Evaluation of the effects of three designs of oxygenators with integrated filters on clinical and haematological outcomes at an Australasian cardiothoracic unit.

INTRODUCTION: Cardiopulmonary bypass (CPB) machines have oxygenators with integrated filters and unique biocompatible coatings to combat systemic inflammatory response syndrome (SIRS) and mitigate coagulopathy. Contemporary oxygenators have undergone comparative studies; however, our study aimed to identify the most appropriate oxygenator for our regional Cardiothoracic unit in Australasia. METHODS: A prospective audit consecutively recruited one-hundred and fifty patients undergoing cardiac surgery at Waikato Hospital, New Zealand between the periods of 29th January 2018 and 31st July 2018. Fifty patients were recruited for each oxygenator arm: Sorin INSPIRE' (Group-S); Terumo CAPIOX'FX (Group-T); and Medtronic Affinity Fusion' (Group-M). The clinical outcomes were transfusions, chest drain output, reoperation and length of hospital stay (LOHS). Routine blood testing protocol included: haemoglobin, protein, albumin, white cell count (WCC), C-reactive protein (CRP), platelet count and coagulations tests including international normalized ratio (INR). RESULTS: Comparing Groups S, T and M there was no statistical difference in chest drain output (650 vs. 500 vs. 595 ml respectively, p = 0.45), transfusions (61 vs. 117 vs. 70 units, p = 0.67), reoperation (6 vs. 8 vs. 12%, p = 0.99) and LOHS (median 7.4 vs. 7.6 vs. 9.5 days, p = 0.42). Group-T had fewer SIRS cases but similar increase in CRP (p = 0.12) and WCC (p = 0.35). Group-M had a significant rise in post-op INR (p = 0.005) but no associated increase in chest drain output (p = 0.62). Group-S and -M required more 4%-albumin and Group-T had more transfusions. Only fresh frozen plasma (FFP) and red blood cell (RBC) transfusion had a significant relationship with LOHS (p < 0.05). CONCLUSION: Biochemically, there was slight difference among the oxygenators which did not translate into clinical difference in outcomes. The oxygenator design and perfusionist choice aided in our decision-making process.

Can We Better Differentiate Type A Dissections: Evaluating the Role of Aortic Ratios.

OBJECTIVES: Type A aortic dissection (ATAAD) is hypothesised as a progression of aneurysmal dilation, but 60% of patients in the International Registry of Acute Aortic Dissection (iRAD) registry had a maximum aortic diameter (MAD)<55 mm. We aim to demonstrate that size ratios and aortic wall stress, assessed using a simplified markers, are unique to aortic patients who have had adverse events (ATAAD) compared to those who have not (thoracic aortic aneurysm [TAA]). METHODS: A retrospective cohort analysis of patients who underwent aortic intervention at Waikato Hospital, New Zealand between 2015-2020, comparing dissection (ATAAD) to TAA patients. MAD; ratio of MAD to standardised-points within the aorta; and MAD-to-height collected from computed tomography (CT)-scans of all patients was undertaken. Receiver operating characteristic (ROC)-analysis to determine cut-off point for each marker was undertaken together with multivariable logistic regression comparing both cohorts, cross-validated by propensity-score matched analysis. RESULTS: Cohort of 215 patients, 78 (36.3%) ATAAD and 137 (63.7%) TAA; median age at intervention 63.3 years, 52 (24.2%) females, both cohorts matched for size. Using the entire cohort, the MAD: sinus of Valsalva (SoV) ratio>1.06 (cut-off value) had 4.5-times greater association with ATAAD (95%CI 1.46-13.8) and a 0.1-unit increased conferred 1.45-times greater association with ATAAD (95%CI 1.00-2.08). MAD>55 mm only seen in 33.3% of ATAAD (n=26/78), and not associated with ATAAD (OR 1.88, 95%CI 0.64-5.51). Compared to MAD, MAD:SoV ratio had greater sensitivity (33% vs 73%), lower number-needed-to-treat (17.9 vs 2.7) and superior discrimination (area under the curve [AUC] 0.54 vs 0.71). Findings were consistent with propensity score matched analysis. CONCLUSIONS: MAD:SoV ratio significantly correlates with ATAAD (4.5 times), with superior sensitivity, discrimination, and attributable-risk-percentage compared to MAD alone.

Full Metal Jacket Endarterectomy of Left Anterior Descending Coronary Artery is Safe With Good Midterm Outcomes.

BACKGROUND: Multiple overlapping stents (Full metal jacket, FMJ) from percutaneous coronary artery intervention (PCI) renders coronary artery bypass modus operandi unmanageable. We report our surgical revascularisation in patients with failed full metal jacket of left anterior descending coronary artery (FMJ-LAD). METHODS: We reviewed 22 patients who presented with FMJ-LAD From 2006 to 2019. Extensive endarterectomy involving almost the whole length of the left anterior descending (LAD) was performed, the arteriotomy patched up with a saphenous vein. All reconstructed LADs were grafted with the left internal mammary artery. We compared the group to propensity-matched patients with single proximal LAD lesions requiring coronary artery bypass graft (CABG). RESULTS: The mean age was 54±3.5 years. Twenty-one (21) patients (95%) were in angina class III or IV despite maximum medical therapy. Fourteen (14) patients (63.6%) presented with MI within 1 month. All patients had a preoperative positive test for ischaemia. Cross-clamp and bypass times were significantly shorter (25.5±7 mins and 65±5 mins, versus 52±3 mins and 77.2±4 mins) in the CABG group compared to FMJ-LAD group, the mean hospital stay of 6±1.5 days was not different between the groups. Postoperative electrocardiograms showed non-specific changes in 75% (n=16) with no enzyme rise. Early postoperative angiography was performed in 10 patients because of the new electrocardiograph (ECG) changes; all FMJ-LAD patients had an angiogram at 1 year, two late angiograms (2 and 3 years postoperatively), and one computed tomography (CT)-angiogram for readmission with angina. All patients in the FMJ-LAD group had 12 months follow-up angiogram or cardiac CT scan. All the endarterectomies' LADs were patent. There was no mortality within the 30 days. Patients' follow-up time was between 1-13 years. CONCLUSIONS: Open stent endarterectomy is a valuable alternative option for patients with "full metal jacket" diseased LAD that is not graftable using standard techniques with acceptable midterm results.

Performance of the AusSCORE II and STS Score for Coronary Artery Bypass Grafting in a New Zealand Population.

BACKGROUND: The updated Australian System for Cardiac Operative Risk Evaluation (AusSCORE II) and the Society of Thoracic Surgeons (STS) Score are well-established tools in cardiac surgery for estimating operative mortality risk. No validation analysis of both risk models has been undertaken for a contemporary New Zealand population undergoing isolated coronary bypass surgery. We therefore aimed to assess the efficacy of these models in predicting mortality for New Zealand patients receiving isolated coronary artery bypass grafting (CABG). MATERIAL AND METHODS: A prospective database was maintained of patients undergoing isolated CABG at a major tertiary referral centre in New Zealand between September 2014 and September 2017. This database collected the patients' demographic, clinical, biochemical, operative and mortality data. The primary outcome measure was the correlation between the predicted AusSCORE II and STS Score mortality risks and the observed 30-day mortality events for all patients in the database using discrimination and calibration statistics. Discrimination and calibration were assessed using receiver operating characteristic (ROC) curves and the Hosmer-Lemeshow test respectively. RESULTS: A total of 933 patients underwent isolated CABG during the 3-year study period. There were seven deaths in the study cohort occurring within 30 days of surgery. Discrimination analysis demonstrated the area under the ROC curve (AUC) of the AusSCORE II and STS Score as 88.2% (95% CI: 85.9-90.2, p<0.0001) and 92.1% (95% CI: 90.2-93.7, p<0.0001) respectively. Calibration analysis revealed Hosmer-Lemeshow test p-values for the AusSCORE II and STS Score as 0.696 and 0.294 respectively. DISCUSSION: ROC curve analysis produced very high and statistically significant AUC values for the AusSCORE II and STS Score. Hosmer-Lemeshow test analysis revealed that both risk scoring tools are well calibrated for our study cohort. Therefore, the AusSCORE II and STS Score are both strongly predictive of 30-day mortality for isolated coronary artery bypass grafting surgery in our New Zealand patient population. Both risk models have performed with excellent discrimination and calibration. There is, however, a need to consider the performance of these risk stratification models in other cardiac surgical procedures outside isolated coronary bypass surgery where appropriate.

Rib Cage Stabilisation With 3D-Printed Polyethylene Sternal Prosthesis Post-Sternotomy Mediastinitis.

BACKGROUND: Post-sternotomy mediastinitis (PSM) is a serious complication of median sternotomy. It is associated with a high mortality rate. Evidence based management recommends debridement followed by closure with vascularised flaps. When large areas of resections are performed, the use of sternal prosthesis could be considered to ensure chest wall stability and cosmesis. METHOD: We report an individualised three-dimensional (3D)-printed high-density polyethylene (HDPE) sternum implantation in a patient with a 10 cm chest wall defect. RESULTS: Chest wall reconstruction was uncomplicated and the patient tolerated the procedure well without cardiorespiratory compromise. Postoperatively, the wound healed well and the chest wall remained stable at outpatient clinic follow-up. CONCLUSION: Three-dimensional-printed HDPE prosthesis offers an alternative implant option for closing large chest wall defects for eroded sternum after cure of mediastinitis.

Assessment of the EuroSCORE II in a New Zealand Tertiary Centre.

BACKGROUND: The updated European System for Cardiac Operative Risk Evaluation (EuroSCORE II) is a well-established cardiac surgery risk scoring tool for estimating operative mortality. This risk stratification system was derived from a predominantly European patient cohort. No validation analysis of this risk model has been undertaken for the New Zealand population across all major cardiac surgery procedures. We aim to assess the efficacy (discrimination and calibration) of the EuroSCORE II for predicting mortality in cardiac surgical patients at a large New Zealand tertiary centre. METHODS: Data was prospectively collected on patients undergoing cardiac surgery from September 2014 to September 2017 at Waikato Hospital, New Zealand. Patient demographic information, preoperative clinical risk factors and outcome data were entered into a national database. Included patients received either isolated coronary artery bypass grafting (CABG), isolated valve surgery, isolated thoracic aortic surgery, or a combination of these procedures. The primary outcome was the discrimination and calibration of predicted EuroSCORE II risk scores compared with observed 30-day mortality events. RESULTS: 1,666 cardiac surgery patients were included during the study period, with an average EuroSCORE II of 2.97% (95% confidence interval (CI): 2.76-3.18). Nine hundred thirty-three (933) patients underwent isolated CABG, 384 underwent isolated valve surgery, 48 received isolated thoracic aortic surgery and 301 received combination procedures. Thirty-day (30-day) mortality events in each of these groups was 7, 4, 2 and 13 deaths respectively. There were 26 deaths across the total cohort at 30-days (observed mortality rate 1.56%). Discrimination analysis using receiver operating characteristic curves demonstrated the area under the curve (AUC) of the EuroSCORE II in each of these groups as 93.4% (95% CI: 91.6-94.9, p<0.0001), 66.3% (95% CI: 61.3-71.0, p=0.37), 37.0% (95% CI: 15.7-58.2, p=0.23) and 74.8% (95% CI: 69.5-79.6, p<0.0001) respectively. The total cohort AUC was 83.1% (95% CI: 81.2-84.9, p<0.0001). Calibration analysis using Hosmer-Lemeshow tests for the subgroups revealed p-values of 0.848, 0.114, 0.638 and 0.2 respectively. The total cohort Hosmer-Lemeshow p-value was 0.317. CONCLUSIONS: EuroSCORE II showed a strong discriminative ability for isolated CABG 30-day mortality in a New Zealand patient cohort. However, the scoring system discriminated poorly across valvular, thoracic aortic or complex combination cardiac surgical procedures. Good calibration of the EuroSCORE II was achieved across both the total cohort and subgroups. It is important to consider the performance of other cardiac surgery risk stratification models for the New Zealand population.

Early Discharge From Intensive Care After Cardiac Surgery is Feasible With an Adequate Fast Track, Stepdown Unit: Waikato Experience.

BACKGROUND: Enhanced recovery programs within cardiothoracic surgery are a well described benefit to patient postoperative outcomes. We describe our Australasian unit's experience of a day zero discharge enhanced recovery unit from the intensive care department. METHODS: A retrospective study was conducted on a prospectively maintained database at Waikato Cardiothoracic Unit from September 2014 till October 2017 with 1,739 patients undergoing cardiac surgery. Twenty-two (22) patients were excluded as deaths either intraoperative or in the intensive care unit (ICU) and therefore never discharged. Total population of the study was 1,717 patients. The primary endpoint of this study was to determine if there is no survival disadvantage for the day zero discharge unit compared to standard treatment in ICU at follow-up. The secondary endpoint of the study was to highlight the association between pre and postoperative variables and the impact on discharge from the ICU. RESULTS: One hundred sixty-eight (168) patients were discharged to the enhanced recovery unit (ERU) day zero. Mean number of hours spent in ICU for the day zero cohort was 7.18 (±1.59. Mean Age 62.5 (±11.22), M:F 4.25:1. Patients were more likely to be discharged day zero if they had a lower EuroSCORE II 1.57 (±1.67) and lower preoperative creatinine 89.4 (±27.5). Those admitted to the ERU on day zero postoperatively were more likely to be discharged with a lower creatinine level, a higher haemoglobin level and have less readmissions per 30days (p<0.05). Survival analysis demonstrated that the patients who were discharged early from ICU had significantly better follow-up survival compared to those who were discharged after 24hours (p<0.05). CONCLUSIONS: A fast track unit increases the efficiency of an ICU and cardiac surgical department. With the advancements of cardiac surgery a higher number of patients will be suitable for a fast track method. Our unit has demonstrated that a day zero fast track unit in New Zealand can perform with adequate patient safety with no increased risk of mortality and with low rates of failure of the day zero discharge fast track therapy.

Position statement for the operator and institutional requirements for a transcatheter aortic valve implantation (TAVI) program.

The Cardiac Society of Australia and New Zealand (CSANZ) and the Australia and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) have joined together to provide recommendations for institutions and individual operators to assess their ability to initiate and maintain a transcatheter valve program. Transcatheter aortic valve replacement has been developed as an alternative to traditional surgical replacement of the aortic valve in high risk patients, particularly the frail elderly. The position paper has endorsed the important role of a multi-disciplinary "Heart Team" in selecting patients for TAVI as fundamental to the establishment of a successful program. The paper outlines recommendations for the cardiologist to have a background in structural intervention and the surgeon to have experience in high-risk aortic valve replacement. It is further recommended that TAVI programs be established in high volume cardiac surgical centres where on site valve surgery is performed. The paper is intended to provide guidance to individual operators and prospective institutions considering the establishment of a successful TAVI program.