Profound hypothermia compared with moderate hypothermia in repair of acute type A aortic dissection

Aortic arch replacement with simultaneous antegrade cerebral and systemic perfusion using a single centrifugal pump driven 'split arterial line' extracorporeal circuit design

The ability to provide antegrade cerebral and systemic perfusion simultaneously may negate the requirement for any prolonged period of circulatory arrest during complex aortic arch reconstruction procedures, depending on the cannulation strategy. We describe the development and successful implementation of a custom 'split arterial line' extracorporeal circuit configuration to facilitate complex aortic surgery. This circuit design offers a wide range of cannulation and perfusion strategies, is safe, adaptable, simple to manage, and avoids the use of roller pumps for blood delivery, which are associated with deleterious haematological complications during prolonged cardiopulmonary bypass cases. The split arterial line approach has now become the standardised methodology for facilitating complex aortic surgery at our institution.

Systematic review and network meta-analysis of various nadir temperature strategies for hypothermic circulatory arrest for aortic arch surgery

BACKGROUND

The optimal nadir temperature for hypothermic circulatory arrest during aortic arch surgery remains unclear. We aimed to assess and compare clinical outcomes of all three temperature strategies (deep, moderate, and mild hypothermia) using a network meta-analysis.

METHODS

After literature search with MEDLINE and EMBASE through December 2021, studies comparing clinical outcomes with deep (<20°C), moderate (20-28°C), or mild (>28°C) hypothermic circulatory arrest were included. The outcomes of interest were perioperative mortality, stroke, transient ischemia attack (TIA), acute kidney injury (AKI), postoperative bleeding, operative time, and length of hospital stay.

RESULTS

Twenty-four comparative studies were identified, including 6018 patients undergoing aortic arch surgery using hypothermic circulatory arrest (deep: 2,978, moderate: 2,525, and mild: 515). Compared to deep hypothermia, mild and moderate hypothermia were associated with lower mortality (mild vs. deep: odds ratio [OR] 0.50; 95% confidence interval (CI) 0.29-0.87, moderate vs. deep: OR 0.68; 95% CI 0.54-0.86). In addition, mild hypothermia was associated with lower stroke (OR 0.50; 95% CI 0.28-0.89), AKI (OR 0.36; 95% CI 0.15-0.88) and postoperative bleeding (OR 0.55; 95% CI 0.31-0.97) compared to deep hypothermia. There was no significant difference between mild and moderate hypothermia in mortality, AKI or bleeding occurrence, while mild hypothermia was associated with shorter operative time and hospital stay. There was no significant difference in TIA rate among three groups.

CONCLUSIONS

Mild hypothermia was associated with overall more favorable clinical outcomes with comparable neurological complications compared to deep hypothermia. Furthermore, considering the shorter operative time and hospital stay compared with moderate hypothermia, mild hypothermia may be warranted when appropriate adjunctive cerebral perfusion is employed.

Deep Versus Moderate Hypothermia in Acute Type A Aortic Dissection: A Propensity-Matched Analysis

BACKGROUND

The ideal temperature for hypothermic circulatory arrest (HCA) during acute type A aortic dissection (ATAAD) repair has yet to be determined. We examined the clinical impact of different degrees of hypothermia during dissection repair.

METHODS

Out of 240 cases of ATAAD between June 2014 and December 2019, 228 patients were divided into two groups according to lowest intraoperative temperature: moderate hypothermic circulatory arrest (MHCA) (20-28°C) versus deep hypothermic circulatory arrest (DHCA) (<20°C). From this, 74 pairs of propensity-matched patients were analysed with respect to operative data and short-term clinical outcomes. Independent predictors of a composite outcome of 30-day mortality and stroke were identified.

RESULTS

Mean lowest temperature was 25.5±3.9°C in the MHCA group versus 16.0±2.9°C in DHCA. Overall 30-day mortality of matched cohort was 11.5% (17 deaths), there were no significant different between matched groups. Cardiopulmonary bypass (CPB) times were longer in DHCA (221.0±69.9 vs 190.7±74.5 mins, p=0.01). Antegrade cerebral perfusion (ACP) during HCA predicted a lower composite risk of 30-day mortality and stroke (OR 0.38). Female sex (OR 4.71), lower extremity ischaemia at presentation (OR 3.07), and CPB >235 minutes (OR 2.47), all portended worse postoperative outcomes.

CONCLUSIONS

A surgical strategy of MHCA is at least as safe as DHCA during repair of acute type A aortic dissection. ACP during HCA is associated with reduced 30-day mortality and stroke, whereas female sex, lower extremity ischaemia, and longer CPB times are all predictive of poorer short-term outcomes.

Ministernotomy approach to aortic arch inclusion and frozen elephant trunk in the treatment of acute Stanford A aortic dissection

This study aimed to report our results of ministernotomy approach to Liu’s aortic root repair technique, Liu’s aortic arch inclusion technique with frozen elephant trunk (FET) in the treatment in type A aortic dissection (TAAD). We retrospectively analyzed data on 68 Stanford A aortic dissection patients from October 2017 to March 2020. All patients underwent Liu’s aortic root repair technique, Liu’s aortic arch inclusion technique with FET and mild-moderate hypothermic circulatory arrest combined with ministernotomy approach. 154 TAAD patients between January 2014 and December 2016 underwent complete sternotomy were selected as control group. Clinical characteristics, data during operation, in-hospital and postoperative outcomes of these patients were observed. The mean hypothermic circulatory arrest time in ministernotomy Patients was 39.3 ± 7.9 min, aortic cross-clamp time was 105.9 ± 12.8 min, cardiopulmonary bypass time was 152.8 ± 24.3 min. Three patients died of multiple organ dysfunction syndrome in ministernotomy Patients. Perioperative temporary neurological dysfunction occurred in three (4.41%) patients, and 53 (77.9%) patients did not require any blood product transfusion during and after operation in ministernotomy Patients. Postoperative CT angiography (CTA) examination at 6-32 months showed excellent outcomes except in three (4.41%) cases where arch false lumen patency persisted. The Liu’s aortic root repair technique, Liu’s aortic arch inclusion technique with FET and mild-moderate hypothermia circulatory arrest simplify the surgical procedure and reduce bleeding, which can be accomplished through minimally invasive approach.

Midterm Outcomes of One-Stage Hybrid Aortic Arch Repair for Stanford Type A Aortic Dissection: A Single Center's Experience

This study sought to identify the midterm outcomes of one-stage hybrid aortic arch repair (HAAR) in patients with Stanford type A aortic dissection (TAAD). Between January 2010 and December 2015, 75 consecutive patients with TAAD involving the aortic arch who underwent one-stage type Ⅱ HAAR at our institution were identified. During this period, 496 consecutive patients with TAAD underwent traditional total aortic arch replacement (TAR) with frozen elephant trunk. The preoperative, perioperative and postoperative data of all patients were compared. A propensity score-matching analysis was applied to adjust for baseline risk factors. 571 patients were included for analysis (428 men; mean age, 48.9±11.1 years). For all patients, the mean follow-up time was 41.1±22.1 months, in-hospital mortality was 4.7% and the 5-year survival rate was 89.5%. Midterm outcomes between the propensity-matched groups were compared (59 HAAR vs TAR pairs). HAAR group showed shorter cardiopulmonary bypass time (105-159 min vs 158-230 min, p < 0.001), aortic cross-clamping time, postoperative ventilation time and intensive care unit stays (33-108 h vs 45-131 h, p = 0.010) than the TAR group. There were no significant differences in in-hospital mortality, rate of stroke and rate of paraplegia between the two groups, however, better 5-year survival rate was found in HAAR group (94.9% vs 75.8%, Log-rank p = 0.005). As compared to propensity matched cohort of TAR patients, HAAR shows good midterm outcomes for patients with TAAD. Further randomized study was needed to clarify the optimal management strategy of TAAD.

Risk Factors for High Blood Product Use in Patients with Stanford Type A Dissection

BACKGROUND

 Intraoperative and postoperative bleeding associated with allogeneic blood transfusion and reoperation is still a common and feared complication in patients undergoing surgery due to acute Type A Aortic Dissection (aTAAD). The aim of our study was to identify risk factors for higher transfusion rates.

METHODS

 In this retrospective single center study we evaluated pre -, intra-, and postoperative data of 121 patients with aTAAD. Depending on the median of received packed red blood cells (PRBCs), patients were divided into Group A (<8 PRBC, n = 53) and Group B (≥8 PRBC n = 68). Statistical analyses (descriptive statistics, univariable and multivariable logistic regression) were performed using SPSS software 25.0. Statistical significance was assumed at p-value <0.05.

RESULTS

 A total of 120 patients received a blood product during their perioperative course. Among others we identified age, hemorrhagic pericardial effusion, and dual antiplatelet therapy as preoperative risk factors, low rectal temperature as intraoperative risk factor and low body temperature, positive fluid balance, high lactate level and beginning development of acute renal failure as postoperative risk factors.

CONCLUSION

 Our study identifies several factors which predict a higher likelihood of bleeding and consecutive blood transfusion. Knowledge of these factors could influence the therapy to reduce transfusion requirements and lead to a targeted and more efficient use of coagulation products.

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

Objective

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

Methods

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

Results

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

Conclusion

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

Incidence, Risk Factors and Outcomes of Postoperative Headache After Stanford Type a Acute Aortic Dissection Surgery

Background: Postoperative headache (POH) is common in clinical practice, however, no studies about POH after Stanford type A acute aortic dissection surgery (AADS) exist. This study aims to describe the incidence, risk factors and outcomes of POH after AADS, and to construct two prediction models.

Methods: Adults who underwent AADS from 2016 to 2020 in four tertiary hospitals were enrolled. Training and validation sets were randomly assigned according to a 7:3 ratio. Risk factors were identified by univariate and multivariate logistic regression analysis. Nomograms were constructed and validated on the basis of independent predictors.

Results: POH developed in 380 of the 1,476 included patients (25.7%). Poorer outcomes were observed in patients with POH. Eight independent predictors for POH after AADS were identified when both preoperative and intraoperative variables were analyzed, including younger age, female sex, smoking history, chronic headache history, cerebrovascular disease, use of deep hypothermic circulatory arrest, more blood transfusion, and longer cardiopulmonary bypass time. White blood cell and platelet count were also identified as significant predictors when intraoperative variables were excluded from the multivariate analysis. A full nomogram and a preoperative nomogram were constructed based on these independent predictors, both demonstrating good discrimination, calibration, clinical usefulness, and were well validated. Risk stratification was performed and three risk intervals were defined based on the full nomogram and clinical practice.

Conclusions: POH was common after AADS, portending poorer outcomes. Two nomograms predicting POH were developed and validated, which may have clinical utility in risk evaluation, early prevention, and doctor-patient communication.

Moderate and Deep Hypothermic Circulatory Arrest Have Comparable Effects on Severe Systemic Inflammatory Response Syndrome After Total Aortic Arch Replacement in Patients With Type A Aortic Dissection

Background: The objective of this study was to compare the incidence of severe systemic inflammatory response syndrome (sSIRS) after total aortic arch replacement between patients who underwent moderate hypothermic circulatory arrest (MHCA) and those who underwent deep hypothermic circulatory arrest (DHCA). Methods: At Fuwai Hospital, 600 patients who underwent total aortic arch replacement with MHCA or DHCA from January 2013 to December 2016 were consecutively enrolled and divided into DHCA (14.1-20.0°C) and MHCA (20.1-28.0°C) groups. Preliminary statistical analysis revealed that some baseline indicators differed between the two groups; therefore, propensity score matching (PSM) was used to balance the covariates. Post-operative sSIRS as the primary outcome was compared between the groups both before and after PSM. Results: A total of 275 (45.8%) patients underwent MHCA, and 325 (54.2%) patients underwent DHCA. After PSM analysis, a total of 191 matched pairs were obtained. The overall incidence of sSIRS was 27.3%. There was no significant difference in post-operative sSIRS between the MHCA group and the DHCA group in either the overall cohort or the PSM cohort (no-PSM: P = 0.188; PSM: P = 0.416); however, post-operative sSIRS was increased by ~4% in the DHCA group compared with the MHCA group in both the no-PSM and PSM cohorts (no-PSM: 29.5 vs. 24.7%; PSM: 29.3 vs. 25.1%). Both before and after PSM, the rates of gastrointestinal hemorrhage and pulmonary infection and post-operative length of stay were significantly increased in the DHCA group compared with the MHCA group (P < 0.05), and the remaining secondary outcomes were not significantly different between the groups. Conclusions: MHCA and DHCA are associated with comparable incidences of sSIRS in patients following total aortic arch replacement for type A aortic dissection. However, the MHCA group had a shorter cardiopulmonary bypass time, a shorter post-operative length of stay and lower pulmonary infection and gastrointestinal hemorrhage rates than the DHCA group. We cautiously recommend the use of MHCA for most total arch replacements in patients with type A aortic dissection.

Anesthesia of a high-altitude area inhabitant who underwent aortic dissection emergency surgery in a low-altitude area

Heart surgery in patients from high-altitude areas is more challenging than usual. Few studies have been published on this issue, and none of them have discussed the effect of an altitude change (from high to low altitude) on a patient’s physiology or its effects on a patient’s perioperative management. Here, we present the case of a 46-year-old man who was a long-time resident of Tibetan area in Sichuan (altitude >3000 m) who underwent Stanford type A aortic dissection emergency surgery on the plain. Anesthetic management occurred through monitoring of the bispectral index (BIS) and transesophageal echocardiography (TEE), and we used a relatively loose fluid hydration strategy. The surgery was performed using cardiopulmonary bypass (CPB), deep hypothermia (DH), and selective antegrade cerebral perfusion. The most prominent anesthesia challenges for these patients are physiological changes due to habitation in an high-altitude environment (chronic hypoxemia), which can cause hyperhemoglobinemia, polycythemia, hypercoagulable blood, and even pulmonary hypertension, cor pulmonale, or congestive heart failure. Optimized perioperative management and close cooperation among the entire cardiac medical team were the key factors in the successful management of this rare case.

Neuroprotective strategies in acute aortic dissection: an analysis of the UK National Adult Cardiac Surgical Audit

OBJECTIVES

The risk of brain injury following surgery for type A aortic dissection (TAAD) remains substantial and no consensus has still been reached on which neuroprotective technique should be preferred. We aimed to investigate the association between neuroprotective strategies and clinical outcomes following TAAD repair.

METHODS

Using the UK National Adult Cardiac Surgical Audit, we identified 1929 patients undergoing surgery for TAAD (2011-2018). Deep hypothermic circulatory arrest (DHCA) only, unilateral (uACP), bilateral antegrade cerebral perfusion (bACP) and retrograde cerebral perfusion were used in 830, 117, 760 and 222 patients, respectively. The primary end point was a composite of death and/or cerebrovascular accident (CVA). Generalized linear mixed model was used to adjust the effect of neuroprotective strategies for other confounders.

RESULTS

The use of bACP was associated with longer circulatory arrest (CA) compared to other strategies. There was a trend towards lower incidence of death and/or CVA using uACP only for shorter CA. In particular, primary end point rate was 27.7% overall and 26.5%, 12.5%, 28.0% and 22.9% for CA <30 min and 28.6%, 30.4%, 33.3% and 33.0% for CA ≥30 min with DHCA only, uACP, bACP and retrograde cerebral perfusion, respectively. The use of DHCA only was associated with five-fold [odds ratio (OR) 5.35, 95% confidence interval (CI) 1.36-21.02] and two-fold (OR 1.77, 95% CI 1.01-3.09) increased risk of death and/or CVA compared to uACP and bACP, respectively, but the effect of uACP was significantly associated with CA duration (hazard ratio 0.97, 95% CI 0.94-0.99; P = 0.04).

CONCLUSIONS

In TAAD repair, the use of uACP and bACP was associated with a lower adjusted risk of death and/or CVA when compared to DHCA. uACP can offer some advantage but only for a shorter CA duration.

Temperatur- und Perfusionsmanagement bei akuter Typ-A-Aortendissektion

Die chirurgische Versorgung der akuten Typ-A-Aortendissektion erfuhr in den letzten Jahrzehnten v. a. im Hinblick auf das Perfusions- und Temperaturmanagement eine ständige Entwicklung. Neurologische Komplikationen sind die Hauptursache der postoperativen Morbidität und Mortalität. Die Verwendung einer Herz-Lungen-Maschine, des Kreislaufstillstands in tiefer Hypothermie, die temporäre Unterbrechung der zerebralen Perfusion oder Hypoperfusion des Gehirns und die Manipulation an der Aorta können zu neurologischen Schäden führen. Der Kreislaufstillstand in tiefer Hypothermie ermöglicht Eingriffe an der thorakalen Aorta, die für die Sanierung einer akuten Dissektion notwendig sein können. Dies hat allerdings Limitationen: Einerseits ist die Eingriffszeit begrenzt, andererseits führt die tiefe Hypothermie selbst zu Schäden. Experimentelle und klinische Studien konnten zeigen, dass der Grad der Hypothermie einen Einfluss auf die Komplikationsrate hat. Auch über den Nutzen der retrograden Hirnperfusion besteht noch Uneinigkeit. Das Konzept des Kreislaufstillstands mit zusätzlicher Hirnperfusion, besonders wenn der Grad der Hypothermie entsprechend der erwarteten Kreislaufstillstandzeit angepasst wird, erwies sich als sichere Methode. Es ermöglicht komplexe Eingriffe an der Aorta bei geringen Komplikationsraten und wird zunehmend als Standardverfahren bei der Versorgung der akuten Typ-A-Dissektion angewandt.

Moderate Versus Deep Hypothermia in Type A Acute Aortic Dissection Repair: Insights from the International Registry of Acute Aortic Dissection

BACKGROUND

The optimal strategy for cerebral protection during repair of type A acute aortic dissection has yet to be determined. We sought to determine the impact of differing degrees of hypothermia in patients undergoing acute dissection repair.

METHODS

All patients in the International Registry of Acute Aortic Dissection Interventional Cohort database who underwent type A acute aortic dissection repair between 2010 and 2018 were identified. Data for operative temperature were available for 1962 patients subsequently divided into 2 groups according to lowest temperature: moderate hypothermic circulatory arrest (MHCA) (20-28°C) versus deep hypothermic circulatory arrest (DHCA) (<20°C). We then propensity matched 362 pairs of patients and analyzed operative data and short-term outcomes.

RESULTS

The median lowest temperature was 25.0°C in the matched MHCA group as compared with 18.0°C in the DHCA group. For the entire cohort of 1962 patients, in-hospital mortality was 14.2% (278 deaths) but was not significantly different between DHCA and MHCA. The perioperative stroke rate was comparable between groups, before and after propensity matching. Circulatory arrest times were significantly longer in the MHCA cohort, regardless of matching. Use of antegrade or retrograde cerebral perfusion was similar in matched groups. There were no differences in 30-day survival or in other major postoperative morbidity between the 2 matched cohorts.

CONCLUSIONS

A surgical strategy of MHCA + antegrade cerebral perfusion is at least as safe as DHCA during repair of acute type A aortic dissection.

Effect of Deep Hypothermic Circulatory Arrest Versus Moderate Hypothermic Circulatory Arrest in Aortic Arch Surgery on Postoperative Renal Function: A Systematic Review and Meta-Analysis

Background

Moderate hypothermic circulatory arrest (MHCA) has been widely used in aortic arch surgery. However, the renal function after MHCA remains controversial. We performed a systematic review and meta‐analysis direct comparison of the postoperative renal function of MHCA versus deep hypothermic circulatory arrest (DHCA) in aortic arch surgery.

Methods and Results

We searched PubMed, Embase, and the Cochrane Library for postoperative renal function after aortic arch surgery with using MHCA and DHCA, published from inception to January 31, 2020. The primary outcome was renal failure. Secondary outcomes were the need for renal therapy and other major postoperative outcomes. The random‐effects model was used for all comparisons to pool the estimates. A total of 14 observational studies with 4142 patients were included. Compared with DHCA, MHCA significantly reduced the incidence of renal failure (odds ratio [OR], 0.76; 95% CI, 0.61–0.94; P=0.011; I²=0.0%) and the need of renal replacement (OR, 0.68; 95% CI, 0.48–0.97; P=0.034; I²=0.0%). Subgroup analysis showed that when the hypothermic circulatory arrest time was <30 minutes, the incidence of renal failure in MHCA group was significantly lower than that in DHCA group (OR, 0.73; 95% CI, 0.54–0.99; P=0.040; I²=1.1%), whereas an insignificant difference between 2 groups when hypothermic circulatory arrest time was >30 minutes (OR, 0.76; 95% CI, 0.51–1.13; P=0.169; I²=17.3%).

Conclusions

MHCA compared with DHCA reduces the incidence of renal failure and the need for renal replacement.

Registration

URL: https://www.crd.york.ac.uk/prospero; Unique identifier: CRD42020169348.

Minimized perfusion circuit for acute type A aortic dissection surgery

A minimized perfusion circuit (MPC) may reduce transfusion requirement and inflammatory response. Its use, however, has not been standardized for complicated cardiovascular surgery. We assessed outcomes of surgery for acute type A aortic dissection (ATAAD) performed with a MPC under circulatory arrest. The study involved 706 patients treated surgically for ATAAD (by hemiarch repair [n = 571] or total arch repair [n = 135]). Total arch repair was performed using selective antegrade cerebral perfusion. Our MPC, a semi-closed bypass system, incorporating a completely closed circuit and a level-sensing reservoir in the venous circuit, was used. Clinical variables, transfusion volume, and outcomes were investigated in patients who underwent hemiarch repair or total arch repair. The overall incidences of shock, organ ischemia, and coagulopathy (prothrombin time-international normalized ratio >1.5) were 26%, 35%, and 8%, respectively. Mean extracorporeal circulation (ECC) time was 149 minutes for the hemiarch repair group and 241 minutes for the total arch repair group, respectively. No patient required conversion to conventional ECC, and there were no complications related to the use of the MPC. The need for transfusion (98% vs. 91%, P = .017) and median transfusion volume (1970 vs. 1680 mL, P = .002) was increased in the total arch repair group. Neither in-hospital mortality (total arch; 12% vs. hemiarch; 7%, P = .11) nor 10-year survival (74.4% vs. 68.4%, P = .79) differed significantly. Outcomes of surgery for ATAAD performed with the MPC were acceptable. The possibility of transfusion and transfusion volume remains high during such surgery, despite the use of the MPC.

Repair of Acute Type-A Aortic Dissection in the Present Era: Outcomes and Controversies

Acute Type-A aortic dissection (AAAD) remains a surgical emergency with a relatively high operative mortality despite advances in medical and surgical management over the past three decades. In spite of the severity of disease, there is a paucity of studies reviewing key controversies surrounding AAAD repair and management. A systematic literature search was performed using Cochrane review and PubMed bibliography review. Abstracts were first reviewed for general pertinence and then articles were reviewed in full. Literature review indicates that use of moderate hypothermia and antegrade cerebral perfusion is a safe alternative to deep hypothermia. In hemodynamically stable patients, axillary cannulation may be substituted for femoral cannulation. With regard to the technical aspects of repair, preserving the aortic root whenever possible and performing the distal anastomosis with the open distal technique rather than with the clamp on is the preferred approach. In patients with a patent false lumen, close monitoring is indicated. As demonstrated by the literature, significant improvement of early and late mortality over the past years has occurred in patients presenting with AAAD. Repair of acute Type-A aortic dissection remains a challenge with high operative mortality; however, improvement of surgical techniques and management have resulted in improvement of early and late clinical outcomes.

Safety of Hypothermic Circulatory Arrest During Unilateral Antegrade Cerebral Perfusion for Aortic Arch Surgery

BACKGROUND

Hypothermic circulatory arrest (HCA) with adjunctive unilateral antegrade cerebral perfusion (UACP) is widely used as a cerebral protection strategy during aortic arch surgery. However, the ideal temperature for HCA during UACP remains unknown. The study compared clinical outcomes of patients in different temperature groups for HCA during UACP.

METHODS

From January 2009 to January 2016, 1691 patients who underwent aortic arch surgery for HCA during UACP in Beijing Anzhen Hospital were categorized into 2 groups according to nasopharyngeal temperature before initiating systemic circulatory arrest: the low temperature group (≤ 24°C, 22.9°C; 22.0°C-23.5°C; n = 1207) and the high temperature group (24.1°C-28.0°C, 24.6°C; 24.3°C-24.9°C; n = 484). After balancing the differences of baseline conditions by propensity score matching, 473 pairs of patients were matched, and the prognosis was compared with matched patients.

RESULTS

The multivariable Cox regression analysis shows the high temperature group was an independent predictor for 30-day mortality (hazard ratio [HR], 0.55; 95% confidence interval [CI], 0.33-0.93; P = 0.03). After matching, the high temperature group was still an independent predictor of 30-day mortality (HR, 0.55; 95% CI, 0.32-0.98; P = 0.04). In subgroup analyses, there was an interaction between the high temperature group and UACP > 40 minutes for 30-day mortality (P_{for interaction}< 0.05). The high temperature group had a significant protective effect in the UACP ≤ 40 minutes subgroup (HR, 0.30; 95% CI, 0.12-0.74; P = 0.01) but not in the UACP > 40 minutes subgroup (HR, 1.00; 95% CI, 0.46-2.20; P = 0.99).

CONCLUSIONS

This study shows that the high temperature (24.1°C-28.0°C) management strategy for HCA during UACP is safer for UACP ≤ 40 minutes. High temperature benefits were not found in patients for UACP > 40 minutes.

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.

Intermittent upper and lower body perfusion during circulatory arrest is safe for aortic repair

Introduction:

We report our initial surgical experience of intermittent upper and lower body retrograde perfusion during aortic repair under circulatory arrest.

Methods:

Between 2007 and 2015, 148 consecutive patients underwent surgical aortic repair using moderate hypothermic circulatory arrest with intermittent upper and lower body retrograde perfusion.

Results:

All patients underwent ascending aorta replacement; eight had hemiarch replacement (5.4%) and 92 had aortic root surgery (62.2%). Twenty-nine patients (19.6%) had re-operations and 60 patients (40.5%) had concomitant procedures. The mean duration of circulatory arrest was 23.2 ± 5.4 minutes (range 13-48 minutes). Hospital length of stay was 11.3 ± 16.9 days (median 7.0 days; interquartile range [IQR] 6 days). Complications included death in 0.7%, stroke in 3.4%, respiratory failure in 12.8%, renal replacement therapy in 2.0% and re-exploration for bleeding in 0.7%. Peak renal and hepatic biomarkers were: creatinine 1.2 ± 0.3 mg/dL, aspartate aminotransferase (AST) 291 ± 1112 U/L (IQR 91.8 U/L), alanine aminotransferase (ALT) 212 ± 924 U/L (IQR 43.0 U/L) and total bilirubin 1.2 ± 0.9 mg/dL. Peak lactate was 5.0 ± 3.3 mmol/L (IQR 3.3 mmol/L) and the mean time to normalization (<2 mmol/L) was 14.3 ± 14.0 hours.

Conclusions:

Intermittent upper and lower body retrograde perfusion during circulatory arrest is safe for aortic repair, resulting in low morbidity and mortality. There were only modest rises in hepatic and renal injury biomarkers as well as the rapid clearance of lactate. These findings support the continued study of this technique to reduce end-organ dysfunction during circulatory arrest, including expansion to patients with longer circulatory arrest duration and a direct comparison with conventional circulatory arrest without retrograde upper and lower body perfusion.

Inflammation is related to preoperative hypoxemia in patients with acute Stanford type A aortic dissection

Background

Preoperative hypoxemia is a frequent complication of acute Stanford type A aortic dissection (ATAAD). The aim of the present study was to determine which factors were associated with hypoxemia.

Methods

A series of data were collected in a statistical analysis to evaluate preoperative hypoxemia in patients with ATAAD. After retrospectively analyzing data for 172 patients, we identified the risk factors for preoperative hypoxemia. Hypoxemia was defined by an arterial partial pressure of oxygen to fraction of inspired oxygen (PaO₂/FiO₂) ratio of 200 or lower. Subsequent to identifying the patient population, a prospective study was conducted using ulinastatin as a preoperative intervention. The ulinastatin group received ulinastatin at a total dose of 300,000 units prior to surgery. All the pertinent factors were investigated through univariate and multiple logistic regression analysis.

Results

The factors associated with preoperative hypoxemia in ATAAD comprised the following: body mass index (BMI) ≥25; white blood cell count (WBC) and neutrophil counts; levels of C-reactive protein (CRP), D-dimer, and interleukin-6 (IL-6); ATAAD involving the celiac trunk, renal artery, or mesenteric artery. Logistic regression analysis showed that CRP and IL-6 levels were independent predictive factors. We found that ulinastatin effectively could improve oxygenation, since compared to the control group the oxygenation in the ulinastatin group was significantly improved.

Conclusions

Systemic inflammatory reactions played a vital role in preoperative hypoxemia after the onset of ATAAD. The oxygenation of the patient could be improved significantly by inhibiting the inflammatory response prior to surgery.

Oxygenation impairment after total arch replacement with a stented elephant trunk for type-A dissection

OBJECTIVE

To study the risk factors of oxygenation impairment in patients with type-A acute aortic dissection who underwent total arch replacement with a stented elephant trunk.

METHODS

In this study, 169 consecutive patients were enrolled who were diagnosed with type-A acute aortic dissection and underwent a total arch replacement procedure at the Qilu Hospital of Shandong University between January 2015 and February 2017. Postoperative oxygenation impairment was defined as arterial oxygen partial pressure/inspired oxygen fraction ≤ 200 with positive end expiratory pressure ≥ 5 cm H₂O that occurred within 72 hours of surgery. Perioperative clinical characteristics of all patients were collected and univariable analyses were performed. Risk factors associated with oxygenation impairment identified by univariable analyses were included in the multivariable regression analysis.

RESULTS

The incidence of postoperative oxygenation impairment was 48.5%. Postoperative oxygenation impairment was associated with prolonged mechanical ventilation time, intensive care unit stay, and hospital stay. Multivariable regression analysis demonstrated that body mass index (odds ratio [OR], 1.204; 95% confidence interval [CI], 1.065-1.361; P = .003), preoperative oxygenation impairment (OR, 9.768; 95% CI, 4.159-22.941; P < .001), preoperative homocysteine (OR, 1.080; 95% CI, 1.006-1.158; P = .032), circulatory arrest time (OR, 1.123; 95% CI, 1.044-1.207; P = .002), and plasma transfusion (OR, 1.002; 95% CI, 1.001-1.003; P = .002) were significantly associated with postoperative oxygenation impairment.

CONCLUSIONS

Postoperative oxygenation impairment is a common complication of surgery for type-A acute aortic dissection. Body mass index, preoperative oxygenation impairment, preoperative homocysteine, circulatory arrest time, and plasma transfusion were independent risk factors for oxygenation impairment after a total arch replacement procedure.

The cannulation strategy in surgery for acute type A dissection

The rates of mortality and morbidity remain high in surgery for acute type A dissection. There is controversy regarding the best cannulation strategy for achieving good clinical results. Each cannulation technique has different anatomical characteristics and a different flow pattern inside the aorta during cardiopulmonary bypass. Some adverse, clinically important outcomes may be related to events at this time. Femoral artery cannulation, axillary artery cannulation, and central aortic cannulation are the three major cannulation strategies that are adopted in many centers in the world. Accumulating results from comparative studies between right axillary artery cannulation and femoral artery cannulation show that right axillary artery cannulation is associated with better clinical outcomes. However, all of the studies have been retrospective, and few studies have compared the results of other combinations of cannulation strategies. Observational studies using newer monitoring techniques clearly show that no perfusion strategy is perfect or free from complications. In summary, the evidence is insufficient to make a strong recommendation regarding cannulation strategies. Based on the fairly consistent results of retrospective studies, more surgeons are tending to switch from a retrograde perfusion strategy to adopt an antegrade perfusion strategy. Regardless of the routine cannulation strategy that is adopted, careful monitoring and a swift response to adverse events are necessary. The further accumulation of evidence is warranted.

Mast cell activation and arterial hypotension during proximal aortic repair requiring hypothermic circulatory arrest

OBJECTIVE

Aortic surgeries requiring hypothermic circulatory arrest evoke systemic inflammatory responses that often manifest as vasoplegia and hypotension. Because mast cells can rapidly release vasoactive and proinflammatory effectors, we investigated their role in intraoperative hypotension.

METHODS

We studied 31 patients undergoing proximal aortic repair with hypothermic circulatory arrest between June 2013 and April 2015 at Duke University Medical Center. Plasma samples were obtained at different intraoperative time points to quantify chymase, interleukin-6, interleukin-8, tumor necrosis factor alpha, and white blood cell CD11b expression. Hypotension was defined as the area (minutes × millimeters mercury) below a mean arterial pressure of 55 mm Hg. Biomarker responses and their association with intraoperative hypotension were analyzed by 2-sample t test and Wilcoxon rank sum test. Multivariable logistic regression analysis was used to examine the association between clinical variables and elevated chymase levels.

RESULTS

Mast cell-specific chymase increased from a median 0.97 pg/mg (interquartile range [IQR], 0.01-1.84 pg/mg) plasma protein at baseline to 5.74 pg/mg (IQR, 2.91-9.48 pg/mg) plasma protein after instituting cardiopulmonary bypass, 6.16 pg/mg (IQR, 3.60-9.41 pg/mg) plasma protein after completing circulatory arrest, and 7.64 pg/mg (IQR, 4.63-12.71 pg/mg) plasma protein after weaning from cardiopulmonary bypass (each P value < .0001 vs baseline). Chymase was the only biomarker associated with hypotension during (P = .0255) and after (P = .0221) cardiopulmonary bypass. Increased temperatures at circulatory arrest and low presurgical hemoglobin levels were independent predictors of increased chymase responses.

CONCLUSIONS

Mast cell activation occurs in cardiac surgery requiring cardiopulmonary bypass and hypothermic circulatory arrest and is associated with intraoperative hypotension.

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.

The Use of Hypothermic Circulatory Arrest During Heart Transplantation Does Not Worsen Posttransplant Survival

BACKGROUND

Hypothermic circulatory arrest (HCA) has been used as an adjunct to cardiopulmonary bypass for decades, both electively and emergently, to facilitate a bloodless operative field while maintaining cerebral protection. The aim of this study is to determine the impact of HCA during heart transplantation on posttransplant outcomes.

METHODS

All adult patients undergoing orthotopic heart transplantation at our institution between 2000 and 2012 were retrospectively reviewed. Patients were stratified based on need for HCA during surgery; patients who required HCA (HCA group, n = 25), and patients who did not (no-HCA group, n = 903). The primary outcomes of interest were 30-day and 1-year mortality and postoperative complication rate.

RESULTS

Indications for HCA included control of significant hemorrhage (n = 9), need for distal aortic procedures (n = 9), or as an aid in difficult mediastinal dissection (n = 7). Mean duration of HCA was 22 ± 18 minutes at a mean temperature of 24.5° ± 5.5°C. Significantly more patients in the HCA group underwent transplant for congenital heart disease (16.0% HCA versus 2.8% no-HCA, p = 0.006), and patients in the HCA group had undergone more prior sternotomies (HCA 1 [interquartile range: 1 to 2] versus no-HCA 1 [interquartile range: 0 to 1], p < 0.001]. There was no statistical difference in 30-day mortality (8.0% HCA versus 4.2% no-HCA, p = 0.29) or 1-year mortality (8.0% HCA versus 12.3% no-HCA, p = 0.76). The HCA group had higher rates of reoperation for mediastinal bleeding and postoperative respiratory failure.

CONCLUSIONS

The need for HCA during heart transplantation is rare but, when required, it is frequently a life-saving adjunct to cardiopulmonary bypass. However, patients who require HCA have higher rates of postoperative complications. Risk factors for needing HCA during transplantation include congenital heart disease and more than one prior sternotomies.

Open and closed distal anastomosis for acute type A aortic dissection repair

OBJECTIVES

The current consensus favours an open distal anastomosis for aortic dissection repair. A small number of experiences have compared early and long-term outcomes between closed and open distal anastomosis in the setting of acute aortic dissection.

METHODS

We reviewed our experience in 204 patients who underwent repair of spontaneous acute type A aortic dissection between January 2000 and December 2013. Open distal repair was performed in 109 patients, whereas 95 patients received a closed anastomosis. The clinical presentation, anatomical characteristics of aortic dissection, surgical techniques and the outcomes were analysed in the overall population and in the subgroup of patients (n = 100; open = 39, closed = 61) with Type 1 DeBakey dissection and a proximal intimal tear. Twenty-six preoperative and operative variables were studied to determine their impact on hospital mortality and postoperative neurological deficits. Imaging follow-up was available in 83 patients.

RESULTS

A more extensive involvement of the aortic arch characterized the open repair group. No differences in terms of mortality, morbidity and survival rates were observed between the two groups of patients. Open repair with cerebral perfusion was associated with a better neurological outcome. Patients who underwent an open distal anastomosis showed a significant higher rate of complete thrombosis of the false lumen.

CONCLUSIONS

An open repair does not increase the risk of early mortality and positively affect the evolution of the false lumen in distal unresected aortic segments. The use of cerebral perfusion reduces the risk of perioperative neurological injury.

Remote Ischemic Preconditioning Reduces Cerebral Oxidative Stress Following Hypothermic Circulatory Arrest in a Porcine Model

Remote ischemic precondition has become prominent as one of the most promising methods to mitigate neurological damage following ischemic insult. The purpose of this study was to investigate whether the effects of remote ischemic preconditioning can be seen in the markers of oxidative stress or in redox-regulating enzymes in a porcine model. A total of 12 female piglets were randomly assigned to 2 groups. The study group underwent an intervention of 4 cycles of 5-minute ischemic preconditioning on the right hind leg. All piglets underwent 60-minute hypothermic circulatory arrest. Oxidative stress marker 8-hydroxydeoxyguanosine (8-OHdG) was measured from blood samples with enzyme-linked immunosorbent assay. After 7 days of follow-up, samples from the brain, heart, kidney, and ovary were harvested for histopathologic examination. The immunohistochemical stainings of hypoxia marker hypoxia-inducible factor-1-α, oxidative stress marker 8-OHdG, DNA repair enzyme 8-oxoguanine glycosylase, and antioxidant response regulators nuclear factor erythroid 2-related factor 2 and protein deglycase were analyzed. The level of 8-OHdG referred to baseline was decreased in the sagittal sinus׳ blood samples in the study group after a prolonged deep hypothermic circulatory arrest at 360 minutes after reperfusion. Total histopathologic score was 3.8 (1.8-6.0) in the study group and was 4.4 (2.5-6.5) in the control group (P = 0.72), demonstrating no statistically significant difference in cerebral injury. Our findings demonstrate that the positive effects of remote ischemic preconditioning can be seen in cellular oxidative balance regulators in an animal model after 7 days of preconditioned ischemic insult.

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.

Rewarming Rate During Cardiopulmonary Bypass Is Associated With Release of Glial Fibrillary Acidic Protein

BACKGROUND

Rewarming from hypothermia during cardiopulmonary bypass (CPB) may compromise cerebral oxygen balance, potentially resulting in cerebral ischemia. The purpose of this study was to evaluate whether CPB rewarming rate is associated with cerebral ischemia assessed by the release of the brain injury biomarker glial fibrillary acidic protein (GFAP).

METHODS

Blood samples were collected from 152 patients after anesthesia induction and after CPB for the measurement of plasma GFAP levels. Nasal temperatures were recorded every 15 min. A multivariate estimation model for postoperative plasma GFAP level was determined that included the baseline GFAP levels, rewarming rate, CPB duration, and patient age.

RESULTS

The mean rewarming rate during CPB was 0.21° ± 0.11°C/min; the maximal temperature was 36.5° ± 1.0°C (range, 33.1°C to 38.0°C). Plasma GFAP levels increased after compared with before CPB (median, 0.022 ng/mL versus 0.035 ng/mL; p < 0.001). Rewarming rate (p = 0.001), but not maximal temperature (p = 0.77), was associated with higher plasma GFAP levels after CPB. In the adjusted estimation model, rewarming rate was positively associated with postoperative plasma log GFAP levels (coefficient, 0.261; 95% confidence intervals, 0.132 to 0.390; p < 0.001). Six patients (3.9%) experienced a postoperative stroke. Rewarming rate was higher (0.3° ± 0.09°C/min versus 0.2° ± 0.11°C/min; p = 0.049) in the patients with stroke compared with those without a stroke.

CONCLUSIONS

Rewarming rate during CPB was correlated with evidence of brain cellular injury documented with plasma GFAP levels. Modifying current practices of patient rewarming might provide a strategy to reduce the frequency of neurologic complications after cardiac surgery.