This volume constitutes selected papers from the Second International Conference on Information Systems and Design, ICID 2021, held as virtual event in September 2021. The 24 full papers and 4 short papers presented were thoroughly reviewed and selected from 51 submissions. They are organized in topical sections on digital transformation of enterprises based on analysis and management tools: practical-focused research; methodological support of analysis and management tools: theoretical-focused research; young scientists research in the areas of enterprise digitalization.

In this book the authors analyse the circadian characteristics of autonomic cardiac control in norm and in pathology through the indices of heart rate variability. The starting hypothesis was that the changes in the circadian nature of the autonomic balance have both specificity and sensitivity, i.e., they have a characteristic profile in the principal cardiovascular pathologies. The material is presented in eight chapters. The first four summarise the anatomical and the functional data on the nerve control of the cardiovascular system, on the circadian nature of the different systems securing that control, and on the variability of the heart rate as a method for studying the autonomic control of the heart. The next four chapters summarise the results of our studies clarifying the profiles of the circadian characteristics of the autonomic control in healthy individuals and in patients with arterial hypertension, ischaemic heart disease and heart failure.