Antegrade Cerebral Perfusion for Acute Type A Aortic Dissection in 120 Consecutive Patients

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.

Retrograde cerebral perfusion for surgery of type A aortic dissection

BACKGROUND

For type A aortic dissection (TAAD), antegrade cerebral perfusion (ACP) was proposed as a more physiological method than retrograde cerebral perfusion (RCP) for intra-operative brain protection, but it is still debatable whether antegrade cerebral perfusion (ACP) or retrograde cerebral perfusion (RCP) is related to the better clinical outcome. The present study was undertaken to compare the results in our patients receiving surgery for TAAD with ACP or RCP. The primary aim of this study was focused on the incidence of and the factors associated with surgical mortality, post-operative neurological outcomes and long-term survival.

METHODS

From February 2001 to March 2019, there were 223 consecutive patients with TAAD treated surgically at our hospital. The median age at presentation was 56 years (range 29-88 years) and 70 patients (31.4%) over 65 years of age. There were 168 patients treated with RCP and 55 patients treated with ACP. The primary endpoints were surgical mortality and neurological outcome. Propensity score matching was used to compare the treatment results of surgeries with RCP or ACP. The long-term survival was also analyzed.

RESULTS

The overall in-hospital mortality rate and the overall 30-day mortality rate were 15.6% and 14.3% respectively. For the patients without pre-operative shock (n = 184), the in-hospital mortality rate was 10.3% and the 30-day mortality rate was 8.7% and higher long-term survival rates (88.3% for 5 years, 86.5% for 10 years, 86.5% for 15 years) were documented for this patient group. There was no significant difference on the surgical mortality between the ACP group and the RCP group. In the entire cohort, there were 23 patients (10.3%) who suffered from post-operative neurological deficits (PND) and there were less PND for the patients with RCP than the patients with ACP (7.7% vs 18.1%, p = 0.027). After propensity score matching, there was still higher incidence of PND in the ACP group than in the RCP group but without statistical significance (18.5% vs 11.1%, p = 0.279).

CONCLUSIONS

Aortic surgery carries high risk for the patients with TAAD and PND is not an unusual post-operative morbidity. In our series, pre-operative shock, pre-operative CPR, CRI, past history with CAD are related to higher surgical mortality. The younger patients (<65 years old) without pre-operative shock got better surgical outcome and long-term survival. RCP could provide acceptable cerebral protection during aortic surgery for the TAAD patients. Old age, pre-operative shock, CRI and past history of CAD are independent risk factors for long-term survival.

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.

Changes in the diagnosis and management of acute aortic syndrome and associated mortality in the last 20 years

INTRODUCTION AND OBJECTIVES

Mortality is high in acute aortic syndrome (AAS), which therefore requires early treatment. This study aimed to analyze changes in the diagnosis and treatment of AAS over 20 years at our center.

METHODS

From 1999 to 2018, 451 patients diagnosed with AAS (336 men; mean age, 60.9±12.4 years) were prospectively included (270 type A and 181 type B). Clinical variables, diagnosis, treatment, and in-hospital complications were analyzed.

RESULTS

The use of computed tomography (CT) as the first-line diagnostic technique increased from 62.8% to 94.2% (P <.001). Surgical treatment of type A AAS rose from 67.4% to 82.5% (P=.09). Mortality from type A AAS decreased significantly from 53.1% to 26.3% (P <.001) as a result of the fall in mortality from surgical treatment (from 45.4% to 17.0%; P <.001). The use of medical treatment alone for type B AAS decreased from 91.8% to 61.7% (P <.001) due to the greater use of endovascular treatment. Mortality from type B AAS showed no significant reduction (16.2% to 10.6%; P=.15).

CONCLUSIONS

The diagnosis and treatment of AAS has changed substantially in the last 2 decades. CT has become the first-line diagnostic technique for AAS. In type A AAS, mortality has fallen significantly due to improvements in the results of surgical treatment. In type B AAS, the use of medical treatment alone has decreased due to the expansion of endovascular treatment, although in-hospital mortality has not decreased significantly.

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.

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.

Identification of CTA-Based Predictive Findings for Temporary and Permanent Neurological Dysfunction after Repair in Acute Type A Aortic Dissection

The aim of this study was to determine CT risk findings predictive of temporary neurological dysfunction (TND) and permanent neurological dysfunction (PND) after surgical repair for acute type A aortic dissection (ATAAD). A total of 255 patients (41 ± 16 years, 79% male) with ATAAD underwent aortic CT angiography (CTA) and surgical repair consecutively from January 2013 to June 2016. The CTA findings of the 255 patients for the thoracic aorta and carotid artery were analysed to identify risk factors predictive of TND and PND. Thirty-eight patients (15%) suffered TND, and 18 (7%) exhibited PND. Common carotid artery (CCA) dissection (OR = 4.63), lower enhancement of unilateral ICA (OR = 3.02) and aortic arch tears (OR = 2.83) were predictors of postoperative TND, while PND was best predicted by retrograde ascending aorta (aAO) dissection (OR = 5.62) and aortic arch tears (OR = 6.74). In CCA dissection, the extent of the entire CCA and proximal ICA (P = 0.014), a low-enhancement false lumen with re-entry (P = 0.000) and a severely narrowed true lumen without re-entry (P = 0.005) significantly increased the risk of postoperative TND. In patients with ATAAD, specific CT findings allow the individual risk of postoperative TND and PND to be identified and may guide subsequent surgical management.

Cerebral perfusion issues in type A aortic dissection

Stroke events are very common in acute type A aortic dissection. Cerebral malperfusion could manifest at presentation due to prolonged arch vessels hypoperfusion or develop after surgery for inadequate cerebral protection during arch repair. To reduce this detrimental complication there are several adjuncts that can be adopted for cerebral protection such as direct antegrade or retrograde cerebral perfusion (RCP) and use period of deep to moderate hypothermic circulatory arrest time; however, they are often insufficient as preoperative malperfusion already caused irreversible ischemic damages. The aim of the current review article is to analyze the principal series reporting on neurological injuries during type A aortic dissection to focus on the outcomes according to the type of surgical management and identify possible predictors to better manage this complication.

The neurologic protection of unilateral versus bilateral antegrade cerebral perfusion in aortic arch surgery with deep hypothermic circulatory arrest: A study of 77 cases

BACKGROUD

Unilateral and bilateral antegrade cerebral perfusions (ACP) are recognized methods of cerebral protection in aortic arch surgery. However, the adequacy of cerebral protection in aortic arch surgery with deep hypothermic circulatory arrest is controversial. In this study, we compared unilateral and bilateral ACP of cerebral protection in aortic arch surgery by assessing the patient's intraoperative and postoperative brain function.

METHODS

A total of 77 patients undergoing aortic arch surgery were included in this study. Unilateral ACP was performed using a cannula in the innominate artery (n = 40), whereas bilateral ACP was conducted using an additional cannula in the left carotid artery (n = 37). Levels of S-100β and neuron specific enolase (NSE) were assayed at the beginning of cardiopulmonary bypass (T1), the beginning of circulatory arrest (T2), and post ACP at T = 25 min (T3), the end of ACP (T4), the end of cardiopulmonary bypass (T5), and at T = 1 h (T6), T = 6 h (T7), and T = 24 h (T8). Transcranial Doppler ultrasonography was used both preoperatively and intraoperatively to detect the blood flow of bilateral middle cerebral artery (MCA), and neurologic deficit incidence and mortality rates were obtained.

RESULTS

At time points T1, T2, and T3, plasma levels of S-100β and NSE were not statistically different between groups. However, S-100β and NSE levels for each time point ranging from T = T4 to T = T8 did show statistically significant differences between groups. Patients who with one side of the middle cerebral artery stenosis, used bilateral antegrade cerebral perfusions method, intraoperative Transcranial Doppler ultrasonography examination showed narrow side blood flow weaker than the normal side during the deep hypothermic circulatory arrest (DHCA), however no significant differences could be observed between the two sides (P > 0.05). The incidence of neurological dysfunction was higher in the unilateral ACP group compared to the bilateral ACP group (25% vs. 8.11%, respectively, P = 0.028). Moreover, no marked differences were observed in mortality (2.5% vs. 5.41%, respectively, P = 1.000).

CONCLUSIONS

When the duration of DHCA was 25 min or less, no significant differences were observed between unilateral and bilateral ACP. However, when DHCA exceeded 25 min, bilateral ACP was more effective compared to unilateral ACP. Due to the high variations in circle of Willis as well as increased safety, simplicity, and efficiency, the bilateral ACP approach is preferred over the unilateral technique.

Diagnosis, management and mortality in acute aortic syndrome: results of the Spanish Registry of Acute Aortic Syndrome (RESA-II)

Background:

Recent advances in the diagnosis and treatment of acute aortic syndrome should improve the outcome of this disease. The Spanish Registry of Acute Aortic Syndrome aimed to assess current results in acute aortic syndrome management in a wide cohort of hospitals in the same geographical area.

Methods:

From January 2012 to January 2014, 26 tertiary hospitals included 629 consecutive patients with acute aortic syndrome: 73% men, mean age 64.7±14 years (range 22–92), 443 type A (70.4%) and 186 type B (29.6%).

Results:

Time elapsed between symptom onset and diagnosis was <12 hours in 70.7% of cases and <24 hours in 84.0% (median 5 hours; 25th–75th percentiles, 2.7–15.5 hours). Computed tomography was the first diagnostic technique in 78% of patients and transthoracic echocardiography in 15%. Surgical treatment was indicated in 78.3% of type A acute aortic syndrome. The interval between diagnosis and surgery was 4.8 hours (quartile 1–3, 2.5–11.4 hours). Among the patients with type B acute aortic syndrome, treatment was medical in 116 cases (62.4%), endovascular in 61 (32.8%) and surgical in nine (4.8%). Type A mortality during hospitalisation was 25.1% in patients treated surgically and 68% in those treated medically. Mortality in type B was 13.8% in those with medical treatment, 18.0% with endovascular therapy and 33.0% with surgical treatment.

Conclusion:

Improvements in the diagnosis and treatment of acute aortic syndrome have not resulted in a significant reduction in hospital mortality. The results of this study reflect more overall and less selected information on acute aortic syndrome management and the need for sustained advances in the therapeutic strategy of acute aortic syndrome.

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.

Contemporary insights into the management of type A aortic dissection

INTRODUCTION

Acute Type A Dissection remains a surgical emergency with a relatively high operative mortality despite advances in cardiac surgical techniques and medical management over the past thirty years.

AREAS COVERED

In this presentation we will discuss the issues surrounding diagnosis, triage, surgical treatment and perioperative medical management as well as long term surveillance of patients suffering from Acute Type A Dissection and present the literature that supports our management strategies. Expert commentary: The ultimate goal of surgical intervention for patients with Type A Acute Aortic Dissection is an alive patient. A more complicated operation which addresses the root and arch and potentially reduces late complications should be approached with caution since it may increase the operative mortality of the procedure itself. With the recent evolution in endovascular techniques, there is hope that later complications can be reduced without increasing the risk of the primary operation. It remains to be seen whether the improved distal aortic remodeling afforded by a combined open/endovascular approach to Acute Type A Dissection will lead to decreased need for aortic reinterventions and overall long term complications of a residual descending thoracic chronic dissection.

Axillary artery cannulation provides balanced cerebral oxygenation

Deterioration of cerebral performance remains a major problem after cardiac surgery. Axillary artery cannulation can improve clinical outcome, but some experimental series show a malperfusion of the right hemisphere. The aim of our clinical study was to analyze the intraoperative investigation of cerebral oxygenation in two different arterial cannulation sites by use of near-infrared spectroscopic oximetry (NIRO). We compared retrospectively the cerebral saturation of 20 patients with aortic cannulation (group AoC) and 20 patients with right axillary artery cannulation (group AxC) during either valve, coronary artery bypass graft (CABG), combined procedures, or aortic surgery. Patients were monitored with bihemispheric NIRO (NIRO-200, Hamamatsu, Herrsching, Germany). The oxygenation data were calculated as tissue oxygenation index (TOI). And the cardiopulmonary bypass time was considered with special regard to potentially dangerous phases for cerebral desaturation like the starting of the extracorporeal circulation (ECC), cross-clamping, rewarming phase, aortic declamping, and stopping of ECC. Patients were then postoperatively evaluated by a standardized neurological examination. During the entire CPB time and the specific phases potentially at risk for cerebral desaturation, no statistically significant drop of cerebral oxygenation (>20 % for >60 s) was detected after aortic and right axillary artery cannulation, respectively. Furthermore, no significant difference in TOI was found comparing the left and right hemisphere in each group. Postoperatively 2 transient confusional syndromes (CS) were observed after aortic and 3 CS after axillary artery cannulation. Right axillary artery cannulation provides balanced cerebral oxygenation in both hemispheres during extracorporeal circulation and its specific phases potentially at risk for cerebral malperfusion. It might therefore reduce the risk of neurological injury by reduction of solid embolization and maintenance of balanced cerebral oxygenation.

Prognostic Implications of Acute Renal Failure after Surgery for Type A Acute Aortic Dissection

BACKGROUND

"Type A" acute aortic dissection (AAAD) is the most challenging among the emergency operations in cardiac surgery. The aim of this study was the evaluation of the role of acute renal failure (ARF) in postoperative survival of patients operated for AAAD.

METHODS

From February 2010 to April 2012, 37 consecutive patients were operated at our department for AAAD. We studied our population by subdividing the patients within groups according to the presence of ARF requiring continuous veno-venous hemofiltration (CVVH) and according to hypothermic circulatory arrest (HCA) times and degrees.

RESULTS

The overall 30-day mortality was 27% (50% group A with ARF, 13% group B no ARF). Acute renal failure requiring CVVH was 37.8%. Multivariate analysis revealed a significant association with 30-day mortality (odds ratio 6.6 and p = 0.020). Preoperative oliguria [urine output less than 30 ml/h (odds ratio 4.7 p = 0.039)], CPB greater than 180 minutes (odds ratio 6.5 p = 0.023) and postoperative bleeding requiring a surgical reopening (odds ratio 12.2 and p = 0.021) were the variables significantly associated with acute kidney injury.

CONCLUSIONS

The data obtained from our analysis bring out the high incidence of renal injuries after surgery for AAAD, and indicate a negative impact on renal injuries of a preoperative oliguria, longer Cardiopulmonary bypass (CBP)/HCA times, and postoperative bleeding requiring a surgical revision. Our data also suggest a better 30-day survival and better renal outcomes in case of shorter HCA and lesser degree of hypothermia. The option of lesser and shorter hypothermia may be very useful, especially for the elderly patients and octogenarians.

Trifurcated graft replacement of the aortic arch: state of the art

OBJECTIVE

To review the contemporary practice in total arch replacement (TAR) by using the trifurcated graft technique.

METHODS

The evolution of the trifurcated graft technique in total arch replacement is described. Axillary artery perfusion with antegrade cerebral perfusion (ACP) is routinely performed, with systemic deep hypothermia based on the anticipated interval of lower body ischemia. Cerebral oxygen saturation is monitored and bilateral ACP (BACP) is performed if the adequacy of collateral circulation is questioned. Potential advantages and disadvantages of unilateral ACP (UACP) vs BACP are discussed.

RESULTS

The advantage of the trifurcated graft technique in TAR is that it facilitates the creation of an "elephant trunk" in the proximal arch, making the operation technically easier and avoiding the risk of recurrent laryngeal nerve injury. The technique is also versatile in a variety of aortic arch anatomies and pathologies, while enabling continuous ACP without hypothermic circulatory arrest for cerebral protection. UACP during TAR is acceptable for shorter intervals (<30-40 minutes) if combined with moderate hypothermia. BACP should be considered for prolonged ACP interval or if left cerebral oxygenation is inadequate during UACP.

CONCLUSIONS

The trifurcated graft technique is a versatile method in TAR that can be applied to a diverse range of aortic anatomies, pathologies and hybrid arch procedures, with concomitant or staged endovascular options. UACP or BACP and lower body ischemia can be performed without adding significant complexity to the procedure, while conferring maximal cerebral, spinal, and lower body protection.

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

Objectives

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

Methods

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

Results

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

Conclusions

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

Impact of organ failure and major complications on outcome in acute Type A aortic dissection

OBJECTIVES

Organ failure and major complications after operations for acute Type A aortic dissection impair outcomes. The objective was to analyze the prevalence of organ failure and major complications, their interrelationship and predictors, and their impact on early and late survival.

DESIGN

All operative survivors 1990-2009 (n = 335) were retrospectively reviewed. Predictors of organ failure and major complications (bleeding, infection, renal or respiratory failure, neurological dysfunction, and multisystem organ failure) and their influence on in-hospital and long-term mortality were analyzed with multivariable statistical methods.

RESULTS

Major complication(s) occurred in 153 patients (46%), most frequently bleeding and permanent neurological dysfunction (19% each). Increasing organ system failure index increased in-hospital mortality markedly: zero (2.9%), one (14%), two (33%), three or more (43%), p = 0.002. Reoperation for bleeding (odds ratio [95% confidence interval]) 2.6 [1.1-6.3], multisystem organ failure 4.3 [1.4-13], and permanent neurological dysfunction 14 [6.2-32] were related to in-hospital mortality. The latter two and respiratory failure also entailed increased long-term mortality.

CONCLUSIONS

Organ failure and major complications were common and impacted negatively on both in-hospital and long-term survival. Strategies to avoid or treat organ failure and major complications should improve early and late survival after surgery for acute Type A aortic dissection.

Modified hypothermic circulatory arrest for emergent repair of acute aortic dissection type a: a single-center experience

Background

Deep hypothermic circulatory arrest (DHCA) with antegrade cerebral perfusion has been historically preferred for organ protection during surgical repair of the acute aortic dissection type A. However, in the past decades, different perfusion-specific strategies with a growing trend to increase the body temperature at circulatory arrest emerged. In this study, we retrospectively analyzed the clinical results of our modified protocol for cardiopulmonary bypass and hypothermia management.

Methods

Between February 2007 and September 2012, 54 consecutive patients suffering from acute aortic dissection type A underwent emergent surgery. All patients received hypothermic circulatory arrest in combination with antegrade cerebral perfusion. The patients were divided into two subsets according to the degree of hypothermia and perfusion strategies: namely the DHCA group and the group of modified hypothermic circulatory arrest (MHCA).

Results

The overall 30-day mortality was 27.8% and was not significantly different between groups (DHCA, 33.3%, MHCA, 19%; p=0.253). The requirement for blood product transfusion in MHCA patients was significantly less as as compared with the patients in the DHCA group. No difference occurred in the incidence of temporary neurologic dysfunction, dialysis-dependent renal failure, or reexploration for bleeding between two groups of patients. The use of MHCA was identified as a protective factor against the postoperative composite complications (OR, 0.78; CI, 0.52 to 0.98; p=0.04) and the prolonged intensive care unit stay (OR, 0.8; 95% CI, 0.56 to 0.98; p=0.04).

Conclusions

Moderate hypothermia in combination with selective brain perfusion and systemic retrograde perfusion is associated with adequate cerebral and visceral protection, reduced postoperative complications and shortened intensive care unit stay in our series. This modified perfusion strategy may help in improving perioperative outcomes in this particular group of patients.

Selective antegrade cerebral perfusion and mild (28°C-30°C) systemic hypothermic circulatory arrest for aortic arch replacement: results from 1002 patients

OBJECTIVES

The use of selective antegrade cerebral perfusion (ACP) makes deep hypothermia nonessential for aortic arch replacement. Consequently, a growing tendency to increase the body temperature during circulatory arrest with ACP has recently been reported from various institutions. However, very little is known about the clinical effect of different modes of ACP (unilateral vs bilateral) on neurologic morbidity. Also, the safe limits of this approach for spinal chord and visceral organ protection are yet to be defined.

METHODS

Between January 2000 and January 2011, 1002 consecutive patients underwent aortic arch repair during ACP (unilateral, 673; bilateral, 329) with mild systemic hypothermia (30°C ± 2°C; range, 26°-34°C) at 2 centers in Germany. The mean patient age was 62 ± 14 years, 663 patients (66%) were men, and 347 patients (35%) had acute type A dissection. Hemiarch replacement was performed in 684 patients (68%), and 318 (32%) underwent total arch replacement.

RESULTS

The cardiopulmonary bypass time accounted for 158 ± 56 minutes and the myocardial ischemic time, 101 ± 41 minutes. Isolated ACP was performed for 36 ± 19 minutes (range, 9-135). We observed new postoperative permanent neurologic deficits in 28 patients (3%; stroke in 25 and paraplegia in 3) and transient neurologic deficits in 42 patients (4%). All 3 cases of paraplegia occurred in patients with acute type A dissection and a broad range of ACP times (24, 41, and 127 minutes). A trend was seen toward a reduced permanent neurologic deficit rate after unilateral ACP (P = .06), but no difference was seen in the occurrence of transient neurologic deficits (P = .6). Overall, the early mortality rate was 5% (n = 52). Temporary dialysis was necessary primarily after surgery in 38 patients (4%). When corrected for the unequal distribution of type A dissection, neurologic morbidity, early mortality, and the need for temporary dialysis were independent of the duration of ACP and were not affected by unilateral versus bilateral ACP.

CONCLUSIONS

Current data suggest that ACP and mild systemic hypothermic circulatory arrest can be safely applied to complex aortic arch surgery even in a subgroup of patients with up to 90 minutes of ACP. Unilateral ACP offers at least equal brain and visceral organ protection as bilateral ACP and might be advantageous in that it reduces the incidence of embolism arising from surgical manipulation on the arch vessels.

Comparative study of brain protection in ascending aorta replacement for acute type A aortic dissection: retrograde cerebral perfusion versus selective antegrade cerebral perfusion

OBJECTIVES

Postoperative disorders of the central nervous system remain a major problem in thoracic aortic surgery. Both retrograde cerebral perfusion and selective antegrade cerebral perfusion have become established techniques for cerebral circulatory management. In this study, we compared neurologic outcomes and mortality between retrograde cerebral perfusion and antegrade selective cerebral perfusion in patients with acute type A aortic dissection who underwent emergency ascending aorta replacement.

METHODS

Between January 2003 and April 2011, a total of 203 patients with acute type A aortic dissection underwent emergency ascending aorta replacement in our hospital. We performed retrograde cerebral perfusion in 109 patients before 2006, and then mainly performed antegrade selective cerebral perfusion in 94 patients from 2006 onward.

RESULTS

Cardiopulmonary bypass time and systemic circulatory arrest time were significantly longer in the antegrade selective cerebral perfusion group (p = 0.04, p < 0.001, respectively). The incidences of transient brain dysfunction and permanent brain dysfunction after surgery did not differ significantly between the groups. There were also no differences between the groups in other intraoperative variables, such as aortic cross-clamp time and the lowest rectal temperature, or in operative outcomes, including postoperative intensive-care-unit stay, mean peak amylase, and lipase levels until postoperative day 7, and 30-day mortality.

CONCLUSION

Both retrograde cerebral perfusion and antegrade selective cerebral perfusion were associated with acceptable levels of postoperative neurologic deficits, mortality, and morbidity. Either of these techniques for brain protection can be used selectively, based on a comprehensive assessment of general condition, in patients undergoing surgery for acute type A aortic dissection.

Evidence, lack of evidence, controversy, and debate in the provision and performance of the surgery of acute type A aortic dissection

Acute type A aortic dissection is a lethal condition requiring emergency surgery. It has diverse presentations, and the diagnosis can be missed or delayed. Once diagnosed, decisions with regard to initial management, transfer, appropriateness of surgery, timing of operation, and intervention for malperfusion complications are necessary. The goals of surgery are to save life by prevention of pericardial tamponade or intra-pericardial aortic rupture, to resect the primary entry tear, to correct or prevent any malperfusion and aortic valve regurgitation, and if possible to prevent late dissection-related complications in the proximal and downstream aorta. No randomized trials of treatment or techniques have ever been performed, and novel therapies-particularly with regard to extent of surgery-are being devised and implemented, but their role needs to be defined. Overall, except in highly specialized centers, surgical outcomes might be static, and there is abundant room for improvement. By highlighting difficulties and controversies in diagnosis, patient selection, and surgical therapy, our over-arching goal should be to enfranchise more patients for treatment and improve surgical outcomes.

State of the art in neuroprotection during acute type A aortic dissection repair

Temporary (TND) or permanent neurologic dysfunctions (PND) represent the main neurological complications following acute aortic dissection repair. The aim of our experimental and clinical research was the improvement and update of the most common neuroprotective strategies which are in present use.

Hypothermic circulatory arrest (HCA): Cerebral metabolic suppression at the clinically most used temperatures (18-22°C) is less complete than had been assumed previously. If used as a ‘stand-alone’ neuroprotective strategy, cooling to 15-20°C with a jugular SO2 ≥ 95% is needed to provide sufficient metabolic suppression. Regardless of the depth of cooling, the HCA interval should not exceed 25 min. After 40 min of HCA, the incidence of TND and PND increases, after 60 min, the mortality rate increases.

Antegrade selective cerebral perfusion (ASCP): At moderate hypothermia (25-28°C), ASCP should be performed at a pump flow rate of 10ml/kg/min, targeting a cerebral perfusion pressure of 50-60mmHg. Experimental data revealed that these conditions offer an optimal regional blood flow in the cortex (80±27ml/min/100g), the cerebellum (77±32ml/min/100g), the pons (89±5ml/min/100g) and the hippocampus (55±16ml/min/100g) for 25 minutes. If prolonged, does ASCP at 32°C provide the same neuroprotective effect?

Cannulation strategy: Direct axillary artery cannulation ensures the advantage of performing both systemic cooling and ASCP through the same cannula, preventing additional manipulation with the attendant embolic risk. An additional cannulation of the left carotid artery ensures a bi-hemispheric perfusion, with a neurologic outcome of only 6% TND and 1% PND.

Neuromonitoring: Near-infrared spectroscopy and evoked potentials may prove the effectiveness of the neuroprotective strategy used, especially if the trend goes to less radical cooling.

Conclusion: A short interval of HCA (5 min) followed by a more extended period of ASCP (25 min) at moderate hypothermia (28°C), with a pump flow rate of 10ml/kg/min and a cerebral perfusion pressure of 50 mmHg, represents safe conditions for open arch surgery.

Cerebral Protection During Surgery for Acute Aortic Dissection Type A

Background—

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

Methods and Results—

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

Conclusions—

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

The impact of deep and moderate body temperatures on end-organ function during hypothermic circulatory arrest

OBJECTIVE

Hypothermic circulatory arrest (HCA) at different temperatures is a protection technique for operations involving the aortic arch. In combination with selective cerebral perfusion, higher arrest temperatures for the remaining body may be permitted. However, the ischaemic/reperfusion injury (I/R) in various organ systems, other than the brain, related to the specific HCA temperature has so far not been evaluated.

METHODS

Fourteen pigs were randomly assigned to 60 min of sole HCA at 20 or 30 °C temperature, weaned from cardiopulmonary bypass (CPB) and followed 4h after HCA. Besides complex haemodynamic monitoring, laser-Doppler spectrophotometry for measuring capillary blood flow, tissue oxygen saturation and post-capillary venous filling pressures of the bowel was installed. At the end of experiment, organs were perfusion fixated and harvested.

RESULTS

During the entire experiment, haemodynamics revealed no differences between the groups. CPB bypass times were 177 ± 12 min in the 20 °C and 158 ± 11 min in the 30 °C group, respectively (p = 0.02). During reperfusion, lactate levels were initially significantly higher in the 30 °C animals (p = 0.001) but subsequently declined. Microcirculatory blood flow and velocity in the bowel were significantly reduced during cooling and reperfusion (p < 0.05), but were independent of final HCA temperature. Histological evaluation revealed significantly more oedema formation in the bowel wall of the 30 °C animals (p = 0.05).

CONCLUSIONS

Higher levels of circulating lactate levels during reperfusion indicate less effective organ protection at 30 than at 20 °C after 60 min of HCA. This is further substantiated by histological evidence for a more pronounced oedema inflammatory response within the bowel wall.

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

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

Impact of pump flow rate during selective cerebral perfusion on cerebral hemodynamics and metabolism

BACKGROUND

Although hypothermic selective cerebral perfusion (SCP) is widely used for cerebral protection during aortic surgery, little is known about the ideal pump-flow management during this procedure. This study explored cerebral hemodynamics and metabolism at two different flow rates.

METHODS

Fourteen pigs (33 to 38 kg) were cooled on cardiopulmonary bypass to 25°C. After 10 minutes of hypothermic circulatory arrest, the animals were randomly assigned to 60 minutes of SCP at two different pump flow rates: 8 mL·kg(-1)·min(-1) (n = 7) and 18 mL·kg(-1)·min(-1) (n = 7). Microspheres were injected at baseline, coolest temperature, and at 5, 15, 25, and 60 minutes of SCP to calculate cerebral blood flow, cerebral vascular resistance, metabolic rate, and intracranial pressure.

RESULTS

Cerebral blood flow decreased during cooling to 41% of the baseline value (from 57 ± 10 to 23 ± 4 mL·min(-1)·100 g(-1)). It recovered during the initial 15 minutes of SCP, showing a significantly higher increase (p = 0.017) at high-flow versus low-flow perfusion (139 ± 41 versus 75 ± 22 mL·min(-1)·100 g(-1)). After 60 minutes of SCP the cerebral blood flow almost returned to baseline values in the low-flow group (43 ± 25 mL·min(-1)·100 g(-1)), but showed an unexpected decrease (30 ± 7 mL·min(-1)·100 g(-1)) in the high-flow group. The highest regional cerebral blood flow was seen in the cortex (66 ± 12 mL·min(-1)·100 g(-1)), followed by the cerebellum (63 ± 12 mL·min(-1)·100 g(-1)), the pons (51 ± 17 mL·min(-1)·100 g(-1)), and the hippocampus (36 ± 9 mL·min(-1)·100 g(-1)). Intracranial pressure increased from 11 ± 3 to 13 ± 5 mm Hg during cooling on cardiopulmonary bypass. During low-flow SCP, it stayed stable at baseline values, whereas high-flow perfusion resulted in significantly higher intracranial pressures (17 ± 3 mm Hg; p = 0.001). Changes in cerebral vascular resistance and metabolic rate showed no significant differences between the groups.

CONCLUSIONS

High-flow SCP provides no benefit during long-term SCP at 25°C. Higher cerebral blood flow during the initial SCP period leads to cerebral edema, with no profit in metabolic rate.

Spanish Acute Aortic Syndrome Study (RESA). Better diagnosis is not reflected in reduced mortality

INTRODUCTION AND OBJECTIVES

Because acute aortic syndrome (AAS) is associated with high mortality, early diagnosis and treatment are vital. The aim of the Spanish Acute Aortic Syndrome Study (RESA) was to investigate the effectiveness of current treatment of AAS in a broad range of tertiary care hospitals in Spain.

METHODS

Between January 2005 and December 2007, 24 tertiary care hospitals reported data on 519 patients with AAS (78% male, mean age 61 +/- 13 years, range 20-92 years): 357 had type-A AAS and 162 had type B.

RESULTS

The time delay between symptom onset and diagnosis was <24 hours in 67% of cases and >72 hours in 11%. Some 80% of patients with type-A AAS were treated surgically. The interval between diagnosis and surgery was <24 hours in 90% of cases. In patients with type-B AAS, 34% received invasive treatment: 11% had surgery and 23% underwent endovascular procedures. Mortality during hospitalization in patients with type-A disease was 33% in those treated surgically and 71% in those treated medically. Mortality in patients with type-B disease was 17% with medical treatment, 27% with endovascular treatment and 50% with surgical treatment.

CONCLUSIONS

Despite significant advances in the diagnosis of AAS, in-hospital mortality remains high. The findings of this study are representative of a broad range of unselected patients undergoing treatment for the disease and support the need for continuing improvements in therapeutic approaches to AAS.

What is the best method for brain protection in surgery of the aortic arch? Selective antegrade cerebral perfusion

Despite considerable progress in the operative management of lesions involving the transverse aortic arch, replacement of this portion of the vessel remains a surgical challenge and is still associated with mortality and morbidity. This situation is due not only to the technical difficulties of the procedure but, often, to the unsatisfactory preservation of the integrity of the central nervous system during the period of arch exclusion. The techniques of cerebral protection during surgery of the aortic arch can be divided into those aimed at suppressing the metabolic demand of the central nervous system and those aimed at maintaining the metabolic supply during the time of exclusion of the cerebral vessels. Whichever technique is used, it must maintain the normal metabolism of the central nervous system or, at least, allow restoration of the physiologic conditions of its function. In this regard, selective antegrade cerebral perfusion has demonstrated experimentally and clinically its superiority over the other proposed protective techniques.