David I. Abramson

A study of electrical activity in the auricles

Abstract The electrocardiographic changes following artificial stimulation and cauterization of the auricles were studied in a series of six cats and five dogs. It was found that on cauterization of the auricular wall, a displacement in the position of the normally isoelectric line present between the P and R-waves, was consistently produced. This portion of the electrocardiogram, designated as the P-Ta segment, became elevated in Lead I when the left auricle was the site of injury and depressed in this lead on cauterization of the right auricle. In Leads II and III, the P-Ta segment assumed a depressed position regardless of which auricle was traumatized. The changes in the position of the P-Ta segment were considered to represent the negative variation of the auricular current of injury and the type of alteration was compared with that observed in the R-T transition following damage to ventricular muscle. It was found that the P-Ta segment change produced by auricular trauma did not end with the onset of the R-wave, but instead extended for some time into the period of ventricular activity. This observation confirmed the view, held by other investigators, that under normal conditions the terminal portion of the recovery period of auricular activity is not ordinarily visible in the electrocardiogram since it occurs during the period in which the ventricular complexes are inscribed. Upon artificial stimulation of the auricles, it was found that the direction of the aberrant P-wave in Lead I generally depended upon the location of the site of origin as to one or the other auricle; being positive for instances of right auricular excitation and negative for left. In Leads II and III, the aberrant P-wave was positively directed for all sites on both auricles. When the results of stimulation and cauterization of the same site were compared, it was observed that the direction of the aberrant P-wave had an inverse relationship to the direction of the displaced P-Ta segment (obtained with normal sinus rhythm).

Plethysmographic studies of peripheral blood flow in man

The various pitfalls associated with plethysmographic determinations of blood flow in the extremities are presented. The criteria used to recognize and eliminate artifacts in the records are discussed.Abstract The various pitfalls associated with plethysmographic determinations of blood flow in the extremities are presented. The criteria used to recognize and eliminate artifacts in the records are discussed.

Plethysmographic studies of peripheral blood flow in man: II. Physiologic factors affecting resting blood flow in the extremities☆☆☆

Abstract The various physiologic factors which may modify normal resting blood flow determinations are discussed, and methods for obviating them are presented. The normal ranges of blood flow values for the hand, forearm, and foot under different states of vasomotor control are presented and their significance discussed. A local reflex is described which produces vasoconstriction of the blood vessels of the lower extremity on release of the occlusion pressure usdd in obtaining blood flow figures.

Localization of experimental ventricular myocardial lesions by the electrocardiogram

Abstract Electrocardiographic changes were studied in relation to the site of damage in thirty-four cats in which localized ventricular myocardial lesions had been produced by the electric cautery. Monophasic type curves were obtained which were classified as of the T 1 and T 3 types of Parkinson and Bedford. With almost complete consistency lesions in similar sites produced the same type of curve. Lesions on the anterior surface of the left ventricle produced curves of the T 1 type, while those on the posterior surface of the left ventricle, including the apex, yielded the T 3 type. All right ventricular sites, except the base anterior in which only a slight change was induced, gave curves of the T 3 type. At the apex posterior alone were the changes comparable in magnitude with those obtained in the left ventricle. Usually the changes produced were marked in two leads. In some the displacement of the R-T segment was oppositely directed in the remaining lead, while in others no significant deviation was observed in this lead. In a few instances an R-T elevation was present in all three leads but as a rule to a greater extent in one lead. In three experiments, in each of which the lesion was located at the base anterior, depression rather than elevation of the R-T segment occurred.

Experimental bundle-branch block in the cat

Abstract 1. 1. Experiments were performed on cats in which either the right or left division of the bundle of His was cut. 2. 2. Both concordant and discordant curves were obtained. On transecting the right division, the chief initial deflection in Lead I was downward in both types, but in Lead III it was upward in the discordant type and the reverse in the concordant. On cutting the left division exactly opposite results were found. 3. 3. In analyzing the curves, the important lead to study in order to decide upon the location of the lesion appeared to be Lead I.

CHANGES IN BLOOD FLOW, OXYGEN UPTAKE AND TISSUE TEMPERATURES PRODUCED BY THERAPEUTIC PHYSICAL AGENTS: I. EFFECT OF ULTRASOUND

Although the use of ultrasound as a therapeutic agent in the field of physical medicine continues to grow, there are still a number of questions concerning its physiologic effects which remain unanswered. With regard to the thermal response, it is generally accepted that practically the entire amount of energy applied to the tissues through this medium is absorbed and converted into heat. As a result, there is a rise in tissue temperature, most marked in the bones and nerves in which selective heating appears to occur (1-3). The effect of ultrasound on blood flow has been investigated by a number of workers. Bickford and Duff (4) reported that in man, exposure of the forearm to 2 watts per square centimeter produced minor increases in local circulation in one-half the cases and no change in the others, while only with dosages of 3-334 watts was a significant augmentation consistently noted. Paul and Imig (5) performed a similar study and obtained essentially the same results. In the case of dogs, Paul and his associates (5, 6) found 1 watt per square centimeter to be an effective quantity of ultrasonic irradiation for the production of a vascular response. In the present study it was decided to

Plethysmographic studies of peripheral blood flow in man: III. Effect of smoking upon the vascular beds in the hand, forearm and foot☆☆☆★

Abstract By means of plethysmographic studies, the effect of smoking on peripheral blood flow was observed in a series of normal subjects and in a series of patients suffering from various peripheral vascular disorders. In most instances measurements of blood flow were obtained in two extremities simultaneously. It was found that a maximal response to smoking was elicited only in an extremity in which the blood vessels were neither excessively dilated nor constricted. In the hand, which is made up largely of skin containing many arteriovenous shunts, smoking produced the greatest decrease in blood flow. In the foot and adjoining portion of the leg the changes were in each instance relatively less marked than in the hand. In the forearm, which contains muscle to the extent of 85 per cent of its volume, there was no change in blood flow under any of the experimental conditions.

VENTRICULAR COMPLEXES OF THE BUNDLE-BRANCH-BLOCK TYPE ASSOCIATED WITH SHORT P-R INTERVALS

Excerpt In recent years a number of electrocardiograms have been reported possessing a shortened P-R interval and a bizarre, widened QRS complex of the type usually associated with an asynchronous ...

Influence of Ergotamine Tartrate Upon Peripheral Blood-Flow in Subjects with Liver Disease

Summary Single doses of ergotamine tartrate (0.5 mg.), injected subcutaneously, produce definite vasoconstriction as indicated by a decrease in peripheral blood-flow. Less commonly, vasodilatation is produced, with increased blood-flow. No significant difference in blood-flow change after ergotamine was noted between normals and subjects with liver disease.

THE NATURE OF ARTERIAL HYPERTENSION WITH SPECIAL REFERENCE TO THE RÔLE OF THE KIDNEY

Excerpt Since cardiac output,1blood volume,2and blood viscosity3are normal in patients with hypertension, the only remaining factor that might produce the elevated blood pressure is an increased pe...