Use of veno-venous extracorporeal membrane oxygenation for stabilization prior to redo sternotomy for aortic pseudoaneurysm repair.

Background: Aortic pseudoaneurysms are particularly dangerous because of the risk of rupture and compression of mediastinal structures, including the trachea, and resultant respiratory distress. If respiratory distress progresses to respiratory failure, extracorporeal membrane oxygenation may be used to provide oxygenation prior to or during pseudoaneurysm repair. Case presentation: A 62-year-old male with a history of emergent aortic ascending and arch replacement for Stanford Type A dissection 10 months prior presented to his primary care physician with dyspnea. Chest radiography revealed a widened mediastinum, and subsequent computed tomography angiogram revealed a pseudoaneurysm at the distal suture line of the aortic arch replacement. Due to the location of the pseudoaneurysm, the patient's trachea was compressed, and he was emergently placed on veno-venous (VV) extracorporeal membrane oxygenation (ECMO) following unsuccessful intubation for respiratory distress. Two days later, the patient underwent a redo sternotomy and repair of a 2-3 mm defect in the anterior aspect of the distal suture line of the prior aortic arch replacement. The patient progressed well and was discharged on postoperative day 13. What we learned: Using a combination of peripheral bypass, hypothermic circulatory arrest, delayed closure, and respiratory support, this case demonstrates how even complex patients can be successfully treated with multiple strategies.

The Society of Thoracic Surgeons Looking to the Future Scholarship Program: A 15-Year Review.

BACKGROUND: It has been postulated that a possible barrier to pursuing cardiothoracic surgery is a lack of exposure and mentorship during training. In 2006, The Society of Thoracic Surgeons began the Looking to the Future Scholarship to expand interest in the field. Undecided trainees with limited exposure were prioritized in the selection process. This report summarizes the career outcomes of general surgery resident and medical student recipients. METHODS: Scholarship recipients and nonrecipients (control) were queried in a Google search. The percentage of those who were cardiothoracic surgeons or in cardiothoracic training (%CTS) was calculated, as well as the percentage of female surgeons in cardiothoracic surgery. RESULTS: From 2006 to 2021, there were 669 awardees. The %CTS was 63.7% for resident recipients and 31.4% for students, respectively. There was no significant difference in %CTS between resident and student recipients compared to nonrecipients. Notably, the percentage of female cardiothoracic surgeons was significantly greater for both resident and student recipients. CONCLUSIONS: The majority of resident recipients are now in cardiothoracic surgery, comparable to nonrecipients. While there was no significant difference between the percentage of recipients and non-recipients in cardiothoracic surgery, these groups differed substantially as nonrecipients had greater exposure and commitment to the field at the time of application.

Impact of intraoperative blood products, fluid administration, and persistent hypothermia on bleeding leading to reexploration after cardiac surgery.

OBJECTIVE: Risk factors for severe postoperative bleeding after cardiac surgery remain multiple and incompletely elucidated. We evaluated the impact of intraoperative blood product transfusions, intravenous fluid administration, and persistently low core body temperature (CBT) at intensive care unit arrival on risk of perioperative bleeding leading to reexploration. METHODS: We retrospectively queried our tertiary care center's Society of Thoracic Surgeons Institutional Database for all index, on-pump, adult cardiac surgery patients between July 2016 and September 2022. Intraoperative fluid (crystalloid and colloid) and blood product administrations, as well as perioperative CBT data, were harvested from electronic medical records. Linear and nonlinear mixed models, treating surgeon as a random effect to account for inter-surgeon practice differences, were used to assess the association between above factors and reexploration for bleeding. RESULTS: Of 4037 patients, 151 (3.7%) underwent reexploration for bleeding. Reexplored patients experienced remarkably greater postoperative morbidity (23% vs 6%, P < .001) and 30-day mortality (14% vs 2%, P < .001). In linear models, progressively increasing IV crystalloid administration (adjusted odds ratio, 1.11, 95% confidence interval, 1.03-1.19) and decreasing CBT on intensive care unit arrival (adjusted odds ratio, 1.20; 95% confidence interval, 1.05-1.37) were associated with greater risk of bleeding leading to reexploration. Nonlinear analysis revealed increasing risk after ∼6 L of crystalloid administration and a U-shaped relationship between CBT and reexploration risk. Intraoperative blood product transfusion of any kind was not associated with reexploration. CONCLUSIONS: We found evidence of both dilution- and hypothermia-related effects associated with perioperative bleeding leading to reexploration in cardiac surgery. Interventions targeting modification of such risk factors may decrease the rate this complication.

Ultrafiltration in cardiac surgery: Results of a systematic review and meta-analysis.

Background: Ultrafiltration is used with cardiopulmonary bypass to reduce the effects of hemodilution and restore electrolyte balance. We performed a systematic review and meta-analysis to analyze the effect of conventional and modified ultrafiltration on intraoperative blood transfusion.Methods: Utilizing the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement, we systematically searched MEDLINE, EMBASE, Web of Science, and Cochrane Library to perform a meta-analysis of studies of randomized controlled trials (RCTs) and observational studies evaluating conventional ultrafiltration (CUF) and modified ultrafiltration (MUF) on the primary outcome of intraoperative red cell transfusions.Results: A total of 7 RCTs (n = 928) were included, comparing modified ultrafiltration (n = 473 patients) to controls (n = 455 patients) and 2 observational studies (n = 47,007), comparing conventional ultrafiltration (n = 21,748) to controls (n = 25,427). Overall, MUF was associated with transfusion of fewer intraoperative red cell units per patient (n = 7); MD -0.73 units; 95% CI -1.12 to -0.35 p = 0.04; p for heterogeneity = 0.0001, I2 = 55%) compared to controls. CUF was no difference in intraoperative red cell transfusions compared to controls (n = 2); OR 3.09; 95% CI 0.26-36.59; p = 0.37; p for heterogeneity = 0.94, I2 = 0%. Review of the included observational studies revealed an association between larger volumes (>2.2 L in a 70 kg patient) of CUF and risk of acute kidney injury (AKI).Conclusion: The results of this systematic review and meta-analysis suggest that MUF is associated with fewer intraoperative red cell transfusions. Based on limited studies, CUF does not appear to be associated with a difference in intraoperative red cell transfusion.

Multiple Arterial Graft Use in Coronary Artery Bypass Surgery: Surgeon Perspective vs Practice.

BACKGROUND: Despite supportive evidence and guidelines, the use of multiple arterial grafts (MAGs) in coronary artery bypass grafting remains low. We sought to determine surgeon perception of personal MAG use and compare this with actual MAG use. METHODS: We conducted a statewide surgeon survey of MAG use, presence of a hospital MAG protocol, and barriers for MAG use, with a response rate of 78% (n = 25). Surgeon survey responses were compared with actual Society of Thoracic Surgeons patient data from January 1, 2017, to December 31, 2020 using χ2 or Fisher's exact tests. RESULTS: Of 5299 patients who had first-time, nonemergent, isolated coronary artery bypass grafting (≥2 grafts) by responding surgeons, 16% received MAG (n = 825). MAG use in patients whose surgeons self-designated as "routine" MAG users was 21% vs 7% for "nonroutine" users. Surgeons with a hospital protocol for MAG use utilized MAG more often (18% vs 14%, P = .001). Surgeons who were unconvinced by the data on the benefits of MAGs used MAGs in 11% vs 22% in surgeons who were convinced. MAG use increased over time, particularly from before to after the survey (13.1% vs 30.5%, P < .001). CONCLUSIONS: Although MAG use increased over time, barriers to routine use remain. In surgeons who reported routine use, only 21% of their patients received MAGs. Hospital protocols, education, and increased awareness may reduce barriers to use and encourage evidence-based clinical practice.

Early Reexploration for Bleeding Is Associated With Improved Outcome in Cardiac Surgery.

BACKGROUND: Reexploration after cardiac surgery, most frequently for bleeding, is a quality metric used to assess surgical performance. This may cause surgeons to delay return to the operating room in favor of attempting nonoperative management. This study investigated the impact of the timing of reexploration on morbidity and mortality. METHODS: This study was a single-institution retrospective review of all adult cardiac surgery patients from July 2010 to June 2020. Time to reexploration was assessed, and outcomes were compared across increasing time intervals. Reported bleeding sites were classified into 5 groups, and bleeding rate (chest tube output) was compared across bleeding sites. Univariable analysis was performed using the Fisher exact and Kruskal-Wallis tests. Multivariable logistic regression models were used for risk-adjusted analyses. RESULTS: Of 10 070 eligible patients, 251 (2.5%) required reexploration for postoperative bleeding. The most common site of bleeding was "any suture line" (n = 70; 28%). Interestingly, in 30% of cases (n = 75) "no active bleeding" site was reported. The highest rate of bleeding (mL/h) was observed in the "any mediastinal structure" group (median, 450; interquartile range [IQR], 185, 8878), and the lowest rate was noted in the "no active bleeding" group (median, 151.2; IQR, 102, 270). Both morbidity rates (0-4 hours, 12.3% vs 25-48 hours, 37.5%; P = .001) and mortality rates (0-4 hours, 3.1% vs 25-48 hours, 43.8%; P = .001) escalated significantly with increasing time to reexploration. CONCLUSIONS: Delayed reexploration for bleeding after cardiac surgery is associated with increased risk for morbidity and mortality. Early surgical intervention, particularly within 4 hours, may improve outcomes. Implications from using reoperation as a performance metric may lead to unnecessary delay and patient harm.

Prediction of operative mortality for patients undergoing cardiac surgical procedures without established risk scores.

OBJECTIVE: Current cardiac surgery risk models do not address a substantial fraction of procedures. We sought to create models to predict the risk of operative mortality for an expanded set of cases. METHODS: Four supervised machine learning models were trained using preoperative variables present in the Society of Thoracic Surgeons (STS) data set of the Massachusetts General Hospital to predict and classify operative mortality in procedures without STS risk scores. A total of 424 (5.5%) mortality events occurred out of 7745 cases. Models included logistic regression with elastic net regularization (LogReg), support vector machine, random forest (RF), and extreme gradient boosted trees (XGBoost). Model discrimination was assessed via area under the receiver operating characteristic curve (AUC), and calibration was assessed via calibration slope and expected-to-observed event ratio. External validation was performed using STS data sets from Brigham and Women's Hospital (BWH) and the Johns Hopkins Hospital (JHH). RESULTS: Models performed comparably with the highest mean AUC of 0.83 (RF) and expected-to-observed event ratio of 1.00. On external validation, the AUC was 0.81 in BWH (RF) and 0.79 in JHH (LogReg/RF). Models trained and applied on the same institution's data achieved AUCs of 0.81 (BWH: LogReg/RF/XGBoost) and 0.82 (JHH: LogReg/RF/XGBoost). CONCLUSIONS: Machine learning models trained on preoperative patient data can predict operative mortality at a high level of accuracy for cardiac surgical procedures without established risk scores. Such procedures comprise 23% of all cardiac surgical procedures nationwide. This work also highlights the value of using local institutional data to train new prediction models that account for institution-specific practices.

Ketamine Mitigates Neurobehavioral Deficits in a Canine Model of Hypothermic Circulatory Arrest.

Hypothermic circulatory arrest is a protective technique used when complete cessation of circulation is required during cardiac surgery. Prior efforts to decrease neurologic injury with the NMDA receptor antagonist MK801 were limited by unacceptable side effects. We hypothesized that ketamine would provide neuroprotection without dose-limiting side effects. Canines were peripherally cannulated for cardiopulmonary bypass, cooled to 18°C, and underwent 90 minutes of circulatory arrest. Ketamine-treated canines (n = 5; total dose 2.85 mg/kg) were compared to untreated controls (n = 10). A validated neurobehavioral deficit score was obtained at 24, 48, and 72 hours (0 = no deficits/normal exam; higher score represents increasing deficits). Biomarkers of neuronal injury in the cerebrospinal fluid were examined at baseline and at 8, 24, 48, and 72 hours. Brain histopathologic injury was scored at 72 hours (higher score indicates more necrosis and apoptosis). Ketamine-treated canines had significantly improved, lower neurobehavioral deficit scores compared to controls (overall P = 0.003; 24 hours: median 72 vs 112, P = 0.030; 48 hours: 47 vs 90, P = 0.021; 72 hours: 30 vs 89, P = 0.069). Although the histopathologic injury scores of ketamine-treated canines (median 12) were lower than controls (16), there was no statistical difference (P = 0.10). Levels of phosphorylated neurofilament-H and neuron specific enolase, markers of neuronal injury, were significantly lower in ketamine-treated animals (P = 0.010 and = 0.039, respectively). Ketamine significantly reduced neurologic deficits and biomarkers of injury in canines after hypothermic circulatory arrest. Ketamine represents a safe and approved medication that may be useful as a pharmacologic neuroprotectant during cardiac surgery with circulatory arrest.

Costs and Readmissions Associated with Type A Aortic Dissections at High- and Low-Volume Centers.

BACKGROUND: Costs and readmissions associated with type A aortic dissection repairs are not well understood. We investigated statewide readmissions, costs, and outcomes associated with the surgical management of type A aortic dissection repairs at low- and high-volume centers. METHODS: We identified all adult type A aortic dissection patients who underwent operative repair in the Maryland Health Services Cost Review Commission's database (2012-2020). Hospitals were stratified into high- (top quartile of total repairs) or low-volume centers. RESULTS: Of the 249 patients included, 193 (77.5%) were treated at a high-volume center. Patients treated at high- and low-volume centers had no differences in age, sex, race, primary payer, or severity (all p > 0.5). High- compared to low-volume centers had a greater proportion of patients transferred in (71.5% vs. 17.9%, p < 0.001). High-volume centers also had longer lengths of stay (12 vs. 8 days, p < 0.001), similar inpatient mortality (13.0% vs. 16.1%, p = 0.6), and similar proportion of patients readmitted (54.9% vs. 51.8%, p = 0.7). High-volume centers had greater index admission costs ($114,859 vs. $72,090, p < 0.001) and similar readmission costs ($48,367 vs. $42,204, p = 0.5). At high-volume centers, transferred patients compared to direct admissions had greater severity of illness (p = 0.05), similar mortality (p = 0.53), and greater lengths of stay (p = 0.05). CONCLUSIONS: High-volume centers had a greater number of patients transferred from other institutions compared to low-volume centers. High-volume centers were associated with increased index admission resource utilization, with transfer patients having higher illness severity and greater resource utilization, yet similar mortality, compared to direct admission patients.

Reoperative CABG in a patient with prior concomitant lung transplantation and two-vessel CABG.

BACKGROUND: Lung transplants (LTx) are being offered to increasingly older patients, and as a result, more concomitant coronary artery disease is being encountered in LTx candidates. While concurrent coronary artery bypass grafting (CABG) and LTx have become more common, the long-term considerations of reoperative CABG in patients following CABG with concomitant LTx are not fully understood. CASE PRESENTATION: A 75-year-old man with a history of bilateral LTx and concomitant CABG X 2 15 years prior presented to the emergency room with tachycardia and chest discomfort radiating to the left upper extremity. Emergent coronary angiography revealed severe three-vessel coronary artery disease with two occluded saphenous vein grafts, severe distal obtuse marginal (OM) and left circumflex disease, a collateralized chronic total occlusion of the mid LAD, and tortuosity of the proximal right innominate artery. The patient underwent a complex redo sternotomy and CABG X 2 due to dense adhesions in the mediastinum and pleura bilaterally. The postoperative course was complicated by left leg SVG harvest site cellulitis treated with IV antibiotics and hypervolemia treated with diuresis. The patient was discharged postoperatively on day 13. DISCUSSION: To our knowledge, this is the first reported successful reoperative CABG in a patient with a history of concomitant LTx and CABG. This case demonstrates feasibility, though additional caution is required due to the technical complexity and risk of immunosuppression in such complex patients.