Mitral valve surgery via repeat median sternotomy versus right mini-thoracotomy: A systematic review and meta-analysis of clinical outcomes

BACKGROUND

Redo mitral valve surgeries have high mortality and morbidity and can be physically demanding for patients. Median sternotomy remains the gold standard for most cardiac surgeries. To tackle certain risks with a re-sternotomy, alternative procedures such as the right anterolateral minithoracotomy have been explored. This review aims to compare the clinical outcomes of re-sternotomy (MS) versus right mini thoracotomy (MT) in mitral valve surgery.

METHODS

A systematic, electronic search was performed according to Preferred Reporting items for Systematic Reviews and Meta-analysis guidelines to identify relevant articles that compared outcomes of the MS versus MT procedures in patients who have had cardiac surgery via a MS approach.

RESULTS

Twelve studies were identified, enrolling 4514 patients. Length of hospital stay(MD = -3.71, 95% confidence interval [CI] [-4.92, -2.49]), 30-day mortality(odds ratio [OR] = 0.59, 95% CI [0.39, 0.90]), and new-onset renal failure(OR = 0.38, 95% CI [0.22, 0.65]) were statistically significant in favor of the MT approach. Infection rates(OR = 0.56, 95% CI[0.25, 1.21]) and length of intensive care unit (ICU) stay (MD = -0.55, 95% CI[-1.16, 0.06]) was lower in the MT group; however, the difference was not significant. No significant differences were observed in the CPB time(MD = -2.33, 95% CI [-8.15, 3.50]), aortic cross-clamp time MD = -1.67, 95% CI[-17.07, 13.76]), and rates of stroke(OR = 1.03, 95% CI[0.55, 1.92]).

CONCLUSION

Right MT is a safe alternative to the traditional re-sternotomy for patients who have had previous cardiac surgery. The approach offers a reduced length of hospital stay, ICU stay, and a lower risk of new-onset renal failure requiring dialysis. This review calls for robust trials in the field to further strengthen the evidence.

Mini-thoracotomy in redo mitral valve surgery: safety and efficacy of a standardized procedure

Background

Re-operative mitral valve surgery is sometimes burdened by a greater technical difficulty and a higher complications rate than the first operation. Minimally invasive cardiac surgery has become routine, and it could significantly reduce the surgical risk in redo surgery. The objective of our retrospective observational study is to assess the results of cardiac reoperations in patients with mitral valve disease approached trough a 5–7 cm right mini-thoracotomy.

Methods

From February 2017 to December 2019, 65 patients underwent re-operative mitral valve surgery in our institution. Cardiopulmonary bypass (CPB) was started by cannulation of the femoral and jugular vein and femoral artery or alternatively right axillary artery. Patients enrolled had a mean age of 66.6±11.5 years. Patients were divided into three groups based on the procedure adopted: external aortic cross-clamp (EAC), EndoAortic balloon occlusion (EABO) and ventricular fibrillation (VF). Major complications were evaluated and compared with a propensity matched population of patients undergoing elective isolated mitral valve surgery via right minithoracotomy (MVS).

Results

The average time between last operation and reoperation was 7.1±3.4 years. Fourteen patients (21%) underwent mitral valve repair and 51 patients (78%) underwent mitral valve replacement; 9 patients (14%) received tricuspid valve surgery. There was no statistically significant difference in CPB time between the groups. Seven patients (11%) had a postoperative renal failure, 5 patients (8%) underwent surgical reopening for bleeding; incidence of post-operative stroke and pace-maker implantation was 3% for both. No deaths were registered during in-hospital stay and at 30-days echocardiographic control all patients respect the criterions of device success according with MVARC. Propensity matched patients of group redo had a longer CPB time (100.8±42.7 versus 72.8±16.7 min, P<0.001) and cross-clamp time (71.9±30.7 versus 59±10.7 min, P<0.001) respect to first operation mitral valve surgery patients.

Conclusions

Minimally invasive mitral valve redo surgery is a safe procedure. Less invasive techniques in redo surgery could minimize morbidity and mortality without prolonging the duration of CPB.

Keeping the heart empty and beating: an alternative technique to preserve hypertrophied hearts during valvular surgery

INTRODUCTION

To determine whether keeping the heart empty and beating is an effective technique to preserve hypertrophied pig hearts, and to investigate the underlying mechanism.

METHODS

Ten Bama Miniature pigs with hypertrophied hearts were divided into 2 groups (n = 5 in each group). One group underwent normothermic normokalemic simultaneous perfusion (NNSP). The other group was subjected to normothermic hypermokalemic simultaneous perfusion (NHSP) and used as controls. Cardiac contractive function, myocardial energy metabolism and myocardial perfusion were assessed using magnetic resonance imaging. Western blot analysis was carried out to determine the expression of Troponin I (cTnI), Troponin T (cTnT), SM-MHC, Casapase-3 and PARP4. TUNEL assay was used to detect apoptotic cardiomyocytes.

RESULTS

Keeping the heart empty and beating with NNSP improved the preservation of contractile function in comparison with cardioplegic arrest using NHSP. No significant differences existed in the effects of NNSP and NHSP in maintaining myocardial energy metabolism. 13 % perfusion defects areas were found in one heart in the NHSP group, whereas none was found in all other hearts in both groups. The expressions of cTnI, cTnT, Casapase-3 and PARP4 in NHSP group were abundantly increased compared to NNSP group as measured by Western blotting. Conversely, the expression of SM-MHC in NHSP group was reduced compared with NNSP group. The number of TUNEL positive nuclei per mm(2) area was significantly increased in NHSP group compared with NNSP group.

CONCLUSIONS

Keeping the heart beating with NNSP is an alternative technique to preserve hypertrophied hearts during valvular surgery.

Redo mitral valve replacement through a right mini-thoracotomy with an unclamped aorta

Redo cardiac surgery represents a clinical challenge due to a higher rate of perioperative morbidity and mortality. Mitral valve (MV) re operations can particularly be demanding in patients with patent coronary grafts, previous aortic valve replacement, calcified aorta or complications following a previous operation (abscesses, leaks or thrombosis). In this article we describe our technique to manage complex mitral reoperations using a minimally invasive approach, moderate hypothermia and avoiding aortic cross-clamping. Minimally invasive procedures with an unclamped aorta have the potential to combine the benefits of less invasive access and continuous myocardial perfusion. The advantage of a right mini-thoracotomy is the avoidance of sternal re-entry and limited dissection of adhesions, reducing the risk of cardiac structures or patent graft injury. Moderate hypothermia and continuous blood perfusion can guarantee adequate myocardial protection particularly in the case of patent grafts, decreasing the dangers of an incomplete or imperfect aortic clamping at mild hypothermia and potential lesions due to demanding clamp placing. Complex MV reoperations can be safely and effectively performed through a smaller right thoracotomy in the fourth intercostal space with an unclamped aorta.

Minimally invasive approach for redo mitral valve surgery

Redo cardiac surgery represents a clinical challenge due to a higher rate of peri-operative morbidity and mortality. Mitral valve re-operations can be particularly demanding in patients with patent coronary artery bypass grafts, previous aortic valve replacement, calcified aorta or complications following a previous operation (abscesses, perivalvular leaks, or thrombosis). Risk of graft injuries, hemorrhage, the presence of dense adhesions and complex valve exposure can make redo valve operations challenging through a median sternotomy. In this review article we provide an overview of minimally invasive approaches for redo mitral valve surgery discussing indications, techniques, outcomes, concerns and controversies. Scientific literature about minimally invasive approach for redo mitral surgery was reviewed with a MEDLINE search strategy combining "mitral valve" with the following terms: 'minimally invasive', 'reoperation', and 'alternative approach'. The search was limited to the last ten years. A total of 168 papers were found using the reported search. From these, ten papers were identified to provide the best evidence on the subject. Mitral valve reoperations can be safely and effectively performed through a smaller right thoracotomy in the fourth intercostal space termed "mini" thoracotomy or "port access". The greatest potential benefit of a right mini-thoracotomy is the avoidance of sternal re-entry and limited dissection of adhesions, avoiding the risk of injury to cardiac structures or patent grafts. Good percentages of valve repair can be achieved. Mortality is low as well as major complications. Minimally invasive procedures with an unclamped aorta have the potential to combine the benefits of minimally invasive access and continuous myocardial perfusion. Less invasive trans-catheter techniques could be considered as the natural future evolution for management of structural heart disease and mitral reoperations. The safety and efficacy of these procedures has never been compared to open reoperations in a randomized trial, although published case series and comparisons to historical cohorts suggest that they are an effective and feasible alternative. Ongoing follow-up on current series will further define these procedures and provide valuable clinical outcome data.

Beating heart continuous coronary perfusion for valve surgery: what next for clinical trials?

Prior to the introduction of cardioplegia, beating heart continuous coronary perfusion (BHCCP) was the only available method of myocardial protection. Currently, cardiac surgery on cardiopulmonary bypass with cardioplegic arrest is the gold standard strategy. Cardioplegic arrest provides an easier and safer way to operate on a still heart. It enables the performance of a broader range of cardiac procedures, and avoids the potential difficulties of continuous perfusion on a beating heart. Despite the overall effectiveness and safety of cardioplegia, some adverse effects remain, mainly due to the insult of ischemia, which results in ischemic reperfusion injury. As a result BHCCP has seen a revival as an alternative to cardioplegia for performing complex valvular surgery. Increasing experience reporting safety and efficacy of BHCCP is being published. However, despite the reported advantages, current available evidence validating safety and efficacy of BHCCP is controversial. This article provides an overview of BHCCP highlighting the current best available evidence supporting this strategy, concerns, controversies and potential areas for further research.