J. Marion Bryant

On the possibility of constructing an Einthoven triangle for a given subject

Abstract In experiments on normal subjects, two small electrodes on the chest were connected to a source of low frequency current. The resulting differences in potential between the extremities and between other points on the body were measured. By the method described by Burger and Van Milaan, triangles and other figures, which present in graphic form the data obtained in this way, have been constructed. When the point midway between the input electrodes was in the midsternal line, the triangle corresponding to the standard limb leads was nearly isosceles, and usually, though not always, of the type in which the side corresponding to Lead I was shorter than the other two. When the input electrodes were to the left of the midline, the side of the triangle corresponding to Lead III, and when they were to the right of the midline, the side corresponding to Lead II, was the longest. When the Burger triangle is oblique, none of the standard or unipolar limb leads yield deflections proportional to either the horizontal or the vertical component of the electrical field. A method of finding two leads, one of which will record the variations of the first of these components, and one which will record the variations of the second, is described. The effect of varying the resistances in the arms of the central terminal upon its potential, and the possibility of reducing the potential variations of this terminal to zero, when the Burger triangle is not equilateral, are discussed. In a few experiments, the isopotential lines corresponding to the potential of one of the limb electrodes when the other two were connected to a source of low frequency current were plotted on the body surface. The three lines obtained in this way intersect at two points, one on the front and the other on the back of the chest.

Low sodium-forced fluid management of hypertensive vascular disease and hypertensive heart disease.

One hundred patients with essential hypertension were placed for periods of several weeks to 12 months on a diet of 2200 calories containing approximately 200 mg of sodium, 2.2 g potassium, 70 g protein, 80 to 175 g fat, 130 to 230 g carbohydrate, and vitamin supplements. A daily fluid intake of 3 liters was maintained. All were outpatients. Blood pressure readings were taken with the subject reclining, sitting and standing. They were made by one observer usually at the same time of day. No pretreatment blood pressure was below 170/100. Medical and dietary checks were ordinarily made once or twice a month. There was a significant lowering of pressure (to or below 155/95) in approximately 20%, and of the diastolic pressure (to or below 95) in an additional 15% of the cases. A number of the patients who improved on this regime had failed to respond satisfactorily to a previous bilateral supradiaphragmatic splanchnicectomy and lower dorsal sympathetic ganglionectomy. The majority with symptoms typical of essential hypertension and hypertensive heart disease showed moderate improvement or were completely relieved of their discomfort. In most of these with angina pectoris the frequency and severity of the seizures were diminished. In all cases in which it was utilized orthodiography demonstrated a definite and progressive decrease in the size of the heart when it was enlarged. The inverted T waves frequently seen in hypertensive heart disease have in some cases become upright. Papilledema diminishes. Peripheral edema and pulmonary congestion invariably disappear. Relief of symptoms and the above described objective changes were not uniformly associated with a significant fall in blood pressure.

An Integrating Circuit for Measurement of the Areas of the Waves in the Electrocardiogram

An electronic circuit capable of integrating the electrocardiogram is described. The net areas of the QRS complex, the T wave and of the entire ventricular complex, QRS-T, in the standard leads may be estimated by measurement of the length of two vertical lines in each of the integrated records. The manifest areas of QRS, T and the gradient (QRS-T) with the orientation of these vectors are easily calculated from the data. An example of an integrated electrocardiogram is reproduced, and the procedure for estimation of the gradient is presented.

The electrocardiogram and the position of the heart

NE of the troublesome problems in the field of electrocardiography is to decide whether certain peculiarities in the tracings are due to abnormalities of the myocardium or to nothing more than an unusual position of the heart. Difficulties of this kind occur in connection with the interpretation of both limb and precordial leads and may limit the value of the records considerably. This paper is not a review of the extensive literature on the subject, but it is an attempt to point out some basic relationships between electrocardiograms and the anatomical position of the heart, to discuss some recent studies which have a bearing on the problem, and to emphasize some difficulties and unanswered questions arising from this work. Einthoven, Fahr, and de Waart ls2 showed that the form of the standard electrocardiogram varies with respiration or change of posture and attributed this to a change in the position of the heart. Some years later, Meek and Wilson,” working with dogs, reported consistent changes in the limb leads when the heart was rotated about the anteroposterior or the longitudinal axis alone and pointed out that, unless care is exercised, movement about the former axis is usually accompanied by rotation about the latter. Since the two types of rotation, so induced, act to shift the electrical axis in opposite directions, erratic and unpredicatable changes in the axis found in their early experiments were satisfactorily explained. These workers emphasized the importance of rotation of the heart on its long axis as a factor which determines the direction of the electrical axis and amply confirmed earlier studies by Groedel and MBnckeberg.4 It has been known for many years that standard electrocardiograms taken on normal subjects and on many patients with heart disease, often show changes if tracings are taken with the body in different positions. Thus, with the subject lying on the left side, a shift of the electrical axis to the right is usually seen, and a shift to the left may occur when the subject is lying on the right side. Alterations of this kind are particularly apt to be found in subjects with relatively From

The potential differences between multiple central terminals each connected to a separate set of limb electrodes

I N A recent publication Groedel’ reports that he has found significantly large potential differences between three central terminals each connected to a separate set of three limb electrodes. He does not mention the size of the resistances between the limb electrodes and the central terminals. One central terminal was attached to electrodes near the junctions of the extremities with the trunk, one to electrodes near their distal ends, and the third to electrodes near the second joints. The largest potential difference observed amounted to approximately 0.5 millivolt. It was stated that “a final electrophysical explanation” could not be given. The conclusions, however, were “that at the central terminal there is a considerable potential, which is neither zero nor approximatel>. zero,” and “that the central terminal offers no practical advantage for its further use in obtaining so-called unipolar chest leads.” It is not our purpose’here to attempt either to prove or to disprove that the potential variations of a central terminal connected to the limb electrodes through large resistances are negligible, but rather to explore the situation which exists when several central terminals are joined to electrodes on the limbs in the manner specified.