Ethnicity Is Associated With Differing Presentation and Outcomes of Patients Undergoing Aortic Valve Replacement for Calcific Aortic Stenosis in Aotearoa New Zealand.

AIM: Surgical aortic valve replacement (SAVR) has been the gold standard for treatment of severe symptomatic aortic stenosis (AS) for decades. We examined whether ethnic differences exist in the presentation and outcomes of patients undergoing aortic valve replacement (AVR) for AS in New Zealand. METHODS: Patients of New Zealand European, Maori, and Pacific Island ethnicities undergoing SAVR with or without other procedures in New Zealand public hospitals from 2017 to 2019 were included. Major postoperative outcomes were compared between ethnic groups, with 30-day mortality being the primary outcome. RESULTS: A total of 1,175 patients were included: 1,085 European, 50 Maori, and 40 Pacific. The mean age was 71.1±9.4 years, and men accounted for more than half of all patients (69.9%). Maori (64.7±9.4 years) and Pacific (65.4±10.1 years) patients were younger when undergoing SAVR compared with European patients (71.7±9.2; analysis of variance p<0.001). Maori and Pacific patients had a higher prevalence of diabetes, poorer renal function, and worse left ventricular function; 30-day mortality was higher in Maori and Pacific compared with European patients (6% and 10% vs 2.4%, respectively; Fisher's exact test p=0.011), with odds ratio of 3.06 (95% confidence interval [CI] 0.88-10.66) for Maori patients after adjustment for EuroSCORE II and odds ratio of 5.23 (95% CI 1.79-16.07) for Pacific patients. CONCLUSIONS: There are significant differences in presentation and outcomes of patients undergoing AVR in New Zealand. Maori and Pacific patients undergo SAVR at a younger age, have more preoperative comorbidities, and have higher rates of 30-day mortality than European patients.

Utilizing retrograde autologous priming for blood conservation in cardiac surgery.

BACKGROUND: The use of crystalloid priming for extracorporeal circuit in adult cardiac surgery causes inevitable haemodilution. The haemodilution can be reduced by using methods such as retrograde autologous priming (RAP) with the patient's blood. This study compares the RAP technique with standard priming with regards to safety and the impact on haemodilution. METHODS: This was a retrospective cohort study between a control group (n = 100) consisting of consecutive patients undergoing first time isolated coronary artery bypass surgery (CABG) with crystalloid priming solution in the circuit, and the RAP group (n = 100) consisting of patients undergoing isolated first time CABG with the RAP method. All demographics, procedure and perfusion data were gathered from the local surgical and perfusion database. RESULTS: Despite starting with comparable mean pre-operative haemoglobin (Hb) levels (control 127 mg/dL versus RAP 129 mg/dL), the RAP group had significantly higher mean post-op Hb level (109 mg/dL versus 92 mg/dL, P < 0.01). Crystalloid use was also significantly lower in RAP group (3.15 L versus 4.17 L P < 0.02). Freedom from red blood cell transfusion (86% versus 76% P = 0.038) and freedom from blood products (78% versus 66%, P = 0.032) was also significantly better in the RAP group. CONCLUSIONS: This study demonstrates that retrograde autologous priming is a safe and effective method for priming the cardiopulmonary bypass circuit in adult cardiac surgery, with significantly beneficial effects on transfusion rates and intra operative fluid requirements. Given these results the RAP method should be considered as a routine step in priming an extracorporeal circuit for adult cardiac operations.

Single-Sided Magnet System for Quantitative MR Relaxometry and Preclinical In-Vivo Monitoring.

OBJECTIVE: We have developed a single-sided magnet system that allows Magnetic Resonance relaxation and diffusion parameters to be measured. METHODS: A single-sided magnet system has been developed, using an array of permanent magnets. The magnet positions are optimised to produce a B0 magnetic field with a spot that is relatively homogenous and can project into a sample. NMR relaxometry experiments are used to measure quantitative parameters such as T2, T1 and apparent diffusion coefficient (ADC) on samples on the benchtop. To explore preclinical application, we test whether it can detect changes during acute global cerebral hypoxia in an ovine model. RESULTS: The magnet produces a 0.2 T field projected into the sample. Measurements of benchtop samples show that it can measure T1, T2 and ADC, producing trends and values that are in line with literature measurements. In-vivo studies show a decrease in T2 during cerebral hypoxia that recovers following normoxia. CONCLUSION: The single-sided MR system has the potential to allow non-invasive measurements of the brain. We also demonstrate that it can operate in a pre-clinical environment, allowing T2 to be monitored during brain tissue hypoxia. SIGNIFICANCE: MRI is a powerful technique for non-invasive diagnosis in the brain, but its application has been limited by the requirements for magnetic field strength and homogeneity that imaging methods have. The technology described in this study provides a portable alternative to acquiring clinically significant MR parameters without the need for traditional imaging equipment.

Stress Ulcer Prophylaxis in Cardiac Surgery: A Retrospective Cohort Study to Analyze the Effects of SUP Cessation.

INTRODUCTION: Upper gastrointestinal bleeding (UGIB) is an important complication among critically ill adults, especially those having cardiac surgery as management is complicated by the requirement for antiplatelet/anticoagulant therapy. As a result, stress ulcer prophylaxis (SUP) has become routine practice in many centers, utilizing either proton pump inhibitors (PPIs) or histamine-2 receptor blockers (H2RBs). Recent evidence from the PEPTIC trial indicated an increase in mortality risk among cardiac surgery patients receiving PPIs compared to H2RBs. Considering these findings, alongside practical difficulties surrounding the transition to H2RBs as a prophylactic agent in New Zealand, Wellington Hospital intensive care unit elected to discontinue routine PPI use for SUP in cardiac surgery patients. A retrospective study was conducted to assess patient outcomes following the discontinuation of routine SUP. METHOD: A retrospective cohort study was conducted of all adult patients who underwent cardiac surgery at Wellington Hospital between February/2018 and January/2022, and divided patients into cohorts before and after the discontinuation of routine use of SUP on the 31st of January 2020. The primary outcomes were the rate of UGIB, oesophagogastroduodenoscopy (OGD) and 180-day postoperative mortality. Secondary outcomes included rates of postoperative Clostridium difficile enteritis, pneumonia, deep sternal wound infection, and length of stay of the index admission. RESULTS: The rate of UGIB statistically significantly increased since the cessation of routine SUP in January 2020 (2.4% vs 5.4%, P-value = .004). This finding was mirrored with the increased rates of OGD (1.9% vs 4.0%, P-value = .005). There were no significant changes in 180-day mortality, hospital length of stay, or any of the postoperative infective complications analyzed, pneumonia, deep sternal wound infection, or C difficile enteritis. CONCLUSION: This study suggests an association between routine use of SUP and reduced rates of clinically significant UGIB and OGD requirements in cardiac surgery patients without increasing risk of infective complications or postoperative mortality.

Case Series of Early Structural Valve Deterioration of Trifecta Bioprosthesis - New Zealand Experience.

PURPOSE: Structural valve deterioration (SVD) remains a limitation on the use of bioprosthetic valves, with patient and valve-related factors contributing to early SVD. The Trifecta valve has been reported to have excellent hemodynamics but studies have highlighted early failure. We present a review and case series at a New Zealand tertiary hospital defining early SVD as failure within 3 years of implant. METHODS: A retrospective review from January 2015 to July 2019 included 525 patients undergoing surgical aortic valve replacement with 263 patients receiving an Abbott Trifecta or Trifecta Glide Technology (GT) valve. Our review found an acceptable safety profile for the valve with excellent hemodynamics, with a low mortality, stroke, and permanent pacemaker rate. RESULTS: Three patients out of 263 were identified from the study period as having early SVD requiring reintervention within 3 years of valve implantation leading to a 1.14% failure rate. One of the valves that had early SVD was a new generation Trifecta GT. An additional four patients were identified to have valves implanted prior to the study period and had valve failure at greater than 3 years post implantation. Five cases had cusp tears as their mechanism of failure, raising concerns about durability. CONCLUSION: The Trifecta valve has an acceptable safety profile and offers good hemodynamics due to the externally mounted leaflets. However, our experience of early SVD and failure is concerning for valve durability. Further comparison to other bioprosthetic valves and longer term follow-up are required to characterize the mechanism of failures.

The Effects of the COVID-19 Pandemic on Cardiac Surgery Volumes and Outcomes in New Zealand.

AIM: New Zealand adopted an "elimination strategy" in response to the 2020 COVID pandemic with strict early border controls and early national lockdowns. The international experience of cardiac surgery provision during the COVID pandemic was of reduced case numbers, difficulties with the provision of elective surgery and in some cases increased morbidity associated with waiting for surgery and from developemnt of the infection in post operative patients. We aim to review the effects the COVID-19 pandemic has had on adult cardiac surgery volumes and outcomes in the Wellington region. METHOD: Utilising local data submitted to the New Zealand National cardiac surgical database, we analysed all cardiac operations completed at a tertiary cardiothoracic centre between January 1st 2019 till December 31st 2020. The COVID-19 lockdown period (March-April 2020) was compared with its' 2019 counterpart as well as the sequential months to analyse for any 'rebound' effect. Number of surgeries, proportion of elective cases, and surgery type were assessed. RESULTS: The lockdown period of March-April/2020 showed a higher number of cardiac surgery cases per month compared to a the same period in  2019 (48.5 vs 39.0 cases/month, P=0.74). A surge in acute cases was noted in September-December 2020 with 57 acute operations completed, compared to 23 for the corresponding time period in 2019. CONCLUSION: The New Zealand response to the COVID pandemic resulted in low relative rates of community transmission and only a small number of patients admitted to hospital.  We did not see a reduction in routine cardiac operations or changes in clincial outcome over this period. Despite the lockdown period, due to low numbers of community and COVID cases in our ICU and hospital we were able to maintain a full operating capacity throughout. We did observe an increase in acute cases following the lockdown likely due to the reduced access to routine cardiology clinics and deferrable diagnostic services.

Cell Populations Expressing Stemness-Associated Markers in Lung Adenocarcinoma.

The stemness-associated markers OCT4, NANOG, SOX2, KLF4 and c-MYC are expressed in numerous cancer types suggesting the presence of cancer stem cells (CSCs). Immunohistochemical (IHC) staining performed on 12 lung adenocarcinoma (LA) tissue samples showed protein expression of OCT4, NANOG, SOX2, KLF4 and c-MYC, and the CSC marker CD44. In situ hybridization (ISH) performed on six of the LA tissue samples showed mRNA expression of OCT4, NANOG, SOX2, KLF4 and c-MYC. Immunofluorescence staining performed on three of the tissue samples showed co-expression of OCT4 and c-MYC with NANOG, SOX2 and KLF4 by tumor gland cells, and expression of OCT4 and c-MYC exclusively by cells within the stroma. RT-qPCR performed on five LA-derived primary cell lines showed mRNA expression of all the markers except SOX2. Western blotting performed on four LA-derived primary cell lines demonstrated protein expression of all the markers except SOX2 and NANOG. Initial tumorsphere assays performed on four LA-derived primary cell lines demonstrated 0-80% of tumorspheres surpassing the 50 µm threshold. The expression of the stemness-associated markers OCT4, SOX2, NANOG, KFL4 and c-MYC by LA at the mRNA and protein level, and the unique expression patterns suggest a putative presence of CSC subpopulations within LA, which may be a novel therapeutic target for this cancer. Further functional studies are required to investigate the possession of stemness traits.

Black Aorta from Alkaptonuria.

A-76-year old male with a past history of alkaptonuria with ochronosis (homogentisic acid deposition in tissues) had symptomatic aortic stenosis. Surgical replacement of the valve was undertaken, and he was noted to have a severely pigmented and porcelain aorta.

Conservative versus conventional oxygen therapy for cardiac surgical patients: A before-and-after study.

Avoiding hypoxaemia is considered crucial in cardiac surgery patients admitted to the intensive care unit (ICU). However, avoiding hyperoxaemia may also be important. A conservative approach to oxygen therapy may reduce exposure to hyperoxaemia without increasing the risk of hypoxaemia. Using a before-and-after design, we evaluated the introduction of conservative oxygen therapy (target SpO2 88%-92% using the lowest FiO2) for cardiac surgical patients admitted to the ICU. We studied 9041 arterial blood gas (ABG) datasets: 4298 ABGs from 245 'conventional' and 4743 ABGs from 298 'conservative' oxygen therapy patients. During mechanical ventilation (MV) and while in the ICU, compared to the conventional group, conservative group patients had significantly lower FiO2 exposure and PaO2 values ( P < 0.001 for each). Accordingly, using the mean PaO2 during MV, more conservative group patients were classified as normoxaemic (226 versus 62 patients, P < 0.01), fewer as hyperoxaemic (66 versus 178 patients, P < 0.01) and no patient in either group as hypoxaemic or severely hypoxaemic. Moreover, more ABG samples were hyperoxaemic or severely hyperoxaemic during conventional treatment ( P < 0.001). Finally, there was no difference in ICU or hospital length of stay, ICU or hospital mortality or 30-day mortality between the groups. Our findings support the feasibility and physiological safety of conservative oxygen therapy in patients admitted to ICU after cardiac surgery.

Initial Experience of the Use of 3-Factor Prothrombin Complex Concentrate and Thromboembolic Complications After Cardiac Surgery.

BACKGROUND: 3-factor prothrombin complex concentrate (3F-PCC) may provide a valuable treatment option for coagulopathy in cardiac surgery patients. However, it may expose patients to increased risk of thromboembolic events. Accordingly, we compared the incidence of thromboembolic events between patients exposed to 3F-PCC and those receiving conventional therapy. METHODS: Demographic, operative and postoperative data was obtained in a cohort of consecutive patients exposed to 3F-PCC and a contemporaneous control population. Propensity-score matching was performed for risk adjustment. Unadjusted and adjusted patient demographics and incidence of thromboembolism were compared. RESULTS: Patients receiving 3F-PCC (PCC) were younger (mean age PCC: 64±14.2 vs. No PCC: 67.6±11.6, p=0.022), and less likely to have diabetes or previous myocardial infarction. PCC patients experienced more prolonged aortic cross clamp times (mean time in minutes PCC: 119.9±58.8 vs. No PCC: 92.3±54), more complex cardiac surgeries and were more likely to have received more fresh frozen plasma (FFP), cryoprecipitate and red blood cells. Despite this, both unadjusted and adjusted 30-day mortality and readmission rates were similar between groups. There were 9 (9.2%) and 34 (6.8%) (p=0.40) thromboembolic events in the unadjusted PCC and control groups respectively. Adjusted risk for thromboembolic event rates was also comparable (Odds ratio: 1.512, 95% Confidence Interval 0.401-5.7, p=0.541). CONCLUSIONS: 3-factor prothrombin complex concentrate was administered to patients at greater risk of complications including bleeding. Our initial experience suggests that the use of PCC does not appear to increase thromboembolic risks compared to conventional treatment.

Acute Lower Leg Compartment Syndrome: A Rare Complication following CABG.

Compartment syndrome of lower legs following coronary artery bypass grafting is a rare complication which results from a combination of local and systemic factors. Early recognition is vital for good outcome. The case discussed describes this rare complication of CABG resulting in long term disability.

Total aortic repair: the new paradigm in the treatment of acute type A aortic dissection.

The surgical management of acute type A aortic dissection (ATAAD) is in a period of rapid evolution. Understanding the complex physiology and anatomy of both acute and chronic dissection has been enhanced by the ready availability of state of the art imaging techniques. Technical advances in the intraoperative monitoring of organ perfusion, together with adjuncts to limit organ injury and increasing sophistication in open and endovascular surgery have led to a major reduction in both perioperative morbidity and mortality. In many centers, there has been a transition in mindset and surgical approach away from a purely central aortic operation focusing on the ascending aorta and a 'live to fight another day' philosophy. The current more global perspective recognizes the importance of aortic valve function, malperfusion, false lumen (FL) patency and the potential for future complex aneurysm development. The time is now right to transition into the next phase of sophistication in the management of ATAAD with the aim of achieving not only a safe acute operation, but to either entirely prevent chronic complications or to greatly simplify their management by the creation of an anatomical situation that facilitates future endovascular intervention in place of complex re-do surgery. We present our view on the evolution of surgery for ATAAD leading to our current technique of Branch First Arch replacement and Total Aortic Repair, which not only provides a safe immediate operation, but also offers the hope of a simplified future management if not a total cure for the pathology.

Surgical management of acute type A aortic dissection: branch-first arch replacement with total aortic repair.

Acute type A dissection (ATAAD) remains a morbid condition with reported surgical mortality as high as 25%. We describe our surgical approach to ATAAD and discuss the indications for adjunct techniques such as the frozen elephant trunk or complete aortic repair with endovascular methods. Arch replacement using the "branch-first technique" allows for complete root, ascending aorta, and arch replacement. A long landing zone is created for proximal endografting with a covered stent. Balloon-assisted intimal disruption and bare metal stenting of all residual dissected aorta to the level of the aortic bifurcation is then performed to obliterate the false lumen (FL) and achieve single true lumen (TL) flow. Additional branch vessel stenting is performed as required.