Heart Disease [antikvár]

PREFACE Knowledge in the basic and clinical sciences related to the practice of cardiology has increased to an extent almost beyond belief during the past 30 years. New investigative techniques utilizing electronic apparatus, computers, radioisotopes, and other instrumentation have made possible extraordinary progress in classic circulatory physiology. These developments have led to different ways of looking at physiology and to new and broad concepts. Thus, it is not overstating the case to insist that every modern physician and surgeon interested in cardiovascular disease must now have a firm grounding in circulatory physiology. Aside from the newer trends in circulatory physiology, two new avenues of exploration— molecular biology and regulatory biology—have revolutionized and will continue to change our concepts of the circulatory system and its diseases. The revolution in physiology initiated by molecular biology is one in which ultrastructure, as revealed by the electron microscope, is being linked more and more closely with the chemistry, enzymology, energetics, and physiology of the cells that constitute the muscles of the heart and those of the blood vessels. Studies of the ultrastructure of the capillary lining in various organs are yielding better insight into the transfer of substances between the vascular system and the extracellular spaces and the intracellular contents. Molecular biology of nerve and skeletal muscle has provided new insight into the nature of the pacemaker of the heart, conduction within the heart, cardiac cell-membrane function, and the excitatory process occurring on the heart cell surface. Similarly, the intimate anatomy of the mitochondria and the sarcoplasmic reticulum has begun to reveal not only the details of the chemical changes within the cell but also of excitation-contraction coupling and the role that the several cations play in this regard. Knowledge of the architecture of the actual contractile elements has grown apace, as has information about the chemistry and physiology of the several proteins that make up these elements. Although knowledge applicable to smooth muscle cells of vessels is not as advanced as that for heart muscle cells, the pathway for acquiring such knowledge is at hand. However, it is not sufficient merely to define the functions of the parts of the cell, of the entire cell, or even of the groups of cells that constitute the various elements of the circulatory apparatus. Such knowledge is, in a sense, static. It is also necessary to understand how the circulatory system responds to changing circumstances, especially during exercise and emotional stress. This involves a physiology different from that disclosed by molecular biology. It is an integrative physiology that derives from regulatory biology. Thus, integrative physiology requires an understanding of the role of the nervous system and humoral factors in regulating the circulatory system in concert with the respiratory system under conditions of stress. This regulation involves the sensory apparatus ; the afferent, connecting, and efferent neurons; the catecholamines and other stores at the nerve endings and, in addition, the various types of autoregulation existing in the circulatory apparatus; the feedback mechanisms; and the integrative properties of the central nervous system. Regulatory biology, therefore, is truly a multifaceted activity requiring that the expert in circulatory physiology become equally knowledgeable in respiratory, nervous, and hormonal physiology. To present the essence of this new kind of physiology as part of the fabric of clinical cardiology is a formidable task for any teacher, if only because of the tremendous volume of knowledge and the rapidity with which it has been accumulated. The efforts by the