Growth of the Heart in Health and Disease [antikvár]

Preface Growth of the heart has been studied by physicians and biologists for more than one hundred years. The principal motives of this search have been to understand when and why an enlarged heart fails as a pump and then how to assist it when it does fail. A remarkable compendium of data has accumulated, yet we are still far from understanding all aspects of heart disease. The relatively biggest advance has been made in the treatment of heart failure, its diagnosis and timing. However, we know practically nothing about the reasons why the failure occurs. Cardiac hypertrophy is clearly an adaptive response, but for a limited time only. The process that first allows an organism to survive eventually leads to its death. Is the sign of death present from the onset of adaptive growth, or is it an "adaptive energy" (a term used by H. Selye in his germinal treatise on the adaptive syndrome) that eventually becomes exhausted? To differentiate these two possibilities, it is necessary to examine and compare the growth of the heart in both health and disease. This is the strategy that we have adopted in developing this volume. In the first section a review of the growth of the heart from the viewpoint of molecular and cellular biology, anatomy, embryology, morphology, and experimental morphology is presented. The second section gives specific examples of cardiac growth associated with disease. In the final section an analysis of the relationship between the size of the heart, the characteristics of the functional demands placed on it, and its function as a pump are discussed. The reader will soon discover that it is not only the failure of the enlarged heart that eludes our understanding, but the processes which regulate growth as well. Yet the understanding of growth has been the central concern of biological studies since the cell theory was advanced. Is the size of an organ in a healthy individual predetermined? Is there a limited number of cell divisions for each cell? What factor(s) determines when a cell is to divide? Is an enlarged organ that is composed of more cells functionally better off than when its constituting cells are larger than normal? These questions, descriptive in nature, are fundamental to cell theory. As far as the causal relationship is concerned, we would like to know what factors regulate the size of an organ. Is it the performed function that provides the growth-regulating signal? Or is it the level of the humoral factor(s) (altered depending on the organ's use or disuse) that predetermines the organ's size? At the mechanistic level, a knowledge of how the putative signals regulate the activity of genes is valuable. The rapid advances made in cellular and molecular biology in recent years hold promise for elucidation of these fundamental questions. Genes for specific cellular constituents have been isolated, and their structure is currently being determined. The complexity of gene regulation in higher organisms is bewildering at present, although in a few instances the switching of specific genes is already being accomplished. Insight into these basic steps of growth will