Edward H. Schwab

Arteriolar hypertension in the American negro

Abstract Attention is directed to the significant fact that, although arteriolar hypertension is practically unknown among the native African negroes, the disease is unusually prevalent in their descendants living in this country, the incidence being actually greater than that in the American white race. The inadequacy of the theory of the biological inheritance of primary hypertension in this connection is stressed. The possible etiological roles played by climate, diet, infections, and the menopause in the pathogenesis of hypertension in the American negro are discussed. On the basis of the neurogenic concept of the development of hypertension, a theory is elaborated to explain the origin of the disease in the American negro and to account for its high incidence. The importance of the environment as a causative factor is emphasized.

Heart disease in the American negro of the South

Abstract In view of the facts that heart disease in the negro as compared with the white race is of greater incidence, occurs at a younger age, pursues a more rapid course, and has a higher mortality rate, the opinion is offered that the cardiovascular system of the American negro of the South is inferior to that of the white race, and is more vulnerable to insult whether this be applied as an infection, a degeneration, a toxemia, or in the form of the stress and strain incident to the complexities and modes of modern occidental civilization.

Observations on the etiology and treatment of paroxysmal ventricular tachycardia

Abstract Although the subject of ventricular tachycardia has been exceedingly well studied, the total number of cases reported in the literature has been small. In this communication three additional cases are reported, two of the usual type and one of the alternating bidirectional variety. In one case the paroxysms were associated with persistent atrioventricular rhythm, a combination not previously reported in the literature. In addition, the effectiveness of quinidine therapy in the alternating bidirectional variety of ventricular tachycardia is demonstrated for the first time.

Blood Pressure Response to a Standard Stimulus in the White and Negro Races

A new concept of the etiology and pathogenesis of essential or arteriolar hypertension, based upon the neurogenic theory, has recently been brought forth by Hines and Brown. 1 According to them there exists a primary constitutional factor manifested by a hypersensitive or hyperreactive vasomotor system which is activated by secondary subsidiary factors in the form of environmental, infectious or toxic agents. Furthermore, they advanced the opinion that this constitutional abnormality should be capable of detection in early life, and, to attain this end, devised a standard vasomotor stimulus based upon the blood pressure response to the application of cold. We have called attention 2 to our discovery of a rather striking difference in the incidence of hypertensive cardiovascular disease in the white and negro races in this locality. We, therefore, felt that, in view of this racial difference, an exceptional opportunity existed to investigate further the possible neurogenic basis of essential hypertension. The “Cold Stimulation Test”, with certain modifications, was applied to 325 young adults, 172 white patients and 153 negroes, approximately equally divided as to sex, and ranging in age from 15 to 35 years, with an average age of 24 years. All subjects were free from cardiovascular disease and had normal blood pressures. After a period of rest in the recumbent position, control blood pressure readings were made at frequent intervals until a constant basal level was reached. The hand and wrist of the opposite arm were then immersed in cold water (4 to 5°C), and determinations were made after 30, 90 and 150 seconds had elapsed. The hand was then removed and readings were made until the blood pressure had returned to its previous resting level.

Effect of Digitalis Administration on Experimental Hypertrophy.

In preliminary experiments it was observed that, after fertilization, the eggs of Strongylocentrotus purpuratus showed, near the periphery, light and dark phases when rotated between crossed Nicols. The effect, however, was partially masked by the opaque granules of the cytoplasm. In order to eliminate this difficulty the unfertilized ova were centrifuged at approximately 60,000 gravities for 3 minutes, flotation of the eggs being insured by the addition of sufficient M/l solution of sucrose to the sea water in the tubes. After centrifugation the eggs were transferred to sea water and microscopic preparations made in the usual way. The eggs appeared elliptical in shape, with the nucleus at the centripetal end and the opaque granules at the opposite pole occupying about ⅓ of the egg. The remaining ⅔ of the egg was transparent and showed no bire-fringent effects with polarized light. Within 3 minutes after fertilization, however, when the membrane was forming and afterward, the clear cytoplasm gave evidence of birefringence so definite that the angle between light and dark phases could be measured. In all 35 measurements of the angle were made and these yield a mean value of 31°, with extremes of 24° and 37°, the intermediate values being consistently distributed on a probability curve. Now the optical section of the egg is something less than 72μ, and since such a minute quantity of polarizing molecules (e. g., sugar) in solution would not be sufficient to rotate the beam of polarized light, it is necessary to assume that the rotation is due to a regular grouping of molecules to form a multimolecular lattice with birefringent properties similar to those of a crystal, a starch grain, a filament of silk, a muscle fibril.

Creatine Content of Digitalized Normal and Hypertrophied Rabbit Heart Muscle.

As a preliminary to a study of the effect of digitalization on the progress of experimental cardiac hypertrophy, we administered digalen and digifoline subcutaneously 0.1 C.U. semi-weekly to one series of 10 rabbits for 4 weeks and to 6 other rabbits for 14 to 18 weeks. These animals were then sacrificed and the hearts divided. Muscle from each ventricle was analyzed for creatine by Myers modification 1 of the method of Rose, Helmar and Chanutin. These values were reduced to terms of dried weight by drying one sample at 105°C. to constant weight, then determining the percentage of solids. Large rabbits such as were used in these and subsequent studies on hypertrophy, weighed 2200 to 3200 gm. and showed normal creatine values averaging 180 mg. % with solids averaging 22.3%. Of the 10 rabbits digitalized for 4 weeks, 3 showed essentially normal creatine and total solids content, while the other 7 showed increased levels, as indicated in Table I. In the series in which digitalis injections were continued for 14 to 18 weeks the creatine percentages were slightly higher while the solids had dropped slightly. Simultaneous studies of the vastus lateralis in all of these rabbits revealed values normal for this muscle creatine (400 mg. %) and solids (24%). Thus the digitalis effect in so far as evidenced by the creatine changes is specific for heart muscle. The digitalization evidently produced no change in the heart weight-body weight or left to right ventricular ratios. The normal ratios are recorded in a preceding report. 2

Electrocardiographic Changes in Acute and Chronic Pericarditis in the Goat

Clinical electrocardiographic experiences emphasized to us the similarity of the subjective, physical and electrocardiographic findings in hemopericardium and acute fulminating pericarditis, but we also noted electrocardiographic changes in the subacute or chronic healing stages of pericardial inflammation. 1 In order to get more exact information, Cohnheims 2 classical experiments were repeated but instead of using oil or saline as Katz, Feil and Scott 3 and the Foulgers 4 had done in the dog, we used air, oxygen and blood as well as saline pressure in the pericardium of the goat. (Fig. 1.) We also found, as others 3 have a direct relationship between intra-pericardial pressure and electrocardiographic changes. After the acute pressure experiments (Fig. 1) protein solution or bacterial cultures were introduced into the sutured closed pericardium and the subsequent developments studied. (Figs. 2 and 3.) The elevation of the RST sector in all 4 leads was produced as shown in Fig. 2 (4–23) by the acute great increase in intrapericardial pressure, also lesser RST interval changes with slight elevation, upward convexity and negative T waves. (Fig. 1.) These changes were preceded by, the probably chiefly the result of, the sharp drop in peripheral BP that resulted from the auricular collapse incident to the increased intrapericardial pressure. (Fig. I KYMO. AIR. P. EXP. I.) The electrocardiographic changes disappeared shortly after the intrapericardial pressure was reduced or as the pericardium stretched or the fluid was absorbed. The electrocardiographic findings in hemopericardium or acute fulminating exudative pericarditis may be explained on the same premises.

Creatine Content of Hypertrophied Rabbits'Heart Muscle.

In connection with studies on the mechanism of cardiac hypertrophy we have analyzed the muscle from 8 hearts of rabbits in which we have experimentally produced cardiac hypertrophy by section of aortic cusps. These animals were sacrificed 14 to 18 weeks after the valve incompetency had been produced. The hearts were divided and the muscle from each ventricle was analyzed for creatine by Myers modification 1 of the method of Rose, Helmer and Chanutin. These values were reduced to terms of dried weight by drying one sample at 105°C. to a constant weight, thus determining the percentage of solids. The average normal creatine and total solids values for large rabbits such as were used in this series were 180 mg. % and 22.3%. Eight rabbits with varying grades of hypertrophy from moderate to great degree showed creatine levels which were high in a few instances but dropped to normal and definitely low levels as the amount of hypertrophy increased. There is a slight drop in total solids, especially of the left ventricle muscle indicating a slight increase probably in intracellular fluid content. In spite of the relatively lowered creatine concentration in the presence of great work hypertrophy the actual creatine content of the individual heart was distinctly elevated. This type of cardiac hypertrophy is comparable to that of hypertension.

Experimental Ablation of Posterior as Contrasted to Anterior Aortic Cusp on Cardiac Hypertrophy in the Rabbit.

During the progress of studies on the results of digitization on experimental aortic insufficiency hypertrophy it was observed that the gross configuration of the hypertrophied heart appeared to differ. Some were globular in form whereas others were elongated or boot shaped. The hearts were dissected by removal of the auricles and division of the ventricular mass by the midseptal method. It was found that the globular heart was associated with ablation of the posterior leaflet and the right ventricular wall appeared to be considerably thickened along with the increased mass of the left heart. The coeur en sabot type, on the other hand, was found occurring usually in those that had destruction of the left anterior cusp. In the latter group the thickness of the right ventricular wall did not appear to be conspicuously increased in thickness, while the left ventricular wall was strikingly so. In a few hearts with combined lesions the configuration depended upon which leaflet damage was the more extensive. The obvious visual impression was substantiated by the weights of the ventricular masses and the ratios of these to one another as shown in Table I. The hypertrophy of the auricles was observed to be greater in the hearts with posterior incompetency and the auricular body weight and the auricular heart weight ratios seem to confirm this. The heart weight body weight ratios show that the amount of total hypertrophy is almost uniformly greater in the hearts with posterior lesions. Difference in the intracardiac dynamics of the circulation with the two types of aortic regurgitation is the probable factor. A relative mitral stenosis (Austin Flint phenomenon) is a possible explanation of concomitant auricular and right ventricular hypertrophy in the presence of the regurgitation through the posterior sector.

Experimental Hypertrophy Without and With Digitalization on Creatine Content of Rabbit Hearts.

In the type of cardiac hypertrophy resulting from nutritional anemia, 1 or following thyroid administration, 2 produced in rats, the percentage of creatine in the heart muscle has been found to drop; the total amount of creatine in the whole heart seemed to remain the same, the percentage decreasing as the heart muscle increased in weight. In a preliminary note, 3 we have recorded the creatine values in hearts in which hypertrophy has been produced by a different method. Using rabbits, the aortic leaflets were torn or punctured, thus producing experimental aortic regurgitation. The degree of hypertrophy has been determined by comparing the Heart-weight/Body-weight ratio with our previously established normal value. 4 The animals were of nearly the same age, and weighed around 3,000 gm. at the completion of the experiment. Creatine determinations were made following the technique of Seecof, Linegar and Myers. 5 In Table I summarized are the creatine values for the completed series of these animals. Some of them have been digitalized, in order to note the effect of this drug on hypertrophy; the remainder have had no digitalis. A control group was injected with digitalis, without having been operated upon. In animals weighing from 2,500 to 3,500 gm., the normal hearts contain 176 mg.% creatine, with a standard deviation of 15.8 mg.%. Solids average 22.1%, S. D. 1.4%. The creatine calculated on the basis of dried weight averaged 825 mg.%±80 mg.%. In the hypertrophied hearts, the average value is slightly higher, with a tendency for the higher values to be found in hearts with moderate hypertrophy, dropping to normal or slightly below as the grade of hyper trophy increased. This means that the absolute amount of creatine in such hypertrophied hearts is definitely increased. In those digitalis control animals who received 0.1 cat unit twice weekly, injected as Digalen or Digifoline, there was a distinct increase in the cardiac creatine content. Those that received larger doses, namely 0.3 or 0.5 cat unit, showed no relative elevation.