The Potential Neurological Impact of Intraoperative Hyponatremia Using Histidine-Tryptophan-Ketoglutarate Cardioplegia Infusion in Adult Cardiac Surgery.

Background and Objectives: The relationship between histidine-tryptophan-ketoglutarate (HTK)-induced hyponatremia and brain injury in adult cardiac surgery patients is unclear. This study analyzed postoperative neurological outcomes after intraoperative HTK cardioplegia infusion. Materials and Methods: A prospective cohort study was conducted on 60 adult patients who underwent cardiac surgery with cardiopulmonary bypass. Of these patients, 13 and 47 received HTK infusion and conventional hyperkalemic cardioplegia, respectively. The patients' baseline characteristics, intraoperative data, brain injury markers, Mini-Mental State Examination (MMSE) scores, and quantitative electroencephalography (qEEG) data were collected. Electrolyte changes during cardiopulmonary bypass, the degree of hyponatremia, and any associated brain insults were evaluated. Results: The HTK group presented with acute hyponatremia during cardiopulmonary bypass, which was intraoperatively corrected through ultrafiltration and normal saline administration. Postoperative sodium levels were higher in the HTK group than in the conventional cardioplegia group. The change in neuron-specific enolase levels after cardiopulmonary bypass was significantly higher in the HTK group (p = 0.043). The changes showed no significant differences using case-control matching. qEEG analysis revealed a significant increase in relative delta power in the HTK group on postoperative day (POD) 7 (p = 0.018); however, no significant changes were noted on POD 60. The MMSE scores were not significantly different between the two groups on POD 7 and POD 60. Conclusions: HTK-induced acute hyponatremia and rapid correction with normal saline during adult cardiac surgeries were associated with a potential short-term but not long-term neurological impact. Further studies are required to determine the necessity of correction for HTK-induced hyponatremia.

Predictors and Outcomes of Acute Brain Injury in Patients on Venoarterial Extracorporeal Membrane Oxygenation after Cardiopulmonary Resuscitation.

Background: Venoarterial (V-A) extracorporeal membrane oxygenation (ECMO) after cardiac arrest often predisposes patients to acute brain injury (ABI), which affects survival and neurological performance. The investigation of the predictors of ABI will be beneficial for further management. Objectives: To explore the predictors and outcomes of ABI and intracerebral hemorrhage (ICH) in patients experiencing cardiac arrest and cardiopulmonary resuscitation (CPR) with V-A ECMO support. Methods: We retrospectively analyzed 150 patients who successfully weaned from V-A ECMO support after pre-ECMO CPR at our institution from January 2009 to December 2021. Short-term and long-term outcomes were evaluated. Characteristics before and during ECMO were analyzed for determining the predictors of ABI and ICH. Results: Of the 150 patients, 66 (44.0%) had ABI. ABI was associated with higher in-hospital mortality (62.1% vs. 21.4%, p < 0.0001) and poorer long-term survival after discharge (p = 0.002). Patients who survived to discharge with ABI had significantly more severe neurological deficits at discharge (84.0% vs. 42.4%, p < 0.0001) and improved little at one year after discharge (33.3% vs. 11.4%, p = 0.027). We found that CPR duration [odds ratio (OR) = 1.04, p = 0.003] was the independent risk factor for ABI, whereas lower platelet counts was the independent risk factor for ICH (OR = 0.96, p = 0.019). Conclusions: After CPR, development of ABI during V-A ECMO support impacted survival and further neurological outcome. Longer CPR duration before ECMO set up significantly increases the occurrence of ABI. Besides, severe thrombocytopenia during ECMO support increases the possibility of ICH.

Continuous Myocardial Perfusion during Distal Anastomosis of Acute Type A Aortic Dissection.

BACKGROUND: The effect of continuous myocardial perfusion (CMP) on the surgical results of acute type A aortic dissection (ATAAD) remains unclear. METHODS: From January 2017 to March 2022, 141 patients who underwent ATAAD (90.8%) or intramural hematoma (9.2%) surgery were reviewed. Fifty-one patients (36.2%) received proximal-first aortic reconstruction and CMP during distal anastomosis. Ninety patients (63.8%) underwent distal-first aortic reconstruction and were placed in traditional cold blood cardioplegic arrest (CA; 4°C, 4:1 blood-to-Plegisol) throughout the procedure. The preoperative presentations and intraoperative details were balanced using inverse probability of treatment weighting (IPTW). Their postoperative morbidity and mortality were analyzed. RESULTS: The median age was 60 years. The incidence of arch reconstruction in the unweighted data was higher in the CMP compared with the CA group (74.5 vs 52.2%, p = 0.017) but was balanced after IPTW (62.4 vs 58.9%, p = 0.932, standardized mean difference = 0.073). The median cardiac ischemic time was lower in the CMP group (60.0 vs 130.9 minutes, p < 0.001), but cerebral perfusion time and cardiopulmonary bypass time were similar. The CMP group did not demonstrate any benefit in the reduction of the postoperative maximum creatine kinase-MB ratio (4.4 vs 5.1% in CA, p = 0.437) or postoperative low cardiac output (36.6 vs 24.8%, p = 0.237). Surgical mortality was comparable between groups (15.5% in CMP vs 7.5% in the CA group, p = 0.265). CONCLUSION: Application of CMP during distal anastomosis in ATAAD surgery, irrespective of the extent of aortic reconstruction, reduced myocardial ischemic time but did not improve cardiac outcome or mortality.

The Predictors and Outcomes of Functional Mitral Stenosis following Surgical Mitral Valve Repair: A Retrospective Analysis.

To optimize mitral valve repair outcomes, it is crucial to comprehend the predictors of functional mitral valve stenosis (FMS), to enhance preoperative assessments, and to adapt intraoperative treatment strategies. This study aimed to identify FMS risk factors, contributing valuable insights for refining surgical techniques. Among 228 selected patients, 215 underwent postoperative echocardiography follow-ups, and 36 met the FMS criteria based on a mean trans-mitral pressure gradient of >5 mmHg. Patients with FMS exhibited higher pulmonary systolic arterial pressure and increased late mortality during the follow-up. Univariable logistic regression analysis identified several risk factors for FMS, including end-stage renal disease, anterior leaflet lesion, concomitant aortic valve replacement, smaller ring size, ring type, and neochordae implantation. Conversely, resection alone and resection combined with neochordae implantation had protective effects against FMS. Multivariable logistic regression analysis revealed that smaller ring sizes and patch repair independently predicted FMS. When focusing on degenerative mitral regurgitation, the neochordae implantation without resection in leaflet repair, emerged as an independent predictor of FMS. Surgeons should weigh the substantial impact of surgical procedures on postoperative trans-mitral pressure gradients, emphasizing preoperative evaluation and techniques such as precise ring size assessment and effective leaflet management.

Aortic root remodeling after surgical repair of acute type A aortic dissection using different anastomosis techniques.

Background: After surgical repair of acute type A aortic dissection (aTAAD), remodeling of the residual aortic segments is the key outcome parameter associated with late reoperation or aorta-related adverse events. In this study, we analyzed the surgical outcomes of aTAAD using either a telescopic or continuous anastomosis technique, focusing on their impact on aortic root remodeling during the longitudinal follow-up. Methods: Between 2012 and 2018, 112 surgical repairs of aTAAD with ascending aorta replacement and without aortic arch or aortic root replacement were performed. The medical records were reviewed retrospectively, and early and late outcomes were compared between the telescopic and continuous anastomosis techniques. The generalized estimating equation method was used to analyze the effects of different anastomosis techniques on serial aortic root remodeling. Results: The telescopic anastomosis technique was used in 46 cases (41.1%), and the conventional continuous anastomosis technique was used in 66 cases (58.9%). There were no differences in in-hospital mortality or the incidence of major complications between the groups. The telescopic anastomosis group demonstrated stable postoperative regression of the aortic root diameter during follow-up. In contrast, the continuous anastomosis group showed a progressive dilatation of the aortic root. There was a trend toward better aortic root adverse event-free survival rates in the telescopic anastomosis group (P = .081). Conclusions: The telescopic anastomosis technique is a safe alternative to the continuous anastomosis technique in the surgical repair of aTAAD, with comparable early results. In addition, telescopic anastomosis was associated with beneficial aortic root remodeling in the medium term compared with continuous anastomosis.

Cognitive Function Deterioration After Cardiopulmonary Bypass: Can Intraoperative Optimal Cerebral Regional Tissue Oxygen Saturation Predict Postoperative Cognitive Function?

OBJECTIVE: Cognitive impairment is a common neurologic complication after cardiac surgery with cardiopulmonary bypass (CPB). This study evaluated postoperative cognitive function to determine predictors of cognitive dysfunction, including intraoperative cerebral regional tissue oxygen saturation (rSO2). DESIGN: A prospective observational cohort study. SETTING: At a single academic tertiary-care center. PARTICIPANTS: A total of 60 adults undergoing cardiac surgery with CPB from January to August 2021. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: All patients underwent Mini-Mental State Examination (MMSE) and quantified electroencephalography (qEEG) 1 day before cardiac surgery, 7 days postoperatively (POD7), and POD60. Intraoperative cerebral rSO2 was monitored continuously. For MMSE, no significant decrease in MMSE score was found on POD7 versus preoperatively (p = 0.09), but POD60 scores showed significant improvement compared with both preoperative (p = 0.02) and POD7 scores (p < 0.001). On qEEG, relative theta power on POD7 was increased versus preoperatively (p < 0.001), but it was decreased on POD60 (POD7 versus POD60, p < 0.001), and was close to preoperative data (p > 0.99). Baseline rSO2 was an independent factor for postoperative MMSE. Both baseline and mean rSO2 showed a significant influence in postoperative relative theta activity, whereas mean rSO2 was the only predictor for the theta-gamma ratio (p = 0.04). CONCLUSIONS: The MMSE in patients undergoing CPB declined at POD7 and recovered by POD60. Lower baseline rSO2 indicated a higher potential for MMSE decline at POD60. Inferior intraoperative mean rSO2 was related to higher postoperative relative theta activity and theta-gamma ratio, implying subclinical or further cognitive impairment.

Influence of confirmed viral infection on adult acute fulminant myocarditis supported with extracorporeal membrane oxygenation.

BACKGROUND: The impact of etiologies of acute fulminant myocarditis (AFM), which requires extracorporeal membrane oxygenation (ECMO), on clinical outcomes remains unknown. This study aimed to investigate the risk factors for ECMO weaning and mortality among patients with AFM due to viral etiologies in a tertiary referral medical center. METHODS: We included 33 adults with AFM who received ECMO and were admitted between January 2002 and January 2021. General demographics, laboratory data, echocardiography findings, and long-term outcomes were analyzed for confirmed viral etiology and unconfirmed etiology groups. RESULTS: The overall hospital survival rate was 54.5%. The age, sex, severity of the hemodynamic condition, and cardiac rhythm were similar between the two groups. Multivariate Cox regression analysis revealed that a confirmed viral etiology (HR 4.201, 95% CI 1.061-16.666), peri-ECMO renal replacement therapy (RRT) (HR 9.804, 1.140-83.333) and a high positive end-expiratory pressure (PEEP) in the ventilator settings at 24 h after ECMO (HR 1.479, 1.020-2.143) were significant prognostic factors for in-hospital mortality. Peri-ECMO RRT was also a significant negative prognostic factor for successful ECMO weaning (OR 0.061, 0.006-0.600) in the multivariate logistic model. CONCLUSIONS: Among AFM patients receiving ECMO support, RRT use was associated with a decreased chance of survival to ECMO weaning. Multiple organ dysfunction and a high PEEP were also predictive of a lower chance of hospital survival. Those with a confirmed diagnosis of viral myocarditis may require more medical attention due to the higher risk of hospital mortality than those without a definite diagnosis.

Prophylactic antibiotic treatment for preventing nosocomial infection in extracorporeal membrane oxygenation-resuscitated circulatory arrest patients.

Objective: We aimed to investigate the characteristics of nosocomial infections (NIs) and the impact of prophylactic antibiotic administration on NI outcomes in patients who underwent extracorporeal cardiopulmonary resuscitation (ECPR). Methods: This retrospective study analyzed the rate, type, pathogens, outcomes, and risk factors of NIs that developed in adult patients who underwent ECPR at our institution between January 2002 and January 2022. Results: Among 105 patients (median age, 58.59 [interquartile range, 46.53-67.32] years), 57 (54.29%) patients developed NIs during their extracorporeal membrane oxygenation courses. The incidence rates per 1000 extracorporeal membrane oxygenation days were 135.91 for overall infections and 40.06 for multidrug-resistant (MDR) infections. Ventilator-associated pneumonia was the most common type of NI (73.68%), followed by bloodstream infections (17.89%). Prophylactic antibiotics with Pseudomonas aeruginosa coverage were protective factors against NI (hazard ratio [HR], 0.518; 95% confidence interval [CI], 0.281-0.953; P = .034). High dynamic driving pressure of the ventilator (cmH2O) was a prognostic factor for hospital mortality (HR, 1.096; 95% CI, 1.008-1.192; P = .032). An Acute Physiology and Chronic Health Evaluation II score of ≥24 (HR, 6.443; 95% CI, 1.380-30.088; P = .018) was a risk factor for developing MDR infections. Conclusions: In patients who undergo ECPR, prophylactic antibiotic treatment with P aeruginosa coverage is associated with a lower incidence of NIs, whereas an Aeruginosa Acute Physiology and Chronic Health Evaluation II score of ≥24 is a risk factor for MDR infections. In the modern era of antibiotic therapy, the development of NIs does not increase hospital mortality among patients undergoing ECPR.

Three-stage approach for aortoesophageal fistula after Roux-en-Y esophagojejunostomy.

Surgical management of post-esophagojejunostomy aortoesophageal fistula (AEF) has been scarcely reported, but is universally fatal. This report described a case of AEF after total gastrectomy with Roux-en-Y esophagojejunostomy and adjuvant chemoradiotherapy for gastric cardiac cancer. A three-stage hybrid approach was used to successfully manage this complication. First, thoracic endovascular aortic repair curbed bleeding. Second, radical fistula resection eradicated infected areas and adjacent structures. Third, esophageal reconstruction using an ileocolonic conduit restored gastrointestinal continuity. This strategy could be safely feasible for managing post-esophagojejunostomy AEF.

Safety Time and Optimal Temperature of Unilateral Antegrade Cerebral Perfusion in Acute Type A Aortic Dissection: A Single-Center 15-Year Experience.

Background: The optimal level of hypothermia and safe time of unilateral antegrade cerebral perfusion (uACP) in acute type A aortic dissection (ATAAD) repair remain controversial. Objectives: To analyze the association of uACP time and circulatory arrest temperature with surgical outcomes of ATAAD. Methods: We retrospectively analyzed 263 patients who had undergone ATAAD repair between 2006 and 2020 using uACP. The patients were stratified by three chronologically equivalent periods (period 1, 2006 to 2010; period 2, 2011 to 2015; period 3, 2016 to 2020) to demonstrate the decade-long evolution of surgical strategy and outcomes. Results: The mean age of the patients was 59.4 ± 12.5 years, and 68.8% were male. The hospital mortality rates were 15.1%, 12.9%, and 11.0% from period 1 to 3 (p = 0.740). The median circulatory arrest temperatures were 20, 23, and 25 °C (p < 0.001), respectively, and the median uACP times were 72, 59, and 41 minutes (p < 0.001). The incidence rates of postoperative permanent neurologic deficits were 13.2%, 10.9%, and 18.3% (p = 0.312), and those of transient neurologic deficits were 9.4%, 10.9%, and 11.9% (p = 0.936), respectively. Multivariate logistic regression analysis showed that uACP time ≥ 60 minutes was an independent predictor of hospital mortality rather than postoperative stroke. ROC curve analysis estimated an optimal cutoff value of 52 minutes of uACP time when the circulatory arrest temperature was ≥ 25 °C to predict hospital mortality (area under the curve: 0.72). Conclusions: Unilateral antegrade cerebral perfusion time was associated with hospital mortality after ATAAD surgery. A safe threshold of 50 to 60 minutes of uACP should be considered.

A Case Report of Posttransplant Lymphoproliferative Disorder After AstraZeneca Coronavirus Disease 2019 Vaccine in a Heart Transplant Recipient.

We report a case of a heart transplant recipient who presented with a rapidly growing Epstein-Barr virus (EBV)-positive, diffuse large B-cell lymphoma 7 days after receiving the first dose of the ChAdOx1 nCoV-19 vaccine. Because of the atypical radiologic presentation, the initial tentative diagnosis was a mediastinal abscess. This observation indicates a potential risk of EBV reactivation after coronavirus disease 2019 (COVID-19) vaccination, which might lead to or aggravate the presentation of posttransplant lymphoproliferative disorder in transplantation patients. Transplant surgeons should be aware of the potential immunomodulatory effects of the COVID-19 vaccination.

Rosuvastatin Failed to Improve Arteriovenous Fistula Patency for Hemodialysis in Diabetic Patients - A Randomized Clinical Trial.

BACKGROUND: Very limited therapeutic strategies exist to prevent the primary failure of arteriovenous (AV) fistulas in patients with diabetes. OBJECTIVES: To investigate whether rosuvastatin could improve the primary patency of AV fistulas in diabetic patients with stage 5 chronic kidney disease (CKD). METHODS: This was a double-blind randomized clinical trial. From July 2012 to September 2018, patients aged between 18 and 65 years with type 2 diabetes and stage 5 CKD were randomized to receive placebo or rosuvastatin (5 mg/day) for 7 days prior to the creation of an AV fistula on the forearm until the 21st day after surgery. Patients were followed up for 180 days after the operation. The primary composite endpoint was the development of fistula immaturity or stenosis. The secondary endpoints were changes in inflammatory markers, oxidative stress, and occurrence of postoperative complications. RESULTS: A total of 60 patients were enrolled in the study. Rosuvastatin resulted in a 20% reduction in total cholesterol from postoperative day 0 to 28 (p = .0006). The overall rate of AV fistula failure (immaturity or stenosis) was 30%, with no significant difference between patients receiving rosuvastatin and those receiving the placebo (33.3% vs. 26.7%, p = .5731). Although not statistically significant, the administration of rosuvastatin might have increased the incidence of postoperative complications (2.99 vs. 2.39 event rate per 1000 patient-days; odds ratio, 1.33; p = .5986). CONCLUSIONS: Rosuvastatin showed no significant beneficial effects on the primary patency of AV fistulas in diabetic patients with stage 5 CKD, but might have been associated with the risk of drug-related complications.

Outcomes of acute type A aortic dissection operations performed by early-career cardiovascular surgeons.

Objective: Surgical outcomes of acute type A aortic dissection have been recognized to be associated with the surgical volume of individual hospitals and surgeons. In this study, we aimed to investigate the results and learning curves of acute type A aortic dissection operations performed by early-career cardiovascular surgeons. Methods: A total of 248 surgical repairs of acute type A aortic dissections were conducted at a tertiary medical center between 2010 and 2018. By using the cumulative sum test, cardiovascular surgeons in their early career were identified, and their performances were assessed. The outcomes of patients who were operated by early-career cardiovascular surgeons were compared with those by experienced or senior surgeons. Results: During the study period, 202 (81.5%) of the 248 acute type A aortic dissection operations were performed primarily by the 4 newly appointed attending cardiovascular surgeons. In cumulative sum curves, all surgeons exhibited a steady performance throughout the study period. On the basis of our institutional result of acute type A aortic dissection operation, early career was defined as performing fewer than 32 acute type A aortic dissection operations. The 30-day mortality rates of acute type A aortic dissection operations performed by early-career surgeons were equivalent to those performed by experienced/senior surgeons (10.9% vs 12.5%, P = .844). There was also no difference in mid-term overall survival and aortic event-free survival between the 2 groups (P = .638 and P = .574, respectively). Conclusions: In a center with a well-established program, cardiovascular surgeons could accomplish surgical repair of acute type A aortic dissection with adequate early- and mid-term results from the initiation of their careers.

Simultaneous Thrombolysis and Extracorporeal Membrane Oxygenation for Acute Massive Pulmonary Emboli.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) has been used in patients with circulatory collapse or extremely unstable hemodynamics caused by acute massive pulmonary embolism (PE). The effectiveness of simultaneous thrombolytic therapy has been rarely investigated in these patients after being stabilized with ECMO. METHODS: From January 2008 to December 2018 consecutive patients with acute massive PE requiring ECMO supported in a tertiary medical center were included for retrospective analysis. RESULTS: Thirteen patients with PE underwent ECMO implantation and received subsequent thrombolytic therapy as a definite treatment for PE. All patients survived their ECMO courses to a successful decannulation, with a mean ECMO support duration of 6.23 ± 4.69 days. Eleven patients (84.62%) survived to hospital discharge. All survivors were alive during follow-up, although 2 patients (18.2%) had permanent dysfunctional neurologic complications. Major bleeding complications occurred in 4 patients (30.77%), whereas no patient had intracranial hemorrhage. Systemic thrombolysis showed comparable outcomes of catheter-directed thrombolysis in our patients who underwent ECMO. CONCLUSIONS: Thrombolysis-based therapeutic strategy under ECMO could be a relatively safe and effective definitive treatment for patients with acute massive PE, even for those who were resuscitated. Bleeding complications remain a major concern and should be monitored and managed immediately.

Post-Coronary Artery Bypass Medications in Dialysis Patients: Do We Need to Change Strategies?

BACKGROUND: Coronary artery bypass grafting (CABG) is frequently performed in patients with end-stage renal disease (ESRD) together with severe coronary artery disease, after which, patients with ESRD have higher surgical risk and poorer long-term outcomes. We report our experience in patients with ESRD who survived in CABG and identify predictors of long-term outcomes. METHODS: We retrospectively investigated 93 consecutive patients with ESRD who survived to discharge after isolated CABG between January 2005 and December 2016 at our institution. Long-term outcomes, including all-cause mortality after discharge, readmission due to major adverse cardiac events, and reintervention, were evaluated. Predictors affecting long-term outcomes were also analyzed. RESULTS: The rates of freedom from all-cause mortality after discharge in 1, 3, 5, and 10 years were 92.1, 81.3, 71.9, and 34.9%, respectively. The rates of freedom from readmission due to major adverse cardiac events in 1, 3, 5, and 10 years were 90.7, 79.1, 69.9, and 55.6%, respectively. The rates of freedom from reintervention in 1, 3, 5, and 10 years were 95.3, 86.5, 79.0, and 66.6%, respectively. Postoperative ß-blocker and statin use significantly improved overall long-term survival (ß-blocker, p = 0.013; statin, p = 0.009). After case-control matching, patients who received statins showed better long-term survival than those without statins. The comparison of long-term survival between patients with and without ß-blockers showed no significant difference after matching. CONCLUSIONS: After CABG, dialysis patients who survived to discharge had acceptable long-term overall survival. Post-CABG statin use in dialysis patients is a predictor of better long-term survival.

"Mantle-style" modification of Cabrol shunt for hemostasis after extended aortic reconstruction in acute type A aortic dissection.

Cabrol shunt and several of its modifications have been used as adjunctive procedures to control inaccessible bleeding occurring after aortic root surgeries. Nevertheless, the hemostatic effect of the shunt is suboptimal when the reconstructive procedure extends to the aortic arch and coronary arteries. We propose a "Mantle-style" modified Cabrol shunt to facilitate hemostasis of the exsanguination from the neo-root after aortic root replacement with concomitant arch and coronary reconstruction.

Postoperative Extracorporeal Membrane Oxygenation Support for Acute Type A Aortic Dissection.

BACKGROUND: Few studies have investigated the use of postoperative extracorporeal membrane oxygenation (ECMO) in acute type A aortic dissection (aTAAD). We identified aTAAD surgical patients at risk of ECMO implantation postoperatively and analyzed the prognosis of these patients. METHODS: We retrospectively reviewed 162 consecutive aTAAD patients undergoing operations from January 2008 to December 2015. Patient data were analyzed for risk factors leading to an ECMO requirement. Short-term and long-term outcomes in patients who did and did not require ECMO were compared. RESULTS: Postoperative ECMO was required in 20 patients (12.3%), and in-hospital mortality was higher in the ECMO group (65.0% vs 8.5%, p < 0.001). Factors predicting postoperative ECMO were preoperative hemodynamic instability (p = 0.049), aortic cross-clamp time (p = 0.036), and postoperative peak creatinine kinase-MB (p = 0.002). ECMO survivors presented at a younger age (p = 0.036) and had a less postoperative blood transfusion (p = 0.034) than ECMO nonsurvivors. The postdischarge survival rate was equivalent in patients with or without ECMO support. CONCLUSIONS: Although postoperative ECMO is an important predictor of in-hospital death, this pilot study showed that aTAAD patients supported with postoperative ECMO who survive to hospital discharge have a long-term survival comparable to patients who did not receive ECMO.