The electrical conductivity of the tissues near the heart and its bearing on the distribution of the cardiac action currents

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32587/1/0000716.pd

Short paroxysms of impure auricular flutter probably induced by normal sinus beats

Electrocardiograms of a patient with transient auricular fibrillation and flutter and complete A-V heart block are presented. Further tracings, taken immediately after the resumption of normal sinus activity, show short paroxysms of what is believed to be impure flutter induced by normal sinus beats. Some experimental evidence tending to support this view is mentioned.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32598/1/0000738.pd

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

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.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32558/1/0000675.pd

The electrocardiogram and the position of the heart

The profound effects that rotation of the heart, particularly about the longitudinal axis, have on the mean electrical axis, as seen in limb leads, are emphasized, and some of the experimental and clinical studies that bear on this matter are discussed. The advantages that spatial vectorcardiograms may have in the evaluation of electrocardiographic changes due solely to an unusual position of the heart are pointed out, but, for a number of practical reasons, it is felt that such records will not be very useful in the solution of these or similar problems in the near future.Peculiarities in the form of tracings from the precordium due entirely to an unusual position of the heart are mentioned, but it is considered unwise (except for purposes of investigation) to recommend a change from the conventional sites for multiple precordial leads because of the suspicion that the heart may be placed in an unusual fashion.The suggestion of Kossmann and co-workers that signs suggesting right ventricular enlargement in both standard and precordial leads may arise as a result of marked clockwise rotation of the heart about the long axis is discussed, and some evidence for and against this view is presented. Since concepts basic in the interpretation of precordial leads are involved in this problem, the need for further studies to decide the matter is emphasized. It is pointed out that tangential rather than purely radial spread of the activation wave over the ventricles may explain some of the difficulties encountered in interpretation of precordial leads, particularly when right ventricular enlargement or left bundle branch block is present.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32545/1/0000656.pd

The precordial electrocardiogram in high lateral myocardial infarction

Six cases of suspected infarction of the basal parts of the lateral wall of the left ventricle are reported. The usual unipolar limb leads and the six standard precordial leads failed to furnish unequivocal evidence of myocardial infarction in these cases. Unipolar leads from points on the anterolateral, lateral, and posterolateral aspects of the upper left thorax supplied electrocardiographic data of greater diagnostic value.The types of lesions differentiated have been classified as high anterolateral, high lateral, and high posterolateral infarcts on the basis of the vertical lines in which the most significant electrocardiographic changes were recorded.The opinion is expressed that in these instances the electrocardiographic changes typical of infarction were most pronounced in leads from the upper left thorax because the infarcted region was more basal and more lateral than is usually the case. It is, however, admitted that rotation of the heart or some other change in the relations of its surfaces to the usual leads may have been responsible for some of the electrocardiographic peculiarities encountered.It is recommended that unipolar leads from the higher levels of the left thorax be taken when the clinical history and Lead I, or Lead VL, both suggest that myocardial infarction has occurred and the standard leads from the left side of the precordium fail to display changes of the kind and magnitude expected.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32567/1/0000693.pd

The mechanism of auricular paroxysmal tachycardia

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32584/1/0000713.pd

Changes in the precordial electrocardiogram produced by extension of anteroseptal myocardial infarction

Electrocardiographic studies are reported on two patients, each of whom had anteroseptal infarction, followed in a few days by lateral extension of the initial lesion. The worth of multiple precordial leads in the diagnosis of extension of such infarcts is illustrated.Evidence is again presented that infarcts which are anteroseptal in location, as shown by diagnostic changes in leads from the right precordial area, often fail to produce equally significant changes in the limb leads.It is suggested that, in cases of coronary arterial disease, some of the attacks of pain which have usually been considered prodromal symptoms of myocardial infarction, actually represent the development of a small, anteroseptal infarct, and that the more characteristic symptoms of acute coronary thrombosis which often occur later are due to an extension of this initial lesion. The true situation must be recognized, if such patients are to be properly treated.We do not wish to convey the impression that we are convinced that all attacks of so-called prodromal pain represent actual myocardial infarction. The data, at present available, bearing on this problem are inadequate to justify this conclusion. Some attacks of this character appear to be due to acute processes developing in the coronary arteries or to transient myocardial ischemia associated with such processes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32570/1/0000697.pd

Persistent displacement of the RS-T segment in a case of metastatic tumor of the heart

A case of carcinoma of the esophagus with massive metastases to the heart is reported. Serial electrocardiograms displayed persistent upward displacement of the RS-T segment in Leads II, III, and Lead VF, and in a number of the unipolar precordial leads. It was probably caused by almost continuous acute myocardial injury as the neoplastic tissue infiltrated the cardiac musculature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32578/1/0000707.pd

Weak decays of 4He-Lambda

We measured the lifetime and the mesonic and non-mesonic decay rates of the 4He-Lambda hypernucleus. The hypernuclei were created using a 750 MeV/c momentum K- beam on a liquid 4He target by the reaction 4He(K-,pi-)4He-Lambda. The 4He-Lambda lifetime was directly measured using protons from Lambda p -> n p non-mesonic decay (also referred to as proton-stimulated decay) and was found to have a value of tau = 245 +/- 24 ps. The mesonic decay rates were determined from the observed numbers of pi-'s and pi0's as Gamma_pi-/Gamma_tot = 0.270 +/- 0.024 and Gamma_pi0/Gamma_tot = 0.564 +/- 0.036, respectively, and the values of the proton- and neutron-stimulated decay rates were extracted as Gamma_p/Gamma_tot = 0.169 +/- 0.019 and Gamma_n/Gamma_tot <= 0.032 (95% CL), respectively. The effects of final-state interactions and possible 3-body Lambda N N decay contributions were studied in the context of a simple model of nucleon-stimulated decay. Nucleon-nucleon coincidence events were observed and were used in the determination of the non-mesonic branching fractions. The implications of the results of this analysis were considered for the empirical Delta I = 1/2 rule and the decay rates of the 4H-Lambda hypernucleus.Comment: 15 pages, 11 figures, published in PRC, revised content to match published versio

The substitution of a tetrahedron for the Einthoven triangle

In an experiment on a cadaver, a potential difference was rhythmically impressed upon two small electrodes thrust into the heart or its immediate neighborhood.The resulting differences in potential between a central terminal and four electrodes connected to it through equal resistances were recorded with the string galvanometer. The four electrodes were on the two arms, the left leg, and the left interscapular region.By assuming that the electrical field generated in the trunk was equivalent to that of a centric doublet in a homogeneous spherical conductor and that the four electrodes were at the apices of a tetrahedron inscribed in this sphere, the experimental and the theoretical amplitudes of the deflections in the four leads could be compared. In general, it may be said that, with one exception, the deflections in the limb leads had the relative magnitudes expected. The deflections in the lead from the back were much smaller than anticipated. The last result is attributed to circumstances peculiar to the single experiment performed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32563/1/0000689.pd