Interactions: The integrated functioning of heart and lungs

The heart and lungs are two dynamic organ systems functioning in a highly integrated inter-relationship within the unique negative pressure environment of the intact thorax. Noninvasive imaging techniques have afforded us the opportunity to study the interdependence of these two organ structures with evaluation focused both on intra and inter organ relationships. It is through a recognition of these interdependent phenomena that one begins to appreciate their importance to the prediction of the total mechanical response of the cardiopulmonary system when piecing together individual response characteristics determined with components of the system held in isolation. Highlights of a number of measurements made from what has been termed dynamic and electron beam x-ray CT as well as recent work utilizing magnetic resonance imaging (MRI) are presented. Our earlier work related to the intracardiac interrelationships serving to maintain the heart at a near constant volume throughout the cardiac cycle. Here we will expand to include heart-lung and lung-heart interactions as they affect both cardiac and pulmonary function. The overall theme is systems integration serving to dictate function and functional efficiency.