The Role of ADAMTS Proteoglycanases in Thoracic Aortic Disease.

Thoracic aortic aneurysm and dissection (TAAD) are complex disease states with high morbidity and mortality that pose significant challenges to early diagnosis. Patients with an aneurysm are asymptomatic and typically present to the emergency department only after the development of a dissection. The extracellular matrix (ECM) plays a crucial role in regulating the aortic structure and function. The histopathologic hallmark termed medial degeneration is characterised by smooth muscle cell (SMC) loss, the degradation of elastic and collagen fibres and proteoglycan (PG) accumulation. Covalently attached to the protein core of PGs are a number of glycosaminoglycan chains, negatively charged molecules that provide flexibility, compressibility, and viscoelasticity to the aorta. PG pooling in the media can produce discontinuities in the aortic wall leading to increased local stress. The accumulation of PGs is likely due to an imbalance between their synthesis by SMCs and decreased proteolysis by A Disintegrin-like and Metalloproteinase with Thrombospondin motifs (ADAMTS) proteoglycanases in the ECM. Mouse models of TAAD indicated that these proteases exert a crucial, albeit complex and not fully elucidated, role in this disease. This has led to a mounting interest in utilising ADAMTS proteoglycanases as biomarkers of TAAD. In this review, we discuss the role of ADAMTSs in thoracic aortic disease and their potential use in facilitating the clinical diagnosis of TAAD and disease progression.

How to test adhesive strength: a biomechanical testing for aortic glue used in type a dissection repair.

OBJECTIVES: The aim of this study was to develop a method to quantify the peel force in an in vitro model simulating repair of ascending aortic dissections with tissue glue (Bioglue). METHODS: This study adapted an adhesive T-Peel test for the determination of the peel strength of adhesives by measuring the peeling force of a T-shaped bonded tissue. Measurements were performed on iatrogenic dissected ascending porcine aorta, which has been repaired with Bioglue using different pressure levels. Four conditions were tested: zero sample pressure according to the manufacturer's recommendation (n = 10), low (504 Pa; n = 11), moderate pressure (1711 Pa; n = 24) and pressure applied by a round shaped vascular 'Borst clamp' (1764 Pa; n = 23). Non-parametric one-way analysis of variance was applied for statistical significance. RESULTS: The median peel force (lower quartile, upper quartile) of aortic samples increased depending on the applied pressure: [no pressure 0.030 N/mm (0.016, 0.057), low pressure 0.040 N/mm (0.032, 0.070) and moderate pressure 0.214 N/mm (0.050, 0.304)]. Samples pressurized with the Borst clamp reached 0.078 N/mm (0.046, 0.152), which was comparable to the peel force of the unpeeled controls [0.107 N/mm (0.087, 0.124)]. Compared to samples without pressure, Bioglue with the application of the Borst clamp (P = 0.021) and with moderate pressure (P = 0.0007) performed significantly better. CONCLUSIONS: The novel T-Peel test offers an attractive method to test tissue glues in defined in vitro environments. Bioglue peel force increased with pressure on the aortic sample in contrast to low or no pressure as per the manufacturer's recommendation. Modifying current recommended use may aid in increasing effectiveness of this approach.

Establishing the Safety of Training in Off-Pump Coronary Artery Bypass Surgery: A Retrospective Comparison of Outcomes between Trainees and a Consultant Surgeon.

BACKGROUND: The safety of training in off-pump coronary artery bypass (OPCAB) surgery and the stage at which trainees should be exposed to this technique remain controversial. This single-center retrospective study aimed to compare outcomes of OPCAB surgery in consultant and trainee cases. METHODS: Between 2014 and 2018, all isolated OPCAB operations performed under the care of a consultant surgeon (G.A.) were analyzed. Cases where a surgeon below consultant grade performed at least 70% of the distal anastomoses were designated as "trainee cases" with the remaining cases designated as "consultant cases." The baseline characteristics of patients, perioperative data, and short-term outcomes were prospectively collated and analyzed. RESULTS: During the study period, 245 OPCAB cases were identified: 142 (58%) consultant and 103 (42%) trainee cases. The trainee cases were performed exclusively by trainees in the final 2 years of the UK National Cardiothoracic Training Program. Both trainee and consultant groups had low mortality with two perioperative deaths occurring in either group. The rates of serious postoperative complications including stroke (n = 1 vs. 2, p = 0.759), resternotomy for bleeding (n = 3 vs. 7, p = 0.431), and mediastinal infection (n = 2 vs. 3, p = 0.926) were low and not significantly different between the two groups. Patients operated on by trainees had a slightly longer hospital stay than those operated on by the consultant surgeon, although this did not reach statistical significance (9.9 vs. 7.9 days). CONCLUSIONS: These results demonstrate comparable outcomes in OPCAB surgery between a consultant surgeon and trainees. This study supports the conclusion that training surgeons in OPCAB is appropriate for trainees in the final years of cardiac surgery training.

Delayed diagnosis of chronic postoperative sternal infection: a rare case of sternal tuberculosis.

Sternal osteomyelitis secondary to mycobacterium tuberculosis (TB) is rare, with <1% of musculoskeletal TB cases reported. The recurrent scenario is unresolving infection and delayed diagnosis. A 75-year-old woman presented with a persistently discharging sternal wound 10 months after coronary artery bypass grafting. Multiple antibiotics, wound debridement and removal of sternal wires was attempted; however, progression to local osteomyelitis and sternoclavicular joint destruction occurred. Tissue biopsies were finally sent for mycobacterial culture testing positive for Mycobacterium tuberculosis High index of suspicion is necessary for diagnosis of sternal tuberculosis, confirmed through timely microbiological investigations. MRI may identify soft-tissue and bone oedema characteristic of TB osteomyelitis. This patient had no TB risk factors. The source of infection is unclear and warrants further investigation. Sternal TB osteomyelitis is uncommon and largely reported through case reports, thus management and indications for surgery remain undefined. If sensitive, standard TB four-drug regimen may be trialled.

Effect of tranexamic acid use on blood loss and thromboembolic risk in hip fracture surgery: systematic review and meta-analysis.

INTRODUCTION: Intravenous tranexamic acid (IV TXA) is a recognised pharmaceutical intervention utilised to minimise blood loss and allogenic blood transfusion. However, the use of IV TXA in hip fracture surgery remains inconclusive. We conducted a meta-analysis to investigate the role of TXA in operative hip fracture management on operative and total blood loss, allogenic blood transfusion requirements and impact on venous thromboembolic (VTE) event incidence. METHODS: A systematic computerised literature search of PubMed, Medline, Embase, Ovid, The Cochrane Controlled Trials Register, Trip and Google was conducted. We reviewed the efficacy of IV TXA on perioperative blood loss, total blood loss, pre- and postoperative haemoglobin differences, duration of surgery, allogenic blood transfusion requirements and VTE events. RESULTS: 8 studies were eligible including 6 randomised control trials and 2 cohort studies. Patients receiving IV TXA had reduced mean total blood loss of 442.9 mls (95% CI, 426.5-459.3; p<0.00001), reduced operative blood loss of 88.5 mls (95% CI, 59.9-117.2; p<0.00001), a decrease in the need for allogenic blood transfusion (OR 0.37; 95% CI, 0.26-0.53; p<0.00001) and a reduction in pre- and postoperative haemoglobin difference (p = 0.013.) There was no significant increase in VTE risk (OR 1.59; 95% CI 0.67-3.75; p>0.29) or significant difference on duration of surgery seen with IV TXA usage (p>0.06). CONCLUSIONS: Our review demonstrated the efficacy of IV TXA in minimising perioperative, reducing total blood loss and lowering the necessity for allogenic blood transfusions with no significant increased risk in VTE events.

Five-year experience with mobile adult extracorporeal membrane oxygenation in a tertiary referral center.

INTRODUCTION: Mobile extracorporeal membrane oxygenation (ECMO) is reserved for critically unstable patients who may not otherwise survive transfer to the ECMO center. We describe our experience with mobile ECMO. METHODS: We retrospectively reviewed adult patients between 2010 and 2014 who were referred for ECMO support and were too unwell for conventional transfer. They were cannulated at their referring center by our team and subsequently transported back to our hospital on ECMO. RESULTS: A total of 102 patients were put on ECMO by our team. Of 102 patients, 95 (93%) were managed by venovenous ECMO, and 7 (7%), by venoarterial ECMO. The average distance traveled was 195 miles (SD, ±256.8; range, 3.6-980). Transportation was via road in 77 cases (77%), by air in 22 cases (22%), and in 3 cases (3%) a combination of road and air was used. A double-lumen Avalon cannula was used in 72 patients (70%). One patient had a ventricular tachycardia arrest during cannulation but was successfully resuscitated. There was no mortality or major complications during transfer. CONCLUSION: The use of mobile ECMO in adult patients is a safe modality for transfer of critically unwell patients. We have safely used double-lumen cannulas in most of these patients.