Congenital Heart Interventions

Impact of Patient Prosthesis Mismatch on the Outcome of Transcatheter Pulmonic Valve Implantation. Takajo D, Forbes TJ, Kobayashi D.Am J Cardiol. 2021 May 27:S0002-9149(21)00376-3. doi: 10.1016/j.amjcard.2021.04.022. Online ahead of print.PMID: 34053630   Take Home Points: Patient prosthesis mismatch (PPM) is an important factor of the outcome in transcatheter aortic valve implantation. However, the impact of PPM in transcatheter pulmonic valve implantation (TPVI) has not been studied. The Geometric Orifice Area indexed by the BSA had the best overall model quality and its optimal cut-off value of iGOA was 1.25 cm2/m2. Both PPM and significant residual RVOT gradient ≥ 15 mmHg after TPVI were significantly associated with the need of re-intervention (p < 0.05). Based on the proposed cut-off value of iGOA 1.25 cm2/m2, the authors made a Table (Table 1) which can be used as a reference value of the Melody stent valve diameters based on BSA and eccentricity index. Commentary from Dr. Varun Aggarwal (Minneapolis, MN, USA), section editor of Congenital Heart Disease Interventions Journal Watch: Patient prosthesis mismatch (PPM) means that the effective Geometric Orifice Area (GOA) of the prosthetic valve is smaller than of a normal human valve (1). The outcomes of transcatheter aortic valve placement have been shown to be affected by the GOA of the valve (2, 3). This however, has not been well studied for transcatheter pulmonic valve implantation (TPVI). In this paper, Takajo D et al (4) performed a single center retrospective review of 101 patients who underwent transcatheter Melody valve placement in the right ventricular outflow tract from 2010 to 2020.   The GOA was calculated with the ellipse formula based on the assumption that the measured narrowest diameters in two projections represent the major and minor axis of the orifice area: GOA = p*(a/2)*(b/2), Figure 1. The GOA was indexed to the BSA, weight and height to derive iGOA (cm2/m2), iGOA (cm2/kg), and iGOA (cm2/m), respectively. Significant RVOT residual gradient (≥ 15 mmHg) was observed in 31 patients (40%). The narrowest diameter in either AP or lateral views was 16.1±2.4 mm. There were 30 patients (30%) having the eccentricity index >1.1. The measured GOA was 2.22±0.67 cm2 and iGOA was 1.42±0.48 cm2/m2. There was significant negative correlation between the post-TPVI residual RVOT gradient and iGOA (cm2/m2) (Pearson correlation -0.620, p < 0.001). The iGOA indexed by the BSA had the best overall model quality (area under the curve 0.873, p < 0.001, Figure 2) and its optimal cut-off value of iGOA was 1.25 cm2/m2. Based on the cut-off value of iGOA, the cohort was divided into two groups: PPM group (n = 42, iGOA < 1.25 cm2/m2) and non-PPM group (n = 59, iGOA ≥1.25 cm2/m2).   Over the mean follow up period of 6.9±2.7 years, 22 patients (22%) required re-interventions (16 transcatheter, 11 surgical, and both in 5 patients). On the Kaplan-Meier survival analysis, both PPM and significant residual RVOT gradient ≥ 15 mmHg were significantly associated with the need of re-intervention (p < 0.05, Figure 3). The final multivariable model showed that the significant predictors were PPM (hazard ratio 2.67, p = 0.021) and homograft (hazard ratio 2.85, p = 0.022). Abnormal eccentricity index was not associated with the presence of PPM. Neither the Ensemble system size nor eccentricity index had no effect on the need of reintervention at follow-up. Based on the proposed cut-off value of iGOA 1.25 cm2/m2, the authors made a Table (Table 1) which can be used as a reference value of the Melody stent valve diameters based on BSA and eccentricity index. This is the first data depicting the importance or GOA and PPM in transcatheter pulmonary valve implantation. These factors should be factored into consideration by operators while performing TPVI using Melody valve.   Figure 1. Measurement of geometric orifice area in the transcatheter pulmonary valve implantation. The narrowest valve stent diameter is measured in anteroposterior (AP) and lateral views (4).     Figure 2: Receiver operator characteristic curve analysis to identify the optimal cut-off value of indexed geometric orifice area (iGOA) by body surface area, weight and height, to detect the significant RVOT residual gradient (≥ 15 mmHg) in transcatheter pulmonic valve implantation(4).     Figure 3: Kaplan-Meier survival curve showing the freedom from the re-intervention in 101 patients undergoing transcatheter pulmonic valve implantation using Melody valve, based on (A) residual right ventricular outflow tract (RVOT) gradient and (B) patient prosthesis mismatch (4).     Table 1: Clinical guide for the Melody valve stent diameter to avoid the patient prosthesis mismatch based on the body surface area (BSA) and eccentricity index, using the cut-off value of the indexed geometric orifice area (GOA) of 1.25 cm2/m2 (4).     References: 1. Muneretto C, Bisleri G, Negri A, Manfredi J. The concept of patient-prosthesis mismatch. J Heart Valve Dis. 2004;13 Suppl 1:S59-62.   2. Pibarot P, Clavel MA. Prosthesis-Patient Mismatch After Transcatheter Aortic Valve Replacement: It Is Neither Rare Nor Benign. J Am Coll Cardiol. 2018;72(22):2712-6.   3. Dayan V, Vignolo G, Soca G, Paganini JJ, Brusich D, Pibarot P. Predictors and Outcomes of Prosthesis-Patient Mismatch After Aortic Valve Replacement. JACC Cardiovasc Imaging. 2016;9(8):924-33.   4. Takajo D, Forbes TJ, Kobayashi D. Impact of Patient Prosthesis Mismatch on the Outcome of Transcatheter Pulmonic Valve Implantation. Am J Cardiol. 2021;151:93-9.    

Preliminary testing and evaluation of the renata minima stent, an infant stent capable of achieving adult dimensions. Zahn EM, Abbott E, Tailor N, Sathanandam S, Armer D. Catheter Cardiovasc Interv. 2021 May 4. doi: 10.1002/ccd.29706. Online ahead of print. PMID: 33942962   Take Home Points: The Renata Minima Stent is a cobalt chromium, balloon-expandable stent that has diameter potential of 4-22mm. In a growing animal model, the vast majority of stents were implanted successfully and were subsequently successfully re-dilated with foreshortening noted with successively larger diameters This stent represents an important advancement in stent design to meet a critical need in congenital cardiac catheterization. Commentary by Dr. Arash Salavitabar (Ann Arbor Michigan) section editor of Pediatric Interventional Cardiology Journal Watch: The authors describe the Renata Minima Stent, which is a cobalt chromium, balloon-expandable stent designed for implantation at small diameters and with significant expansion potential, tested here in a growing animal model. The stent diameter ranges from 4-22mm, with all stents having an initial length of 17mm. The stent is designed with its own delivery system, which consists of an inner balloon and a braided “delivery sheath” designed to cover the stent for delivery and allows for hand angiograms during stent positioning, and is currently available with its custom delivery balloon in 6 or 8mm diameters for implantation. Importantly, this is a low profile system that has an outer diameter reportedly comparable to that of a 4-French sheath, and can be delivered over a 0.014” or 0.018” guide wire or via a 6-French sheath.   In this animal model, 21/22 (95%) stents were successfully implanted in 6 piglets (initial weight 4.6 +/- 0.5kg), with the one unsuccessful implant being delivered through an early delivery system prototype. The majority of stented sites were either in the aorta or branch pulmonary artery. Stents were implanted with an average balloon inflation pressure of 11.8 +/−2.1 atm, resulting in an implant diameter of 6.9 +/− 1.2 mm and stent length of 16.9 +/− 0.8 mm. Average stent recoil was 0.8 mm +/− 0.5 (9.8% +/− 6.2). Four piglets had subsequent catheterizations and redilations were performed in 17/22 total stents. Stents were successfully re-dilated at an average of 54 days post-implantation, at which time stent diameter increased by 54% +/− 25% (p < .001) with foreshortening to a final stent length of 16.1 +/−1.5 mm. Three piglets (mean weight 95kg +/- 13.1) with 11 total stents had re-catheterizations at 5 months post-implantation, with re-dilation performed on 8 of those stents. Stent dilation diameters represented a 61% +/− 28% increase from the prior procedure, or a 125% +/− 35% increase in diameter since stent implantation. Two stents were over-dilated with 18mm and 16mm balloons, respectively, with a foreshortening of 23% +/− 9% and average final stent length of   13.1 mm (+/−1.5). There were no complications, however a strut fracture was noted after re-dilation to 16mm in one aortic and one LPA stent.   Two piglets were sacrificed at 1 month for histopathology, which showed neointimal cell growth was present in varying degrees, fibromuscular tissue, and mild-to-moderate   strut-associated inflammation. In late histopathologic evaluation of a recently dilated LPA stent, irregular neointimal growth and vascular wall damage was identified.   These are promising early results for a new stent option that aims to solve a common and extremely important problem: stent implantation in the infant or child that will allow for lifelong expansion potential to match vessel and somatic growth. There are several aspects that will need to be further tested in animal models, such as treatment of truly stenotic vessels, followed by trials in humans in order to determine efficacy and safety. Nonetheless, this is a much needed advancement in congenital cardiac catheterization.