Bøger af S. Sideman

The cardiac system represents one of the most exciting challenges to human ingenuity. Critical to our survival, it consists of a tantalizing array of interacting phenomena, from ionic microscopic transport, membrane channels and receptors through cellular metabolism, energy production to fiber mechanics, microcirculation, electrical activation to the global, clinically observed, function, which is measured by pressure, volume, coronary flow, heart rate, shape changes and responds to imposed loads and pharmaceutical challenges. It is a complex interdisciplinary system requiring the joint efforts of the life sciences, the exact sciences, engineering and technology to understand and control the pathologies involved. The Henry Goldberg Workshops were set up to address these challenges. Briefly, our goals are: 1. To foster interdisciplinary interaction between scientists from different areas of cardiology, identify missing links, and catalyze new questions. 2. To relate micro scale cellular phenomena to the global, clinically manifested cardiac function. 3. To relate conceptual modeling and quantitative analysis to experimental and clinical data. 4. To encourage international cooperation so as to disperse medical and technological know how and lead to better understanding of the cardiac system. Today we celebrate the 7th birthday of a dream come true; a dream to bring together the diversified expertise in the various fields of science, engineering and medicine, to relate to the numerous interactive parameters and disciplines involved in the performance of the heart.

depolarization in cardiac muscle involve quantities, such as Vmax' that are not directly descriptive of the underlying mechanisms of propagation.

The ultrasound velocity tomography allows measurement of cardiac geometries for various phases in the cardiac cycle. The present tomograph makes reconstruc­ tions at intervals of 20 ms. Because of a lack of clear (intramural) landmarks (except the roots of the papillairy muscle), it is difficult to pinpoint spatial trajectories of particular points in the heart. Therefore, a second method was developed of injecting radiopaque markers in the heart and following their motion patterns during the cardiac cycle with help of a biplane X-ray equipment. The data obtained with both methods can be implemented in our finite element model of the heart to compute intramural stresses and strains. The results obtained sofar with the extended Darcy equation to account for the interaction of blood rheology and tissue mechanics look promising. Further testing with more sophisticated subjects than mentioned in Figure 9 is required before it will be implemented in our finite element model of the heart. We conclude that analysis of regional cardiac function, including regional myocardial blood flow, requires still a major research effort but the results obtained sofar justify, to our opinion, a continuation in this direction. Acknowledgement The authors acknowledge Dr. C. Borst and coworkers for doing the animal experiments and prof. Van Campen and dr. Grootenboer for their participation is some aspects of this work.