1. Hydraulics Laboratory, Institute of Biomedical Technology, Ghent University, B-9000 Gent, Belgium;
2. Biomedical Engineering Laboratory, Ecole Polytechnique Fédéralé de Lausanne, Parc Scientifique d'Ecublens, 1015 Lausanne, Switzerland; and
3. Laboratory for Physiology, Institute for Cardiovascular Research, Vrije Universiteit University Medical Center, Amsterdam, The Netherlands