Cardiac Asthma (Paroxysmal Cardiac Dyspnea)

Paroxysmal dyspnea in patients with heart disease is of both practical and theoretical importance. The attacks often disable and endanger the life of patients with an otherwise apparently good state of the circulation. Unlike other types of cardiac dyspnea, it frequently occurs without exertion and without longstanding severe physical or chemical derangement of the circulation. Although its importance has been emphasized from time to time, the condition, on the whole, is obscure. Most of the available information centers on the clinical description of attacks and on statistical data relating to the nature of heart disease underlying them. The explanation of the sequence of events leading to the attack, as well as the circulatory state before and during the paroxysm, is based on inferences from clinical symptoms and signs and on postmortem observations. The more precise study of the condition is difficult, for it cannot be reproduced in animals; moreover, in