PEDS10: Characterizing the Fit of Transvalvular Left Ventricular Micro-Axial Flow Pumps in Pediatric Patients

Abstract

Background: There are few FDA approved mechanical circulatory support (MCS) devices for pediatric patients. Physicians in the US and Europe have increasingly elected to use the Impella platform to support pediatric patients including use in axillary arteries with diameters as small as 4.8 mm for the Impella 5.5 with SmartAssist (21 F) without complication. Given the increasing use of these devices in pediatric patients, there is a need to quantify and characterize the device fit in this population. Methods: 3D anatomical reconstructions were built from pediatric cardiac CT scans (n=23, age 0.8-9.3 years, BSA 0.45-1.09 m2). The length of the left ventricle & ascending aorta and the diameters of the brachiocephalic & lower left subclavian arteries were measured via clinical CT practices and modeled as a scalar relationship to BSA using simple linear regression & bounded by critical Impella dimensions to evaluate transvalvular fit. Estimated distal artery diameters were calculated via published vessel models to evaluate intravascular device delivery potential. The models were tested on pediatric Impella patient data as reported in published case studies (n=27, age 4-19 years, BSA 0.91-2.38 m2). Results: CT scan reconstructions suggest sufficient LV length in 0.6 m2 and 1.2 m2 BSA patients for Impella 5.5 and Impella CP, respectively. For direct aortic implant, BSA >1.1 m2 may be required due to ascending aortic length. The ostial segments of the brachiocephalic and left subclavian arteries were of adequate size for Impella 5.5 in patients with BSA as small as 0.53 m2. Published models correlating vessel diameter with BSA suggest BSA >0.86 m2 and >1.15 m2 patients could fit Impella CP and Impella 5.5, respectively, via midclavicular axillary access. Modeled vessel diameters predict that all pediatric Impella patients evaluated (27/27) would fit an Impella CP, and 74% (20/27) would fit an Impella 5.5 compared with the minimum vessel size reported in the literature. Conclusions: These analyses outline critical parameters for current Impella devices to fit pediatric patients. Further characterization of pediatric vessel sizes based on readily available clinical metrics such as BSA may aid physician decisions for MCS use in patients in critical need.