The Effect of Exercise in the Supine Position on Pulmonary Vascular Dynamics in Patients With Left-to-Right Shunts

Abstract

The effect of exercise on pulmonary artery pressure, blood flow, and resistance has been studied extensively in normal subjects (1-5), and in patients with rheumatic heart disease (6, 7). However, only brief reports have appeared concerning the response of patients with intracardiac or great vessel shunts (8,9). The dearth of published information probably is due in part to uncertainty as to the exact diagnosis in a sufficient number of cases. This paper concerns the changes in pulmonary and systemic blood flows, pressures, and resistances, and the associated variations in intracardiac or aortopulmonary shunts caused by leg exercise in the supine position in 30 patients with single congenital anomalies. In those patients with pulmonary hypertension the pulmonary blood flow was found to change only slightly during exercise irrespective of the magnitude of the left-toright shunt, while pulmonary artery pressure and pulmonary resistance values were increased. In patients without pulmonary hypertension there was a more definite increase in pulmonary blood flow; but as in the preceding group, a decrease was observed in the magnitude of the left-to-right shunt. Complete data for accurate anatomic appraisal had been obtained in all instances, and operative confirmation of the diagnosis was available in the great majority. METHODS AND MATERIALSProcedure. The following procedure was adhered to, with minor variations. The patient received 0.5 grain (30 mg.) of codeine and 1.5 grains of secobarbital (Seconal®) immediately prior to the start of the procedure. He lay supine on a horizontally positioned fluoroscopy table. A No. 5 or 6 Cournand cardiac catheter (designated catheter 1) was introduced, usually by percutaneous needle puncture of a vein in the right antecubital fossa (10) and advanced to the heart. Oxy-'The Mayo Foundation, Rochester, Minnesota, is a part of the Graduate School of the University of Minnesota.gen saturations of blood samples obtained from various locations within the heart and great vessels were measured by a cuvette oximeter (11) to ascertain the oxygen saturation of the mixed venous blood and to determine the magnitude and location of the left-to-right shunt. The catheter tip was located in the main pulmonary artery, and a needle was inserted into a radial artery. Pressures in the systemic and pulmonary artery systems were recorded by means of strain-gauge manometers. It was desirable in a number of patients to obtain simultaneously samples of blood from the inferior vena cava as well as from the pulmonary artery. To make this possible a second catheter (designated catheter 2) was inserted and advanced directly into the inferior vena cava. The rate of oxygen consumption was then determined by collection of the expired air for five minutes in a largevolume, low-resistance plastic balloon. Analysis of the expired air was carried out immediately by the Haldane method. Midway during the period of collection of expired air, blood samples were obtained for analysis of the oxygen content by the method o...

Haemodynamic changes on exercise in patients with left-to-right shunts.

“…2 and supposing with them a normal slope of increase of systemic flow, a small over-all increase in left-to-right shunt would be apparent rather than a decrease, though we have no comparable data at maximal exercise levels. Swan et al (1958) studied the heemodynamics during supine exercise in 30 patients with septal defects. Their data show that there were 9 patients in the Eisenmenger category: in these the pulmonary flow remained essentially unchanged, while the increase in systemic flow was less than normal.…”

“…They found a larger increase in this than the anticipated rise of systemic flow, indicating an increased left-to-right shunt with effort. These authors concluded that the upright posture explained their differences from Swan et al (1958).…”

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There have been several studies of the effect of exercise on the htmodynamics in patients with cardiac septal defects and left-to-right shunts (Jonsson, Linderholm, and Pinardi, 1957;Scebat et al, 1957;Bruce and John, 1957;Swan, Marshall, and Wood, 1958;Stephens, Shafter, and Bliss, 1964), but some uncertainty remains about the conclusions. Since any attempt to understand the disability of such patients depends on these, we have attempted a further investigation into the changes occurring during exercise.

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The Effect of Exercise on the Size of the Shunt in Patients With Atrial Septal Defects

“…There are only a few studies available on the changes occurring during exercise in the shunt of patients with ASD and normal pressure in the pulmonary artery. Swan et al (11) found in two cases a fall in the PFR during exercise, whilst the shunt fell in the one patient and increased in the other. Scebat et al (8) found a constant decrease in the PFR whilst the shunt flow increased in five cases and fell in twenty-six, whereas the pulmonary flow underwent less well defined changes.…”

The Blood Flow in the Caval Veins at Rest and During Exercise in Normal Subjects

“…In studies at rest the following have been used as an expression of the oxygen content of mixed venous blood: (a) the oxygen saturation in the SVC (3,5,8,9), (b) the mean value of the oxygen saturation in the IVC and SVC (2, lo), or (c) the mean value of two samples taken from the IVC and one sample from the SVC (1). In studies during exercise the same methods have been used as those in the studies at rest (1,8,10). As it must be presumed that an alteration takes place in the ratio of the blood flows in the venae cavae during exercise using the lower extremities, and as this has not been studied employing the method used for investigating patients with atrial septal defects, we have considered it of interest to carry out such an investigation.…”