3. Projects

Simulation of the hemodynamic Performance of Skeletal Muskle Ventricles

Cardiac assist by stimulated skeletal muscle is investigated by several groups as an alternative to heart transplantation or blood pumps. The muscle is either wrapped around the heart or used for aortic counterpulsation. \par Based on animal studies of a skeletal muscle ventricle (SMV) which was positioned in parallel to the aorta, a computer model was developed to evaluate the hemodynamic efficacy. Simulations were performed at both physiological and pathological conditions with different settings of the stimulation rhytm, length and delay. The results demonstrate an impressive improvement of endocardial viability, which raises up to 230% compared to that of a nonassisted failing heart. However, stroke work and cardiac output could not be satisfact orily improved. Even highly significant changes of the arterial pressure waveform between supported and non-supported heart cycles did not reduce mean left ventricular stroke work at an increase of CO in the range of 10%, even at optimal stimulation timing conditions. It is concluded, that aortic counterpulsation by skeletal muscle can considerable improve the endocardial viability, but has only limited effect to the stroke work of the assisted heart.

Schematic of a skeletal muscle ventricle, made of an aortic homograft and the musculus latissimus dorsi

Ovine aortic homograft, adopted
to a ventricle with pericardium

Hemodynamics of a stimulated skeletal
muscle ventricle (in-vivo, paced 1:3)

Computer simulation of
SMV - support (paced 1:2)

Contact Persons:	Heinrich Schima
	Gerhard Wipplinger
	Werner Girsch, MD
	Reinald Seitelberger, MD

Cooperating Institutions:

Dept. of Plastics Surgery, Univ. of Vienna, Austria
Dept. of Anatomy, Univ. of Vienna, Austria

References:

1. Girsch, W., R. Koller, H. Lanmüller, M. Rab, R. Avanessian, H. Schima, E. Wolner, and R. Seitelberger. Experimental development of an electrically stimulated biological skeletal muscle ventricle for chronic aortic counterpulsation. Eur J Cardiothorac Surg 13(1): 78-83, 1998.

2. Wipplinger, G., M. Rab, W. Girsch, R. Koller, W. Haslik, L. P. Kamolz, S. Sauermann, H. Lanmüller, and H. Schima. A Computer-Model for the evaluation of the hemodynamic efficacy of a skeletal muscle ventricle in counterpulsation mode. 6th Vienna International Workshop on Functional Electrostimulation, ISBN 3-900928-04-5 57-60, 1998 (Original Paper under Preparation).

3. Girsch, W., R. Koller, H. Lanmüller, R. Seitelberger, M. Rab, L. Huber, H. Schima, H. G. Stöhr, U. M. Losert, and E. Wolner. Kreislaufunterstützung durch elektrisch stimulierte Muskellappen - Experimentelle Erfahrungen. Handchir.Mikrochir.Plast.Chir. 29: 83-89, 1996.