Boucek DM, Qureshi AM, Aggarwal V, Spigel ZA, Johnson J, Gray RG, Martin MH. Cardiol Young. 2023 Nov;33(11):2282-2290. doi: 10.1017/S104795112200405X. Epub 2023 Jan 27.PMID: 36705001
Take Home Points:
- Right ventricle to pulmonary artery conduits can be dilated beyond 110% of their implant diameter.
- Procedural complications were more common in the over-dilation group but these were mostly managed in the catheterization lab without significant morbidity and mortality.
- The ability to over-dilate small diameter conduits can allow patients with right ventricular outflow tract dysfunction to defer or avoid surgical pulmonary valve replacement.
Commentary from Dr. Konstantin Averin (Cohen Children’s Heart Center), catheterization section editor of Pediatric Cardiology Journal Watch:
Trans-catheter pulmonary valve replacement (TPVR) with the Medtronic Melody valve is now routinely utilized in treatment of right ventricular outflow tract pathology, especially in dysfunctional right ventricular to pulmonary artery conduits. The original indication for the Melody valve was for conduits with implant diameters of 16mm or greater, excluding many patients with smaller conduits from this therapy. There has been increasing experience with overdilation of conduits beyond a theoretical guideline of 110% of their implant diameter. The authors sought to compare outcomes of conduit dilation to >110% of nominal diameter with a control group of ≤ 100%.
From November 2010 to March 2017, 172 patients were included in the study – 51 in the overdilation group and 121 in the control group with the overdilation group being younger (11.2 vs 16.7 years, p < 0.001) and smaller (32.8 vs 57.8 kg, p < 0.001) than the controls. There were more homograft conduits in the overdilation group (73 vs 44%). The success rate for TPVR was 98% in both groups with the relationship of original conduit size to average final valve diameter in the overdilation group demonstrated in Figure 1. Amazingly, even conduits <12mm at implant were usually able to be dilated to an average of approximately 20mm.
Procedural complications were more common in the overdilation group (18% vs 7%, p = 0.046). In the overdilation group complications included 1 uncontained conduit tear requiring ECMO and emergent surgical pulmonary valve replacement; 7 patients had contained tears and 1 had an MPA pseudoaneurysm treated with a vascular plug. There were no differences in TVPR durability at a mean follow-up of 3.6 years (overdilation) vs 4.1 years (control) – including a combined freedom from reintervention of 89%. Endocarditis was more common in the overdilation group (16%) compared to the control group (5%) suggesting that a smaller implant conduit diameter (independent of final TPVR diameter or pressure gradient) could be a risk factor for endocarditis.
The authors conclude that right ventricle to pulmonary artery conduits can be dilated beyond 110% of their implant diameter. While complications were more common in the overdilation group these could safely be managed in the catheterization lab without serious morbidity or mortality. This study continues to add to the literature supporting the overdilation of small conduits to adult diameters, in fact the authors report dilating 9mm conduits to 20+ mm (>200% of implant diameter). Diseases of the right ventricular outflow tract requiring conduit implant are life-long conditions that will necessitate multiple surgical and catheter-based interventions. If small conduits can be dilated to large diameters (as suggested by the authors) with relative safety this will allow providers to minimize the number of lifetime surgical interventions.
Figure 1.
