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.

Low copper levels measured in the aortic wall of New Zealand patients with non-syndromic ascending thoracic aortic aneurysm.

OBJECTIVES: Studies in animals have shown causal relationships between copper (Cu) deficiency and the development of thoracic aortic aneurysms (TAAs) [1, 2]. Cu deficiency is widespread in New Zealand (NZ) soils; the high soil pH from the use of lime fertilizers reduces the bioavailability of Cu for grazing animals and growing plants; this, in turn, reduces Cu availability in the NZ human food chain. Our study is a pilot study to explore associations between Cu and TAA. We measured Cu levels in aneurysmal aortic tissues in patients undergoing Bentall procedures and non-aneurysmal aortic tissue from coronary artery bypass graft patients. METHODS: Aortic samples were collected from 2 groups of patients during elective open-heart surgery over 4 months between November 2017 and February 2018. The groups were a TAA group, patients with non-syndromic aortic aneurysm and without the bicuspid aortic valve or known infectious or inflammatory condition (ANEURYSM; n = 13), and a control coronary artery bypass graft group (CONTROL; n = 44). Standardized digested dry tissue weighed samples were analysed from both groups. Tissue extraction of trace elements was carried out using HCl-H2O2 digestion and a highly sensitive analytical technique, inductively coupled plasma mass spectrometry-used to measure elemental concentrations. RESULTS: Cu concentration (mean ± SD) was significantly lower in ANEURYSM (3.34 ± 0.16 µg/g) when compared to the CONTROL group tissues (4.33 ± 0.20 µg/g) (dry weight; mean ± SD; Student's t-test, P < 0.05). Over 46% of the Aneurysm patients were Maori and live in a geographically Cu-deficient NZ territory. CONCLUSIONS: Cu deficiency may play a role in the development or progression of non-syndromic ascending aortic aneurysms in NZ. Maori patients are more at risk as they commonly live in rural NZ, dependent on locally grown nutritional sources. Further studies are required to confirm this exciting finding and to establish cause and effect relationship.

Early diagnosis of surgically curable lung cancer is commonly serendipitous.

AIMS: Lung cancer is the largest cause of cancer death in New Zealand, accounting for 18.3% of cancer-related deaths.[[1,2]] There is limited literature on how patients with lung cancer clinically present in New Zealand. The aim of this cohort study was to identify the rate of incidentally diagnosed lung cancer in the Midland Region, the common symptomatology and route of diagnosis. METHODS: This retrospective cohort study included patients with lung cancer who underwent potentially curative thoracic surgery between January 2011 to June 2018 at Waikato Hospital, New Zealand. Symptoms or signs recorded were cough, dyspnoea, haemoptysis, lymphadenopathy, chest pain, hoarseness, fatigue, weight loss and finger clubbing. The lung cancer cases were grouped into incidental finding, symptomatic general practitioner, symptomatic emergency department and surveillance. RESULTS: Three hundred and ten patients with lung cancer had thoracic surgery with curative intent at Waikato Hospital. Two hundred and fourteen (69%) patients had symptoms which prompted presentation to a treating physician and 96 (31%) patients were asymptomatic. Incidental diagnosis was demonstrated in 121 (39.4%) patients. Of the patients diagnosed incidentally, 36.4% (n=44) had symptoms of lung cancer with the main symptoms including 45% with cough (n=20), 28% with dyspnoea (n=12) and 28% chest pain (n=12). CONCLUSIONS: In New Zealand, a large amount of lung cancer is still diagnosed incidentally with symptoms of cough, dyspnoea and chest pain. Further research into the development of a lung cancer screening program in New Zealand for a high-risk population is warranted.

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.

Left Atrial Appendage Closure: Novel Cor-Knot Lasso Technique Ensures Complete and Safe Ligation.

The significance of the left atrial appendage has been well known for a half century. Surgeons used a number of left atrial appendage closure techniques to reduce the risk of stroke without increasing the chance of bleeding from fragile left atrial appendage. Removal and oversewing are simple and effective. Current procedures, however, have the disadvantage of 30% to 40% residual appendage. Here, we discuss our innovative lasso technique using a Cor-Knot device for left atrial appendage closure in 50 consecutive patients between January 2018 and January 2019 who underwent mitral valve surgery. This technique ensured complete closure, with no new cerebrovascular events during the 2-year follow-up.

Transcatheter Aortic Valve Replacement in Pure Native Aortic Valve Regurgitation: Challenging Pathology Awaiting Specialized Devices.

Patients with aortic incompetence frequently present with anatomical and pathological challenges such as elliptical dilated annulus, dilated aortic root, dilated ascending aorta, and with no calcification in the aortic cusps or annulus. Patients are commonly in graver clinical condition as a result of a long silent clinical course before overt congestive heart failure. All of the above make transcatheter therapies for native aortic valve regurgitation more challenging with poorer outcomes, escalating the risk of insufficient anchoring, prosthesis migration, and residual paravalvular leak compared with current transcatheter aortic valve replacement (TAVR) outcomes for aortic stenosis. There is a need for specialized TAVR devices to address this complex pathology. Surgical aortic valve replacement is the current treatment option and the gold standard for patients with aortic incompetence (AR). Currently, the specific off-label indication for TAVR in pure native AR could be a feasible and reasonable option, as a compassionate treatment is limited to inoperable patients and agreed on by the heart team.

Cardiac surgery simulation: a low-cost feasible option in an Australasian setting.

BACKGROUND: Simulation training is a useful adjunct to surgical training and education (SET) in Cardiothoracic Surgery yet training opportunities outside the Royal Australasian College of Surgery or industry-sponsored workshops are rare due to high cost and limited training faculty, time, assessment tools or structured curricula. We describe our experience in establishing a low-cost cardiac simulation programme. METHODS: We created low-cost models using hospital facilities, hardware stores, abattoirs and donations from industry. Three workshops were conducted on coronary anastomoses, aortic and mitral valve replacement. RESULTS: Whole porcine hearts were sourced from local farms. Industry donations of obsolete stock were used for suture and valve material-stations constructed using ironing-board, 2-L buckets and kebab-skewers. Suture ring holders were fashioned from recycled cardboard or donated. All participants were asked to complete pre and post simulation self-assessment forms. Across three workshops, 45 participants (57.8% female) with a median age 27 (interquartile range 24-31) attended. Training level consisted of nurses (8, 17.8%), medical students (17, 37.8%), residents/house officers (6, 13.3%) and registrars (14, 31.1%). There were improvements in knowledge of anatomy (mean difference 18%; 95% confidence interval 12%-24%), imaging (16%; 10%-22%) and procedural components (34%; 28%-42%); and practical ability to describe steps (30%; 24%-38%), partially (32%; 26%-38%) or fully complete (32%; 28%-38%) the procedure. CONCLUSIONS: Simulation-based training in cardiac surgery is feasible in a hospital setting with low overhead costs. It can benefit participants at all training levels and has the potential to be implemented in training hospitals as an adjunct to the SET programme.

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.