Editorial analysis: impact of perfusion strategy on stroke risk for minimally invasive cardiac surgery

Clinical outcomes associated with retrograde arterial perfusion in minimally invasive mitral valve surgery: a systematic review

INTRODUCTION

Given several reports of an increased neurologic risk with retrograde arterial perfusion in minimally invasive mitral valve surgery, we sought to identify and synthesize the best available evidence on the influence of perfusion strategy on post-operative clinical outcomes in this population.

METHODS

A systematic search of PubMed, EMBASE, MEDLINE, and Cochrane library databases was performed to identify publications comparing clinical outcomes associated with antegrade and retrograde arterial perfusion in minimally invasive mitral valve surgery. Pre-specified outcomes of interest were neurologic events, mortality, and renal failure. The search was performed by two independent reviewers, with data abstraction following.

RESULTS

Seven observational studies were included in this review, with a total patient population of 5,385. Six were retrospective cohort in design, with a single small prospective cohort study identified. When available, adjusted publication-specific risk estimates were abstracted and included preferentially over unadjusted or reviewer-derived risk estimates. Meta-analysis was felt to be heavily flawed in the context of few small studies identified and was not performed. In adjusted estimates, there appeared to be an increased risk of neurologic complications with retrograde arterial perfusion. There was a null pattern apparent between arterial perfusion strategy and each of 30-day mortality and renal failure.

CONCLUSION

Retrograde arterial perfusion in minimally invasive mitral valve surgery may be associated with an increased risk of neurologic events, without affecting the risk of 30-day mortality or renal failure. Although these patterns were identified, an overall paucity of evidence justifies further study.

Anesthetic challenges in minimally invasive cardiac surgery: Are we moving in a right direction?

Continuously growing patient's demand, technological innovation, and surgical expertise have led to the widespread popularity of minimally invasive cardiac surgery (MICS). Patient's demand is being driven by less surgical trauma, reduced scarring, lesser pain, substantially lesser duration of hospital stay, and early return to normal activity. In addition, MICS decreases the incidence of postoperative respiratory dysfunction, chronic pain, chest instability, deep sternal wound infection, bleeding, and atrial fibrillation. Widespread media coverage, competition among surgeons and hospitals, and their associated brand values have further contributed in raising awareness among patients. In this process, surgeons and anesthesiologist have moved from the comfort of traditional wide incision surgeries to more challenging and intensively skilled MICS. A wide variety of cardiac lesions, techniques, and approaches coupled with a significant learning curve have made the anesthesiologist's job a challenging one. Anesthesiologists facilitate in providing optimal surgical settings beginning with lung isolation, confirmation of diagnosis, cannula placement, and cardioplegia delivery. However, the concern remains and it mainly relates to patient safety, prolonged intraoperative duration, and reduced surgical exposure leading to suboptimal treatment. The risk of neurological complications, aortic injury, phrenic nerve palsy, and peripheral vascular thromboembolism can be reduced by proper preoperative evaluation and patient selection. Nevertheless, advancement in surgical instruments, perfusion practices, increasing use of transesophageal echocardiography, and accumulating experience of surgeons and anesthesiologist have somewhat helped in amelioration of these valid concerns. A patient-centric approach and clear communication between the surgeon, anesthesiologist, and perfusionist are vital for the success of MICS.

Can the Learning Curve of Totally Endoscopic Robotic Mitral Valve Repair be Short-Circuited?

Objective

A concern with the initiation of totally endoscopic robotic mitral valve repair (TERMR) programs has been the risk for the learning curve. To minimize this risk, we initiated a TERMR program with a defined team and structured learning approach before clinical implementation.

Methods

A dedicated team (two surgeons, one cardiac anesthesiologist, one perfusionist, and two nurses) was trained with clinical scenarios, simulations, wet laboratories, and “expert” observation for 3 months. This team then performed a series of TERMRs of varying complexity.

Results

Thirty-two isolated TERMRs were performed during the first programmatic year. All operations included mitral valve repair, left atrial appendage exclusion, and annuloplasty device implantation. Additional procedures included leaflet resection, neochordae insertion, atrial ablation, and papillary muscle shortening. Longer clamp times were associated with number of neochordae ( P < 0.01), papillary muscle procedures ( P < 0.01), and leaflet resection ( P = 0.06). Sequential case number had no impact on cross-clamp time ( P = 0.3). Analysis of nonclamp time demonstrated a 71.3% learning percentage ( P < 0.01; ie, 28.7% reduction in nonclamp time with each doubling of case number). There were no hospital deaths or incidences of stroke, myocardial infarction, unplanned reoperation, respiratory failure, or renal failure. Median length of stay was 4 days. All patients were discharged home.

Conclusions

Totally endoscopic robotic mitral valve repair can be safely performed after a pretraining regimen with emphasis on experts’ current practice and team training. After a pretraining regimen, cross-clamp times were not subject to learning curve phenomena but were dependent on procedural complexity. Nonclamp times were associated with a short learning curve.

Minimally invasive mitral valve surgery: influence of aortic clamping technique on early outcomes

BACKGROUND

Several methods of aortic clamping have been described for minimally invasive mitral valve surgery (MIMVS). The aim of this study was to compare the endoaortic balloon occlusion technique with the transthoracic clamp approach in terms of perioperative outcomes.

METHODS

Between May 2006 and October 2011, a total of 259 patients underwent MIMVS through a 4 to 5 cm right anterolateral minithoracotomy. In 243 (93.8%) of these, the aorta was clamped using either the endoaortic balloon occlusion technique (endoballoon, n = 140) or the transthoracic clamp technique (transthoracic, n = 103).

RESULTS

Patients in the endoballoon group had significantly longer operating time (4.3 ± 1.0 hours vs 3.2 ± 0.8 hours, p < 0.001), cardiopulmonary bypass time (143 ± 44 minutes vs 111 ± 29 minutes , p < 0.001), and cross-clamp time (114 ± 38 minutes vs 86 ± 23 minutes , p < 0.001). Perioperative blood loss was higher in the endoballoon group (287 ± 239 mL vs 213 ± 189 mL, p = 0.008) as was the mean postoperative creatinine kinase-MB level (36 ± 44 μg/L vs 26 ± 12 μg/L, p = 0.011). The repair rate was 99% or greater in both groups (p = 0.99). All patients left the operating room with no or trivial residual mitral regurgitation on transesophageal echocardiographic evaluation. In the endoballoon group there was 1 stroke (1%) and 5 myocardial infarctions (4%), compared with 2 strokes (2%) in the transthoracic group (p = not significant). There were 4 cases of postoperative cardiogenic shock, all of which occurred in the endoballoon group (p = 0.14). In-hospital mortality occurred in 2 patients from each group (p = 0.99).

CONCLUSIONS

Minimally invasive mitral valve surgery can be performed successfully using either the endoaortic balloon technique or the transthoracic clamp approach. However, the transthoracic technique results in shorter operation time, less perioperative bleeding and better myocardial protection.

Minimally invasive mitral valve surgery: a systematic review

In the recent years minimally invasive mitral valve surgery (MIMVS) has become a well-established and increasingly used option for managing patients with a mitral valve pathology. Nonetheless, whether the purported benefits of MIMVS translate into clinically important outcomes remains controversial. Therefore, in this paper we provide an overview of MIMVS and discuss results, morbidity, mortality, and quality of life following mitral minimally invasive procedures. MIMVS has been proven to be a feasible alternative to the conventional full sternotomy approach with low perioperative morbidity and short-term mortality. Reported benefits of MIMVS include also decreased postoperative pain, improved postoperative respiratory function, reduced surgical trauma, and greater patient satisfaction. Finally, compared to standard surgery, MIMVS demonstrated comparable efficacy across a range of long-term efficacy measures such as freedom from reoperation and long-term survival.

Use of Axillary Cannulation for Simultaneous Endo-Occlusion and Antegrade Perfusion during Minimally Invasive Surgery

Objective

We aimed to develop an antegrade arterial perfusion method that would allow a single suture line on the heart.

Methods

Using an 8-mm Dacron graft sewn to the right axillary artery, we performed antegrade arterial flow and simultaneous endo-occlusion, as well as the delivery of antegrade cardioplegia.

Results

Five patients underwent right axillary antegrade flow, with intention to use axillary endo-occlusion. There were no deaths, axillary artery injuries, or conversions to sternotomy. One patient who had a small (6 mm) axillary artery required femoral arterial balloon placement with axillary arterial flow. When using a 100-mm endobal-loon, transesophageal echo alone is suitable for placement of the endo-balloon. All patients are alive and doing well at least 1 year after surgery.

Conclusions

The right axillary artery is a suitable conduit for simultaneous endo-occlusion, antegrade flow, and antegrade cardioplegia delivery during mitral valve surgery.