title: Right-left ventricular output balance in the totally implantable artificial heart.
abstract: Pneumatically powered artificial hearts readily accommodated the higher net stroke volumes by the right ventricle than from the left ventricle. We published that this discrepancy was approximately 8% of the left ventricular cardiac output. A variety of methods have been used to achieve balance between the right and left atrial pressures. Relatively large volume-displacement chambers (VDC) present potential problems, but do provide balance. The VDC in volumetrically coupled right-left stroke volumes was eliminated by using a small-diameter interatrial shunt (IAS). Preliminary studies demonstrated excellent balance in contracted and expanded blood volume (preload) and by hypotension and hypertension created with vasoactive drugs (afterload). At a mean aortic pressure of 120 mmHg, heart rate of 120 BPM, cardiac output of 8 L/minute and right atrial pressure of 13 mmHg, the peak IAS flow was 3.2 ml/beat in a right to left direction and 8.0 ml/beat in a left to right direction. The net left to right flow was 4.8 ml/beat. Over a wide range of preload (2 to 20 mmHg) and afterload (45 to 180 mmHg), the left atrial pressure was routinely 5 mm Hg more than the right atrial pressure. Elimination of the VDC reduces the number of components, volume, and weight of the totally implantable artificial heart. The IAS offers a simple solution to a very complex problem and provides a device that is simpler to implant and is possible to explant.
authors.affiliation: Artificial Heart Research Laboratory, University of Utah, Salt Lake City.
authors.forename: D B
authors.initials: DB
authors.lastname: Olsen
authors.forename: R K
authors.initials: RK
authors.lastname: White
authors.forename: J W
authors.initials: JW
authors.lastname: Long
authors.forename: P S
authors.initials: PS
authors.lastname: Khanwilkar
mesh_terms: D000818:Animals; D002302:Cardiac Output; D002417:Cattle; D004867:Equipment Design; D006354:Heart, Artificial; D006439:Hemodynamics / Q000502:physiology*; D012212:Rheology; D013318:Stroke Volume; D016276:Ventricular Function