brain from ischemic insults, that is, unilateral/bilateral antegrade cerebral perfusion (ACP) and retrograde cerebral perfusion (RCP). Despite sophisticated and increasingly individualized surgical approaches for complex aortic pathologies, there remains a lack of consensus regarding the optimal method of cerebral protection and circulatory management during the time of arch exclusion. Many recent studies argue in favor of ACP with various degrees of hypothermic arrest during arch reconstruction and its advantages have been widely demonstrated. In fact ACP with more moderate degrees of hypothermia represents a paradigm shift in the cardiac surgery community and is widely adopted as an emergent strategy; however, many centers continue to report good results using other perfusion strategies. Amidst this important discussion we review currently available surgical strategies of cerebral protection management and compare the results of recent European multicenter and single-center data.

Cardiothoracic surgical emergencies in the intensive care unit

Patients with cardiothoracic surgical emergencies are frequently admitted to the ICU, either prior to operative intervention or after surgery. Recognition and appropriate timing of operative intervention are key factors in improving outcomes. A collaborative team approach with the cardiothoracic service is imperative in managing this patient population.

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.

Outcomes of Aortic Arch Replacement Performed Without Circulatory Arrest or Deep Hypothermia

BACKGROUND

Aortic arch replacement using standard techniques, including deep hypothermic circulatory arrest and selective antegrade cerebral perfusion, is still associated with significant mortality and cerebral morbidity. We have previously described the "branch-first" technique that avoids circulatory arrest or profound hypothermia with excellent outcomes. We now describe our clinical experience with a larger cohort of patients as well as follow-up of our earlier results. We also describe a further technical simplification to this technique.

METHODS

From 2005 to 2010, 43 patients underwent a "branch-first continuous perfusion" technique for aortic arch replacement. In this technique, arterial perfusion is peripheral, usually by femoral inflow. Disconnection of each arch branch and anastomosis to a perfused trifurcation graft proceeds sequentially from the innominate to the left subclavian artery, with uninterrupted perfusion of the heart and viscera by the peripheral cannula. In the first cohort perfusion to the trifurcation graft was by right axillary cannulation. Since 2009, a modification was introduced such that perfusion is supplied directly by a sidearm on the trifurcation graft. This was used in the last 18 patients of this series. After reconstruction of the debranched arch and ascending aorta, the common stem of the trifurcation graft is anastomosed to the arch graft. In this series, there were 27 males, and mean age was 63 ± 13 years. Fifteen cases (35%) were performed with urgent/emergent priority. Nineteen patients (44%) were operated for aortic dissection, and the remainder for aneurysms. Seven patients (16%) had previously undergone a cardiac surgical procedure.

RESULTS

There were two (4.7%) early mortalities while one patient (2.3%) experienced a permanent stroke. One patient (2%) required mechanical support while three (7%) required hemofiltration for renal support. Extubation was achieved within 24 hours in 21 patients (49%) while 19 (42%) were discharged from the Intensive Care Unit (ICU) within two days. Eight patients (19%) did not require any transfusion of red cells or platelets. Mean follow-up duration was 21 ± 19 months and was 100% complete. At three years, survival was 95 ± 3.2%. No patients required subsequent aortic reoperation during this early follow-up period.

CONCLUSIONS

This modified branch-first continuous perfusion technique brings us closer to the goal of arch surgery without cerebral or visceral circulatory arrest and the morbidity of deep hypothermia. Our early experience is encouraging although greater numbers and longer follow-up will reveal the full potential of this approach.

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.

Improved brain and myocardial protection during complex aortic reinterventions

In redo aortic surgery, an important issue of brain and myocardial protection is raised in patients presenting with large aneurysm (or pseudoaneurysm) adherent to the sternum and severe aortic valve regurgitation. We present our technique involving antegrade brain perfusion before resternotomy and left ventricle venting through the apex using a small anterolateral left thoracotomy.

Cerebral Protection During Surgery for Acute Aortic Dissection Type A

Background—

Cerebral protection during surgery for acute aortic dissection type A relies on hypothermic circulatory arrest, either alone or in conjunction with cerebral perfusion.

Methods and Results—

The perioperative and intraoperative conditions of 1558 patients submitted from 44 cardiac surgery centers in German-speaking countries were analyzed. Among patients with acute aortic dissection type A, 355 (22.8%) underwent surgery with hypothermic circulatory arrest alone. In 1115 patients (71.6%), cerebral perfusion was used: Unilateral antegrade cerebral perfusion (ACP) in 628 (40.3%), bilateral ACP in 453 (29.1%), and retrograde perfusion in 34 patients (2.2%). For 88 patients with acute aortic dissection type A (5.6%), no circulatory arrest and arch intervention were reported (cardiopulmonary bypass–only group). End points of the study were 30-day mortality (15.9% overall) and mortality-corrected permanent neurological dysfunction (10.5% overall). The respective values for the cardiopulmonary bypass–only group were 11.4% and 9.1%. Hypothermic circulatory arrest alone resulted in a 30-day mortality rate of 19.4% and a mortality-corrected permanent neurological dysfunction rate of 11.5%, whereas the rates were 13.9% and 10.0%, respectively, for unilateral ACP and 15.9% and 11.0%, respectively, for bilateral ACP. In contrast with the ACP groups, there was a profound increase in mortality when systemic circulatory arrest times exceeded 30 minutes in the hypothermic circulatory arrest group ( P <0.001). Mortality-corrected permanent neurological dysfunction correlated significantly with perfusion pressure in the ACP groups.

Conclusions—

This study reflects current surgical practice for acute aortic dissection type A in Central Europe. For arrest times less than 30 minutes, hypothermic circulatory arrest and ACP lead to similar results. For longer arrest periods, ACP with sufficient pressure is advisable. Outcomes with unilateral and bilateral ACP were equivalent.

Recommendations for haemodynamic and neurological monitoring in repair of acute type a aortic dissection

During treatment of acute type A aortic dissection there is potential for both pre- and intra-operative malperfusion. There are a number of monitoring strategies that may allow for earlier detection of potentially catastrophic malperfusion (particularly cerebral malperfusion) phenomena available for the anaesthetist and surgeon. This review article sets out to discuss the benefits of the current standard monitoring techniques available as well as desirable/experimental techniques which may serve as adjuncts in the monitoring of these complex patients.

Branch-first aortic arch replacement with no circulatory arrest or deep hypothermia

BACKGROUND

For aortic arch surgery, the potential risks of deep hypothermic circulatory arrest with or without antegrade cerebral perfusion have been widely documented. We hereby describe our early experience with a "branch-first continuous perfusion" technique that, by avoiding deep hypothermia and circulatory arrest, has the potential to reduce morbidity and mortality.

METHODS

Arterial perfusion is peripheral using femoral and axillary inflows. Disconnection of each arch branch, and anastomosis to the trifurcation graft, proceeds sequentially from the innominate to the left subclavian artery, with continuous perfusion of the heart and viscera by lower body and brain by upper body arterial return. After the descending aorta is clamped, the debranched arch may then be replaced and connected to the ascending aorta before the common stem of the trifurcation graft is joined to the arch graft. Thirty patients underwent this technique. Twelve patients were operated on for aortic dissection and the remainder for aneurysms.

RESULTS

With experience, minimum pump temperature rose from 16°C to 34°C. There was 1 (3.3%) death, and 2 (6.7%) patients had neurological dysfunction. Extubation was achieved within 24 hours in 12 (40%) patients, whereas 14 (47%) left the intensive care unit within 2 days. Ten (33%) patients were discharged from the hospital within 7 days. Eight (27%) patients required no transfusion of blood or blood products.

CONCLUSIONS

This technique brings us closer to the goal of arch surgery without cerebral or visceral circulatory arrest and the morbidity of deep hypothermia. Early results are encouraging.

[Type A dissection. Principles of anesthesiological management]

Acute type A dissection is among the most dangerous of vascular diseases and is associated with a high lethality. Surgery for type A dissection is a complex procedure which is accompanied by relevant blood losses and severe deterioration of the coagulation system. Either due to the dissection or the surgical procedure, perfusion of affected organs can be diminished or completely disrupted with the risk of irreversible organ damage especially in the brain. Perioperative anesthesiological management for type A dissection is demanding and involves maintaining hemodynamic stability, surveillance of cerebral oxygenation and transesophageal echocardiographical diagnostic support for the decision-making of the most appropriate surgical approach. Furthermore, reestablishment of sufficient hemostasis can be challenging and requires thorough understanding of the relevant aspects affecting normal hemostasis during surgical repair of aortic dissection. In this article relevant pathophysiological aspects and basic principles of anesthesiological management of type A dissection are described.

T-graft technique under antegrade cerebral perfusion for aortic arch aneurysm

We have devised a T-graft technique for selected extensive aortic arch replacement under antegrade cerebral perfusion. Under hypothermic circulatory arrest using antegrade cerebral perfusion, one graft was island-anastomosed to the supraaortic arteries. The other graft was anastomosed to the descending aorta. Proximal and distal grafts were then end-to-side anastomosed in a T-shape. During rewarming, the ascending aorta and proximal graft were anastomosed. The surgical field was good in the 6 patients included in this report. No perioperative deaths or serious complications were encountered. This procedure was effective for patients with extensive aortic arch aneurysm and relatively intact orifices of the supraaortic arteries.

Integrated Cerebral Protection Combined Antegrade and Retrograde Cerebral Perfusion during Deep Hypothermic Circulatory Arrest

Objective

Aortic arch surgery requires temporary interruption of cerebral perfusion. Hypothermic circulatory arrest (HCA) is an established method of central nervous system protection for limited periods of absent cerebral blood flow. Adjuncts to increase the safe duration of circulatory arrest include either retrograde cerebral perfusion (RCP) or antegrade cerebral perfusion (ACP), with most complex aortic operations now performed using HCA with ACP. We reasoned that optimal cerebral protection might be achieved with a combination of ACP and RCP (integrated brain protection) and present an early clinical experience that supports this approach.

Methods

The integrated brain protection strategy included sequential overlapping periods of RCP, ACP, and RCP during HCA. Moderate systemic hypothermia (25°C) was used. Patient data were gathered through retrospective chart review.

Results

Between 2008 and 2009, six consecutive patients underwent ascending aortic graft replacement for acute type A dissection using HCA and integrated brain protection. The mean minimum systemic temperature was 22.9 ± 1.8°C, the mean total HCA time was 34 ± 5 minutes, and the mean duration of ACP and RCP was 22 ± 6 and 7 ± 5 minutes, respectively. Patients were awake and followed commands 10.1 ± 3.4 (range, 5–13) hours after operation, and there was no evidence of temporary neurologic dysfunction. There was no operative mortality.

Conclusions

Integrated brain protection using both RCP and ACP during HCA is a promising approach for the safe performance of complex aortic surgery and is worthy of evaluation in larger clinical series.

Safety of Mild Hypothermic Circulatory Arrest with Selective Cerebral Perfusion

Although hypothermic circulatory arrest with antegrade selective cerebral perfusion is used for cerebral protection, optimal perfusion characteristics are still unclear. Between May 2006 and March 2008, 26 patients (mean age, 68.9 years; 14 males) underwent thoracic aortic repair with mild hypothermic circulatory arrest (34.3°C ±1.9°C) and antegrade selective cerebral perfusion (30°C) for various indications including 16 acute type A aortic dissections. Mean cerebral perfusion rate was 21.1 ± 4.3mL kg−1 min−1. Non-elective operations were carried out in 16 (61.5%) cases. Operative procedures were ascending aortic replacement in 16 patients, hemiarch replacement in 4, and total arch replacement in 6. Cardiopulmonary bypass time was 209 ± 61 min, cardiac ischemic time was 141 ± 45 min, cerebral perfusion time was 81 ± 67 min, and lower body circulatory arrest time was 65 ± 22 min. Mean rectal temperature drifted to 30.6°C ± 1.3°C. There was 1 (3.8%) hospital death due to rupture of a residual descending thoracic aneurysm. One patient needed reexploration for bleeding, and 2 (7.7%) suffered permanent neurologic dysfunction. No postoperative spinal cord dysfunction was observed. Mild hypothermic circulatory arrest with antegrade selective cerebral perfusion could be performed safely in our patient population.

Neurological complications of cardiac surgery

Neurological injury resulting from cardiac surgery has a range of manifestations from focal neurological deficit to encephalopathy or coma. As the safety of drug-eluting stents comes into question, more patients will likely undergo coronary artery bypass graft surgery. These projections, along with the growing proportions of elderly patients and those with comorbidities, portend the potential for rising rates of perioperative neurological complications. The risk for neurological injury may be determined by the type of procedure, by patient-specific characteristics, and by the extent of cerebral embolization and hypoperfusion during and after surgery. Changes in surgical techniques, including the use of off-pump surgery, have not decreased rates of brain injury from cardiac surgery. When appropriate, modern neuroimaging techniques should be used in postoperative patients to confirm diagnosis, to provide information on potential etiology, to direct appropriate therapy, and to help in prognostication. Management of postoperative medications and early use of rehabilitation services is a recommended strategy to optimize the recovery for individuals with neurological injury after cardiac surgery.

Neonatal Aortic Arch Hemodynamics and Perfusion During Cardiopulmonary Bypass

The objective of this study is to quantify the detailed three-dimensional (3D) pulsatile hemodynamics, mechanical loading, and perfusion characteristics of a patient-specific neonatal aortic arch during cardiopulmonary bypass (CPB). The 3D cardiac magnetic resonance imaging (MRI) reconstruction of a pediatric patient with a normal aortic arch is modified based on clinical literature to represent the neonatal morphology and flow conditions. The anatomical dimensions are verified from several literature sources. The CPB is created virtually in the computer by clamping the ascending aorta and inserting the computer-aided design model of the 10 Fr tapered generic cannula. Pulsatile (130 bpm) 3D blood flow velocities and pressures are computed using the commercial computational fluid dynamics (CFD) software. Second order accurate CFD settings are validated against particle image velocimetry experiments in an earlier study with a complex cardiovascular unsteady benchmark. CFD results in this manuscript are further compared with the in vivo physiological CPB pressure waveforms and demonstrated excellent agreement. Cannula inlet flow waveforms are measured from in vivo PC-MRI and 3 kg piglet neonatal animal model physiological experiments, distributed equally between the head-neck vessels and the descending aorta. Neonatal 3D aortic hemodynamics is also compared with that of the pediatric and fetal aortic stages. Detailed 3D flow fields, blood damage, wall shear stress (WSS), pressure drop, perfusion, and hemodynamic parameters describing the pulsatile energetics are calculated for both the physiological neonatal aorta and for the CPB aorta assembly. The primary flow structure is the high-speed canulla jet flow (∼3.0 m/s at peak flow), which eventually stagnates at the anterior aortic arch wall and low velocity flow in the cross-clamp pouch. These structures contributed to the reduced flow pulsatility (85%), increased WSS (50%), power loss (28%), and blood damage (288%), compared with normal neonatal aortic physiology. These drastic hemodynamic differences and associated intense biophysical loading of the pathological CPB configuration necessitate urgent bioengineering improvements—in hardware design, perfusion flow waveform, and configuration. This study serves to document the baseline condition, while the methodology presented can be utilized in preliminary CPB cannula design and in optimization studies reducing animal experiments. Coupled to a lumped-parameter model the 3D hemodynamic characteristics will aid the surgical decision making process of the perfusion strategies in complex congenital heart surgeries.

Article Commentary: Managing Dissections of the Thoracic Aorta

Thoracic aortic dissection is associated with substantial morbidity and mortality, and it requires timely and accurate diagnosis and treatment. Long-term antihypertensive therapy remains critical for the treatment of this disease. Surgical intervention, although still a formidable undertaking, has evolved to better address both acute and chronic dissection, and the results have improved. Basic and clinical research, as well as technological advances, have increased our understanding of this challenging disease state.

Hypothermia treatment potentiates ERK1/2 activation after traumatic brain injury

Traumatic brain injury (TBI) results in significant hippocampal pathology and hippocampal-dependent memory loss, both of which are alleviated by hypothermia treatment. To elucidate the molecular mechanisms regulated by hypothermia after TBI, rats underwent moderate parasagittal fluid-percussion brain injury. Brain temperature was maintained at normothermic or hypothermic temperatures for 30 min prior and up to 4 h after TBI. The ipsilateral hippocampus was assayed with Western blotting. We found that hypothermia potentiated extracellular signal-regulated kinase 1/2 (ERK1/2) activation and its downstream effectors, p90 ribosomal S6 kinase (p90RSK) and the transcription factor cAMP response element-binding protein. Phosphorylation of another p90RSK substrate, Bad, also increased with hypothermia after TBI. ERK1/2 regulates mRNA translation through phosphorylation of mitogen-activated protein kinase-interacting kinase 1 (Mnk1) and the translation factor eukaryotic initiation factor 4E (eIF4E). Hypothermia also potentiated the phosphorylation of both Mnk1 and eIF4E. Augmentation of ERK1/2 activation and its downstream signalling components may be one molecular mechanism that hypothermia treatment elicits to improve functional outcome after TBI.