James A.L. Mathers

Studies of blood pressure, heart rate, and the electrocardiogram in adult twins☆

Abstract Studies of blood pressure, heart rate, and the electrocardiogram have been analyzed for 53 pairs of twins. All subjects were over 18 years of age, and judged to be in good general health on the basis of histories of health, complete medical examinations, and laboratory tests. Every effort was made to maintain the basal state during the course of the study and to assure comparability for the two members of the pairs of twins. In a comparative analysis of the different measurements taken a strong genetic component of variability was found in the QRS and Q-T intervals of the electrocardiogram. Systolic, diastolic, and mean pressures also gave some indication of genetic variability, but these measurements were found to be most importantly characterized by sex influences.

The Abnormal Serum Lipid Pattern in Patients with Coronary Arteriosclerosis

Studies in experimental arteriosclerosis have indicated that the relative level of serum lipid phosphorus may be as significant a factor as the absolute level of serum cholesterol in the production of arterial lesions. For this reason, the serum lipid pattern of 82 patients with coronary arteriosclerosis has been compared with that of 112 healthy adults. An elevation of the serum cholesterol, serum lipid phosphorus and the serum cholesterol-lipid phosphorus molar ratio has been found in most of the patients with coronary arteriosclerosis.

Diagnosis of Coarctation of the Aorta with the Aid of the Low Frequency, Critically Damped Ballistocardiograph

Ballistocardiograms taken with the low frequency, critically damped ballistocardiograph on 17 patients having coarctation of the aorta have a characteristic pattern in which the K wave is absent. In the patients in whom the coarctation was surgically removed, the pattern returned toward the normal type with reappearance of the K wave.

A study of the physical properties of the ballistocardiograph

Abstract Fourier analyses of the displacement ballistocardiograms of seven subjects recorded from four types of instruments have been made. The coefficients of these series were corrected for the distortion introduced by the ballistic bed and by transmission through the body. The coefficients representing the ballistic pattern from the four instruments were for each subject quite different in value in the corresponding terms. The effect of applying the corrections was to converge the coefficients of the corresponding terms of the series toward a common value. The common pattern thus predicted represents a basic acceleration pattern (or forcing function) and, by appropriate steps of integration, the associated velocity and displacement patterns. The coefficients of these basic series were compared with those of the original series obtained from the analyses of the patterns from the various instruments. This comparison was made in order to determine how closely the basic patterns are approximated by the records made by these instruments. The best agreement is between the pattern obtained from the low-frequency, critically damped ballistocardiograph and the basic velocity pattern. The next best correlation was between the high-frequency underdamped system and the basic acceleration pattern. It is also suggested from this research that the acceleration, velocity, and displacement can be represented with sufficient accuracy by Fourier series carried out to 11, 7, and 4 terms, respectively. This finding indicates, for example, that a ballistocardiograph adequate to represent the acceleration pattern must have a frequency response which is linear to 11 cycles per second and that adequate mechanical or electrical filtering must be present to eliminate the distortion introduced by the transmission of impulses through the body.

Abnormal ballistocardiographic patterns in cardiovascular disease as recorded with the low-frequency, critically-damped ballistocardiograph

Abstract Using a high frequency ballistocardiograph, Starr 1,2 has shown that certain abnormal patterns are associated with cardiac disease and that there is an improvement in the pattern of those individuals to whom digitalis is administered. In the present study of pattern abnormalities in disease, the low-frequency, critically-damped ballistocardiograph designed by Nickerson and Curtis 3 has been used because of the belief that it is a superior instrument. 4,5 It has been calibrated by Nickerson, Warren, and Brannon 4 against the method according to the Fick principle, using atrial catheterization. We have attempted to study the patterns qualitatively with the idea of (1) correlating pattern type with specific disease processes, and (2) correlating changes in a series of records with variations in clinical condition following treatment. As an example, we refer to the observations made in patients with coarctation of the aorta, in whom the pattern changes from an abnormal to a normal type after surgical removal of the constricted portion of the vessel. 6

The prognostic significance of the anoxemia test in coronary heart disease; a follow-up study of 254 subjects.

Abstract 1. 1. In order to appraise the prognostic value of the anoxemia test, a follow-up study was made of 254 individuals on whom it was performed during the decade 1937 to 1947. Included were 141 patients with manifest or suspected coronary heart disease, ten with hypertension, and 103 with no evidence of a cardiovascular disorder. The average follow-up period was six years. 2. 2. Sixty-three individuals died during the course of the study. In the sixteen cases in which an autopsy was performed, the clinical diagnosis was confirmed. 3. 3. The material was analyzed by statistical methods in an effort to find correlations between the result of the anoxemia test, the clinical status, and the prognosis. The results were inconclusive. 4. 4. A comparison of the cumulative mortality rates of the patients with coronary sclerosis and anginal pain and the noncardiac subjects, grouped according to the result of the initial anoxemia test, showed distinct differences. In the coronary patients whose tests were positive, the prognosis was significantly worse, with respect to longevity, than in those whose tests were negative. It should be emphasized, however, that, whereas this obtains for the group as a whole, it does not necessarily apply to any individual patient. 5. 5. The anoxemia test furnishes an index of the coronary reserve only at the time of its performance. Because of the numerous uncontrollable variables affecting the lesions of atherosclerosis, it is not possible to predict accurately, within a wide range of probability, the future clinical course of the patient with coronary heart disease.

THE VARIABILITY OF BLOOD PRESSURE: BASAL AND CASUAL MEASUREMENTS IN ADULT TWINS.

Abstract Basal and casual blood pressure measurements have been obtained under standardized conditions of study in 53 adult pairs of twins who were determined to be in good general health on the basis of health histories and medical examinations. These data have afforded an analysis of: differences between the left and right arms, and differences between casual and basal blood pressure measurements in individuals, and within and between pairs of twins. In both the casual and basal studies it can be seen from the critical MZ:DZ ratios that variability in the measured levels of the blood pressure (in these adult subjects in good general health) is predominantly under environmental influences. However, different comparisons of the monozygotic twin intrapair casual and basal variances indicate that there may be genetic as well as sex influences which are not effectively defined by single blood pressure measurements, at least in the normal range of this variable. It was found that: (1) Although the average of the blood pressures is unaffected by the arm employed, differences between pressures on the left arm and those on the right arm are an important consideration when comparing measurements taken on the same individual, or between the two members of a pair of twins. (This would also be an important consideration in the study of siblings and families.) (2) The conditions of study have a greater effect upon the interpretation of blood pressure data than might be implied by the relatively small differences in the average of the blood pressures taken under varying conditions of study. (3) Measurement of genetic, environmental, and sex influences upon blood pressure, as well as the association of blood pressure with such variables as weight and ponderal index, depend upon the conditions of study. (4) There are genetic and sex-influenced factors related to cardiac function which are not effectively described by single measurements of the level of the blood pressure. The analyses of these data on twins pose the question whether measured levels of the blood pressure constitute the most critical manifestation of the genetic and sexinfluenced variables to be investigated. The lability of the blood pressure, its reactivity to specific stimuli, the relationship of systolic to diastolic pressure, and, possibly, the correlation of blood pressure with other attributes may be the most promising avenues for further genetic investigations of this clinically important measurement.

Some effects on the circulation of smoking cigarettes with varying nicotine content.

Abstract It is generally agreed that the smoking of cigarettes produces immediate changes in the circulation in practically all persons. The effects are shown by an increase in heart rate and blood pressure as well as by constriction of the peripheral vessels. 1 In some patients the occurrence of vasospasm has been reported in coronary and retinal arteries. 2,3 Variability in the degree of response in different subjects depends to a greater degree on individual susceptibility to tobacco than on the presence of cardiovascular disease. 4 Most investigators have ascribed to the nicotine in the smoke the chief role in producing these vascular reactions. 5,6,7 Some, however, still question its importance in this respect, and the suggestion has been made that sympathetic stimulation brought about by the irritating action of the smoke upon the respiratory tract may be responsible for the changes noted. 8 Others have attributed the effects to deep breathing. 9 Such varying opinions leave the issue still unsettled. Because the matter is of some practical importance, particularly for patients with cardiovascular diseases, this study was planned.