Left Atrial Unloading in Heart Failure With Preserved Ejection Fraction: In-Vitro Study of Interatrial Shunting and Continuous Flow Pumping

Heart failure with preserved ejection fraction (HFpEF) often presents with elevated left atrial (LA) pressure. Interatrial shunt devices (IASD) were developed and rotary blood pumps implanted off-label to reduce LA pressure in HFpEF patients. This study modeled an HFpEF patient in a mock circulation loop, comparing pulmonary decompression using an IASD (2-12 mm diameter) and a continuous flow (CF) centrifugal rotary blood pump (HeartMate 3; Abbott Laboratories, Abbott Park, IL) in LA to aortic configuration (1-6 L/min support). Left atrial pressure, pulmonary artery pressure (PAP), and cardiac output (CO) at 12 mm shunt diameter and 6 L/min pump support were primarily used to quantify pulmonary decompression. The IASD reduced LA pressure by 28% and 45%, while the CF reduced LA pressure by 135% and 51% at rest and exercise, respectively. Both devices reduced mean PAP by 13% (IASD) and 57% (CF) at rest and by 21% (IASD) and 32% (HM3) at exercise. The IASD resulted in reduced CO (rest: 14%, exercise 8%), but the CF increased CO (rest: 63%, exercise: 28%) and ventricular loading due to the LA to aortic configuration. Automated changes to rotary blood pump speed or IASD diameter may assist with unloading as physiologic conditions change.