Effects of an interatrial shunt on rest and exercise hemodynamics: results of a computer simulation in heart failure

Background: A treatment based on an interatrial shunt device has been proposed for counteracting
elevated pulmonary capillary wedge pressure (PCWP) in patients with heart failure and mildly reduced
or preserved ejection fraction (HFpEF). We tested the theoretical hemodynamic effects of this approach
with the use of a previously validated cardiovascular simulation.
Methods and Results: Rest and exercise hemodynamics data from 2 previous independent studies of patients
with HFpEF were simulated. The theoretical effects of a shunt between the right and left atria (diameter
up to 12 mm) were determined. The interatrial shunt lowered PCWP by w3 mm Hg under simulated
resting conditions (from 10 to 7 mm Hg) and by w11 mm Hg under simulated peak exercise conditions
(from 28 to 17 mm Hg). Left ventricular cardiac output decreased w0.5 L/min at rest and w1.3 L/min at
peak exercise, with corresponding increases in right ventricular cardiac output. However, because of the
reductions in PCWP, right atrial and pulmonary artery pressures did not increase. A majority of these effects
were achieved with a shunt diameter of 8e9 mm. The direction of flow though the shunt was left to
right in all of the conditions tested.
Conclusions: The interatrial shunt reduced left-sided cardiac output with a marked reduction in PCWP.
This approach may reduce the propensity for heart failure exacerbations and allow patients to exercise
longer, thus attaining higher heart rates and cardiac outputs with the shunt compared with no shunt. These
results support clinical investigation of this approach and point out key factors necessary to evaluate its
safety and hemodynamic effectiveness.