Remote ischaemic preconditioning: is it a flag on the field?

Ischaemic preconditioning is one of several different techniques that have been proposed to render the heart more resistant to ischaemia/reperfusion injuries. A significant reduction of troponin release is 'proof of concept', however, whether ischaemic preconditioning leads to improved clinical outcomes is still to be proven. Moreover, the exact mechanism of action still remains unknown since very few studies have investigated the signal transmission in humans.

Off-pump versus on-pump revascularization in females: a meta-analysis of observational studies.

BACKGROUND: Coronary revascularization in female patients presents several challenges, including smaller target vessels and smaller conduits. Furthermore, late presentation and more co-morbidities than males may increase complication rates. The aim of this study was to assess whether off-pump coronary artery bypass (OPCAB) improves outcomes when compared to on-pump coronary artery bypass (ONCAB) in the female population. METHODS: A systematic literature review identified six observational studies, incorporating 23313 patients (n=9596 OPCAB, 13717 ONCAB). These were meta-analyzed using random effects modeling. Heterogeneity, subgroup analysis, quality scoring and publication bias were assessed. The primary endpoints were 30-day mortality and major cardiac, respiratory and renal complications. Secondary endpoints were the number of grafts per patient. RESULTS: No statistically significant difference was observed in 30-day mortality between the OPCAB and ONCAB groups (4.8% vs. 0.7%; OR 0.96; 95% CI [0.41, 2.24], p=0.92). Significant inter-study heterogeneity was also present (I2=94%) and was not explained by study size or quality. Peri-operative myocardial infarction (OR 0.65; 95% CI [0.51, 0.84], p=0.0009) was significantly lower with OPCAB without significant heterogeneity; however, OPCAB did not significantly alter other morbidity outcomes. OPCAB was associated with a trend towards fewer grafts per patient than ONCAB. CONCLUSIONS: OPCAB is a safe alternative to ONCAB in the surgical revascularisation of female patients and may reduce post-operative myocardial infarction (MI). However, this does not translate into a reduction in 30-day mortality and OPCAB does not significantly improve other cardiovascular, renal or neurological outcomes. Late outcome data remains lacking and a well-structured, randomized trial is required to answer vital questions regarding the effect of OPCAB on women in the long-term.

Understanding innovations in the evolving practice of blood and crystalloid cardioplegia.

The use of cardioplegia solution has substantially increased the safety of cardiac surgery. It protects the myocardium by inducing a rapid and complete diastolic arrest, minimizing myocardial energy requirements, preventing ischaemic damage during the arrest phase and minimizing or preventing reperfusion injury once coronary blood flow is restored. This article is a summary of important information that has accumulated in the literature about cardioplegia and describes how our understanding of cardioplegia has evolved. The basic principles of myocardial ischaemia and reperfusion injury and how they relate to myocardial protection are described. Blood and crystalloid cardioplegia are compared with respect to biochemical and physiological differences. Recent patient demographic changes, with surgeons operating on older, more complex patients who have more severe and diffuse disease, are discussed. This cohort of patients potentially requires prolonged elective ischaemia; hence, improved myocardial protection would be of benefit. We highlight areas of study that have demonstrated a new concept of myocardial protection, known as polarized arrest. Many pharmacological agents have been shown (in experimental studies) to have the ability to induce a polarized arrest and to provide improved protection.

Haemolysis: the harbinger of recurrent mitral regurgitation after mitral valve repair.

We present a case of severe haemolysis post mitral valve repair that presented within the first week of operation. Despite assurance of a good repair, with initial postoperative echocardiographic evidence, the patient subsequently developed haemolysis and required forty units of blood over three months. We emphasize that an unexplained anaemia post mitral valve repair should trigger suspicion for mechanical haemolysis and suggest disease progression or failure of repair.

Does off-pump coronary revascularization reduce mortality in re-operative coronary artery surgery? A meta-analysis of observational studies.

BACKGROUND: Re-operative coronary artery bypass grafting (CABG) is a challenging operation that is often performed in a high-risk patient group. Avoiding cardiopulmonary bypass (CPB) in these patients is hypothesised to be advantageous due to the reduced invasiveness and physiological stress of off-pump coronary artery bypass grafting (OPCAB). The aims of this study were to assess whether OPCAB may improve outcomes in patients undergoing re-operative CABG. METHODS: Twelve studies, incorporating 3471 patients, were identified by systematic literature review. These were meta-analysed using random-effects modelling. Primary endpoints were 30-day and mid-term mortality. Secondary endpoints were completeness of revascularization, mean number of grafts per patient and the effect of intra-operative conversion on mortality. RESULTS: A significantly lower rate of 30-day mortality was observed with OPCAB (OR 0.51, 95% CI [0.35, 0.74]), however, no difference was demonstrated in mid-term mortality. Significantly less complete revascularization and mean number of grafts per patient were observed in the OPCAB group. Meta-regression revealed no change in 30-day mortality when the effect of conversion from one technique to the other was assessed. CONCLUSIONS: Off-pump techniques may reduce early mortality in selected patients undergoing re-operative CABG; however, this does not persist into mid-term follow-up. OPCAB may also lead to intra-operative conversion and, although this did not affect outcomes in this study, these results are constrained by the limited data available. Furthermore, OPCAB may increase target vessel revascularization and, consequently, incomplete revascularization which, whilst not reflected in the short-term outcomes, requires longer-term follow-up in order to be fully assessed.

Safety of training and assessment in operating theatres--a systematic review and meta-analysis.

OBJECTIVE: Procedural outcomes can be used to assess the performance of specialists and trainees. This article establishes a systematic evidence base for the safety of training in the operating theatre. It also explores the possibility of using early, intermediate and late procedural outcomes of cardiac surgical operations to evaluate the performance of the clinicians and the healthcare system. METHODS: Medline, EMBASE and PsycINFO databases were searched. Comparative studies evaluating quality indicators of cardiac surgical procedures (coronary artery bypass grafting (CABG) and valve surgery) were included. guidelines from the preferred reporting items for systematic reviews and meta-analyses (PRISMA) were used. RESULTS: Fourteen studies met the inclusion criteria. For CABG, meta-analysis of outcomes did not show any significant differences between the technical and non-technical skills of trainees versus specialists apart from bypass time (less for specialists) and intensive care unit (ICU) length of stay (less for trainees). Studies reporting outcomes on valve surgery also did not report any statistically significant differences amongst the outcomes. CONCLUSION: This systematic review did not discern any significant differences between the procedural outcomes of trainees and specialists, which indicates that trainees are safe to operate under senior supervision. In addition, this article recommends that various procedural outcomes can be used to evaluate the performance of clinicians and healthcare systems. Prospective studies need to be performed, taking into account the specific contribution of trainees and specialists during the procedure. This will give a clearer indication of safety and performance of trainees and specialists in the operating theatre.

Assessment of platelet function in patients on antiplatelet therapy undergoing cardiac surgery: a review.

Increasing numbers of patients are undergoing cardiac surgery on dual antiplatelet therapy following previous percutaneous coronary intervention. The dilemma of stopping antiplatelet therapy prior to surgery with risk of stent thrombosis, versus continuation and risk of post-operative bleeding has received much debate. Currently, an accurate and standardised method of predicting antiplatelet drug efficacy has not yet been determined and significant inter-individual variance has been shown. This review focuses on the most widely used laboratory and point of care assays currently available to measure platelet function and recent published data evaluating these methods. Further studies may enable predictive values to be defined, to guide the practicing clinician in balancing the risk of thrombosis versus haemorrhage.

Miniaturized extracorporeal circulation vs. off-pump coronary artery bypass grafting: what the evidence shows?

Recognition of the potentially deleterious effects of esxtracorporeal circulation led to off-pump coronary artery surgery (OPCAB) experiencing a surge in popularity in the initial decade after its conception. However, OPCAB has its own limitations and technical difficulties, such as coronary access, increased left ventricular size and reduced function, which may lead to the potential for suboptimal revascularization. As an alternative technique, miniaturized extracorporeal circulation (mECC) may provide a more controlled operative field in which the heart may be manipulated whilst minimizing the inflammatory, coagulopathic and haemodilutional effects of cardiopulmonary bypass. In this review, we outline the proposed benefits of the mECC system, discuss the pitfalls associated with mECC, and directly compare mECC to 'off-pump' coronary surgery for a variety of clinical and non-clinical outcomes.

Hyperinflation of lungs during redo-sternotomy, a safer technique.

Increasing numbers of patients are being referred for repeat cardiac procedures and redo-sternotomy is technically more arduous as well as time consuming. We describe our unique technique to overcome this challenging task by hyperinflating the lungs as a useful manoeuvre.

An audit of a steriod withdrawal regimen in cardiac transplantation patients.

BACKGROUND: Heart transplantation is optimal treatment for many patients with end-stage heart failure. Current data report 1-year graft survival rates of 85% after transplantation. The success of transplantation in large part is attributable to immunosuppression, including steroids, one of the mainstay agents. Despite its efficacy to treat acute graft rejection, steroids show numerous adverse effects. With newer immunosuppressive agents, steroid withdrawal is possible. MATERIAL AND METHODS: We compared cardiac transplant patients who died versus survived between 2001 and 2006. We obtained Personal, transplant, occurrence of and cause of death data as well as postoperative intervals. Steroid therapy details were gathered, particularly whether the patient had been weaned off these agents. We calculated steroid doses and steroid-free years, as well as the steroid therapy status of posttransplant patients who remained alive in 2006. RESULTS: Fifty cardiac transplant patients died between 2001 and 2006 excluding 6 who had graft failure and 2 who died of multiorgan failure before initial discharge. Of the 42 patient who died, 29 (69%) were on and 13 (31%) had been withdrawn from steroid therapy at time of death. There were 132 posttransplant patients currently alive in April 2006, including 43 (33%) on and 89 (67%) withdrawn from steroids. The percentages of patients who were on versus off steroids were compared for main causes of death. Thirty-eight percent of patients on steroids at the time of death died of graft vasculopathy compared with 46% of patients who had been weaned off steroids. Fifteen percent of deceased patients taking steroids at the time of death died of chronic rejection. DISCUSSION: The current literature focuses on early withdrawal or reduction of steroids or steroid avoidance after organ transplantation. Although steroid avoidance remains controversial, steroid withdrawal has been generally incorporated into immunosuppressive protocols. Early steroid withdrawal has a positive influence on the emergence of de novo osteoporosis and cataracts. The benefits of steroid avoidance versus withdrawal are controversial topics being currently debated.

Surgical reconstruction of the mitral valve.

From Cutler's first attempt to treat the mitral valve by inserting a tenotomy knife through the left ventricle, to Carpentier's introduction of several repair techniques and a functional classification for assessing mitral valve lesions, the history of mitral valve treatment is exciting. Mitral diseases may be degenerative, ischaemic, infective or rheumatic, with or without superimposed impaired left ventricular function and calcification. Understanding the underlying pathological features is also important in determining whether mitral valve repair is feasible, how the valve should be repaired and the prospect for long-term durability of the repair. Recent advances in minimally invasive mitral valve surgery are promising but more effort is needed to ensure timely mitral valve repair.

The Coronary Artery Revascularisation in Diabetes (CARDia) trial: background, aims, and design.

BACKGROUND: Patients with diabetes have an increased incidence and severity of ischemic heart disease, which leads to an increased requirement for coronary revascularization. Comparative information regarding mode of revascularization--coronary artery bypass graft surgery surgery (CABG) or percutaneous coronary intervention (PCI)--is limited, mainly confined to a subanalysis of the Bypass Angioplasty Revascularization (BARI) trial, suggesting a mortality benefit of CABG over PCI. No prospective trial has specifically compared these modes of revascularization in patients with diabetes. OBJECTIVE: The Coronary Artery Revascularisation in Diabetes (CARDia) trial is designed to address the hypothesis that optimal PCI is not inferior to modern CABG as a revascularization strategy for diabetics with multivessel or complex single-vessel coronary disease. The primary end point is a composite of death, nonfatal myocardial infarction, and cerebrovascular accident at 1 year. METHOD: A total of 600 patients with diabetes are to be randomized to either PCI or CABG, with few protocol restrictions on operative techniques or use of new technology. This gives a power of 80% to detect non-inferiority of PCI assuming that the PCI 1-year event rate is 9%. A cardiac surgeon and a cardiologist must agree that a patient is suitable for revascularization by either technique prior to recruitment into the study. Twenty-one centers in the United Kingdom and Ireland are recruiting patients. Data on cost effectiveness, quality of life, and neurocognitive function are being collected. Long-term (3-5 year) follow-up data will also be collected.

Lipomatous hypertrophy of the interatrial septum: a commonly misdiagnosed mass often leading to unnecessary cardiac surgery.

Lipomatous hypertrophy of the interatrial septum is a benign cardiac mass that should be considered as part of the differential diagnosis for any atrial cardiac tumour. In the reported case, this lesion was initially suspected to be malignant and the patient was thus referred directly to cardiac surgeons for surgical removal. Unnecessary surgical intervention was swiftly averted because the cardiac surgeon promptly referred the patient for an expert echocardiogram that confirmed the diagnosis of lipomatous hypertrophy. The authors discuss the characteristic features of this lesion and how the diagnosis may be made based on several non-invasive imaging modalities without the need for a tissue biopsy. This condition is more common than initially thought and remains under-recognised by most clinicians. In such cases an increased awareness of this lesion along with the opinion of a specialist echocardiologist would help to avoid a misdiagnosis and unnecessary intervention.

Clinical inhibition of the seven-transmembrane thrombin receptor (PAR1) by intravenous aprotinin during cardiothoracic surgery.

BACKGROUND: Protease-activated receptor-1 (PAR1) is the principal thrombin receptor in the vasculature, and antagonists against this receptor are in preclinical trials. Aprotinin, already approved for clinical use to reduce transfusion requirements in cardiopulmonary bypass (CPB) surgery, has been shown to inhibit PAR1 activation in vitro. Here, we exploit CPB as a model for thrombin generation in humans to examine whether aprotinin can inhibit platelet PAR1 activation clinically. METHODS AND RESULTS: PAR1 expression and function on platelets was examined in coronary artery bypass grafting (CABG) patients randomized into 2 groups: (1) those receiving saline infusion during CPB (n=17) and (2) those receiving aprotinin (2x10(6) kallikrein inhibitor units [KIU] in pump prime, 2x10(6) KIU loading dose, followed by 0.5x10(6) KIU/h [n=13]). Platelets in the saline group showed loss of PAR1-specific function at 2 hours after CPB, but this was preserved in the aprotinin group (P<0.001). These effects were most likely targeted at PAR1 receptor cleavage, because (1) the level of thrombin generated during CPB did not vary significantly between groups, (2) expression of SPAN12, which detects only uncleaved PAR1 receptors, was preserved in the aprotinin but not the placebo group (P<0.05), and (3) supporting evidence in vitro showed reduced thrombin-induced PAR1 cleavage (P<0.001) and platelet aggregation (P<0.001) in the presence of aprotinin. CONCLUSIONS: This study demonstrates that platelet PAR1 activation by thrombin can be inhibited by aprotinin. Our results extend the clinical mechanism of action of aprotinin and provide the first proof of principle that PAR1 can be inhibited clinically. This has implications beyond cardiac surgery for the development of therapeutic PAR1 blockade.

An evaluation of existing risk stratification models as a tool for comparison of surgical performances for coronary artery bypass grafting between institutions.

OBJECTIVE: Risk stratification systems are used in cardiac surgery to estimate mortality risk for individual patients and to compare surgical performance between institutions or surgeons. This study investigates the suitability of six existing risk stratification systems for these purposes. METHODS: Data on 5471 patients who underwent isolated coronary artery bypass grafting at two UK cardiac centres between 1993 and 1999 were extracted from a prospective computerised clinical data base. Of these patients, 184 (3.3%) died in hospital. In-hospital mortality risk scores were calculated for each patient using the Parsonnet score, the EuroSCORE, the ACC/AHA score and three UK Bayes models (old, new complex and new simple). The accuracy for predicting mortality at an institutional level was assessed by comparing total observed and predicted mortality. The accuracy of the risk scores for predicting mortality for a patient was assessed by the Hosmer-Lemeshow test. The receiver operating characteristic (ROC) curve was used to evaluate how well a system ranks the patient with respect to their risk of mortality and can be useful for patient management. RESULTS: Both EuroSCORE and the simple Bayes model were reasonably accurate at predicting overall mortality. However predictive accuracy at the patient level was poor for all systems, although EuroSCORE was accurate for low to medium risk patients. Discrimination was fair with the following ROC areas: Parsonnet 0.73, EuroSCORE 0.76, ACC/AHA system 0.76, old Bayes 0.77, complex Bayes 0.76, simple Bayes 0.76. CONCLUSIONS: This study suggests that two of the scores may be useful in comparing institutions. None of the risk scores provide accurate risk estimates for individual patients in the two hospitals studied although EuroSCORE may have some utility for certain patients. All six systems perform moderately at ranking the patients and so may be useful for patient management. More results are needed from other institutions to confirm that the EuroSCORE and the simple Bayes model are suitable for institutional risk-adjusted comparisons.

Concomitant thymectomy and cardiac operation in a patient with pure red cell aplasia.

Pure red cell aplasia is a rare condition resulting in severe anemia. Medical therapy is indicated, unless a thymoma is present. In patients with concurrent cardiac pathology requiring operation, simultaneous operation should be contemplated to avoid risky resternotomy. We describe an exceptionally rare case of a patient with pure red cell aplasia secondary to a thymoma who underwent concomitant thymectomy and coronary artery grafting with a successful surgical outcome.