The Cardiac Output in Patients With Arteriovenous Fistulas 1

The study of arteriovenous fistulas, and the al-terations in local and systemic circulation which they produce, has been a means of not only under-standing this particular lesion better, but of ex-tending our knowledge of many other more com-mon circulatory phenomena. In peacetime, investi-gations have been conducted on the relatively rare clinical cases and on animals with fistulas pro-duced in the laboratory. The recent war, with its many vascular injuries, presented an unusual op-portunity to study the circulatory alterations in patients with arteriovenous fistulas. This and suc-ceeding reports deal with observations on a large group of patients treated at Ashford General Hospital. The clinical manifestations exhibited by patients with an arteriovenous fistula have been described elsewhere (1, 2). It is generally recognized that these patients may develop congestive heart fail-ure. There has been controversy, however, re-garding the mechanism producing the circulatory failure. Some have ascribed it to greatly increased demands on the heart, others to diminution of coronary blood flow secondary to the lowered mean arterial pressure (3). Since a knowledge of the output of the heart is so important in defining the mechanism of the altered circulatory dynamics in these patients, we have measured the cardiac out-put as part of a general study of the circulation in patients with arteriovenous fistulas. In 1923 Lewis and Drury (4) reported the re-sults of their studies of arteriovenous fistulas in both man and the experimental animal. In the latter, using a glass cardiometer to enclose the heart, they found an increase in cardiac output, in