Temporary neurological dysfunction after deep hypothermic circulatory arrest: a clinical marker of long-term functional deficit

Outcomes of ascending aorta and partial arch replacement with entry resection for DeBakey type I acute aortic dissection

OBJECTIVES

This study investigated early and late outcomes between ascending aorta/partial arch replacement and total arch replacement with entry resection in DeBakey type I acute aortic dissection (DIAAD) repair.

METHODS AND RESULTS

This study included 98 patients who underwent DIAAD repair from January 2005 to December 2020. Seventy-four patients underwent ascending aorta and partial arch replacement with entry resection (Non-TAR group), and 24 underwent total arch replacement with entry resection (TAR group). The mean follow-up period was 4.8 ± 3.2 years. The follow-up rate was 92.3%. The mean age in the Non-TAR and TAR groups was 68.8 ± 10.4 years and 61.6 ± 13.7 years, respectively (P = 0.046). No difference in preoperative shock and malperfusion syndrome was observed between the groups. Hospital death was observed in 5.4% and 12.5% of the Non-TAR and TAR groups, respectively (P = 0.241). Postoperative permanent neurologic deficits and temporary hemodialysis were more frequently seen in the TAR compared to the Non-TAR group (P = 0.03 and 0.003, respectively). The 5-year survival rates were 95.1% ± 3.4% and 89.2% ± 7.2% in the Non-TAR and TAR groups, respectively (Log-rank P = 0.603). Freedom from downstream aorta-related reinterventions at 5 years was 87.8% ± 4.5% and 64.1% ± 11.0% in the Non-TAR and TAR groups, respectively (Log-rank P = 0.007). Three patients in each group underwent thoracic endovascular aortic repair for residual aortic dissection.

CONCLUSIONS

Early and late outcomes in the Non-TAR group were satisfactory compared to those in the TAR group. Entry resection with graft replacement remains a standard approach in DIAAD repair.

Clinical outcomes of mild versus moderate hypothermic circulatory arrest with antegrade cerebral perfusion in adult aortic arch surgery: A systematic review and meta-analysis

OBJECTIVES

In adult aortic arch surgery, moderate hypothermic circulatory arrest (HCA) with selective antegrade cerebral perfusion (SACP) (MoHACP) is widely used, but the application of mild HCA with SACP (MiHACP) is still controversial. This meta-analysis aimed to compare clinical outcomes using MiHACP or MoHACP.

METHODS

Studies comparing outcomes of MiHACP or MoHACP in adult aortic arch surgery were searched from four databases from inception through April 2022. Primary outcomes were postoperative permanent neurological deficit (PND), temporary neurological deficit (TND), and mortality. Secondary outcomes included other common complications. Meta-analysis was conducted using a random-effects model in all cases.

RESULTS

Eleven comparative studies were included, with 1555 patients in MiHACP group and 1499 patients in MoHACP group, and the mean HCA temperature were 29.4°C and 24.8°C, respectively. Postoperative PND, TND, mortality, paraplegia, dialysis, tracheotomy, reexploration for bleeding, and chest tube drainage volume were comparable in the two groups (p > 0.05). Ventilator time, intensive care unit and in-hospital length of stay were shorter in MiHACP group (p < 0.05). Outcomes were also comparable or had some benefits in MiHACP group when subgroup analyses were conducted according to hemiarch or total arch replacement, unilateral or bilateral SACP, HCA time, emergency aortic dissection surgery, and concomitant procedure.

CONCLUSION

The present meta-analysis showed acceptability of MiHACP in adult aortic arch surgery. Results need to be taken with caution as moderate risk of bias and very low quality of evidence were observed in this meta-analysis. Randomized controlled trials are needed for further analysis.

A nomogram-based model to predict postoperative transient neurological dysfunctions in patients receiving acute type A aortic dissection surgery

The purposes of this study were to develop and validate a nomogram for predicting postoperative transient neurological dysfunctions (TND) in patients with acute type A aortic dissection (AAAD) who underwent modified triple-branched stent graft implantation. This retrospective study developed a nomogram-based model in a consecutive cohort of 146 patients. Patient characteristics, preoperative clinical indices, and operative data were analyzed. Univariate and multivariable analyses were applied to identify the most useful predictive variables for constructing the nomogram. Discrimination and the calibration of the model was evaluated through the receiver operating characteristic curve (ROC), the Hosmer-Lemeshow goodness-of-fit test and the decision curve analysis (DCA). At the same time, to identify and compare long-term cumulative survival rate, Kaplan-Meier survival curve was plotted. The incidence rate of postoperative TND observed in our cohort were 40.9%. Supra-aortic dissection with or without thrombosis, creatinine >115 μmol and albumin <39.7 g/L, selective antegrade cerebral perfusion (SACP) time >7 min and total operation time >303 min, were confirmed as independent predictors that enhanced the likelihood of TND. Internal validation showed good discrimination of the model with under the ROC curve (AUC) of 0.818 and good calibration (Hosmer-Lemeshow test, p > .05). DCA revealed that the nomogram was clinically useful. In the long-term survival there was no significant difference between patients with or without TND history. The results showed the predict model based on readily available predictors has sufficient validity to identify TND risk in this population, that maybe useful for clinical decision-making.

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.

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.

Association between Duration of Deep Hypothermic Circulatory Arrest and Surgical Outcome in Patients with Acute Type A Aortic Dissection: A Large Retrospective Cohort Study

(1) Background: Deep hypothermic circulatory arrest (DHCA) with selective antegrade cerebral perfusion (ACP) is an established cerebral protection technique for the conduction of complex surgical procedures involving the aortic arch. It is controversial whether the duration of DHCA is associated with adverse outcome in patients with acute type A aortic dissection (AAAD). Our goal was to investigate whether DHCA time was associated with surgical outcome in patients undergoing a surgical treatment of AAAD. (2) Methods: A total of 410 patients were divided into two groups based on the DHCA time less than 60 min and equal to or longer than 60 min. (3) Results: Patients with longer DHCA times were significantly younger (p = 0.001). Intraoperatively, complex procedures with aortic arch surgery were more common in patients with longer DHCA times (p < 0.001). Accordingly, cardiopulmonary bypass (p < 0.001), cross-clamping (p < 0.001) and DHCA times (p < 0.001) were significantly longer in this group. Postoperatively, only the duration of mechanical ventilation (p < 0.001) and the rate of tracheotomy were significantly higher in these patients. Thirty-day mortality was satisfactory for both groups (p = 0.746). (4) Conclusions: Our results showed that improvements in perioperative management including ACP allow for the successful performance of surgical treatment of AAAD under DHCA with a duration of even longer than 60 min.

Unilateral versus bilateral cerebral perfusion during aortic surgery for acute type A aortic dissection: a multicentre study

OBJECTIVES

The aim of this retrospective multicentre study was to investigate and compare clinical outcomes of unilateral and bilateral antegrade cerebral perfusion (ACP) strategies on cerebral protection during surgery for type A aortic dissection.

METHODS

Data from 646 patients who underwent surgical repair of thoracic type A aortic dissection using unilateral and bilateral ACP with moderate hypothermic circulatory arrest in 3 cardiac surgical institutions between 2008 and 2018 were analysed. Propensity matching was performed to assess which technique ensured better outcomes.

RESULTS

Unilateral and bilateral ACP techniques were performed in 250 (39%) and in 396 (61%) patients, respectively. Propensity score analysis identified 189 matched pairs. In the matched cohort, the lowest core temperature was 27.5°C and 28°C in the bilateral and unilateral groups, respectively (P < 0.001). The unilateral technique required significantly shorter aortic cross-clamp and cardiopulmonary bypass times than bilateral technique [82 min vs 100 min (P < 0.001); 170 min vs 195 min (P < 0.001)]. The 30-day mortality was comparable (P = 0.325). The bilateral group reported a significantly higher incidence of permanent neurologic deficits (P < 0.001), left brain hemisphere stroke (P = 0.007) and all-combined complications (P < 0.001). Ten-year survival was comparable (P = 0.45).

CONCLUSIONS

Unilateral and bilateral ACP are both valid brain protection strategies in the landscape of aortic arch surgery. While admitting all the study limitations, unilateral technique could offer some clinical advantages.

CLINICAL REGISTRATION NUMBER

76049.

Plasma interleukin-6 is a potential predictive biomarker for postoperative delirium among acute type a aortic dissection patients treated with open surgical repair

OBJECTIVES

The relationship between inflammatory cytokines and postoperative delirium (POD) remains to be further investigated, especially in patients undergoing acute type A aortic dissection (AAD). Interleukin-6 (IL-6) is involved in the inflammatory process and has recently been identified as a biomarker of cerebral dysfunction. We explored the hypothesis that IL-6 was one of the critical causes of POD after surgical repair of AAD.

METHODS

Plasma IL-6 was measured using electrochemiluminescence technology in patients preoperatively and 24 h, 48 h, and 72 h after surgical repair of acute type A aortic dissection. After the first three postoperative days, delirium was evaluated twice daily using the Confusion Assessment Method. ROC curves were used to evaluate the ability of IL-6 measurements to distinguish POD.

RESULTS

The incidence of POD was 14.03% (31 of 221 patients). The patients in the POD group were significantly older than the patients in the non-POD group (56.48 ± 11.68 years vs 52.22 ± 10.50 years, P = 0.040). Plasma IL-6 concentrations were significantly higher in the POD group than in the non-POD group at three time points: preoperatively, after 24 h, and after 48 h. The AUC values corresponding to IL-6 preoperatively and 24 h after surgery were 0.73 and 0.72, respectively.

CONCLUSIONS

Cerebral dysfunction after the surgical repair of AAD shows elevated stress levels and inflammatory responses. Plasma IL-6 is a potential biomarker to predict the onset of POD in acute type A aortic dissection patients following surgical repair.

Triptolide improves neurobehavioral functions, inflammation, and oxidative stress in rats under deep hypothermic circulatory arrest

This study investigated the neuroprotective effects of triptolide (TPL) in a rat model of cardiopulmonary bypass with deep hypothermia circulatory arrest (DHCA). Rats were randomly divided into six groups: control, sham, DHCA, and DHCA + TPL (100, 200, 300 μg/kg). Neurobehavioral functions were measured using the elevated plus-maze, Y-maze, and Morris water maze tests. Levels of inflammatory cytokines, oxidative stress indices, and brain neurotrophins were measured by ELISA. Microglial activation and cell death was measured by immunofluorescence staining and TUNEL assay, respectively. Finally, activation of the Nrf2 pathway and NF-κB were detected by western blot. The elevated plus-maze, Y-maze, and Morris water maze tests all showed that TPL mitigated anxiety-like behavior, working memory, spatial learning, and memory in DHCA rats. TPL inhibited inflammatory responses and oxidative stress, as well as increased brain neurotrophin levels in DHCA rats. Moreover, TPL attenuated microglia activation and cell death in DHCA rats. Finally, TPL activated the Nrf2 pathway and inhibited NF-κB activity in DHCA rats. These results demonstrated that TPL improved neurobehavioral functions, neuroinflammation, and oxidative stress in DHCA rats, which may be associated with the Nrf2 and NF-κB pathways.

Brain Protection in Aortic Arch Surgery: An Evolving Field

Despite advances in cardiac surgery and anesthesia, the rates of brain injury remain high in aortic arch surgery requiring circulatory arrest. The mechanisms of brain injury, including permanent and temporary neurologic dysfunction, are multifactorial, but intraoperative brain ischemia is likely a major contributor. Maintaining optimal cerebral perfusion during cardiopulmonary bypass and circulatory arrest is the key component of intraoperative management for aortic arch surgery. Various brain monitoring modalities provide different information to improve cerebral protection. Electroencephalography gives crucial data to ensure minimal cerebral metabolism during deep hypothermic circulatory arrest, transcranial Doppler directly measures cerebral arterial blood flow, and near-infrared spectroscopy monitors regional cerebral oxygen saturation. Various brain protection techniques, including hypothermia, cerebral perfusion, pharmacologic protection, and blood gas management, have been used during interruption of systemic circulation, but the optimal strategy remains elusive. Although deep hypothermic circulatory arrest and retrograde cerebral perfusion have their merits, there have been increasing reports about the use of antegrade cerebral perfusion, obviating the need for deep hypothermia. With controversy and variability of surgical practices, moderate hypothermia, when combined with unilateral antegrade cerebral perfusion, is considered safe for brain protection in aortic arch surgery performed with circulatory arrest. The neurologic outcomes of brain protection in aortic arch surgery largely depend on the following three major components: cerebral temperature, circulatory arrest time, and cerebral perfusion during circulatory arrest. The optimal brain protection strategy should be individualized based on comprehensive monitoring and stems from well-executed techniques that balance the major components contributing to brain injury.

Influence of moderate hypothermic circulatory arrest on outcome in patients undergoing elective replacement of thoracic aorta

Background

The ideal technique of cerebral protection in the surgical operation of the ascending aorta.is currently controversial. The current analysis evaluates the influence of moderate hypothermic circulatory arrest (MHCA) on elective replacement of the ascending aorta.

Methods

The study included 905 consecutive patients between 2001 and 2015, who underwent replacement of ascending aorta in MHCA. Patients were divided according to the postoperative 30-day mortality into survivor und non-survivor group.

Results

The average age was 66.5±11.1 in survivors vs. 70.0±10.5 years in non-survivors (P=0.057). The survivor group had a significantly lower Euro-SCORE II than non-survivors [4.0% (2.3, 6.6) vs. 9.5% (4.8, 20.9); P<0.001)]. The incidence of coronary heart disease (38.0% vs. 58.3%; P=0.022) and chronic renal failure (10.0% vs. 33.3%, P<0.001 was significantly higher in non-survivors. Intraoperatively, the cardiopulmonary bypass time [140 min (112, 185) vs. 194 min (164, 271); P<0.001] and cross-clamping time [91 min (64, 124) vs.119 min (94, 157); P<0.001] were significantly longer in non-survivors. However, the MHCA time was similar in both groups with statistical significance (P=0.023). Postoperatively, re-exploration due to bleeding was highly significant in non-survivors (5.4% vs. 33.3%; P<0.001) with a higher incidence of stroke (4.6% vs. 33.3%; P<0.001). The duration of mechanical ventilation was significantly shorter in survivors than in non-survivors [17 h (12, 26) vs. 147 h (49, 337); P<0.001] with a lower incidence of pulmonary infection (6.0% vs.16.7%; P=0.023). The multivariable logistic regression analysis showed age, female gender, aortic aneurysm, additional CABG, total arch replacement and cardiopulmonary bypass time were independent risk factors for 30-day mortality.

Conclusions

The acceptable morbidity and mortality rates show that MHCA can be considered as a safe technique for cerebral protection in surgical replacement of thoracic aorta.

Effect of moderate hypothermic circulatory arrest on neurological outcomes in elderly patients undergoing replacement of the thoracic aorta

BACKGROUND

Various studies evaluated the relationship between hypothermic circulatory arrest and neurological outcome in patients undergoing replacement of ascending aorta. The current analysis focuses on the effect of moderate hypothermic circulatory arrest (MHCA) on elderly patients. The aim of our study was to evaluate the impact of MHCA on neurological outcomes in elderly patients undergoing replacement of the ascending aorta.

RESULTS

We retrospectively analyzed 905 consecutive patients, who underwent elective replacement of ascending aorta in MHCA (24 ± 2 °C, nasopharyngeal) between 2001 and 2015. Patients with acute aortic dissection were excluded from this study. Patients were divided into two groups: those aged 75 years and older (elderly group 22.4%, n = 203) and those younger than 75 years (younger group 77.6%, n = 702). The average age was 63.2 ± 10.2 in the young group vs. 78.7 ± 3.0 years in elderly group (p < 0.001). The elderly group had a significantly higher EuroSCORE II [26.7% (18.1, 36.3) vs. 11.6% (7.4, 19.9); p < 0.001)]. The incidence of coronary heart disease (49.8% vs. 35.6%, p < 0.001) and chronic renal failure (17.2% vs. 9.1%, p = 0.001) was significantly higher in the elderly group. Intraoperatively, the time of MHCA [14 min (12, 17) vs. 15 min (12, 18); p = 0.42], cardiopulmonary bypass [139 min (110, 183) vs. 144 min (113, 189); p = 0.225], and cross-clamping [91 min (63, 116) vs. 92 min (65, 127); p = 0.348] was similar in both groups. Postoperatively, a higher incidence of delirium was significantly reported in the elderly group (24.1% vs. 9.0%, p < 0.001). However, there was no significant difference regarding neurological complications between both groups. A 30-day mortality was acceptable for the elderly group, but significantly higher compared with the younger group (7.1% vs. 3.5%, p = 0.031).

CONCLUSIONS

Our study suggests that surgical replacement of the ascending aorta in MHCA can also be applied safely in elderly patients without increasing the risk of severe neurological complications.

Anticipating Postoperative Delirium During Burst Suppression Using Electroencephalography

OBJECTIVE

This study develops an electro-encephalography-based method for predicting postoperative delirium early during cardiac surgeries involving deep hypothermia circulatory arrest (DHCA), potentially providing an opportunity to intervene and minimize poor surgical outcome. DHCA is a surgical technique used during cardiac surgeries to facilitate repairs. Deep hypothermia is induced and supplemented by perfusion techniques to protect the brain during circulatory arrest, but concern for cerebral injury still remains.

METHODS

This research studies whether or not monitoring burst suppression, an electrophysiological phenomenon observed during patient cooling and warming, helps in predicting postoperative delirium, a correlate of poor prognosis. A metric called the burst suppression duty cycle (BSDC), akin to burst suppression ratio, is formulated to characterize this electrophysiological activity.

RESULTS

Assuming no complications occur prior to circulatory arrest, delirium diagnoses are correlated with the time elapsed until suppression activity ceases since resuming cardiopulmonary bypass. By comparing against a benchmark the times when BSDC reaches 100%, 15 of 16 cases can be correctly predicted. Similar accuracy can be achieved when querying BSDC progress earlier during warming.

CONCLUSION

Our results show that our BSDC metric is a promising candidate for early detection of postoperative delirium, and motivates further analysis of the causal relationship between postoperative delirium and the procedure transitioning out of circulatory arrest.

SIGNIFICANCE

The developed methodology anticipates incidences of postoperative delirium during rewarming, which potentially provides an opportunity to intervene and avert it.

A novel target to reduce microglial inflammation and neuronal damage after deep hypothermic circulatory arrest

BACKGROUND

Neuroinflammation acts as a contributor to neurologic deficits after deep hypothermic circulatory arrest. However, the molecular mechanism remains unclear. This study postulates that cold-inducible RNA-binding protein can promote deep hypothermic circulatory arrest-induced neuroinflammation.

METHODS

Rats were randomly assigned into 3 groups (n = 5, each group): sham group, deep hypothermic circulatory arrest group, and deep hypothermic circulatory arrest + Cirp^-/- group (Cirp^-/- group). Murine microglial BV2 cells were administered by adeno-associated viral vectors containing cold-inducible RNA-binding protein small interference RNA or negative control small interference RNA at 2 days before 4-hour oxygen-glucose deprivation at 18°C. Microglial activation, cell death, neuroinflammation, and related protein expression were assessed in tissue samples and cell cultures.

RESULTS

Cold-inducible RNA-binding protein was elevated along with evident neuroinflammation and neuronal damage in rats exposed to deep hypothermic circulatory arrest. In Cirp^-/- rats, histologic injury (3.00 [interquartile range, 2.00-3.00] vs 1.00 [interquartile range, 1.00-1.50] neuropathological score, P < .001) and microglial activation (40 ± 4 vs 13 ± 7 CA1 area, P < .001) were alleviated after deep hypothermic circulatory arrest. With RNA-sequencing analysis, this associated with reduction of key proinflammatory cytokines induced by inhibiting Brd2-NF-κB signals. In BV2 cells treated with small interference RNA-cold-inducible RNA-binding protein, similar protective effects were observed, including decreased proinflammatory cytokines and cytotoxicity. Brd2-NF-κB signals were confirmed by the addition of Brd2 inhibitor JQ1. Notably, the conditioned medium from BV2 cells transfected with small interference RNA cold-inducible RNA-binding protein significantly reduced apoptosis in neural SH-SY5Y cells after oxygen-glucose deprivation, which was similar to that after JQ1 administration.

CONCLUSIONS

Enhanced cold-inducible RNA-binding protein in microglia aggravates neuronal injury by promoting the release of proinflammatory cytokines, which might be mediated through Brd2-NF-κB signals during deep hypothermic circulatory arrest.

Retrograde Inferior Vena caval Perfusion for Total Aortic arch Replacement Surgery (RIVP-TARS): study protocol for a multicenter, randomized controlled trial

Background

During total aortic arch replacement surgery (TARS) for patients with acute type A aortic dissection, the organs in the lower body, such as the viscera and spinal cord, are at risk of ischemia even when antegrade cerebral perfusion (ACP) is performed. Combining ACP with retrograde inferior vena caval perfusion (RIVP) during TARS may improve outcomes by providing the lower body with oxygenated blood.

Methods

This study is designed as a multicenter, computer-generated, randomized controlled, assessor-blind, parallel-group study with a superiority framework in patients scheduled for TARS. A total of 636 patients will be randomized on a 1:1 basis to a moderate hypothermia circulatory arrest (MHCA) group, which will receive selective ACP with moderate hypothermia during TARS; or to an RIVP group, which will receive the combination of RIVP and selective ACP under moderate hypothermia during TARS. The primary outcome will be a composite of early mortality and major complications, including paraplegia, postoperative renal failure, severe liver dysfunction, and gastrointestinal complications. All patients will be analyzed according to the intention-to-treat protocol.

Discussion

This study aims to assess whether RIVP combined with ACP leads to superior outcomes than ACP alone for patients undergoing TARS under moderate hypothermia. This study seeks to provide high-quality evidence for RIVP to be used in patients with acute type A aortic dissection undergoing TARS.

Trial registration

Clinicaltrials.gov, ID: NCT03607786. Registered on 30 July 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3319-2) contains supplementary material, which is available to authorized users.

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.

Cerebral Circulation During Retrograde Cerebral Perfusion: Evaluation Using Laser Speckle Flowgraphy

BACKGROUND

The cerebroprotective effect of retrograde cerebral perfusion (RCP) and selective antegrade cerebral perfusion (SCP) still remains controversial. Laser speckle flowgraphy has shown much promise for novel perioperative neuromonitoring by assessing blood flow of the optic nerve head. This study aimed to evaluate the cerebral microcirculation in humans using laser speckle flowgraphy during simple circulatory arrest, RCP, and SCP under moderate hypothermia and to investigate whether RCP under moderate hypothermia is a reliable method of cerebral protection.

METHODS

A total of 23 consecutive patients who underwent a scheduled aortic arch or hemiarch surgical procedure on thoracic aorta aneurysm were enrolled. The laser speckle flowgraphy measurement that calculates mean blur ratio, a parameter of cerebral circulation, was obtained 6 times: after induction of anesthesia, baseline (T1), after initiation of cardiopulmonary bypass with cardiac arrest (T2), simple circulatory arrest (T3), RCP (T4), SCP (T5), and after the termination of cardiopulmonary bypass (T6).

RESULTS

Both mean blur ratios of simple circulatory arrest and RCP were significantly decreased compared with baseline. In contrast, no significant differences were observed between simple circulatory arrest and RCP. The mean blur ratio of SCP was significantly increased compared with both simple circulatory arrest and RCP.

CONCLUSIONS

In conclusion, no significant difference was observed in the cerebral circulation between RCP and simple circulatory arrest without adjunctive strategy under moderate hypothermia. In contrast, the cerebral circulation during SCP was significantly higher than simple circulatory arrest and RCP. These results suggest that cerebral microcirculation may not be adequate during RCP compared with SCP under 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.

Selective Cerebral Perfusion with the Open Proximal Technique during Descending Thoracic or Thoracoabdominal Aortic Repair: An Option of Choice to Reduce Neurologic Complications

PURPOSE

Selective cerebral perfusion with the open proximal technique for thoracoabdominal aortic repair has not been conclusively validated because of its procedural complexity and unreliability. We report the clinical outcomes, particularly the cerebroneurological complications, of an open proximal procedure using selective cerebral perfusion.

METHODS

A retrospective chart review identified 30 patients between 2007 and 2015 who underwent aortic repair through left lateral thoracotomy with selective cerebral perfusion, established through endoluminal brachiocephalic and left carotid artery and retrograde left axillary artery.

RESULTS

The mean durations of the open proximal procedure and cerebral ischemia (the duration of the open proximal procedure minus the duration of selective cerebral perfusion) were 110.3 ± 40.1 min and 24.8 ± 13.0 min, respectively. There were two cases (7%) of permanent neurologic dysfunction (PND) but no in-hospital deaths. Multivariate analysis identified the duration of cerebral ischemia as an independent risk factor for neurologic complications including temporary neurologic dysfunction (TND; odds ratio (OR): 1.13; p = 0.007), but no correlation was found between selective cerebral perfusion duration and neurologic complications.

CONCLUSION

Despite the relatively long duration of the open proximal procedure, selective cerebral perfusion has a potential to protect against cerebral complications during thoracic aortic repair through a left lateral thoracotomy.

Varying Evidence on Deep Hypothermic Circulatory Arrest in Thoracic Aortic Aneurysm Surgery

Cardiovascular surgeons have long debated the safe duration of deep hypothermic circulatory arrest during thoracic aortic aneurysm surgery. The rationale for using adjunctive cerebral perfusion (or not) is to achieve the best technical aortic repair with the lowest risk of morbidity and death. In this literature review, we highlight the debates surrounding these issues, evaluate the disparate findings on deep hypothermic circulatory arrest durations and temperatures, and consider the usefulness of adjunctive perfusion.

Intraoperative care for aortic surgery using circulatory arrest

The total circulatory arrest (CA) is necessary to achieve optimal surgical conditions in certain aortic pathologies, especially in those affecting the ascending aorta and aortic arch. During this procedure it is necessary to protect all the organs of ischemia, especially those of the central nervous system and for this purpose several strategies have been developed. The first and most important protective method is systemic hypothermia. The degree of hypothermia and the route of application have been evolving and currently tend to use moderate hypothermia (MH) (20.1-28 °C) associated with unilateral or bilateral selective cerebral perfusion methods. In this way the neurological results are better, the interval of security is greater and the times of extracorporeal circulation are smaller. Even so, it is necessary to take into account that there is the possibility of ischemia in the lower part of the body, especially of the abdominal viscera and the spinal cord, therefore the time of circulatory stop should be limited and not to exceed 80 minutes. Evidence of possible neurological drug protection is very weak and only mannitol, magnesium, and statins can produce some benefit. Inhalational anesthetics and some intravenous seem to have advantages, but more studies would be needed to test their long-term benefit. Other important parameters to be monitored during these procedures are blood glucose, anemia and coagulation disorders and acid-base balance. The recommended monitoring is common in complex cardiovascular procedures and it is of special importance the neurological monitoring that can be performed with several techniques, although currently the most used are Bispectral Index (BIS) and Near-Infrared Spectroscopy (NIRS). It is also essential to monitor the temperature routinely at the nasopharyngeal and bladder level and it is important to control coagulation with rotational thromboelastometry (ROTEM).

Aortic Surgery and Deep-Hypothermic Circulatory Arrest: Anesthetic Update

Aortic arch surgery has become increasingly complex, and novel surgical approaches have been utilized. Efforts aimed at improving neurological outcomes in this patient population have been numerous, with varying degrees of success. This article summarizes the anesthetic considerations for procedures on the aortic arch, including evidence-based outcomes with respect to temperature management, perfusion strategies, hemodynamic goals, adjunct agents, and neuromonitoring.

Temperature Management for Aortic Arch Surgery

Surgical treatment of aortic arch disease is a technically challenging procedure that requires complex circulation management strategies involving the use of hypothermic circulatory arrest. The definition of hypothermia has evolved with comfort and surgical adjuncts. This review describes the various circulation and temperature management strategies used during hemiarch and total arch replacement.

Deep Hypothermia and Circulatory Arrest in Adults

Brain protection during cardiopulmonary bypass has been the subject of intense research. Deep hypothermic circulatory arrest (DHCA) continues to be used for that goal during complex aortic arch and large intracranial aneurysm surgeries. The anesthetic management for adult patients undergoing these types of procedures requires specific knowledge and expertise. Based on our experience and review of the current literature, the authors highlight the key areas of the anesthetic plan, discussing the risk factors associated with adverse neurologic outcome as well as the rationale for decisions regarding specific monitors and medications. In the conclusion an anesthetic protocol for adult patients undergoing DHCA is suggested.

The Postoperative Care of Adult Patients Exposed to Deep Hypothermic Circulatory Arrest

Deep hypothermic circulatory arrest with cardiopulmonary bypass is indicated for complex surgical operations in adult patients involving the aortic arch, thoracoabdominal aorta, cerebral vasculature, and tumors extending into the vena cava and heart. Understanding the principles of ischemic-reperfusion injury and the effects of hypothermia in attenuating this process is fundamental to the delivery of effective postoperative care. Neurologic injury is the most troublesome adverse effect after the use of deep hypothermic circulatory arrest and cardiopulmonary bypass, presenting as either a transient neurologic deficit (5.9% to 28.1%) or an irreversible neurologic injury (1.8% to 13.6%). In patients with neurological injury, early postoperative mortality is markedly increased (18.2%), and for those patients that survive, long-term cognitive disability is still evident 6 months later. Early postoperative support of organ function, along with timely diagnosis and treatment of organ injury, is essential in minimizing perioperative morbidity, particularly neurologic morbidity. Meticulous management of fluids, maintaining stable cardiovascular hemodynamics with particular attention to systolic blood pressure, optimizing oxygen delivery, limiting ventilatorassociated lung injury, intensive insulin therapy for control of blood glucose levels, and avoidance of hyperthermia are essential in limiting organ injury and reducing perioperative morbidity and mortality.

Optimal temperature management in aortic arch operations

Hypothermic circulatory arrest is a critical component of aortic arch procedures, without which these operations could not be safely performed. Despite the use of hypothermia as a protective adjunct for organ preservation, aortic arch surgery remains complex and is associated with numerous complications despite years of surgical advancement. Deep hypothermic circulatory arrest affords the surgeon a safe period of time to perform the arch reconstruction, but this interruption of perfusion comes at a high clinical cost: stroke, paraplegia, and organ dysfunction are all potential-associated complications. Retrograde cerebral perfusion was subsequently developed as a technique to improve upon the rates of neurologic dysfunction, but was done with only modest success. Selective antegrade cerebral perfusion, on the other hand, has consistently been shown to be an effective form of cerebral protection over deep hypothermia alone, even during extended periods of circulatory arrest. A primary disadvantage of using deep hypothermic circulatory arrest is the prolonged bypass times required for cooling and rewarming which adds significantly to the morbidity associated with these procedures, especially coagulopathic bleeding and organ dysfunction. In an effort to mitigate this problem, the degree of hypothermia at the time of the initial circulatory arrest has more recently been reduced in multiple centers across the globe. This technique of moderate hypothermic circulatory arrest in combination with adjunctive brain perfusion techniques has been shown to be safe when performing aortic arch operations. In this review, we will discuss the evolution of these protection strategies as well as their relative strengths and weaknesses.

Immediate ICU Care for Patients Following Aortic Arch Surgery

Patients undergoing aortic arch surgery are at high risk for stroke, delirium, low cardiac output, respiratory failure, renal failure, and coagulopathy. A significantly higher mortality is seen in patients experiencing any of these complications when compared with those without complications. As surgical, perfusion, and anesthetic techniques improve, the incidence of major complications have decreased. A recent paradigm shift in cardiac surgery has focused on rapid postoperative recovery, and a similar change has affected the care of patients after arch surgery. Nevertheless, a small subset of patients experience significant morbidity and mortality after aortic arch surgery, and rapid identification of any organ dysfunction and appropriate supportive care is critical in these patients. In this article, the current state of postoperative care of the patient after open aortic arch surgery will be reviewed.

Nanotechnology Approaches to Targeting Inflammation and Excitotoxicity in a Canine Model of Hypothermic Circulatory Arrest-Induced Brain Injury

BACKGROUND

Neurocognitive dysfunction and injury remain problematic after cardiac procedures requiring hypothermic circulatory arrest (HCA). Due to poor blood-brain barrier penetrance and toxicities associated with systemic drug therapies, clinical success has been elusive. Accordingly, we explored targeted dendrimer (a nanoparticle) drug therapies in our well-established canine model of HCA to characterize the biodistribution and cellular localization of these nanoparticles in areas of known neuronal apoptosis and necrosis.

METHODS

Class A, 27- to 30-kg male hounds were administered an initial intravenous bolus (10% of the total dose [200 mg]) of generation-six polyamidoamine dendrimer (6.7 nm) labeled with cyanine 5, and cardiopulmonary bypass with peripheral cannulation was initiated. After 90 minutes of HCA, 70% of the total dose was infused over a 6-hour period. The final 20% of the total dose was given 24 hours post-HCA. The brain was harvested 48 hours later (72 hours post-HCA) and analyzed for dendrimer 6-cyanine 5 biodistribution.

RESULTS

The dorsal hippocampus demonstrated the highest brain accumulation of dendrimer 6-cyanine 5, which closely corresponds to the distribution of apoptotic neurons evident with histologic staining and on confocal imaging. In injured brain regions, dendrimer traversed the blood-brain barrier and localized within the target cells (injured neurons and microglia).

CONCLUSIONS

These findings have exciting implications for the future development of novel therapeutics to mitigate neurocognitive deficits in this group of patients.

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.

Inhibition of microRNA-29c protects the brain in a rat model of prolonged hypothermic circulatory arrest

OBJECTIVE

We sought to investigate the cerebroprotection of a novel microRNA mechanism by targeting peroxisome proliferator-activated receptor gamma coactivator 1-alpha in a rat model of prolonged deep hypothermia circulatory arrest.

METHODS

The right carotid artery and jugular vein of male Sprague-Dawley rats were cannulated for cardiopulmonary bypass. Circulatory arrest was conducted for 60 minutes when the pericranial temperature was cooled to 18°C. The sham group received the surgical procedure without cardiopulmonary bypass and deep hypothermia circulatory arrest; the deep hypothermia circulatory arrest group received cardiopulmonary bypass and deep hypothermia circulatory arrest; lentivirus control vector or lentiviral vector containing antagomiR-29c was given to the deep hypothermia circulatory arrest + vector group or the deep hypothermia circulatory arrest + antagomiR-29c group by intracerebroventricular administration 5 days before cardiopulmonary bypass (n = 8, for each of the 4 groups). Neurologic function was evaluated by the modified hole board test and beam balance task during 14 postoperative days. Expressions of caspase-3, peroxisome proliferator-activated receptor gamma coactivator 1-alpha, and miR-29c in the hippocampus were measured by Western blot and quantitative reverse transcription polymerase chain reaction. Malondialdehyde was measured using the Malondialdehyde Assay Kit (Beyotime, Jiangsu, China).

RESULTS

Pretreatment with antagomiR-29c significantly decreased the expression of microRNA-29c and increased the expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha in the hippocampus (P < .05 vs deep hypothermia circulatory arrest group). The level of malondialdehyde in the hippocampus was lower in the deep hypothermia circulatory arrest + antagomiR-29c group (P < .05 vs deep hypothermia circulatory arrest group). The neurologic functions were markedly protected in rats pretreated with antagomiR-29c as evidenced by improvement of vestibulomotor and cognitive performance during the early postoperative period. In the deep hypothermia circulatory arrest + antagomiR-29c group, histologic scores of the hippocampus were improved and the level of caspase-3 in the hippocampus was lower (P < .05 vs deep hypothermia circulatory arrest group).

CONCLUSIONS

Inhibition of miR-29c attenuates neurologic injuries induced by prolonged deep hypothermia circulatory arrest through a peroxisome proliferator-activated receptor gamma coactivator 1-alpha pathway.

Prolonged Antegrade Cerebral Perfusion via Right Axillary Artery (≥60 min) Does Not Affect Early Outcomes in a Repair of Type A Acute Aortic Dissection

PURPOSE

We aim to investigate whether the duration of antegrade cerebral perfusion (ACP) via right axillary artery with an 8-mm prosthetic graft affects early outcomes in a repair of type A acute aortic dissection (AAD).

METHODS

Over the 24 months from April 2010, a repair of AAD under ACP via the right axillary artery and mild hypothermic circulatory arrest (rectum temperature, 28-30°C) was performed in 34 patients. Mean age was 64.5 ± 13.7 years of age.Preoperative shock status was in three due to cardiac tamponade. Organ malperfusion occurred in 11 patients preoperatively. Mean follow-up period was 9.6 ± 8.4 months and follow-up rate was 100%.

RESULTS

Hospital mortality rate was 8.8%. No newly required hemodialysis and new onset of temporary or permanent neurologic deficits were present in survivors.There were no statistically significant differences of mortality rate, new onset of permanent or temporary neurologic deficits and distal organ dysfunction between ACP duration <60 min and ≥60 min. The 12-month survival was 84.4% ± 6.4%. And, freedom from aorta-related events at 12 and 18 months were 100% ± 0.0% and 88.9% ± 10.5%, respectively.

CONCLUSIONS

The duration of ACP via right axillary artery does not affect early outcomes following a repair of AAD.

Diffusion-weighted magnetic resonance imaging lesions after repair of acute type A aortic dissection: association with neurocognitive outcomes†‡

OBJECTIVES

We sought to analyse the preoperative status of arch vessels by postoperative diffusion-weighted magnetic resonance imaging (DWI) as a potential surrogate marker for cerebral thromboembolism and its relationship to neurocognitive outcomes.

METHODS

Preoperative computed tomography (CT) and postoperative DWI were available for 50 patients who received surgery for acute type A aortic dissection. Two radiologists evaluated CT and DWI scans. Mini-mental status examinations (MMSE) were performed on the same day with DWI.

RESULTS

Mean age of participants was 57 ± 14 years. MMSE and DWI were performed 6 ± 3 days after surgery. New cerebral embolisms were evident in 35 of 50 patients (70%) and often occurred as multiple lesions (28/35, 80%; range 2-21). Among patients with multiple lesions, 23 (66%) were clinically silent. Pathological lesions at the origin of the arch vessels correlated with the number and volume of new DWI lesions (P < 0.05). Degree of neurocognitive dysfunction tested by MMSE was negatively associated with age (r = -0.48, P < 0.0001) and left-sided DWI lesion number and volume (r = -0.74, P < 0.0001; r = -0.707, P < 0.0001).

CONCLUSIONS

DWI revealed new cerebral embolisms in 70% of patients following surgery for acute type A aortic dissection. Lesion number and volume significantly correlated with pathological status of arch vessels. MMSE was representative of left-sided lesions.

Thoracic aortic aneurysms in octogenarians: the results of open surgical repair using hypothermic circulatory arrest with antegrade selective cerebral perfusion

OBJECTIVE

Although recent progress has expanded the indications for thoracic aortic surgery to include elderly patients, the procedure remains extremely invasive. We performed a chart review to determine the early and late outcomes of thoracic aortic surgery using hypothermic circulatory arrest (HCA) and antegrade selective cerebral perfusion (ASCP) in octogenarians.

MATERIALS AND METHODS

Of 79 patients who underwent surgery for thoracic aortic aneurysms from April 2007 through December 2012, 8 patients 80 years or older were selected for analysis. Mean age at the time of surgery was 84.3±1.39 years. The diagnoses were aortic dissection in 5 patients and degenerative thoracic aneurysm in 3 patients. All patients underwent surgery with HCA. The lowest body temperature was 25℃ ASCP was used as an additional brain-protection technique. Emergency operations were performed in 5 patients (62.5%).

RESULTS

The mean duration of HCA was 60.4±19.7 minutes, that of aortic cross-clamping time was 143.0±30.4 minutes, and mean pump time was 207.8±44.4 minutes. The hospital mortality rate was 0%. Major postoperative complications occurred in 3 (37.5%) patients: stroke, temporary neurologic dysfunction, and paraparesis in 1 patient each. No patients required temporary dialysis for new-onset renal dysfunction. There were no deaths during the 65-month follow-up period.

CONCLUSION

The early and late outcomes after thoracic aortic surgery at our hospital using HCA with ASCP in octogenarians are acceptable. The operations are performed with an acceptable operative risk, even under emergency situations, including acute aortic dissection.