Nature of Neurological Complications and Outcome After Surgery for Type A Aortic Dissection

Surgery for type A aortic dissection (TAAD) is frequently complicated by neurologic complications. The prognostic impact of neurologic complications of different nature has been investigated in this study. The subjects of this analysis were 3,902 patients who underwent surgery for acute TAAD from the multicenter European Registry of Type A Aortic Dissection (ERTAAD). During the index hospitalization, 722 patients (18.5%) experienced stroke/global brain ischemia. Ischemic stroke was detected in 539 patients (13.8%), hemorrhagic stroke in 76 patients (1.9%) and global brain ischemia in 177 patients (4.5%), with a few patients having had findings of more than 1 of these conditions. In-hospital mortality was increased significantly in patients with postoperative ischemic stroke (25.6%, adjusted odds ratio [OR] 2.422, 95% confidence interval [CI] 1.825 to 3.216), hemorrhagic stroke (48.7%, adjusted OR 4.641, 95% CI 2.524 to 8.533), and global brain ischemia (74.0%, adjusted OR 22.275, 95% CI 14.537 to 35.524) compared with patients without neurologic complications (13.5%). Similarly, patients who experienced ischemic stroke (46.3%, adjusted hazard ratio [HR] 1.719, 95% CI 1.434 to 2.059), hemorrhagic stroke (62.8%, adjusted HR 3.236, 95% CI 2.314 to 4.525), and global brain ischemia (83.9%, adjusted HR 12.777, 95% CI 10.325 to 15.810) had significantly higher 5-year mortality than patients without postoperative neurologic complications (27.5%). The negative prognostic effect of neurologic complications on survival vanished about 1 year after surgery. In conclusion, postoperative ischemic stroke, hemorrhagic stroke, and global cerebral ischemia increased early and midterm mortality after surgery for acute TAAD. The magnitude of risk of mortality increased with the severity of the neurologic complications, with postoperative hemorrhagic stroke and global brain ischemia being highly lethal complications.

Femoral arterial cannulation for surgical repair of stanford type A aortic dissection

BACKGROUND

The benefits and harms associated with femoral artery cannulation over other sites of arterial cannulation for surgical repair of acute Stanford type A aortic dissection (TAAD) are not conclusively established.

METHODS

We evaluated the outcomes after surgery for TAAD using femoral artery cannulation, supra-aortic arterial cannulation (i.e., innominate/subclavian/axillary artery cannulation), and direct aortic cannulation.

RESULTS

3751 (96.1%) patients were eligible for this analysis. In-hospital mortality using supra-aortic arterial cannulation was comparable to femoral artery cannulation (17.8% vs. 18.4%; adjusted OR 0.846, 95% CI 0.799-1.202). This finding was confirmed in 1028 propensity score-matched pairs of patients with supra-aortic arterial cannulation or femoral artery cannulation (17.5% vs. 17.0%, p = 0.770). In-hospital mortality after direct aortic cannulation was lower compared to femoral artery cannulation (14.0% vs. 18.4%, adjusted OR 0.703, 95% CI 0.529-0.934). Among 583 propensity score-matched pairs of patients, direct aortic cannulation was associated with lower rates of in-hospital mortality (13.4% vs. 19.6%, p = 0.004) compared to femoral artery cannulation. Switching of the primary site of arterial cannulation was associated with increased rate of in-hospital mortality (36.5% vs. 17.0%; adjusted OR 2.730, 95% CI 1.564-4.765). Ten-year mortality was similar in the study cohorts.

CONCLUSIONS

In this study, the outcomes of surgery for TAAD using femoral arterial cannulation were comparable to those using supra-aortic arterial cannulation. However, femoral arterial cannulation was associated with higher in-hospital mortality than direct aortic cannulation.

TRIAL REGISTRATION

ClinicalTrials.gov registration code: NCT04831073.

Classification of the Urgency of the Procedure and Outcome of Acute Type A Aortic Dissection

Surgery for type A aortic dissection (TAAD) is associated with a high risk of early mortality. The prognostic impact of a new classification of the urgency of the procedure was evaluated in this multicenter cohort study. Data on consecutive patients who underwent surgery for acute TAAD were retrospectively collected in the multicenter, retrospective European Registry of TAAD (ERTAAD). The rates of in-hospital mortality of 3,902 consecutive patients increased along with the ERTAAD procedure urgency grades: urgent procedure 10.0%, emergency procedure grade 1 13.3%, emergency procedure grade 2 22.1%, salvage procedure grade 1 45.6%, and salvage procedure grade 2 57.1% (p <0.0001). Preoperative arterial lactate correlated with the urgency grades. Inclusion of the ERTAAD procedure urgency classification significantly improved the area under the receiver operating characteristics curves of the regression model and the integrated discrimination indexes and the net reclassification indexes. The risk of postoperative stroke/global brain ischemia, mesenteric ischemia, lower limb ischemia, dialysis, and acute heart failure increased along with the urgency grades. In conclusion, the urgency of surgical repair of acute TAAD, which seems to have a significant impact on the risk of in-hospital mortality, may be useful to improve the stratification of the operative risk of these critically ill patients. This study showed that salvage surgery for TAAD is justified because half of the patients may survive to discharge.

Metabolic Syndrome and Heart Transplantation: An Underestimated Risk Factor?

Metabolic Syndrome (MetS), a multifactorial condition that increases the risk of cardio-vascular events, is frequent in Heart-transplant (HTx) candidates and worsens with immunosuppressive therapy. The aim of the study was to analyze the impact of MetS on long-term outcome of HTx patients. Since 2007, 349 HTx patients were enrolled. MetS was diagnosed if patients met revised NCEP-ATP III criteria before HTx, at 1, 5 and 10 years of follow-up. MetS was present in 35% of patients pre-HTx and 47% at 1 year follow-up. Five-year survival in patients with both pre-HTx (65% vs. 78%, p < 0.01) and 1 year follow-up MetS (78% vs 89%, p < 0.01) was worst. At the univariate analysis, risk factors for mortality were pre-HTx MetS (HR 1.86, p < 0.01), hypertension (HR 2.46, p < 0.01), hypertriglyceridemia (HR 1.50, p=0.03), chronic renal failure (HR 2.95, p < 0.01), MetS and diabetes at 1 year follow-up (HR 2.00, p < 0.01; HR 2.02, p < 0.01, respectively). MetS at 1 year follow-up determined a higher risk to develop Coronary allograft vasculopathy at 5 and 10 year follow-up (25% vs 14% and 44% vs 25%, p < 0.01). MetS is an important risk factor for both mortality and morbidity post-HTx, suggesting the need for a strict monitoring of metabolic disorders with a careful nutritional follow-up in HTx patients.

Baseline risk factors of in-hospital mortality after surgery for acute type A aortic dissection: an ERTAAD study

Background

Surgery for type A aortic dissection (TAAD) is associated with high risk of mortality. Current risk scoring methods have a limited predictive accuracy.

Methods

Subjects were patients who underwent surgery for acute TAAD at 18 European centers of cardiac surgery from the European Registry of Type A Aortic Dissection (ERTAAD).

Results

Out of 3,902 patients included in the ERTAAD, 2,477 fulfilled the inclusion criteria. In the validation dataset (2,229 patients), the rate of in-hospital mortality was 18.4%. The rate of composite outcome (in-hospital death, stroke/global ischemia, dialysis, and/or acute heart failure) was 41.2%, and 10-year mortality rate was 47.0%. Logistic regression identified the following patient-related variables associated with an increased risk of in-hospital mortality [area under the curve (AUC), 0.755, 95% confidence interval (CI), 0.729-0.780; Brier score 0.128]: age; estimated glomerular filtration rate; arterial lactate; iatrogenic dissection; left ventricular ejection fraction ≤50%; invasive mechanical ventilation; cardiopulmonary resuscitation immediately before surgery; and cerebral, mesenteric, and peripheral malperfusion. The estimated risk score was associated with an increased risk of composite outcome (AUC, 0.689, 95% CI, 0.667-0.711) and of late mortality [hazard ratio (HR), 1.035, 95% CI, 1.031-1.038; Harrell's C 0.702; Somer's D 0.403]. In the validation dataset (248 patients), the in-hospital mortality rate was 16.1%, the composite outcome rate was 41.5%, and the 10-year mortality rate was 49.1%. The estimated risk score was predictive of in-hospital mortality (AUC, 0.703, 95% CI, 0.613-0.793; Brier score 0.121; slope 0.905) and of composite outcome (AUC, 0.682, 95% CI, 0.614-0.749). The estimated risk score was predictive of late mortality (HR, 1.035, 95% CI, 1.031-1.038; Harrell's C 0.702; Somer's D 0.403), also when hospital deaths were excluded from the analysis (HR, 1.024, 95% CI, 1.018-1.031; Harrell's C 0.630; Somer's D 0.261).

Conclusions

The present analysis identified several baseline clinical risk factors, along with preoperative estimated glomerular filtration rate and arterial lactate, which are predictive of in-hospital mortality and major postoperative adverse events after surgical repair of acute TAAD. These risk factors may be valuable components for risk adjustment in the evaluation of surgical and anesthesiological strategies aiming to improve the results of surgery for TAAD.

Clinical Trial Registration

https://clinicaltrials.gov, identifier NCT04831073.

Protective Effects of Home T2DM Treatment with Glucagon-Like Peptide-1 Receptor Agonists and Sodium-Glucose Co-transporter-2 Inhibitors Against Intensive Care Unit Admission and Mortality in the Acute Phase of the COVID-19 Pandemic: A Retrospective Observational Study in Italy

INTRODUCTION

Type 2 diabetes mellitus (T2DM) is a relevant risk factor for severe forms of COVID-19 (SARS coronavrus 2 [SARS-CoV-2] disease 2019), and calls for caution because of the high prevalence of T2DM worldwide and the high mortality rates observed in patients with T2DM who are infected with SARS-CoV-2. People with T2DM often take dipeptidyl peptidase-4 inhibitors (DPP-4is), glucagon-like peptide-1 receptor agonists (GLP-1ras), or sodium-glucose co-transporter-2 inhibitors (SGLT-2is), all of which have clear anti-inflammatory effects. The study aimed to compare (i) the severity and duration of hospital stay between patients with T2DM categorized by pre-hospitalization drug class utilization and (ii) the COVID-19-related death rates of those three groups.

METHODS

We designed an observational, retrospective, multi-center, population-based study and extracted the hospital admission data from the health care records of 1916 T2DM patients over 18 years old who were previously on GLP-1ra, SGLT-2i, or DPP-4i monotherapy and were hospitalized for COVID-19 (diagnosis based on ICD.9/10 codes) between January 2020 and December 2021 in 14 hospitals throughout Italy. We analyzed general data, pre-admission treatment schedules, date of admission or transfer to the intensive care unit (ICU) (i.e., the index date; taken as a marker of increased COVID-19 disease severity), and death (if it had occurred). Statistics analyzed the impact of drug classes on in-hospital mortality using propensity score logistic regressions for (i) those admitted to intensive care and (ii) those not admitted to intensive care, with a random match procedure used to generate a 1:1 comparison without diabetes cohort replacement for each drug therapy group by applying the nearest neighbor method. After propensity score matching, we checked the balance achieved across selected variables if a balance was ever achieved. We then used propensity score matching between the three drug classes to assemble a sample in which each patient receiving an SGLT-2i was matched to one on a GLP-1ra, and each patient on a DPP-4i was matched to one on a GLP-1ra, adjusting for covariates. We finally used GLP-1ras as references in the logistic regression.

RESULTS

The overall mortality rate (MR) of the patients was 14.29%. The MR in patients with COVID was 53.62%, and it was as high as 42.42% in the case of associated T2DM, regardless of any glucose-lowering therapy. In those on DPP-4is, there was excess mortality; in those treated with GLP-1ras and SGLT-2is, the death rate was significantly lower, i.e., almost a quarter of the overall mortality observed in COVID-19 patients with T2DM. Indeed, the odds ratio (OR) in the logistic regression resulted in an extremely high risk of in-hospital death in individuals previously treated with DPP-4is [incidence rate (IR) 4.02, 95% confidence interval (CI) 2.2-5.7) and only a slight, nonsignificantly higher risk in those previously treated with SGLT-2is (IR 1.42, 95% CI 0.6-2.1) compared to those on GLP-1ras. Moreover, the longer the stay, the higher the death rate, which ranged from 22.3% for ≤ 3-day stays to 40.3% for 4- to 14-day stays (p < 0.01 vs. the former) and 77.4% for over-14-day stays (p < 0.001 vs. both the others).

DISCUSSION

Our data do not support a protective role of DPP-4is; indeed, this role has already been questioned due to previous observations. However, the data do show a strong protective effect of SGLT-2is and GLP-1ras. Beyond lowering circulating glucose levels, those two drug classes were found to exert marked anti-phlogistic effects: SGLT-2is increased adiponectin and reduced urate, leptin, and insulin concentrations, thus positively affecting overall low-grade inflammation, and GLP-1ras may also greatly help at the lung tissue level, meaning that their extra-glycemic effects extend well beyond those acknowledged in the cardiovascular and renal fields.

CONCLUSIONS

The aforedescribed observational clinical data relating to a population of Italian inpatients with T2DM suggest that GLP-1ras and SGLT-2is can be considered antidiabetic drugs of choice against COVID-19, and might even prove beneficial in the event of any upcoming pandemic that has life-threatening effects on the pulmonary and cardiovascular systems.

Influence of a regional network combined with a systematic multidisciplinary approach on the outcomes of patients with acute type A aortic dissection

BACKGROUND

Whether in patients with acute type A aortic dissection reduction of intervals between onset of symptoms and diagnosis influences patient outcomes is still not completely defined.

METHODS

In 199 patients with acute type A aortic dissection, the efficacy of a systematic multidisciplinary approach and institution of a regional network were evaluated; 90 patients operated before 2016 (Group1) were compared with 109 repaired after 2016 (Group2) for early and late outcomes.

RESULTS

Mortality was reduced from 13% in Group1 to 4% in Group2 (p = 0.013). In Group2 a more patients (46%) had arch replacement compared to Group1 (29%)(p = 0.06). In Group2 axillary artery cannulation was almost routinely used (91% vs 67%, p < 0.001) with shorter circulatory arrest time (37 vs 44 min, p < 0.001). The interval from diagnosis to surgery dropped from 210 min in Group1 to 160 min in Group2 (p < 0.001); this reduction was evident both in patients admitted to the emergency department of a spoke and/or a hub center. Patients presenting with or developing shock were reduced from Group1 to Group2 and in particular those reaching the hub center from spoke centers. Survival at 1 and 5 years was 82 ± 4% and 70 ± 5% in Group1 vs 92 ± 3% and 87 ± 8% in Group2 (p = 0.007).

CONCLUSIONS

Outcomes of patients with acute type A aortic dissection improved using a systematic multidisciplinary approach while a network between spoke and hub centers reduced intervals between diagnosis, transportation to hub center and repair, limiting the incidence of tamponade and shock.

Direct Aortic Versus Supra-Aortic Arterial Cannulation During Surgery for Acute Type A Aortic Dissection

AIMS

In this study we evaluated the impact of direct aortic cannulation versus innominate/subclavian/axillary artery cannulation on the outcome after surgery for type A aortic dissection.

METHODS

The outcomes of patients included in a multicenter European registry (ERTAAD) who underwent surgery for acute type A aortic dissection with direct aortic cannulation versus those with innominate/subclavian/axillary artery cannulation, i.e. supra-aortic arterial cannulation, were compared using propensity score matched analysis.

RESULTS

Out of 3902 consecutive patients included in the registry, 2478 (63.5%) patients were eligible for this analysis. Direct aortic cannulation was performed in 627 (25.3%) patients, while supra-aortic arterial cannulation in 1851 (74.7%) patients. Propensity score matching yielded 614 pairs of patients. Among them, patients who underwent surgery for TAAD with direct aortic cannulation had significantly decreased in-hospital mortality (12.7% vs. 18.1%, p = 0.009) compared to those who had supra-aortic arterial cannulation. Furthermore, direct aortic cannulation was associated with decreased postoperative rates of paraparesis/paraplegia (2.0 vs. 6.0%, p < 0.0001), mesenteric ischemia (1.8 vs. 5.1%, p = 0.002), sepsis (7.0 vs. 14.2%, p < 0.0001), heart failure (11.2 vs. 15.2%, p = 0.043), and major lower limb amputation (0 vs. 1.0%, p = 0.031). Direct aortic cannulation showed a trend toward decreased risk of postoperative dialysis (10.1 vs. 13.7%, p = 0.051).

CONCLUSIONS

This multicenter cohort study showed that direct aortic cannulation compared to supra-aortic arterial cannulation is associated with a significant reduction of the risk of in-hospital mortality after surgery for acute type A aortic dissection.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04831073.

Preoperative arterial lactate and outcome after surgery for type A aortic dissection: The ERTAAD multicenter study

Background

Acute type A aortic dissection (TAAD) is associated with significant mortality and morbidity. In this study we evaluated the prognostic significance of preoperative arterial lactate concentration on the outcome after surgery for TAAD.

Methods

The ERTAAD registry included consecutive patients who underwent surgery for acute type A aortic dissection (TAAD) at 18 European centers of cardiac surgery.

Results

Data on arterial lactate concentration immediately before surgery were available in 2798 (71.7 %) patients. Preoperative concentration of arterial lactate was an independent predictor of in-hospital mortality (mean, 3.5 ± 3.2 vs 2.1 ± 1.8 mmol/L, adjusted OR 1.181, 95%CI 1.129-1.235). The best cutoff value preoperative arterial lactate concentration was 1.8 mmol/L (in-hospital mortality, 12.0 %, vs. 26.6 %, p < 0.0001). The rates of in-hospital mortality increased along increasing quintiles of arterial lactate and it was 12.1 % in the lowest quintile and 33.6 % in the highest quintile (p < 0.0001). The difference between multivariable models with and without preoperative arterial lactate was statistically significant (p = 0.0002). The NRI was 0.296 (95%CI 0.200-0.391) (p < 0.0001) with -17 % of events correctly reclassified (p = 0.0002) and 46 % of non-events correctly reclassified (p < 0.0001). The IDI was 0.025 (95%CI 0.016-0.034) (p < 0.0001). Six studies from a systematic review plus the present one provided data for a pooled analysis which showed that the mean difference of preoperative arterial lactate between 30-day/in-hospital deaths and survivors was 1.85 mmol/L (95%CI 1.22-2.47, p < 0.0001, I2 64 %).

Conclusions

Hyperlactatemia significantly increased the risk of mortality after surgery for acute TAAD and should be considered in the clinical assessment of these critically ill patients.

Current Outcome after Surgery for Type A Aortic Dissection

OBJECTIVE

The aim of this study was to evaluate the outcomes of different surgical strategies for acute Stanford type A aortic dissection (TAAD).

SUMMARY BACKGROUND DATA

The optimal extent of aortic resection during surgery for acute TAAD is controversial.

METHODS

This is a multicenter, retrospective cohort study of patients who underwent surgery for acute TAAD at 18 European hospitals.

RESULTS

Out of 3902 consecutive patients, 689 (17.7%) died during the index hospitalization. Among 2855 patients who survived 3 months after surgery, 10-year observed survival was 65.3%, while country-adjusted, age-adjusted, and sex-adjusted expected survival was 81.3%, yielding a relative survival of 80.4%. Among 558 propensity score-matched pairs, total aortic arch replacement increased the risk of in-hospital (21.0% vs. 14.9%, P =0.008) and 10-year mortality (47.1% vs. 40.1%, P =0.001), without decreasing the incidence of distal aortic reoperation (10-year: 8.9% vs. 7.4%, P =0.690) compared with ascending aortic replacement. Among 933 propensity score-matched pairs, in-hospital mortality (18.5% vs. 18.0%, P =0.765), late mortality (at 10-year: 44.6% vs. 41.9%, P =0.824), and cumulative incidence of proximal aortic reoperation (at 10-year: 4.4% vs. 5.9%, P =0.190) after aortic root replacement was comparable to supracoronary aortic replacement.

CONCLUSIONS

Replacement of the aortic root and aortic arch did not decrease the risk of aortic reoperation in patients with TAAD and should be performed only in the presence of local aortic injury or aneurysm. The relative survival of TAAD patients is poor and suggests that the causes underlying aortic dissection may also impact late mortality despite surgical repair of the dissected aorta.

Graft preservation in heart transplantation: current approaches

Heart transplantation (HTx) represents the current best surgical treatment for patients affected by end-stage heart failure. However, with the improvement of medical and interventional therapies, the population of HTx candidates is increasingly old and at high-risk for mortality and complications. Moreover, the use of "extended donor criteria" to deal with the shortage of donors could increase the risk of worse outcomes after HTx. In this setting, the strategy of donor organ preservation could significantly affect HTx results. The most widely used technique for donor organ preservation is static cold storage in ice. New techniques that are clinically being used for donor heart preservation include static controlled hypothermia and machine perfusion (MP) systems. Controlled hypothermia allows for a monitored cold storage between 4°C and 8°C. This simple technique seems to better preserve the donor heart when compared to ice, probably avoiding tissue injury due to sub-zero °C temperatures. MP platforms are divided in normothermic and hypothermic, and continuously perfuse the donor heart, reducing ischemic time, a well-known independent risk factor for mortality after HTx. Also, normothermic MP permits to evaluate marginal donor grafts, and could represent a safe and effective technique to expand the available donor pool. However, despite the increasing number of donor hearts preserved with these new approaches, whether these techniques could be considered superior to traditional CS still represents a matter of debate. The aim of this review is to summarize and critically assess the available clinical data on donor heart preservation strategies employed for HTx.

Interinstitutional analysis of the outcome after surgery for type A aortic dissection

PURPOSE

To evaluate the impact of individual institutions on the outcome after surgery for Stanford type A aortic dissection (TAAD).

METHODS

This is an observational, multicenter, retrospective cohort study including 3902 patients who underwent surgery for TAAD at 18 university and non-university hospitals.

RESULTS

Logistic regression showed that four hospitals had increased risk of in-hospital mortality, while two hospitals were associated with decreased risk of in-hospital mortality. Risk-adjusted in-hospital mortality rates were lower in four hospitals and higher in other four hospitals compared to the overall in-hospital mortality rate (17.7%). Participating hospitals were classified as overperforming or underperforming if their risk-adjusted in-hospital mortality rate was lower or higher than the in-hospital mortality rate of the overall series, respectively. Propensity score matching yielded 1729 pairs of patients operated at over- or underperforming hospitals. Overperforming hospitals had a significantly lower in-hospital mortality (12.8% vs. 22.2%, p < 0.0001) along with decreased rate of stroke and/or global brain ischemia (16.5% vs. 19.9%, p = 0.009) compared to underperforming hospitals. Aggregate data meta-regression of the results of participating hospitals showed that hospital volume was inversely associated with in-hospital mortality (p = 0.043). Hospitals with an annual volume of less than 15 cases had an increased risk of in-hospital mortality (adjusted OR, 1.345, 95% CI 1.126-1.607).

CONCLUSION

The present findings indicate that there are significant differences between hospitals in terms of early outcome after surgery for TAAD. Low hospital volume may be a determinant of poor outcome of TAAD.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04831073.

The impact of the distance between patient residency and heart transplant center on outcomes after heart transplantation

INTRODUCTION

Heart transplant (HTx) recipients require continuous monitoring and care in order to prevent and treat possible complications related to the graft function or to the immunosuppressive treatment promptly. Since heart transplantation centers (HTC) are more experienced in managing HTx recipients than other healthcare facilities, the distance between patient residency and HTC could negatively affect the outcomes.

METHODS

Data of patients discharged after receiving HTx between 2000 and 2021, collected into our institutional database, were retrospectively analyzed. The population was divided into three groups: A (n = 180), B (n = 157), and C (n = 134), according to the distance tertiles between patient residency and HTC. The primary end-point was survival, secondary end-points were incidences of complications.

RESULTS

Recipient and donor characteristics did not differ between the three groups. Survival at 10 years was 66 ± 4%, 66 ± 4%, and 65 ± 5%, respectively, for groups A, B, and C (p = .34). Immunosuppressive regimen and rate of complications did not differ between groups. However, the rates of outpatient visits and of hospitalization performed at HTC were higher in group A than others.

CONCLUSION

Distance from the HTC does not represent a barrier to a successful outcome for HTx recipients, as long as regular and continuous follow-up is provided.

Outcome after Surgery for Iatrogenic Acute Type A Aortic Dissection

(1) Background: Acute Stanford type A aortic dissection (TAAD) may complicate the outcome of cardiovascular procedures. Data on the outcome after surgery for iatrogenic acute TAAD is scarce. (2) Methods: The European Registry of Type A Aortic Dissection (ERTAAD) is a multicenter, retrospective study including patients who underwent surgery for acute TAAD at 18 hospitals from eight European countries. The primary outcomes were in-hospital mortality and 5-year mortality. Twenty-seven secondary outcomes were evaluated. (3) Results: Out of 3902 consecutive patients who underwent surgery for acute TAAD, 103 (2.6%) had iatrogenic TAAD. Cardiac surgery (37.8%) and percutaneous coronary intervention (36.9%) were the most frequent causes leading to iatrogenic TAAD, followed by diagnostic coronary angiography (13.6%), transcatheter aortic valve replacement (10.7%) and peripheral endovascular procedure (1.0%). In hospital mortality was 20.5% after cardiac surgery, 31.6% after percutaneous coronary intervention, 42.9% after diagnostic coronary angiography, 45.5% after transcatheter aortic valve replacement and nihil after peripheral endovascular procedure (p = 0.092), with similar 5-year mortality between different subgroups of iatrogenic TAAD (p = 0.710). Among 102 propensity score matched pairs, in-hospital mortality was significantly higher among patients with iatrogenic TAAD (30.4% vs. 15.7%, p = 0.013) compared to those with spontaneous TAAD. This finding was likely related to higher risk of postoperative heart failure (35.3% vs. 10.8%, p < 0.0001) among iatrogenic TAAD patients. Five-year mortality was comparable between patients with iatrogenic and spontaneous TAAD (46.2% vs. 39.4%, p = 0.163). (4) Conclusions: Iatrogenic origin of acute TAAD is quite uncommon but carries a significantly increased risk of in-hospital mortality compared to spontaneous TAAD.

Left subclavian artery as an alternative site for left ventricular assist device outflow graft in challenging situations

Left ventricular assist device (LVAD) has emerged as an effective surgical therapy for end-stage heart failure. In an attempt to reduce invasiveness and avoid difficult sternal re-entries, alternative surgical approaches have been adopted. In particular, when the thoracic aorta is severely diseased or difficult to expose, subclavian arteries could serve as site for outflow graft anastomosis. However, major concerns regarding the utilization of subclavian arteries are the small caliber of these vessels that could lead to inadequate LVAD flow, arm complications related to excessive blood flow, and possible outflow graft compression. In the present case series, we describe an innovative technique for LVAD implantation, in which the left subclavian artery was employed as an outflow graft anastomosis site, and the left ventricular apex was approached through a mini-thoracotomy. Technical issues were considered to prevent possible complications: the adequacy of left subclavian artery diameter, the banding of the artery distal to the anastomosis site to limit left arm overflow, and the outflow graft covering with a reinforced vascular graft to avoid any external compression. During follow-up, the technique reported was found to be effective in ensuring good LVAD function and flow, and no complications related to the procedure were reported.

Surgical management and outcomes in patients with acute type A aortic dissection and cerebral malperfusion

Objective

The study objective was to evaluate the surgical results in patients with acute type A aortic dissection and cerebral malperfusion.

Methods

From 2000 to 2019, 234 patients with type A aortic dissection and cerebral malperfusion were stratified into 3 groups: 50 (21%) with syncope (group 1), 152 (65%) with persistent loss of focal neurological function (group 2), and 32 (14%) with coma (group 3). Results were evaluated and compared by univariable and multivariable analyses.

Results

Median age was higher in group 1, and incidence of cardiogenic shock was higher in group 3. The femoral artery was the most common cannulation site, whereas the axillary artery was used in 18% of group 1, 30% of group 2, and 25% of group 3 patients (P = .337). Antegrade cerebral perfusion was performed in more than 80% of patients, and ascending aorta/arch replacement was performed in 40% of group 1, 27% of group 2, and 31% of group 3 (P = .21). In-hospital mortality was 18% in group 1, 27% in group 2, and 56% in group 3 (P = .001). Survival at 5 years is 57.0% in group 1, 57.7% in group 2, and 38.7% in group 3 (P = .0005). On multivariable analysis, age, cardiopulmonary bypass time, and group 3 versus group 2 were independent risk factors for mortality, whereas axillary cannulation was a protective factor.

Conclusions

Patients with aortic dissection and cerebral malperfusion without preoperative coma showed acceptable mortality, and those with coma had a high in-hospital mortality regardless of the type of brain protection. Overall axillary artery cannulation appeared to be a protective factor.

P41 ORAL ANTICOAGULATION AFTER REPAIR OF ACUTE TYPE A AORTIC DISSECTION: A REAL RISK ON LONG–TERM?

Objective

To analyse the effects of chronic oral anticoagulation on long–term outcomes after repair of type A acute aortic dissection and its influence on false lumen fate.

Methods

We studied 188 patients (median age 62 years; 74% males) who had repair of type A aortic dissection; patients receiving postoperative chronic oral anticoagulation (n = 59) were compared to those on antiplatelet therapy alone (n = 129).

Results

Median age was similar: 60 (18–79 years) vs 64 years (22–86) (p = 0.11); patients on anticoagulants were more frequently males (88% vs 67%, p = 0.003). After a median follow–up of 8.4 years (2 months to 30 years) 58 patients died, 18 for aortic–related causes, and 37 underwent aortic reintervention. After multivariable adjustment, anticoagulation showed no significant effect on long–term survival (HR 0.85, 95% CI 0.41–1.76; p = 0.66) neither on risk of reintervention (HR 0.55, 95% CI 0.27–1.15; p = 0.11). Analysis of 127 postoperative computed tomography scans showed a patent false lumen in 53% of anticoagulated vs 38% of not anticoagulated patients (p = 0.09); partially thrombosed in 8% vs 28% (p = 0.01) and thrombosed in 39% vs 34% (p = 0.63). In patients with a control computed tomography there were 6 late aortic–related deaths, 1 among patients anticoagulated and 5 in those who were not.

Conclusions

Chronic anticoagulation after repair of type A acute aortic dissection favours persistent late false lumen patency which is not a risk factor for late mortality or reoperation. Chronic anticoagulation can be administered safely to patients with repaired type A acute aortic dissection regardless of its specific indication.

P45 OUTCOME AFTER ACUTE TYPE A AORTIC DISSECTION: THE ROLE OF AN AORTIC TEAM AND AN AORTIC REGIONAL NETWORK

Background

The outcome of acute type–A aortic dissection (A–AAD) repair is strictly related both to surgical factors and patient conditions. Improvement in surgical experience and in diagnosis and treatment protocols could significantly increase survival for patients affected by A–AAD. The aim of this study was to assess the impact on patients outcomes of a standardized integrated surgical approach and of a regional aortic hub and spokes network.

Materials and Methods

From 2004 to 2021, a total of 258 patients underwent repair of A–AAD. In 2010 in our Institution was created the Aortic Team, with cardiac surgeons dedicated on the treatment of aortic pathologies, while in 2017 was created a regional aortic network between hub and spokes in order to standardize the diagnosis and treatment algorithm. Thus, patients were distributed among three periods: 2004–2010 (Era 1, n = 90), 2011–2016 (Era 2, n = 87), and 2017–2021 (Era 3, n = 81).

Results

Baseline demographic characteristics of the groups were similar. Compared to Era1 and Era2, clinical status at time of operation was better in Era3, because of less rates of malperfusion (16% vs 11% vs 4%, p = 0.01) and hemodynamic compromise (34% vs 38% vs 22%, p = 0.07). Patients of Era 3 were less likely to Axillary artery cannulation was almost routinely used in Eras 2 (86%) and 3 (91%) while femoral artery was mainly cannulated in Era 1 (91%) (p &lt; 0.01). Retrograde cerebral perfusion was predominantly used in Era 1 (60%) while antegrade cerebral perfusion was preferred in Eras 2 (94%,) and 3 (100%); (p &lt; 0.01). There was a significant increase of arch replacement procedures from Era 1 (11%) to Eras 2 (33%) and 3 (48%) (p &lt; 0.01). Frozen elephant trunk was mainly performed in Era 3. Operative mortality was 13% in Era 1, 11% in Era 2, and 4% in Era 3 (p = 0.07, p = 0.03 between Era 1 and Era3). Actuarial survival at 3 years is 74%, in Era 1, 78% in Era 2, and 89% in Era 3 (p = 0.05). Patients of Era 3 received less re–exploration for bleeding (p = 0.02) and less high inotropic support (p = 0.04).

Conclusions

With increasing experience and a more aggressive approach, including total arch replacement, repair of A–AAD can be more tailored to patients conditions, being performed with low operative mortality in many patients. Moreover, patient care and treatment by a multidisciplinary regional organization allows faster diagnosis and effective clinical stabilization allowing to further improve early and late outcomes.

Hemiarch Versus Arch Replacement in Acute Type A Aortic Dissection: Is the Occam's Razor Principle Applicable?

BACKGROUND AND AIM OF THE STUDY

In patients with acute Type A aortic dissection (A-AAD) whether repair should be limited to ascending aorta/hemiarch replacement or extended to include the aortic arch is still debated. We have analyzed our experience to compare outcomes of patients with A-AAD treated with these 2 different surgical strategies.

METHODS

From 2006 to 2020, a total of 213 patients have undergone repair of A-AAD at our Center; in 163 of them ascending aorta/hemiarch replacement (Group 1) and in 75 ascending aorta and arch replacement (Group 2) were performed. The primary endpoint was early survival and secondary endpoints late survival, freedom from late complications and reoperations. Patients were compared according to era of operation: 2006 to 2013 (Era 1) and 2014 to 2020 (Era 2).

RESULTS

Overall hospital mortality was 12% and 5% in Group 1 and 2; mortality remained stable in Era 1 and 2 for Group 1 (15%), while it decreased from 8% to 1% in Group 2 patients (p = 0.24). Actuarial survival at 5 and 10 years is 72 ± 4% and 49 ± 5% in Group 1 and 77 ± 6% and 66 ± 9% in Group 2 (p = 0.073). Actuarial freedom from reoperation in the entire series is 94 ± 2% and 92 ± 3% at 5 and 10 years. Freedom from reoperation at 5 and 10 years is 92 ± 2% and 89 ± 3% in Group 1 and 98 ± 1% at all intervals in Group 2 (p = 0.068).

CONCLUSIONS

An aggressive approach to A-AAD provides superior long-term results without increasing mortality. Furthermore, arch replacement during A-AAD repair represents a more stable solution with lower incidence of late aortic-related complications. Immediate aortic arch replacement should be considered in the treatment of A-AAD especially in experienced centers.

An Integrated Approach for Treatment of Acute Type A Aortic Dissection

Background and objective: We reviewed a single-institution experience to verify the impact of surgery during different time intervals on early and late results in the treatment of patients with type A acute aortic dissection (A-AAD). Materials and Methods: From 2004 to 2021, a total of 258 patients underwent repair of A-AAD; patients were equally distributed among three periods: 2004-2010 (Era 1, n = 90), 2011-2016 (Era 2, n = 87), and 2017-2021 (Era 3, n = 81). The primary end-point was to assess whether through the years changes in indications, surgical strategies and techniques and increasing experience have influenced early and late outcomes of A-AAD repair. Results: Axillary artery cannulation was almost routinely used in Eras 2 (86%) and 3 (91%) while one femoral artery was mainly cannulated in Era 1 (91%) (p < 0.01). Retrograde cerebral perfusion was predominantly used in Era 1 (60%) while antegrade cerebral perfusion was preferred in Eras 2 (94%,) and 3 (100%); (p < 0.01). There was a significant increase of arch replacement procedures from Era 1 (11%) to Eras 2 (33%) and 3 (48%) (p < 0.01). A frozen elephant trunk was mainly performed in Era 3. Hospital mortality was 13% in Era 1, 11% in Era 2, and 4% in Era 3 (p = 0.07). Actuarial survival at 3 years is 74%, in Era 1, 78% in Era 2, and 89% in Era 3 (p = 0.05). Conclusions: With increasing experience and a more aggressive approach, including total arch replacement, repair of A-AAD can be performed with low operative mortality in many patients. Patient care and treatment by a specific team organization allows a faster diagnosis and referral for surgery allowing to further improve early and late outcomes.

Type A acute aortic dissection with ≥40-mm aortic root: results of conservative and replacement strategies at long-term follow-up

OBJECTIVES

We evaluated the long-term results of aortic root (AR) preservation and replacement in patients operated on for acute type A aortic dissection.

METHODS

Out of 302 patients discharged after repair of acute aortic dissection (1977-2019), 124 patients had an AR ≥40 mm, which was preserved in 84 (68%, group A) patients and replaced in 40 (32%, group B) patients. Group B patients were younger (mean age 57 ± 12 vs 62 ± 11 years, P = 0.07), with a mean AR of 47 vs 43 mm and ≥moderate aortic insufficiency in 65% vs 30%. Survival, causes of death and reoperations were analysed at mean follow-up of 9 ± 8 years (6 months to 40 years).

RESULTS

Actuarial survival of discharged patients at 5, 10 and 15 years was 97% (0.89-0.99), 78% (0.67-0.90) and 75% (0.64-0.88) in group A, and 85% (0.71-0.95), 62% (0.44-0.78) and 57% (0.39-0.76) in group B (log-rank test P = 0.2). Nine patients in group A (7 patients for aortic insufficiency and dilatation of the root and 2 patients for pseudoaneurysm) and 1 patient of group B (pseudoaneurysm of the right coronary button) required proximal reoperation without deaths. At 5, 10 and 15 years, the cumulative incidence of proximal aortic reoperations was 5%, 9% and 25% in group A, and 0%, 3% and 3% in group B (P = 0.02). At multivariable analysis AR >45 mm [hazard ratio (HR) 6.8, P = 0.026] and age (HR 0.9, P = 0.016) were independently associated with proximal reoperation.

CONCLUSIONS

AR preservation in acute type A dissection showed acceptable long-term outcomes. Nevertheless, a more aggressive approach appears a valid option, especially in patients with AR diameter >45 mm.

Bentall procedure with the CarboSeal™ and CarboSeal Valsalva™ composite conduits: long-term outcomes

 

OBJECTIVES

Data on the long-term results with the standard CarboSeal™ mechanical conduit used for the modified Bentall procedure are lacking as well as information on performance of the Valsalva CarboSeal™ conduit.

METHODS

We have analysed 208 recipients of a standard (n = 110) or a Valsalva (n = 98) CarboSeal™ conduit. The median age was 60 years and 90% were males; 35 (17%) had type A aortic dissection and 65 (30%) a bicuspid aortic valve. Data were retrospectively analysed and results were compared between the 2 conduit models.

RESULTS

Early mortality was 1.9%; the mean follow-up was 175 ± 95 for standard and 94 ± 51 months for Valsalva conduits (P < 0.01). Actuarial survival was 86 ± 4%, 75 ± 6%, 59 ± 7% and 51 ± 9% at 5, 10, 15 and 20 years, respectively. There were 13 thromboembolic episodes with 3 deaths with an actuarial freedom of 98 ± 1%, 94 ± 2%, 90 ± 3% and 89 ± 4% at 5, 10, 15 and 20 years, respectively. Reoperation on the aortic root was performed in 9 patients for endocarditis (n = 8) and pseudoaneurysm at the right coronary button (n = 1) with an actuarial freedom of 97 ± 1%, 95 ± 2%, 92 ± 3% and 87 ± 4% at 5, 10, 15 and 20 years, respectively. There were no differences between the 2 conduit models in survival and major postoperative complications.

CONCLUSIONS

The CarboSeal™ conduit has shown gratifying overall performance up to 20 years and appears a valid option for a modified Bentall operation, when a mechanical prosthesis is indicated. Both CarboSeal™ conduit models provided not statistically different overall long-term results.

Late complications of the Djumbodis system in patients with type A acute aortic dissection

The Djumbodis system is a metallic stent designed to prevent false lumen dilatation after repair of acute aortic dissection. Although the exact number of Djumbodis stents inserted worldwide could not be ascertained from a review of the literature, available data indicate 9 specific device-related complications from 4 patient series and 3 case reports: stent deformity or fracture (4), progressive enlargement of the distal false lumen (3) and distal pseudoaneurysm (1); a further patient with pseudoaneurysm of the distal suture line is added from personal observation. The present review confirms the inability of the Djumbodis stent to provide reduction and/or elimination of the false lumen after repair of type A dissection, highlighting peculiar device-related complications. Current survivors with a Djumbodis stent should undergo close follow-up to prevent possible catastrophic events due to device failure.

Recipient age impact on outcome after cardiac transplantation: should it still be considered in organ allocation?

OBJECTIVES

Improvement of clinical results in heart transplantation (HTx) has favoured the expansion of indication criteria towards aged population. The impact of increasing recipient age is controversial and, owing to donor shortage, the debate still remains whether HTx is justified for older patients. We analysed age as a prognostic factor at long-term after HTx and if it should be a determinant in organ allocation.

METHODS

Data of 364 consecutive patients who underwent cardiac transplantation between 1999 and 2014 at the University Hospital of Udine were analysed. Patients were divided into three groups according to age (Group 1: 18-40, Group 2: 41-59, Group 3: ≥ 60 years) and survival and major complications were evaluated at long-term (mean follow-up 6.7 ± 4.5 years, range 1-15.7 years).

RESULTS

Preoperatively, renal failure (2.9, 16.1, 39.5%, P < 0.01) and cardiovascular factors such as diabetes (1.2, 17.1, 36.4%, P < 0.01), systemic hypertension (5.9, 31.5, 40.8%, P < 0.01) and dyslipidaemia (5.9, 40.3, 42.9%, P < 0.01) were more common in older patients (Group 3), as well as ischaemic cardiopathy (0, 42.6, 49.7%, P < 0.01). Donor age was lower in younger recipients (Group 1) (33 ± 15, 39 ± 14, 45 ± 14 years, P < 0.01). Older patients showed a worse long-term survival (hazard ratio 1.7; 1.1-2.5), also after adjusting for major cardiovascular risk factors, renal failure and donor age. In fact, 15-year survival was 100% in Group 1, while at 1, 5, 10 and 15 years survival was 88, 78, 69 and 56% in Group 2, and 87, 68, 49 and 43% in Group 3, respectively. Even major long-term complications were less frequent in younger patients in terms of neoplasms (P < 0.01), rehospitalizations (P < 0.01) and a tendency to higher freedom from other complications such as cytomegalovirus infections, renal failure and dialysis.

CONCLUSIONS

Our results showed a significantly different outcome according to recipient age, even when adjusted for major risk factors. Notably, patients younger than 40 years showed 100% long-term survival, and apparent lower rate of complications due to immunosuppression. Since 15-year survival in patients ≤40 years is twice that of patients ≥60 years, recipient age should be taken into account in organ allocation.

Surgical management of destructive aortic endocarditis: left ventricular outflow reconstruction with the Sorin Pericarbon Freedom stentless bioprosthesis†

OBJECTIVES

The treatment of complicated aortic endocarditis with periannular abscesses and root disarrangement is a surgical challenge, and includes left ventricular outflow tract (LVOT) reconstruction with the patch technique or homograft implantation. The results of a simplified technique to reconstruct the LVOT in destructive endocarditis of either the aortic native valve or valve prosthesis with the Sorin Pericarbon Freedom stentless valve are reported.

METHODS

Since August 2007, 40 patients with destructive endocarditis (mean age: 69 ± 12, 75% males, European System for Cardiac Operative Risk Evaluation II (EuroSCORE II): 19 ± 13, New York Heart Association (NYHA) class: ≥3 in all cases) have undergone LVOT reconstruction with a Sorin Pericarbon Freedom stentless bioprosthesis. Seven patients (17.5%) were in septic or cardiogenic shock preoperatively, and 18 patients (45%) suffered from moderate or severe aortic regurgitation. Eleven patients (27.5%) experienced preoperative systemic embolizations. Thirty-six cases (90%) were valve redos and 9 patients (22.5%) had concomitant procedures. The mean follow-up was 26 ± 25 months.

RESULTS

One patient (2.5%) died early (<30 days) and another 3 patients never discharged died due to multiorgan failure and septic shock. Actuarial survival rate was 85 ± 6% at 1 year, and 76 ± 8% at 3 and 5 years, respectively. Twelve patients (30%) required pacemaker implantation because of atrioventricular block and 20 patients (50%) developed or showed a progression of renal failure. One patient (2.5%) had an endocarditis relapse, and 1 (2.5%) showed a mild paraprosthetic aortic leak. No patient needed reoperation. At the last echocardiographic evaluation, mean gradient, peak gradient and left ventricular ejection fraction were 7.9 ± 5.0 mmHg, 15.1 ± 7.2 mmHg and 63.3 ± 9.3%, respectively.

CONCLUSIONS

The Sorin Pericarbon Freedom stentless prosthesis, with the modified technique herein described, seems to be a good option in most of cases of destructive aortic valve endocarditis. It is promptly available in different sizes, easy to implant and, due to its pericardial inflow skirt, ideal for extensive reconstruction of the LVOT with good haemodynamic performance and low risk of relapse.

Effect of taurohyodeoxycholic acid on biliary lipid secretion in humans

This study aimed to determine the effect in humans of taurohyodeoxycholic acid, a 6alpha-hydroxylated bile acid with hydrophilic properties, on bile lipid secretion. Four cholecystectomized patients who had gallstones and an interrupted enterohepatic circulation were intraduodenally infused with taurohyodeoxycholic and tauroursodeoxycholic acids on separate occasions at a dose of 0.8 to 1 g/h for 3 hours. In hourly bile samples collected for 8 hours after the beginning of the infusion, biliary bile acid composition (by high-performance liquid chromatography), biliary lipid concentrations (by standard methods), and distribution of biliary carriers (by gel chromatography) were evaluated. Blood liver function tests were performed before and after the infusions. Taurohyodeoxycholic and tauroursodeoxycholic acids became the predominant biliary bile acids in all patients except for one infused with taurohyodeoxycholic acid. Taurohyodeoxycholic acid stimulated significantly greater (P < .05) cholesterol and phospholipid secretion per unit of secreted bile acid (0.098 and 0.451 micromol/micromol, respectively) compared with tauroursodeoxycholic acid (0.061 micromol/micromol for cholesterol and 0.275 micromol/micromol for phospholipids). The secretory ratio between phospholipid and cholesterol was significantly higher after infusion of taurohyodeoxycholic acid (3.88 micromol/micromol) compared with taroursodeoxycholic acid (3.09 micromol/micromol) (P < .05). Biliary enrichment with taurohyodeoxycholic acid was positively related with percent concentration of phospholipids but not with that of cholesterol. The opposite trend was observed in tauroursodeoxycholic acid-enriched biles. In both taurohyodeoxycholic acid- and tauroursodeoxycholic acid-rich bile, 80% to 90% of cholesterol was carried in a gel-chromatographic fraction corresponding to an apparent molecular weight of 80 to 200 kd. No alteration in liver function test results was observed after taurohyodeoxycholic acid infusion. In conclusion, taurohyodeoxycholic acid stimulates greater cholesterol and phospholipid secretion than tauroursodeoxycholic acid, but with a higher phospholipid/cholesterol secretory ratio. In bile enriched with both bile acids, biliary cholesterol is transported in non-micellar aggregates. Finally, in the conditions of our study, taurohyodeoxycholic acid was not hepatotoxic.

Macrophages in the Brain: Friends or Enemies?

Cells of the macrophage lineage are ubiquitously distributed in the body, including the central nervous system. They represent an essential host defense system to protect from infections. However, recent evidence indicates that brain macrophages may also be responsible for tissue destruction, including loss of neurons and demyelination.

Involvement of the cystine transport system xc- in the macrophage-induced glutamate-dependent cytotoxicity to neurons

Macrophages have been found to release glutamate and thereby induce neuronal cell death by excitotoxicity, a mechanism that seems to be operative in various neurologic diseases. In this study, it is shown that the presence of both cystine and glutamine in the culture medium is indispensable for brain macrophages to release glutamate and to cause neuronal cell death. Furthermore, release of glutamate requires protein synthesis since cycloheximide prevented accumulation of the neurotoxic molecule in supernatants of microglial cell cultures. Aminoadipate, which was shown to inhibit the uptake of cystine by system xc- in fibroblasts, efficiently reduced the release of glutamate. The requirement of glutamine and cystine for the release of glutamate by microglial cells as well as the inhibitory effect observed with aminoadipate shows the transport system xc- to be essential for the release of the excitotoxin glutamate by microglial cells. Phagocytosis of zymosan particles and stimulation with different bacterial components, such as LPS, protein A, tuberculin, and Staphylococcus enterotoxin A increased glutamate release two- to threefold above basal values. In addition, the effect of bacterial components was mimicked by TNF-alpha, but not by IL-1 and IL-6. Cytokines known to deactivate macrophages, such as TGF-beta, IL-4, and IL-10, did not affect the transport system xc- in microglial cells. However, dexamethasone suppressed the glutamate release up to 50%.

Involvement of the cystine transport system xc- in the macrophage-induced glutamate-dependent cytotoxicity to neurons

Macrophages have been found to release glutamate and thereby induce neuronal cell death by excitotoxicity, a mechanism that seems to be operative in various neurologic diseases. In this study, it is shown that the presence of both cystine and glutamine in the culture medium is indispensable for brain macrophages to release glutamate and to cause neuronal cell death. Furthermore, release of glutamate requires protein synthesis since cycloheximide prevented accumulation of the neurotoxic molecule in supernatants of microglial cell cultures. Aminoadipate, which was shown to inhibit the uptake of cystine by system xc- in fibroblasts, efficiently reduced the release of glutamate. The requirement of glutamine and cystine for the release of glutamate by microglial cells as well as the inhibitory effect observed with aminoadipate shows the transport system xc- to be essential for the release of the excitotoxin glutamate by microglial cells. Phagocytosis of zymosan particles and stimulation with different bacterial components, such as LPS, protein A, tuberculin, and Staphylococcus enterotoxin A increased glutamate release two- to threefold above basal values. In addition, the effect of bacterial components was mimicked by TNF-alpha, but not by IL-1 and IL-6. Cytokines known to deactivate macrophages, such as TGF-beta, IL-4, and IL-10, did not affect the transport system xc- in microglial cells. However, dexamethasone suppressed the glutamate release up to 50%.

Glutamate uptake by astrocytes is inhibited by reactive oxygen intermediates but not by other macrophage-derived molecules including cytokines, leukotrienes or platelet-activating factor

By their property to release glutamate and reactive oxygen intermediates, macrophages may play an important role in neurotoxicity. In the present study we have investigated whether macrophage-derived molecules also impair the detoxification of glutamate by astrocytes. Cytokines, including interleukin (IL)-1, 6 and 10, interferon (IFN)-alpha/beta, tumor necrosis factor (TNF)-alpha and transforming growth factor (TGF)-beta 1, as well as leukotriene (LT) B4 and C4, prostaglandin (PG) E2 and nitric oxide radicals had no effect on the uptake of [3H]glutamate by murine astrocytes in culture. In contrast, exposure of astrocytes to the enzyme glucose oxidase (100-200 mU ml-1), which maintains steady-state levels of hydrogen peroxide, reduced glutamate uptake by 30-50%. By their dual effect, comprising secretion of glutamate and inhibition of its detoxification by astrocytes, activated macrophages and microglial cells may contribute to exacerbate excitotoxic mechanisms in neurological diseases.

Immune-mediated injury in bacterial meningitis

Cytokines are involved in the host response to bacterial infections. In bacterial meningitis, intrathecal synthesis of TNF-alpha and IL-1 is likely to contribute to CNS injury by recruitment and activation of inflammatory cells with subsequent release of toxic factors, such as reactive oxygen intermediates and excitatory amino acids (glutamate), leading to neuronal cell death with neurologic sequelae. In rats with experimental meningitis, pretreatment with TGF-beta inhibits cerebrovascular changes and brain edema formation in the early, TNF-alpha-independent phase. Provided its local production in bacterial infection, TGF-beta may comprise a host factor interfering with immune pathologic events altering the integrity of the endothelial barrier.

Macrophage-induced cytotoxicity of N-methyl-D-aspartate receptor positive neurons involves excitatory amino acids rather than reactive oxygen intermediates and cytokines

The co-localization of activated macrophages and damaged neurons observed in brain injury and degenerative brain diseases may hint to macrophage-induced neuronal cytotoxicity. Recently, macrophages have been found to secrete neurotoxic molecules such as radical oxygen intermediates and glutamate, the latter interacting with N-methyl-D-aspartate (NMDA) receptors. As shown in the present study, brain macrophages termed microglial cells co-cultured with differentiated cerebellar neurons excert potent neurotoxic effects. Neurotoxicity is unlikely to be due to cytokines since tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, IL-6 and interferon (IFN)-alpha/IFN-beta/IFN-gamma had no such effects. In contrast, when treating neurons with H2O2 or oxygen radical-generating systems cytotoxicity was induced. Furthermore, microglia were found to produce O2- and H2O2 when triggered with phorbol 12-myristate 13-acetate. However, in co-cultures of neurons and microglia, oxygen-radical scavengers catalase and superoxide dismutase, failed to protect neurons from microglia-induced killing. Moreover, when using undifferentiated neurons which are susceptible to H2O2 but not to NMDA receptor-dependent killing, microglia did not destroy the neurons. Thus, the amount of reactive oxygen intermediates produced by microglia in co-culture do not reach the critical concentrations required for neurotoxicity. As dibenzocyclohepteneimide, an antagonist to NMDA receptors neutralized neurotoxicity in microglia-neuronal co-cultures, excitatory amino acids released by microglia are suggested to compose the major determinant of neurotoxicity.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) production by glioblastoma cells. Despite the presence of inducing signals GM-CSF is not expressed in vivo

One of the morphologic hallmarks of human gliomas are inflammatory infiltrates with accumulation of macrophages in the tumor site. The signals leading to the macrophage response are only at the beginning of being understood. Novel chemotactic factors that have recently been characterized as secretory products of glioblastoma cells may attract mononuclear cells from the blood. Within the tumor tissue blood-derived monocytes and macrophages of the brain tissue, the microglial cells, may increase in cell numbers due to tumor-derived growth factors. Both astrocytoma cell lines and cultured astrocytes have been shown recently to produce granulocyte-macrophage (GM)-CSF. We show that in vitro not only astrocytoma but also glioblastoma cell lines secrete GM-CSF when stimulated with TNF-alpha or IL-1. However, there is no evidence for GM-CSF production by glioblastoma cells in vivo: fresh tumor samples lack the mRNA for GM-CSF and the protein is not detectable in the tumor cyst fluids or the cerebrospinal fluids of glioblastoma patients. This contrasts IL-1 and IL-6 that are detectable in the tumor cyst fluids and IL-6 also in the cerebrospinal fluids of the patients. Unlike GM-CSF, transforming growth factor-beta 2 mRNA is expressed in ex vivo tested glioblastoma tissues. Absence of GM-CSF in vivo may be explained by the presence of tumor-derived inhibitory factors, such as transforming growth factor-beta 2 and PGE which suppress GM-CSF production by glioblastoma cells in vitro. The accumulation of macrophages at the tumor site may be due to local elaboration of chemoattractants and/or not yet defined growth factors rather than due to GM-CSF production.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) production by glioblastoma cells. Despite the presence of inducing signals GM-CSF is not expressed in vivo

One of the morphologic hallmarks of human gliomas are inflammatory infiltrates with accumulation of macrophages in the tumor site. The signals leading to the macrophage response are only at the beginning of being understood. Novel chemotactic factors that have recently been characterized as secretory products of glioblastoma cells may attract mononuclear cells from the blood. Within the tumor tissue blood-derived monocytes and macrophages of the brain tissue, the microglial cells, may increase in cell numbers due to tumor-derived growth factors. Both astrocytoma cell lines and cultured astrocytes have been shown recently to produce granulocyte-macrophage (GM)-CSF. We show that in vitro not only astrocytoma but also glioblastoma cell lines secrete GM-CSF when stimulated with TNF-alpha or IL-1. However, there is no evidence for GM-CSF production by glioblastoma cells in vivo: fresh tumor samples lack the mRNA for GM-CSF and the protein is not detectable in the tumor cyst fluids or the cerebrospinal fluids of glioblastoma patients. This contrasts IL-1 and IL-6 that are detectable in the tumor cyst fluids and IL-6 also in the cerebrospinal fluids of the patients. Unlike GM-CSF, transforming growth factor-beta 2 mRNA is expressed in ex vivo tested glioblastoma tissues. Absence of GM-CSF in vivo may be explained by the presence of tumor-derived inhibitory factors, such as transforming growth factor-beta 2 and PGE which suppress GM-CSF production by glioblastoma cells in vitro. The accumulation of macrophages at the tumor site may be due to local elaboration of chemoattractants and/or not yet defined growth factors rather than due to GM-CSF production.

Murine brain macrophages induced NMDA receptor mediated neurotoxicity in vitro by secreting glutamate

Supernatants (SN) of brain macrophages in culture induce death of cerebellar granule cells in vitro, while those of astrocytes and endothelial cells do not. This toxicity can be prevented by N-methyl-D-aspartate (NMDA) receptor antagonists. Macrophage SN contain high concentrations of glutamate. Reducing the glutamate level of macrophage SN, either by exposure to astrocytes or by enzymatic degradation abolished the toxic effect. Thus, macrophage neurotoxicity is mediated by glutamate acting on NMDA receptors, and might play a role in vivo in traumatic and cerebrovascular brain lesions.