Research

Characterization of the hypercoagulable state following severe orthopedic trauma

by

White AE, Edelman JJ, Lott N, Bannon PG, McElduff P, Curnow JL, Balogh ZJ

J Trauma Acute Care Surg 2014 Aug;77(2):231-7

PMID: 25058247

Abstract

BACKGROUND: Acute traumatic coagulopathy develops in seriously injured patients, which is followed by a paradoxical hypercoagulable state. The hypercoagulable state contributes to venous thromboembolism, and yet, there are no sensitive tests available to detect it. The aim of this study was to characterize the hypercoagulable state caused by major orthopedic trauma using the overall hemostatic potential (OHP) assay.

METHODS: Major orthopedic trauma patients admitted during a 7-month period in 2012 were included in the study. Blood samples were drawn 1 hour before surgery, then 1, 7, 24 hours and 3, 5, 10, and 42 days postoperatively. The assay parameters were determined and analyzed according to injury severity (polytrauma or nonpolytrauma), type of surgical intervention, and shock status. Values were compared with 20 healthy controls.

RESULTS: Forty-one consecutive patients were enrolled (age, 41.5 ± 2.7 years; 70% male; Injury Severity Score [ISS], 21.5 ± 2.1). Hypercoagulability based on OHP was present in the preoperative sample compared with the controls (OHP, 13.8 ± 1.4 U vs. 8.1 ± 0.5 U; p = 0.020) and then further elevated after surgery (1 hour postoperative, 17.8 ± 2.0 U vs. preoperative, 13.8 ± 1.4 U, p = 0.008). Polytrauma patients were more hypercoagulable than nonpolytrauma at the preoperative sample time (17.7 ± 2.6 U vs. 10.7 ± 1.2 U, p = 0.040) and postoperative period (24.3 ± 3.4 U vs. 11.9 ± 1.4 U, p = 0.006). The OHP for patients undergoing open pelvic surgery (28.3 ± 3.0 U) was higher than both intramedullary nailing (16.2 ± 2.0 U) and percutaneous pelvic surgery (17.0 ± 1.7 U) on Day 5 (p < 0.05). Patients demonstrated a higher OHP than controls did at all time points, except at 6 weeks (patients, 10.8 ± 1.7 U vs. controls, 8.1 ± 0.5 U; p = 0.400).

CONCLUSION: The OHP assay detected the hypercoagulable state following major orthopedic trauma and surgical intervention, which was present for 10 days postoperatively. The extent of hypercoagulability could be associated with polytrauma and the type of surgical intervention; however, further studies are needed to confirm this.

LEVEL OF EVIDENCE: Epidemiologic study, level III.

Natural history of hypercoagulability in patients undergoing coronary revascularization and effect of preoperative myocardial infarction

by

Edelman JJ, Reddel CJ, Kritharides L, Bannon PG, Fraser JF, Curnow JL, Vallely MP

J. Thorac. Cardiovasc. Surg. 2014 Aug;148(2):536-43

PMID: 24280714

Abstract

OBJECTIVES: The balance between hyper- and hypocoagulable states is critical after coronary artery surgery both with (coronary artery bypass grafting [CABG]) and without (off-pump coronary artery bypass [OPCAB]) cardiopulmonary bypass to prevent thrombotic or bleeding complications. We aimed to quantify novel parameters of coagulation, fibrinolysis, and overall hemostasis ≤6 months after CABG and OPCAB and to determine the influences on these parameters.

METHODS: A total of 63 patients (30 CABG, 33 OPCAB) had blood collected before and at various points ≤6 months after surgery. Fibrin and fibrinolysis time curves were generated by measuring the absorption of 405 nm each minute for 100 minutes after the addition of tissue factor and tissue plasminogen activator to cell-free plasma. The parameters were compared with those from a group of healthy controls.

RESULTS: The patients’ preoperative prothrombotic assay parameters were compared with those from healthy controls. Both CABG and OPCAB patients were hypercoagulable until at least day 10 after surgery, with elevation of fibrin generation (CABG, peak day 3, +28.9%; OPCAB, peak day 1, +16.3% vs preoperative baseline) and impairment of fibrinolysis capacity (CABG, day 1, -58.4%; OPCAB, day 1, -22.6%). Surgical revascularization resulted in resolution of preoperative hypercoagulability by 6 months postoperatively. Patients with preoperative myocardial infarction (MI) had prolonged hypercoagulability after surgery that was most exaggerated after CABG (overall hemostatic potential day 5, no MI, +64.1% vs with MI, +128.9% compared with baseline; P = .013).

CONCLUSIONS: Patients will be vulnerable to thrombotic events for ≤6 weeks after coronary surgery yet will have resolution of hypercoagulability by 6 months. Preoperative factors, such as MI, could require individualized management of thrombosis prophylaxis in the postoperative period.

Systematic review of the cost-effectiveness of transcatheter aortic valve implantation

by

Indraratna P, Ang SC, Gada H, Yan TD, Manganas C, Bannon P, Cao C

J. Thorac. Cardiovasc. Surg. 2014 Aug;148(2):509-14

PMID: 24280719

Abstract

OBJECTIVE: Transcatheter aortic valve implantation (TAVI) has emerged as an alternative treatment to aortic valve replacement (AVR) for selected patients with severe aortic stenosis. The present systematic review was conducted to analyze the cost-effectiveness of this novel technique within reimbursed healthcare systems.

METHODS: Two reviewers used 7 electronic databases from January 2000 to November 2012 to identify relevant cost-effectiveness studies of TAVI versus AVR or medical therapy. The primary endpoints were the incremental cost-effectiveness ratio (ICER) and the probability of cost-effectiveness. The eligible studies for the present systematic review included those in which the cost-effectiveness data were measured or projected for TAVI and either medical therapy or AVR. All forms of TAVI were included, and all retrieved publications were limited to the English language.

RESULTS: Eight studies were included for quantitative assessment. The ICER for TAVI compared with medical therapy for surgically inoperable patients ranged from US$26,302 to US$61,889 per quality-adjusted life year gained. The probability of TAVI being cost-effective compared with medical therapy ranged from 0.03 to 1.00. The ICER values for TAVI compared with AVR for high-risk surgical candidates ranged from US$32,000 to US$975,697 per quality-adjusted life year gained. The probability of TAVI being cost-effective in this cohort ranged from 0.116 to 0.709.

CONCLUSIONS: Depending on the ICER threshold selected, TAVI is potentially justified on both medical and economic grounds compared with medical therapy for patients deemed to be surgically inoperable. However, in the high-risk surgical patient cohort, the evidence is currently insufficient to economically justify the use of TAVI in preference to AVR.

Clinical utility of magnetic resonance imaging in the follow-up of chronic aortic type B dissection

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Sherrah AG, Vallely MP, Grieve SM, Jeremy RW, Hendel PN, Puranik R

Heart Lung Circ 2014 Jul;23(7):e157-9

PMID: 24735714

Abstract

Several imaging modalities are utilised in the assessment of disease progression in chronic aortic dissection. We present the case of a 66 year-old male who underwent ascending aorta repair for Stanford type A aortic dissection. On follow-up the persisting dissection of the descending thoracic aorta was observed to regress on magnetic resonance imaging (MRI). MRI has several advantages over computed tomography (CT) scanning and echocardiography in the follow-up phase of this disease.

Transapical aortic valve implantation – an Australian experience

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Seco M, Martinez G, Bannon PG, Cartwright BL, Adams M, Ng M, Wilson MK, Vallely MP

Heart Lung Circ 2014 May;23(5):462-8

PMID: 24315653

Abstract

BACKGROUND: The aim of this study was to report our initial experience with the transapical approach to transcatheter aortic valve implantation (TAVI) at an Australian institution.

METHODS: All patients with severe, symptomatic aortic stenosis were assessed by our multidisciplinary team. A total of 32 patients received a transapical TAVI using an Edwards SAPIEN prosthesis. Data were prospectively collected and analysed according to the Valve Academic Research Consortium version 2 guidelines.

RESULTS: Intraoperative outcomes included: 100% device success with no conversion to surgical valve replacement, extracorporeal membrane oxygenation was used electively in 15.6% and emergently in 6.3%, and no valve migration or malpositioning requiring prosthesis retrieval and re-implantation. Outcomes at 30 days post-TAVI included: No mortality, 3.1% myocardial infarction, no disabling stroke, 3.1% non-disabling stroke, no transient ischaemic attacks, 6.3% life-threatening bleeding, 15.6% major bleeding, 3.1% major vascular complications, and 12.5% postoperative acute kidney injury requiring renal replacement therapy. Mild paravalvular regurgitation was present in 29%, and there was no moderate or severe regurgitation. Mean follow-up time was 28.8±12.9 months. Cumulative results included: 9.4% mortality, 6.3% stroke, 6.3% myocardial infarction, and no repeat procedures. At one year postoperation, echocardiography demonstrated that the mean pressure across the prosthesis was 10.1±1.7mmHg, and the mean aortic valve area was 1.4±0.2cm(2).

CONCLUSION: Good short-term outcomes and low or zero mortality are achievable with transapical TAVI at an Australian institution.

The silent and apparent neurological injury in transcatheter aortic valve implantation study (SANITY): concept, design and rationale

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Fanning JP, Wesley AJ, Platts DG, Walters DL, Eeles EM, Seco M, Tronstad O, Strugnell W, Barnett AG, Clarke AJ, Bellapart J, Vallely MP, Tesar PJ, Fraser JF

BMC Cardiovasc Disord 2014;14:45

PMID: 24708720

Abstract

BACKGROUND: The incidence of clinically apparent stroke in transcatheter aortic valve implantation (TAVI) exceeds that of any other procedure performed by interventional cardiologists and, in the index admission, occurs more than twice as frequently with TAVI than with surgical aortic valve replacement (SAVR). However, this represents only a small component of the vast burden of neurological injury that occurs during TAVI, with recent evidence suggesting that many strokes are clinically silent or only subtly apparent. Additionally, insult may manifest as slight neurocognitive dysfunction rather than overt neurological deficits. Characterisation of the incidence and underlying aetiology of these neurological events may lead to identification of currently unrecognised neuroprotective strategies.

METHODS: The Silent and Apparent Neurological Injury in TAVI (SANITY) Study is a prospective, multicentre, observational study comparing the incidence of neurological injury after TAVI versus SAVR. It introduces an intensive, standardised, formal neurologic and neurocognitive disease assessment for all aortic valve recipients, regardless of intervention (SAVR, TAVI), valve-type (bioprosthetic, Edwards SAPIEN-XT) or access route (sternotomy, transfemoral, transapical or transaortic). Comprehensive monitoring of neurological insult will also be recorded to more fully define and compare the neurological burden of the procedures and identify targets for harm minimisation strategies.

DISCUSSION: The SANITY study undertakes the most rigorous assessment of neurological injury reported in the literature to date. It attempts to accurately characterise the insult and sustained injury associated with both TAVI and SAVR in an attempt to advance understanding of this complication and associations thus allowing for improved patient selection and procedural modification.

Immobilisation of a fibrillin-1 fragment enhances the biocompatibility of PTFE

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Hajian H, Wise SG, Bax DV, Kondyurin A, Waterhouse A, Dunn LL, Kielty CM, Yu Y, Weiss AS, Bilek MM, Bannon PG, Ng MK

Colloids Surf B Biointerfaces 2014 Apr;116:544-52

PMID: 24572497

Abstract

Current vascular biomaterials exhibit poor biocompatibility characterised by failure to promote endothelialisation, predisposition to neoinitmal hyperplasia and excessive thrombogenicity. Fibrillin-1, a major constituent of microfibrils is associated with elastic fibres in the arterial wall. Fibrillin-1 binds to endothelial cells through an RGD cell adhesion motif in the fourth TB module. The RGD motif is present in PF8, a recombinant fibrillin-1 fragment. We investigated the potential of PF8 to improve the biocompatibility of PTFE. PF8 enhanced endothelial cell attachment and cell proliferation to a greater extent than fibronectin (p<0.01). PF8 immobilised on PTFE using plasma immersion ion implantation (PIII), retained these favourable cell interactive properties, again promoting endothelial cell attachment and proliferation. The thrombogenicity of covalently bound PF8 on PTFE was assessed in both static and dynamic conditions. In static conditions, uncoated PIII treated PTFE was more thrombogenic than untreated PTFE, while PF8 coating reduced thrombogenicity. Under flow, there was no difference in the thrombogenicity of PF8 coated PTFE and untreated PTFE. Immobilised PF8 shows a striking ability to promote attachment and growth of endothelial cells on PTFE, while providing a non-thrombogenic surface. These features make PF8 a promising candidate to improve the biocompatibility of current synthetic vascular grafts.

Standardizing clinical end points in aortic arch surgery: a consensus statement from the International Aortic Arch Surgery Study Group

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Yan TD, Tian DH, Lemaire SA, Hughes GC, Chen EP, Misfeld M, Griepp RB, Kazui T, Bannon PG, Coselli JS, Elefteriades JA, Kouchoukos NT, Underwood MJ, Mathew JP, Mohr FW, Oo A, Sundt TM, Bavaria JE, Di Bartolomeo R, Di Eusanio M, Trimarchi S,

Circulation 2014 Apr;129(15):1610-6

PMID: 24733540

Abstract

Detection of serious complications by MR imaging in asymptomatic young adults with repaired coarctation of the aorta

by

Padang R, Dennis M, Semsarian C, Bannon PG, Tanous DJ, Celermajer DS, Puranik R

Heart Lung Circ 2014 Apr;23(4):332-8

PMID: 24210077

Abstract

BACKGROUND: Despite early repair, patients with aortic coarctation (CoA) continue to have a reduced life expectancy due to the development of late complications. We sought to define the rate of aortic abnormalities in patients with previous CoA repair, referred for surveillance magnetic resonance (MR) imaging.

METHODS: We evaluated 59 asymptomatic adults consecutively for repaired CoA with MR imaging between 2008 and 2012.

RESULTS: Patients were aged 29 ± 8 (16-49) years; 34 males (58%) and 34 with bicuspid aortic valve (58%). Median age at the time of initial repair was two years. Surveillance MR imaging was performed 23 ± 8 years post-procedure. The three most common interventions performed were subclavian-flap repair (25%), end-to-end repair (33%) and patch aortoplasty (33%). Re-intervention with balloon angioplasty or repeat surgery had been performed in 22% of subjects. There were 28 cases of recoarctation (48%), of which seven were at least moderate in severity. Repair site and ascending aortic aneurysm occurred in eight (14%) and four (7%) subjects, respectively. Freedom from any degree of recoarctation and other aortic complications was observed in eight subjects (14%).

CONCLUSION: MR imaging detected a high rate of aortic abnormalities in asymptomatic adults after CoA repair, including 27% with clinically significant recoarctation and/or local aneurysm formation.

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