This book comprises the essential records from a Boerhaave course given in June 1971 for specialists in cardiology and other fields of internal medicine interested in the subject of quantitation in cardiology. It is evident that in the wide field of medicine, and particularly in cardiology, there is a growing need for exact and detailed information in conjunction with existing diag­ nostic methods. This is apparent in the greater precision in anatomical and haemodynamic details required by the thoracic surgeon as the number of available heart operations gradually increases. In retrospect it is hardly surprising that the high initial mortality after the introduction of each operation depended to a large extent upon the degree of accuracy with which the diagnosis was made. Another urgent need for precise and quantitative information became apparent when monitoring of high-risk patients, in order to forestall compli­ cations and/or death, became routine. The same applies for the diagnostic procedures used to estimate the patient's chances of surviving an operation and/or rehabilitation after a serious incident, such as myocardial infarction. In these fields there is a vast amount of data to be handled and - in modern diagnostic procedures - it must be processed so rapidly that the human mind cannot suffice and computer equipment has becomeindispensable.