An Experimental Study of the Immediate Hemodynamic Adjustments to Acute Arteriovenous Fistulae of Various Sizes 1

Abstract

In the past thirty years, numerous observations have been made on the hemodynamic effects of arteriovenous fistulae. Arteriovenous fistulae of variable size and location have been studied in patients as well as in animals. Such studies have consisted a) in observing the effect of suddenly opening and closing a fistula in acute experiments, b) in studying the effects of suddenly closing and opening a fistula in an animal or a patient who had had such a fistula for a relatively long time, and c) in recording the effect of complete surgical eradication of a long-standing fistula. While some agreement has been reached on many points, there persists some controversy about most of them (1). It is now generally agreed that an acute as well as a chronic arteriovenous fistula increases the cardiac output (1-8). However, Lewis and Drury (9) came to the conclusion that the cardiac output is not increased unless the arteriovenous shunt is very large. Van Loo and Heringman (10) concluded that acute arteriovenous fistulae increase the cardiac output although the flow of blood in certain vascular areas outside the fistula circuit is decreased. The venous pressure is definitely increased near the site of the arteriovenous communication, but most investigators have found that the increment of venous pressure decreases rapidly as the pressure is measured further down the venous bed toward the right atrium, and in the venae cavae and right atrium the pressure is elevated little or not at all I This work was made possible by a grant-in-aid from the New York Heart Association, the Sidney A. Legendre Gift, and the Charles A. Frueauff Gift. It was presented at the Annual Meeting of the American Physiological Society in New York City in 1952.2Fellow of the New York Heart Association. (3, 4, 11). However, one group of workers (12) has reported more striking increases of right atrial pressure in dogs with an arteriovenous fistula. The blood volume seems to be increased by an arteriovenous fistula of a certain size and duration (3, 13) although some observers (4) suggest that this increase in blood volume occurs only in the presence of an incipient or frank cardiac failure.Since the magnitude of the effects of an arteriovenous fistula would seem a priori to depend upon the volume of blood shunted through the abnormal pathway, it is rather surprising that in no study has any attempt been made to measure simultaneously the rate of flow through the fistula and the other functions of interest such as cardiac output, arterial and venous pressures. The present study was undertaken in an attempt to determine the acute cardiovascular adjustments to arteriovenous fistulae of different sizes, by recording simultaneously and continuously the flow of blood through the fistula, the flow of blood into the systemic circulation exclusive of the arteriovenous fistula circuit, the mean arterial blood pressure and the mean central venous pressure. METHODSFifteen dogs weighing between 13 and 28 kilograms were anesthetized by the intravenous infusion of 100 m...

Left ventricular function in experimental aorto-caval fistula with circulatory congestion and fluid retention

“…In man the cardiac output, heart rate, and right atrial pressure are elevated, arterial pulse pressure is increased (1)(2)(3)(4), and the blood volume is expanded (5). Similar effects have been observed in the dog with an experimentally induced fistula (6)(7)(8)(9)(10), and a reduction in peripheral blood flow (7) and renal blood flow (10) also has been observed. In addition, maximum cardiac output, attainable by transfusion, may be greater in dogs with an arteriovenous shunt than in normal dogs, whereas the maximum stroke work is less (8).…”

“…The mechanisms of fluid retention in the dog with an aorto-caval fistula have been well documented by previous workers. A large systemic arteriovenous shunt, under either acute or chronic conditions, leads to a fall in renal blood flow (10,24), as well as reductions in flow to other organs and the limbs (7,9). Renal plasma flow and glomerular filtration rate are decreased, and there is an increased production of aldosterone (1), presumably mediated by the renin-angiotensin system (25).…”

The Effect of Acute Arteriovenous Fistula on Renal Functions 1

“…Most investigators are agreed that acute and chronic arteriovenous fistulae produce an increase in cardiac output (1,2). Furthermore, a chronic fistula of sufficient size produces an increase of the blood volume (1,2) and, upon closure of such a chronic fistula, a diuresis of sodium and water (3).…”

Blood volume and body fluid compartments in lambs with aortopulmonary left-to-right shunts.

“…The adaptation to the left-to-right shunt, an increase in blood volume, thus is similar to that observed in mature dogs with aortocaval left-to-right shunts and humans with arteriovenous fistulas (2, 3) and may serve to compensate for the effects of a too low circulating blood volume on cardiac performance. In dogs with acute left-to-right shunts cardiac performance was shown to be limited by blood volume, although no blood was lost (35). Opening of a large aortocaval fistula led to an increase in left ventricular output, but effective systemic blood flow fell below control values because the increase in left ventricular output was not large enough to compensate for the shunt flow.…”