The aim of present-day treatment of hypertension is no longer as the effective reduction of blood pressure, regarded merely but as the ever-increasing application of new therapeutic prin­ ciples to prevent such consequences of hypertension as left heart hypertrophy, medial hypertrophy of the vessels and ar­ teriosclerosis. In this context special attention has been di­ rected to stimulation of the endogenous vasocilator hormonal systems such as the prostaglandins. The great interest in our book, which has meanwhile appeared in a French edition, seems to confirm this trend and has encouraged us to include in the book the new findings published in the last twelve months. These changes and additions maintain the current status of the book and provide an even more complete survey of the available information about prostacyclin in hyperten­ sion. We wish to thank all those colleagues who have made useful suggestions for this second edition, as well as Springer­ Verlag and its associates, who ensured a uniformly smooth passage in the production of the book. Cologne and MUnster, January 1990 Gerd Bonner Karl-Heinz Rahn v Preface to the First Edition Diseases of the heart and circulation currently constitute the commonest causes of death in our population. Hypertension, as evidenced by a pathologic increase in blood pressure, is one of the most important risk factors. Primary hypertension can be established in about 15 % of adults. Patients with hyperten­ sion usually feel well subjectively and only rarely complain of symptoms.