Predicting the Dimensions of an Intracardiac Partial-Assist Pump for Percutaneous Delivery by Analytical and Numerical Methods.

A minimally invasive ventricular assist device is under development for percutaneous insertion into the left atrium via transseptal access from the right atrium (RA). This study aimed to mathematically describe the vascular anatomy along possible insertion pathways to determine the device's maximum outer dimensions. We developed 2-dimensional mathematical models describing the vascular anatomy to the RA from three access points: subclavian vein (SCV), internal jugular vein (IJV), and femoral vein (FV). All pathways terminated by turning from the superior or inferior vena cava (SVC/IVC) into the RA. The model equations were based on restriction points in the pathways and were solved using anatomic size values 1 SD below published mean values so that the device will accommodate most patients. Vessels were considered rigid so that vessel deformation (and therefore risk) is minimized during device insertion. Maximum device length was calculated for a range of device diameters. The length at the most constraining angle in each turn was the maximum allowable device length. The least restrictive pathway was from the right FV, the turn from the IVC through the atrial septum being the most restrictive point. For a 10-mm diameter device, the length restriction for this pathway was 45 mm, whereas those for the right IJV and SCV were 42 and 21 mm, respectively. Medical device developers can apply these models to determine size specifications of new devices, whereas interventional physicians can apply them to determine if an existing device is appropriate for an individual patient.