An interatrial shunt (IAS) was developed and tested to balance a volumetrically coupled electrohydraulic total artificial heart (EHTAH). The IAS diameter was determined theoretically with the equation: D=(8/24rH Q2/C2δP)1/4 where D = orifice diameter, δP = pressure drop across the orifice, ρ = fluid density, Q = volume flow through the orifice, and C = empiric constant. The calculated orifice diameter was 2.9–5.3 mm to keep a 3–5 mmHg pressure difference between left and right atria, with 0.42–1.05 L/min of expected flow through the IAS. Three different sizes (3.4, 5.4, and 5.5 mm) of IAS were implanted and tested in four calves. The in vivo left-right pressure difference ranged from 3 to 8 mmHg, with 0.57–1.38 L/min of theoretically calculated flow through the IAS. At autopsy, none of the IAS showed macroscopic thrombus formation.
©1991 American Society of Artificial Internal Organs