Evaluation of Hybrid Surgical Access Approaches for Pulmonary Valve Implantation in an Acute Swine Model

Hybrid approach for harmony transcatheter pulmonary valve replacement

The Harmony™ Transcatheter Pulmonary Valve (Medtronic) was recently approved by the Food and Drug Administration for transcatheter pulmonary valve replacement in native right ventricular outflow tracts. Despite this milestone, some patients have main pulmonary arteries that are severely dilated and continue to require surgical pulmonary valve replacement. The hybrid approach combines surgical creation of a landing zone, transcatheter valve deployment, and suture stabilization of the implanted valve. In this case series, we report the first use of a hybrid approach for Harmony™ transcatheter pulmonary valve replacement. Two cases are reported with varying approaches for surgical creation of a landing zone followed by successful placement of a Harmony™ valve.

Single‐Center Experience of Hybrid Pulmonary Valve Replacement Using Left Anterior Thoracotomy With Pulmonary Artery Plication in Patients With Large Right Ventricular Outflow Tract

Background

Until recently, a large right ventricle outflow tract interfered with the feasibility of standard transcatheter pulmonary valve replacement (PVR). We are describing our experience using a hybrid approach for PVR using a left anterior thoracotomy approach to allow for plication of the main pulmonary artery followed by a transcatheter PVR using a Sapien S3 valve.

Methods and Results

This is a single‐center, retrospective review of patients who were evaluated to be appropriate for a hybrid PVR approach. The patients' demographics, procedure details, and follow‐up data were collected. Between May 2018 and April 2021, a total of 11 patients presented for hybrid transcatheter PVR. The median age and weight were 24 years (interquartile range, 19–43 years) and 81.8 kg (interquartile range, 69–91 kg), respectively. Nine out of 11 patients received a transcatheter PVR after main pulmonary artery plication. There were no procedurally related deaths. One major complication was encountered in which the valve was malpositioned requiring successful surgical PVR. Minor complications included acute kidney injury (n=1) and a broken rib (n=1). The median length of stay was 4 days (interquartile range, 2–4 days), with median follow‐up of 7 months (interquartile range, 3–18 months). A well‐functioning pulmonary valve was observed in all patients at the last follow‐up.

Conclusions

A hybrid approach using left anterior thoracotomy with pulmonary artery plication followed by transcatheter Sapien S3 PVR provides a less‐invasive option for patients with an enlarged right ventricular outflow tract. Preliminary results demonstrated this to be a safe option with good short‐term outcomes.

The susceptibility of the aortic root: porcine aortic rupture testing under cardiopulmonary bypass

Background

In our earlier study on the functional limits of the aneurysmal aortic root we determined the pig root is susceptible to failure at high aortic pressures levels. We established a pig rupture model using cardiopulmonary bypass to determine the most susceptible region of the aortic root under the highest pressures achievable using continuous flow, and what changes occur in these regions on a macroscopic and histological level. This information may help guide clinical management of aortic root and ascending aorta pathology.

Methods

Five pigs underwent 4D flow MRI imaging pre surgery to determine vasopressor induced wall sheer stress and flow parameters. All pigs were then placed on cardiopulmonary bypass (CPB) via median sternotomy, and maximal aortic root and ascending aorta flows were initiated until rupture or failure, to determine the most susceptible region of the aorta. The heart was explanted and analysed histologically to determine if histological changes mirror the macroscopic observations.

Results

The magnetic resonance imaging (MRI) aortic flow and wall sheer stress (WSS) increased significantly in all regions of the aorta, and the median maximal pressures obtained during cardiopulmonary bypass was 497 mmHg and median maximal flows was 3.96 L/m. The area of failure in all experiments was the non-coronary cusp of the aortic valve. Collagen and elastin composition (%) was greatest in the proximal regions of the aorta. Collagen I and III showed greatest content in the inner aortic root and ascending aorta regions.

Conclusions

This unique porcine model shows that the aortic root is most susceptible to failure at high continuous aortic pressures, supported histologically by different changes in collagen content and subtypes in the aortic root. With further analysis, this information could guide management of the aortic root in disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-021-01667-9.