Sukumaran Nair

Ex vivo lung perfusion: a comprehensive review of the development and exploration of future trends.

There is a critical mismatch between the number of donor lungs available and the demand for lungs for transplantation. This has created unacceptably high waiting-list mortality for lung transplant recipients. Currently (2012) in the United Kingdom, there are 216 patients on the lung transplant waiting list and 17 on heart and lung transplant list. The waiting times for suitable lungs average 412 days, with an increasing mortality and morbidity among the patients on the lung transplant list. Ex vivo lung perfusion (EVLP) has emerged as a technique for the assessment, resuscitation, and potential repair of suboptimal donor lungs. This is a rapidly developing field with significant clinical implications. In this review article, we critically appraise the background developments that have led to our current clinical practice. In particular, we focus on the human and animal experience, the different perfusion-ventilation strategies, and the impact of different perfusates and leukocyte filters. Finally, we examine EVLP as a potential research tool. This will provide insight into EVLP and its future development in the field of clinical lung transplantation.

The influence of endoscopic vein harvesting on outcomes after coronary bypass grafting: a meta-analysis of 267 525 patients

In recent times, practice in cardiac surgery has shifted towards using endoscopic techniques to harvest the saphenous vein from the leg for use as a bypass graft. A paper published in the New England Journal of Medicine (NEJM) in 2009 raised concerns over increased graft occlusion rates in veins harvested endoscopically. This NEJM paper has been criticized, but has nonetheless been influential in guiding practice. We have undertaken this meta-analysis to provide evidence on the clinical outcomes of endoscopic vein harvesting (EVH), so that clinicians can make an informed judgement about whether this technique, popular as it is with patients, should still be offered. We systematically reviewed the global literature and performed a meta-analysis of clinical outcomes after endoscopic and open vein harvesting. In all outcomes, endoscopic harvesting appears to be equal, if not superior, to open harvesting. The suspicion of higher rates of vein graft occlusion was not borne out by randomized studies. When considering evidence from only randomized studies, there is no statistical difference in vein graft stenosis or occlusion between open and endoscopically harvested veins. In conclusion, EVH reduces pain and leg wound complications. At a median follow-up of 2.6 years, we found no significant difference in mortality, myocardial infarction, repeat revascularization, angina recurrence, vein graft stenosis or occlusion. Therefore, the authors support the ongoing use of endoscopic harvesting techniques.

Comparison between cellular and acellular perfusates for ex vivo lung perfusion in a porcine model

BACKGROUND Ex vivo lung perfusion with acellular solutions is an established technique for assessing marginal donor lungs. We evaluated the utility of a blood-based lung preservation fluid as an alternative perfusate. METHODS Donor lungs from 50-kg donation after cardiac death pigs (n = 24) were randomized into 3 groups: acellular, commercial blood-based, and Papworth-Blood. Physiologic function was evaluated using conventional markers of pulmonary vascular resistance, pulmonary compliance, lactate excretion, partial pressure of oxygen/fraction of inspired oxygen, and wet-to-dry ratios. The immunologic profile was assessed by fluorescence-activated cell sorting analysis of bronchoalveolar lavage and cells entrapped in the leucocyte filter. Cytokines were quantified using a commercial platform. RESULTS No significant difference was noted in pulmonary vascular resistance (p = 0.26), compliance (p = 0.12), partial pressure of oxygen/fraction of inspired oxygen (p = 0.06) and wet-to-dry ratios (p = 0.26) between groups. There was no difference between the percentages of lymphocytes (p = 0.51), macrophages (p = 0.87), monocytes (p = 0.68), and dendritic cells (p = 0.65) in the leukocyte filters. Interleukin (IL)-1β (p = 0.36), IL-6 (p = 0.08), IL-8 (p = 0.64), and IL-18 (p = 0.14) were elevated in all groups. In bronchoalveolar lavage, IL-8 was significantly higher in the acellular group (p = 0.04). Electron microscopy cell characteristics were similar among the groups. CONCLUSIONS This study demonstrated no significant difference in the physiologic, immunologic, or ultrastructural parameters between lungs perfused with cellular or acellular solutions. The Papworth-Blood solution is a potential alternative perfusate for ex vivo lung perfusion.

Size matching in lung transplantation: an evidence-based review.

The evidence base for size matching between donors and recipients in lung transplantation has not recently been reviewed in a comprehensive manner. Our aim in this study was to assimilate published studies that have addressed size matching of donors to recipients and to establish a pragmatic understanding of the range of lung sizes that may be used for lung transplantation. A comprehensive literature search was performed using Medline and PubMed up to and including September 2012, to identify scientific articles that relate to size matching between donors and lung transplant recipients. Seventy-two articles were identified, of which 21 had addressed the question of the impact of size mismatching on outcomes in lung transplantation. No study has specifically tested the consequences of intentionally mismatching above or below the hypothetical limits for double lung transplantation of a predicted total lung capacity for the donor of between 75% and 125% of the recipient predicted total lung capacity as set out in the ISHLT consensus report on lung donor acceptability criteria. Research is lacking that has robustly defined limits for size mismatch for single lung transplantation and for recipients with restrictive lung pathologies such as pulmonary fibrosis. Published research on the impact of size mismatching between lung transplant donors and recipients is limited by study design and size. It is centered on addressing the issue of mismatch in double lung transplantation in cohorts with a diagnostically heterogeneous make-up and in single lung transplant patients with chronic obstructive pulmonary disease.

Role of concomitant tricuspid surgery in moderate functional tricuspid regurgitation in patients undergoing left heart valve surgery

Functional tricuspid regurgitation (FTR) is frequently present in patients undergoing aortic, and particularly mitral valve, surgery. Untreated FTR may lead to right heart failure. Reoperative cardiac surgery for late FTR is associated with high morbidity and mortality. Therefore, severe FTR has emerged as a Class I indication for concomitant tricuspid valve surgery in patients undergoing left valve surgery. Concomitant tricuspid valve surgery during left heart valve surgery to address moderate and mild FTR is controversial. This review addresses this issue and proposes an algorithm for the treatment of FTR in patients undergoing left heart valve surgery.

Coagulopathy associated with massive cell salvage transfusion following aortic surgery

Cell saver blood is used within the peri-operative setting of cardiothoracic surgery to reduce the need for transfusion of allogenic blood products. Several meta-analyses have proven a significant decrease in allogenic transfusion with the use of cell salvage techniques. Washing of red cells by the cell saver and subsequent transfusion of suspended red cells can occasionally cause coagulopathy, particularly when using high concentration heparin saline to wash the spilled blood. We present the case of a 74-year-old female who underwent complicated aortic surgery and was transfused large volumes of cell-saved blood due to post-operative bleeding, which subsequently led to coagulopathy.

The effect of retrograde autologous priming on intraoperative blood product transfusion in coronary artery bypass grafting

Introduction: Retrograde autologous priming (RAP) of the cardiopulmonary bypass (CPB) circuit could reduce the degree of haemodilution associated with priming with acellular solutions. However, there is no strong evidence to prove that the practice of RAP reduced intraoperative packed red cell (PRC) or blood product transfusion. Objective: To evaluate the effect of RAP on intraoperative PRC usage in coronary artery bypass grafting (CABG). Methods: This study is a prospective, observational study on patients who underwent first-time, isolated CABG using CPB between April 2012 and July 2012. Two groups of patients were identified: 1. Non-RAP group (n=128) and 2. RAP group (n=73). The primary outcome for the study was the amount of PRC and blood product usage between the induction of anaesthesia and the cessation of CPB. Results: Use of PRC and blood products in the operating room was comparable in both groups. Univariate logistic regression showed that RAP was not an independent predictor of PRC or blood product transfusion (p=0.43). Multivariate logistic regression showed that CPB time, preoperative haemoglobin (Hb) levels and creatinine clearance were independent predictors of blood product transfusion. Conclusion: Practising RAP with mean volumes of 300 ml does not necessarily reduce PRC and other blood product transfusion requirements during CABG. In our practice, RAP was performed, aiming at displacing CPB circuit prime volume with which the perfusionist felt comfortable and dictated by haemodynamic parameters prior to commencing CPB. We presume this is the case in many units around the world. This practice, in our opinion, is not enough to achieve the benefits of RAP, if any, in the form of a reduction of packed red cell transfusion requirements. The true advantages of RAP in cardiac surgery need to be studied in a prospective, randomized, controlled trial.

Survival after surgical repair of ischemic ventricular septal rupture

Objectives: We reviewed our results and experience over a 14-year period to identify predictors of outcome following surgical repair of postinfarction ventricular septal rupture. Methods: A retrospective review was carried over a 14-year period. All patients had surgical repair of a postinfarction ventricular septal rupture. Patient demographics, perioperative variables, and survival data were collected. Logistic regression identified independent predictors of 30-day mortality. Multivariate analysis determined the effects of independent risk factors on survival. Results: Surgery for postinfarction ventricular septal rupture was carried out on 59 patients. The median age was 69 years, and 69% were male. In 54% of patients, the ventricular septal rupture was anterior, and 75% had concomitant coronary artery bypass grafting. Mortality was 39% at 30 days. Age was the most important predictor of 30-day and long-term outcome. Logistic regression analysis identified age, preoperative ventilation, and female sex as significant predictors of 30-day mortality. Cardiogenic shock, preoperative ventilation, and advanced age were associated with reduced medium-term survival. Surprisingly, anterior ventricular septal rupture was associated with reduced long-term survival. Concomitant coronary artery bypass grafting did not influence 30-day or long-term outcome. Conclusions: Despite advances, the surgical mortality from ventricular septal rupture remains high. Age remains the most important predictor of outcome, and concomitant coronary artery bypass grafting does not appear to have a demonstrable benefit. Interestingly, anterior ventricular septal rupture had poorer long-term outcome than inferior ventricular septal rupture.

Mini-Stern Trial: A randomized trial comparing mini-sternotomy to full median sternotomy for aortic valve replacement

Objective: Aortic valve replacement (AVR) can be performed either through full median sternotomy (FS) or upper mini‐sternotomy (MS). The Mini‐Stern trial aimed to establish whether MS leads to quicker postoperative recovery and shorter hospital stay after first‐time isolated AVR. Methods: This pragmatic, open‐label, parallel randomized controlled trial (RCT) compared MS with FS for first‐time isolated AVR in 2 United Kingdom National Health Service hospitals. Primary endpoints were duration of postoperative hospital stay and the time to fitness for discharge from hospital after AVR, analyzed in the intent‐to‐treat population. Results: In this RCT, 222 patients were recruited and randomized (n = 118 in the MS group; n = 104 in the FS group). Compared with the FS group, the MS group had a longer hospital length of stay (mean, 9.5 days vs 8.6 days) and took longer to achieve fitness for discharge home (mean, 8.5 days vs 7.5 days). Adjusting for valve type, sex, and surgeon, hazard ratios (HRs) from Cox models did not show a statistically significant effect of MS (relative to FS) on either hospital stay (HR, 0.874; 95% confidence interval [CI], 0.668–1.143; P = .3246) or time to fitness for discharge (HR, 0.907; 95% CI, 0.688–1.197; P value = .4914). During a mean follow‐up of 760 days (745 days for the MS group and 777 days for the FS group), 12 patients (10%) in the MS group and 7 patients (7%) in the FS group died (HR, 1.871; 95% CI, 0.723–4.844; P = .1966). Average extra cost for MS was £1714 during the first 12 months after AVR. Conclusions: Compared with FS for AVR, MS did not result in shorter hospital stay, faster recovery, or improved survival and was not cost‐effective. The MS approach is not superior to FS for performing AVR.

Chest X-ray and electrocardiogram in post-cardiac surgery follow-up clinics: should this be offered routinely or when clinically indicated?

OBJECTIVES Many centres in the UK carry out routine chest X-ray (CXR) and/or electrocardiogram (ECG) when patients attend follow-up clinic after cardiac surgery. Current evidence to support this practice is weak. This study investigated the appropriateness of carrying out these investigations in the absence of clinical indication. METHODS All patients attending routine 6- to 8-week follow-up clinic after cardiac surgery in this hospital were prospectively reviewed over a 6-month period (October 2011-April 2012). Two groups were identified for comparison. Group A comprised patients who had CXR and/or ECG requested routinely, and those in Group B had the investigations only when clinically indicated. A proforma was designed to screen each patient for cardiac and respiratory symptoms, predischarge CXR abnormalities and the presence of atrial fibrillation/flutter postoperatively. Management alterations based on the findings from the investigations were noted. Patients who had thoracic, major aortic, or heart transplant surgery were excluded from the audit. RESULTS Three hundred and fifty patients were reviewed: 250 were in Group A and 100 in Group B. No patient had a significant management alteration in the absence of an indication for the tests. There were no differences in outcome between the two groups. In Group A, 111 (45%) patients had CXR and ECG done without indication and no abnormality was detected. In Group B, 52 patients had no indication for either tests and were thus not tested. None of these patients required readmission/intervention following discharge from clinic. Overall, 271 patients had CXR carried out, with only 83 being indicated. This led to a management alteration in 33 patients (12% overall, 40% if indicated). Two hundred and eighty-six patients had ECG carried out with 140 indicated. Management was altered in 122 patients (43% overall, 87% if indicated). The correlation between the clinical indication-based investigation and the resulting change in patient management was found to be significant (Goodman-Kruskal Gamma: 0.99, P = 0.000 for both investigations). CONCLUSIONS There is a strong correlation between clinical indication for CXR and/or ECG and management alterations. These investigations should be performed during the routine follow-up of adult cardiac surgical patients using a patient-centred approach based on signs and symptoms.