Limited versus full sternotomy for aortic valve replacement

BACKGROUND

Aortic valve disease is a common condition that is easily treatable with cardiac surgery. This is conventionally performed by opening the sternum longitudinally down the centre ("median sternotomy") and replacing the valve under cardiopulmonary bypass. Median sternotomy is generally well tolerated, but as less invasive options have become available, the efficacy of limited incisions has been called into question. In particular, the effects of reducing the visibility and surgical access has raised safety concerns with regards to the placement of cannulae, venting of the heart, epicardial wire placement, and de-airing of the heart at the end of the procedure. These difficulties may increase operating times, affecting outcome. The benefits of smaller incisions are thought to include decreased pain; improved respiratory mechanics; reductions in wound infections, bleeding, and need for transfusion; shorter intensive care stay; better cosmesis; and a quicker return to normal activity.

OBJECTIVES

To assess the effects of minimally invasive aortic valve replacement via a limited sternotomy versus conventional aortic valve replacement via median sternotomy in people with aortic valve disease requiring surgical replacement.

SEARCH METHODS

We performed searches of CENTRAL, MEDLINE, Embase, clinical trials registries, and manufacturers' websites from inception to July 2016, with no language limitations. We reviewed references of identified papers to identify any further studies of relevance.

SELECTION CRITERIA

Randomised controlled trials comparing aortic valve replacement via a median sternotomy versus aortic valve replacement via a limited sternotomy. We excluded trials that performed other minimally invasive incisions such as mini-thoracotomies, port access, trans-apical, trans-femoral or robotic procedures. Although some well-conducted prospective and retrospective case-control and cohort studies exist, these were not included in this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial papers to extract data, assess quality, and identify risk of bias. A third review author provided arbitration where required. The quality of evidence was determined using the GRADE methodology and results of patient-relevant outcomes were summarised in a 'Summary of findings' table.

MAIN RESULTS

The review included seven trials with 511 participants. These included adults from centres in Austria, Spain, Italy, Germany, France, and Egypt. We performed 12 comparisons investigating the effects of minimally invasive limited upper hemi-sternotomy on aortic valve replacement as compared to surgery performed via full median sternotomy.There was no evidence of any effect of upper hemi-sternotomy on mortality versus full median sternotomy (risk ratio (RR) 1.01, 95% confidence interval (CI) 0.36 to 2.82; participants = 511; studies = 7; moderate quality). There was no evidence of an increase in cardiopulmonary bypass time with aortic valve replacement performed via an upper hemi-sternotomy (mean difference (MD) 3.02 minutes, 95% CI -4.10 to 10.14; participants = 311; studies = 5; low quality). There was no evidence of an increase in aortic cross-clamp time (MD 0.95 minutes, 95% CI -3.45 to 5.35; participants = 391; studies = 6; low quality). None of the included studies reported major adverse cardiac and cerebrovascular events as a composite end point.There was no evidence of an effect on length of hospital stay through limited hemi-sternotomy (MD -1.31 days, 95% CI -2.63 to 0.01; participants = 297; studies = 5; I2 = 89%; very low quality). Postoperative blood loss was lower in the upper hemi-sternotomy group (MD -158.00 mL, 95% CI -303.24 to -12.76; participants = 297; studies = 5; moderate quality). The evidence did not support a reduction in deep sternal wound infections (RR 0.71, 95% CI 0.22 to 2.30; participants = 511; studies = 7; moderate quality) or re-exploration (RR 1.01, 95% CI 0.48 to 2.13; participants = 511; studies = 7; moderate quality). There was no change in pain scores by upper hemi-sternotomy (standardised mean difference (SMD) -0.33, 95% CI -0.85 to 0.20; participants = 197; studies = 3; I2 = 70%; very low quality), but there was a small increase in postoperative pulmonary function tests with minimally invasive limited sternotomy (MD 1.98 % predicted FEV1, 95% CI 0.62 to 3.33; participants = 257; studies = 4; I2 = 28%; low quality). There was a small reduction in length of intensive care unit stays as a result of the minimally invasive upper hemi-sternotomy (MD -0.57 days, 95% CI -0.93 to -0.20; participants = 297; studies = 5; low quality). Postoperative atrial fibrillation was not reduced with minimally invasive aortic valve replacement through limited compared to full sternotomy (RR 0.60, 95% CI 0.07 to 4.89; participants = 240; studies = 3; moderate quality), neither were postoperative ventilation times (MD -1.12 hours, 95% CI -3.43 to 1.19; participants = 297; studies = 5; low quality). None of the included studies reported cost analyses.

AUTHORS' CONCLUSIONS

The evidence in this review was assessed as generally low to moderate quality. The study sample sizes were small and underpowered to demonstrate differences in outcomes with low event rates. Clinical heterogeneity both between and within studies is a relatively fixed feature of surgical trials, and this also contributed to the need for caution in interpreting results.Considering these limitations, there was uncertainty of the effect on mortality or extracorporeal support times with upper hemi-sternotomy for aortic valve replacement compared to full median sternotomy. The evidence to support a reduction in total hospital length of stay or intensive care stay was low in quality. There was also uncertainty of any difference in the rates of other, secondary outcome measures or adverse events with minimally invasive limited sternotomy approaches to aortic valve replacement.There appears to be uncertainty between minimally invasive aortic valve replacement via upper hemi-sternotomy and conventional aortic valve replacement via a full median sternotomy. Before widespread adoption of the minimally invasive approach can be recommended, there is a need for a well-designed and adequately powered prospective randomised controlled trial. Such a study would benefit from performing a robust cost analysis. Growing patient preference for minimally invasive techniques merits thorough quality-of-life analyses to be included as end points, as well as quantitative measures of physiological reserve.

Recurrent ventral herniation in Ehlers-Danlos syndrome

Ehlers-Danlos syndrome is an inherited collagen disorder characterized by skin hyperextensibility, joint laxity, and tissue friability. In this study, it was hypothesized that Ehlers-Danlos syndrome is frequently undiagnosed in patients who present for repair of ventral abdominal wall hernias. A retrospective chart review was conducted, and patients who had presented for elective repair of recurrent abdominal wall herniation were identified. In all patients, one or more prior attempts at repair with either mesh or autologous tissues had failed. Patients in whom abdominal wall components were lost secondary to extirpation or trauma, patients who had required acute closure, and patients with less than 2 months of follow-up were excluded. Twenty patients met these criteria. Twenty cases of recurrent ventral hernia repairs were reviewed, with special attention to identification of the preoperative diagnosis of Ehlers-Danlos syndrome. Patients ranged in age from 29 to 75 years, with a mean age of 54 years. Five patients were male (25 percent), and 15 were female (75 percent). The majority (95 percent) were Caucasian. The most common initial procedures were gynecologic in origin (35 percent). A precise closure technique that minimizes recurrence after ventral hernia repairs was used. With use of this technique, there was only one recurrence over a follow-up period that ranged from 2 to 60 months (mean follow-up duration, 25.7 months). Two patients with Ehlers-Danlos syndrome were identified, and their cases are presented in this article. The "components separation" technique with primary component approximation and mesh overlay was used for defect closure in the two cases presented. The identification of these two patients suggests the possibility of underdiagnosis of Ehlers-Danlos syndrome among patients who undergo repeated ventral hernia repair and who have had previous adverse postoperative outcomes. There are no previous reports in the literature that address recurrent ventral abdominal herniation in patients with Ehlers-Danlos syndrome.

In vivo analysis of bacterial biofilm formation on facial plastic bioimplants

OBJECTIVES

This study examines the formation of biofilm on biomaterials commonly used in facial plastics and reconstruction including titanium, silicone, ion-bombarded silicone (Ultrasil), e-PTFE (Gore-Tex), e-PTFE with silver/chlorhexidine (Gore-Tex Plus), and PHDPE (Medpor).

METHODS

These biomaterials were implanted subcutaneously in the dorsum of 11 guinea pigs after contamination with Staphylococcus aureus and examined with scanning electron microscopy after 7 days. Wounds were also inspected for infection and extrusion rates.

RESULTS

Results show biofilm formation on titanium, silicone, ion-bombarded silicone, e-PTFE, and PHDPE associated with high rates of extrusion and infection. Implants of e-PTFE with silver/chlorhexidine, on the other hand, appeared resistant to biofilm formation and demonstrated significantly lower rates of extrusion and infection.

CONCLUSIONS

Contamination of bioimplants in vivo leads to formation of bacterial biofilm on the surface of the biomaterial, causing infection, pus formation, and extrusion. The authors hypothesize that the antiseptic agents impregnated in the biomaterial form a protective coat of silver, chlorhexidine, and inflammatory cells that inhibits initial bacterial adhesion to the biomaterial surface.