Research

Geriatric cardiac surgery: chronology vs. biology

Seco M, Edelman JJ, Forrest P, Ng M, Wilson MK, Fraser J, Bannon PG, Vallely MP

Heart Lung Circ 2014 Sep;23(9):794-801

PMID: 24851829

Abstract

Cardiac surgery is increasingly performed in elderly patients, and whilst the incidence of common risk factors associated with poorer outcome increases with age, recent studies suggest that outcomes in this population may be better than is widely appreciated. As such, in this review we have examined the current evidence for common cardiac surgical procedures in patients aged over 70 years. Coronary artery bypass grafting (CABG) in the elderly has similar early safety to percutaneous intervention, though repeat revascularisation is lower. Totally avoiding instrumentation of the ascending aorta with off-pump techniques may also reduce the incidence of neurological injury. Aortic valve replacement (AVR) significantly improves quality of life and provides excellent short- and long-term outcomes. Combined AVR and CABG carries higher risk but late survival is still excellent. Mini-sternotomy AVR in the elderly can provide comparable survival to full-sternotomy AVR. More accurate risk stratification systems are needed to appropriately select patients for transcatheter aortic valve implantation. Mitral valve repair is superior to replacement in the elderly, although choosing the most effective method is important for achieving maximal quality of life. Minimally-invasive mitral valve surgery in the elderly has similar postoperative outcomes to sternotomy-based surgery, but reduces hospital length of stay and return to activity. In operative candidates, surgical repair is superior to percutaneous repair. Current evidence indicates that advanced age alone is not a predictor of mortality or morbidity in cardiac surgery. Thus surgery should not be overlooked or denied to the elderly solely on the basis of their “chronological age”, without considering the patient’s true “biological age”.

Minimally invasive mitral valve surgery using single dose antegrade Custodiol cardioplegia

Matzelle SJ, Murphy MJ, Weightman WM, Gibbs NM, Edelman JJ, Passage J

Heart Lung Circ 2014 Sep;23(9):863-8

PMID: 24767979

Abstract

OBJECTIVE: Our unit began a minimally invasive mitral surgery (MIMS) program utilising antegrade Custodiol solution as the sole cardioplegia. The aim of this paper is to report our results of this program.

PATIENTS/METHODS: Early clinical outcomes were identified and assessed for the first consecutive 100 MIMS patients with comparisons made to a historical group operated via a sternotomy (n=113). The efficacy of myocardial protection was assessed using surrogate outcomes of myocardial protection with serial sodium concentrations also analysed.

RESULTS: Six hours postoperatively 12 patients required inotropic support. Peak troponin-I in the first 24 hours was 5.1 (0.8-40 μg/L [median(range)]. Sodium levels decreased following administration of Custodiol but by six hours postoperatively the sodium had returned to greater than 130 mmol/L in all but five patients. Blood transfusion was smaller in the MIMS versus historical group (RBC 17% vs. 65%). MIMS patients had a shorter duration of ventilation, hospital stay and one-year mortality rate (0%).

CONCLUSIONS: In this series of patients undergoing MIMS, single dose antegrade Custodiol offers satisfactory and safe myocardial protection. Early clinical outcomes were also satisfactory. Whilst our findings are observational, they nevertheless support the use of this less invasive approach to mitral surgery using single dose Custodiol for myocardial protection.

A meta-analysis of endoscopic versus conventional open radial artery harvesting for coronary artery bypass graft surgery

Cao C, Tian DH, Ang SC, Peeceeyen S, Allan J, Fu B, Yan TD

Innovations (Phila) 2014 Jul-Aug;9(4):269-75

PMID: 25084252

Abstract

OBJECTIVE: The radial artery has been demonstrated to provide superior long-term patency outcomes compared with saphenous veins for selected patients who undergo coronary artery bypass graft surgery. Recently, endoscopic radial artery harvesting has been popularized to improve cosmetic and perioperative outcomes. However, concerns have been raised regarding the effects on long-term survival and graft patency of this relatively novel technique. The present meta-analysis aimed to assess the safety and the efficacy of endoscopic radial artery harvesting versus the conventional open approach.

METHODS: A systematic review of the current literature was performed on five electronic databases. All comparative studies on endoscopic versus open radial artery harvesting were included for analysis. Primary endpoints included mortality and recurrent myocardial infarction. Secondary endpoints included graft patency, wound infection, hematoma formation, and paresthesia.

RESULTS: Twelve studies involving 3314 patients were included for meta-analysis according to predefined selection criteria. There were no statistically significant differences in overall mortality, recurrent myocardial infarction, or graft patency between the two surgical techniques. However, patients who underwent endoscopic harvesting were found to have significantly lower incidences of wound infection, hematoma formation, and paresthesia.

CONCLUSIONS: Current literature on endoscopic harvesting of the radial artery for coronary artery bypass graft surgery is limited by relatively short follow-up periods as well as differences in patient selection and surgical techniques. In addition, there are currently no randomized controlled trials to provide robust clinical data. However, the available evidence suggests that the endoscopic approach is associated with superior perioperative outcomes without clear evidence demonstrating compromised patency or survival outcomes.

Characterization of the hypercoagulable state following severe orthopedic trauma

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

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

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

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

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

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.

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