Slow Pulse Rate Research Articles

Habitual leisure‐time physical activity is associated with differences in various risk factors for coronary artery disease

Various risk factors for coronary artery disease (CAD) were compared in 100 healthy, male factory workers, divided into two groups of 50 each on the basis of their leisure-time activity. The two groups, designated as sedentary and physically active, were similar in terms of age and body mass index, but the physically active group had a significantly slower pulse rate. In addition, the plasma glucose and insulin responses to an oral glucose load were significantly lower in physically active individuals. Furthermore, fasting plasma triglyceride concentration was significantly lower and the high-density lipoprotein-cholesterol concentration was higher in the physically active individuals. Thus, substantial benefits in terms of CAD risk were associated with increased leisure-time physical activity.

Relative fertility in hybridization experiments using three song types of the held crickets Gryllus integer and Gryllus rubens

Species-specific calling songs of male field crickets attract conspecific females. Each wing closure results in a pulse of sound, and the song is composed of pulses arranged in species-specific patterns of short chirps, long continuous trills, or intermediates between chirps and trills. California Gryllus integer has a song with pulses of sound delivered in groups of two or three to produce a chirp, but in central Texas, the G. integer song has a variable number of pulses delivered in long continuous trills. Gryllus rubens occurs from eastern Texas to Florida and has a trilling song with a slower pulse rate than that of Texas G. integer. Identification of these three groups in the laboratory was confirmed by recording and analyzing songs for California and Texas G. integer and G. rubens males. All possible crosses were performed in the laboratory between conspecifics and heterospecifics. No progeny resulted in California G. integer and Texas G. integer or California G. integer and G. rubens crosses. Hybrids were produced in G. rubens and Texas G. integer crosses. Results suggest that California and Texas G. integer are different species, or at least populations geographically separated enough to result in reproductive incompatibility and different song types. Texas G. integer and G. rubens are apparently closely related species.

Bradyarrhythmias: Clinical significance and management

Clinicians have long recognized the potentially serious manifestations of extreme bradycardia. However, even marked bradycardia can often be physiologic, and in the presence of impaired ventricular function may offer important compensatory hemodynamic effects. Disorders of the sinoatrial node producing bradycardia include failure of impulse formation, sinoatrial conduction block, concealed sinus-perinodal reentry, carotid sinus hypersensitivity and the constellation of brady- and tachyarrhythmias that compose the "sick sinus syndrome." Bradycardia can also result from intraatrial block, atrioventricular nodal block or infranodal block. In addition, paroxysmal supraventricular tachyarrhythmias may produce concealment into the atrioventricular junction and simultaneous suppression of sinus node rhythmicity, resulting in long pauses. Pseudobradycardias manifesting as slow peripheral pulse rates can result from frequent, nonconducted early atrial premature beats, from ventricular bigeminy or runs of ventricular extrasystoles or from mechanical alternans.Cardiac pacemakers play an important role in the management of patients with severe symptoms attributable to bradyarrhythmias. However, excessive use of pacemakers and the inappropriate selection of physiologically unfavorable pacemaker systems should be avoided. Frequently, patients who are only mildly symptomatic with bradycardia should not receive a cardiac pacemaker because the prognosis is favorable. Patients with the tachy-bradycardia syndrome often require both pharmacologic and pacemaker therapy. In selected patients electrophysiologic testing may be helpful, but the majority of patients are best managed by careful attention to the history, electrocardiogram and ambulatory electrocardiographic recordings.

The response of malnourished babies to cold.

1. Twelve malnourished Jamaican children, aged 4-16 months, were studied before and after treatment, to see whether malnutrition impaired their response to cold.2. When they were studied in the post-absorptive state and in a neutral thermal environment, they had a lower rate of oxygen consumption per kg body weight, a slower pulse rate, lower body temperatures, lower R.Q., and evidence of a smaller peripheral blood flow on admission to hospital than they did after recovery.3. The malnourished children failed to increase their heat production above resting levels at 25 degrees C, and their rectal temperature fell at a rate of 1 degrees C/hr in spite of a further decrease in peripheral circulation.4. When they had recovered they maintained their body temperature within the normal range on exposure to this temperature, while increasing their heat production by 20%. The thermogenesis was apparently of the non-shivering type.5. There was evidence of increased metabolic activity in the interscapular brown fat pad at 25 degrees C both on admission and before discharge. In the malnourished children this activity was not sufficient to produce a measurable increase in total oxygen consumption.6. Interscapular brown fat was examined at autopsy in thirteen malnourished and fifteen well nourished children aged 1-24 months. Lipid depletion was found in this tissue in the former but not in the latter. This may explain the impaired response of the malnourished child to cold.

Pulsed microwave breakdown in gases with a low degree of preionization

This paper presents the results of experiments on microwave breakdown at an open-end waveguide antenna in air, argon, nitrogen, carbon dioxide, and methane at pressures of 0.3 and 30 Torr. The antenna was operated at 9.375 GHz under pulsed conditions at varying pulse rates. Very low degrees of preionization were obtained by adjusting to very slow pulse rates. The power needed to maintain the discharge was measured and from that the electric field strength was calculated. This is presented as a function of pressure for each gas at pulse rates ranging from 10 to 500 pulses/sec. At low pulse rates, significantly higher power levels are needed to maintain the discharge. An interesting feature is the double minima observed at low pulse rates in the data for breakdown field strength as a function of pressure for carbon dioxide and methane. The data were also used to calculate ionization frequency as a function of effective electric field for all five gases. Where possible, these data are compared with data reported by other investigators.

Permanent paralysis of the atrium in a patient with facioscapulohumeral muscular dystrophy

A 32 year old man with the facioscapulohumeral (Landouzy-Dejerine) type of muscular dystrophy was evaluated because of a slow pulse rate. Hemodynamic studies were performed at rest and during ventricular pacing. The patient's atria were found to be electrically and mechanically silent. This unusual disorder of permanent atrial paralysis (standstill) is reviewed. There seems to be more than a casual relation between permanent atrial paralysis and this form of muscular dystrophy.

The athletic heart syndrome. Five-year cardiac evaluation of a champion athlete.

Although there has been considerable elucidation of the athletic heart syndrome in Europe,^1-4this entity has not yet become universally recognized or accepted in the United States.^5-9The athletic heart may simulate the diseased heart by exhibiting a systolic murmur, a slow pulse rate, a variety of arrhythmias and disturbances of cardiac conduction, elevation of the S-T segments, and cardiac enlargement by x-ray. Despite the history of athletic endurance, many unfortunate athletes are classified as cardiac patients and are requested to stop athletic training. For the past five years, we have observed a superbly trained athlete with chronic cardiac changes. He has had a large globular heart, an intermittent systolic ejection murmur, sinus bradycardia and arrhythmia, a wandering atrial pacemaker, occasional nodal premature beats, elevation of the S-T segments, broad peaked T waves, and the ability to meet the severe physical demands of training and competitive rowing at

Attempted Suicide With Methyprylon

METHYPRYLON is a nonbarbiturate central nervous system depressant frequently prescribed for nighttime sedation. It is relatively safe but there have been reports of acute methyprylon intoxication 1 including one fatal poisoning. 2 The following case history describes a suicidal attempt with this drug in which the alleged intake was 26.4 to 30 gm —the largest single dose ingestion to date. Report of a Case The patient is a 36-year-old married nurse and mother of three children with a five-year history of bizarre fever and possible breast pathology. She was admitted to the emergency room at about 8 PM on Sept 25, 1964, soon after an alleged suicidal ingestion of presumably one hundred 300-mg capsules of methyprylon (Noludar) and one hundred 50-mg capsules of dimenhydrinate (Dramamine). On arrival, she was comatose with a blood pressure of 80/40 mm Hg and a slow pulse rate. There was no cyanosis or pulmonary edema,

Morphological and Mating Call Comparisons in the Bufo valliceps Complex

Morphological and mating call comparisons have been made of seven species in the Bufo valliceps complex in order to clarify their evolutionary relationships. The species studied are: Bufo canaliferus Cope, B. cavifrons Firschein, B. coccifer 'Cope, B. cristatus Wiegmann, B. gemmifer Taylor, B. mazatlanensis Taylor, and B. valliceps Wiegmann. Mating calls were recorded in the field and analyzed by means of a sound spectrograph. The calls of B. gemmifner, B. mazatlanensis, B. cavi/rons, and B. valliceps are similar. The call of B. canaliferus differs in having a much slower pulse rate while that of B. coccifer possesses a much faster pulse rate. No recordings were obtained for B. cristatus. Much of the intraspecific variation among B. valliceps calls appears to be related to body size. Morphological comparisons indicate a close relationship between B. gemmifer and B. mazatlanensis and between B. cavi/rons and B. cristatus. Bufo valliceps appears to be closely related to both of these complexes. Bufo canaliferus and B. coccifer bear neither a close resemblance to each other nor to the other five species. These findings agree with interpretations of biochemical comparisons in that B. canaliferus and B. coccifer appear to belong to different species groups than that to which B. valliceps belongs.

Rheumatic endocarditis complicated by typhoid.

Laboratory findings can provide an early diagnosis of coexistent rheumatic heart disease and typhoid. A boy 12 years of age was hospitalized because penicillin and sulfonamide compounds failed to control a week-long episode of fever, chills, headache, nausea, and nonproductive cough. He had had rheumatic heart disease (with aortic stenosis and mitral insufficiency) four years before the admission; at the time of admission he had a fever and slow pulse rate. The cardiac state was unchanged as compared to previous examination. Absence of anemia and absence of elevated sedimentation rate and leukocyte count cast doubt on presence of either active rheumatic fover or subacute bacterial endocarditis. A gram-negative bacillus was found in the blood culture. The agglutination reaction was positive for typhoid O agglutinins. The patient was treated for and cured typhoid with a total of 33.5 Gm. of chloramphenicol over a period of 18 days. No sequelae developed within the subsequent four years.

Longevity with complete atrioventricular block.

Two case reports of patients known to have complete heart block for 35 years are presented for the purpose of adding to the literature further information on the important aspect of prognosis in this disease of the heart. Atrioventricular block has always been an important clinical problem in itself and also in indicating the existence of serious disease or toxic states. Occasionally, however, and possibly more often than is generally appreciated, etiological factors may influence strikingly the course of this disease. REPORT OF CASES Case 1.— Miss L. W., aged 57, a white registered nurse, was known to one of us (J. E. B.) for 35 years. In 1910, when she was hospitalized for a minor surgical procedure, it was noted that she had a pulse. The patient's mother told her that when she was very young the family doctor had observed her unusually slow pulse rate. She had

A case of acute rheumatic carditis with heart-block

A case of rheumatic carditis has been studied in detail. The occurrence of heart-block has been demonstrated. This was scarcely suspected in a clinical examination. A slow pulse rate in the presence of a grave general condition was all that could suggest a heart-block. Electrocardiographical examinations revealed the true nature of the case. This sign should in any case be borne in mind in cases of rheumatic infection. A close follow-up of the case in all details shows that the block may be essentially a feature of rheumatic infection. Therapeutic measures to control the block and the progress of the disease have been depicted in charts and curves. The importance and value of adjuvant treatment of the associated blood condition with liver extract preparation has been pointed out.

The influence of thyroid extract and hyperthyroidism on the electrocardiogram, with special reference to the T-waves

It is apparent, therefore, that there has been no uniformity in the electrocardiographic findings in patients with thyrotoxicosis. The “thyroid” T-waves seem to bear no relation to the pulse rate nor to the basal metabolic rate. Furthermore, there is no constancy in their occurrence. Patients with marked degrees of tachycardia may fail to show T-waves of high amplitude and, conversely, with a slow pulse rate they may be encountered. This would seem to eliminate the heart rate as a factor in determining the height of the T-waves. And similarly it appears that the basal metabolic rate can be shown to have no relation to the amplitude of the T-waves. Characteristic, so-called “thyroid” T-waves have been found in our records of patients with thyrotoxicosis with metabolic rates as low as —32. Some other factor must be sought to explain their occurrence. This factor, we believe, is probably unrelated to the thyroid gland per se, since we have found similar T-waves in cases of neurocirculatory asthenia. Since a high pulse pressure is common in thyrotoxicosis and is not infrequent in neurocirculatory asthenia, we are investigating its relation to the amplitude of the T-waves, but can express no opinion at the present time.

POSTURAL HYPOTENSION OCCURRING IN A NEGRO WITH ADDISON’S DISEASE

In 1925 Bradbury and Eggleston (1) reported three cases of a condition which they termed “postural hypotension.” Later Ghrist and Brown (2) described two patients apparently suffering from the same sort of disturbance, the outstanding features of which were syncopal attacks accompanying a marked fall in both systolic and diastolic blood pressure after changing from the supine to the upright position; slow pulse rate uninfluenced by change in blood pressure, anhidrosis, lowering of the basal metabolic rate, slight and indefinite changes in the nervous system, and increase of symptoms during the heat of summer. A similar case has been recently reported by Riecker and Upjohn (3). This postural response of the blood pressure appears to be an exaggeration of the response which occurs in some normal individuals and which has been extensively studied by Crampton (4). It is possibly similar to the postural response of patients convalescent from long continued infectious diseases. None of the patients described in...

Myxedema heart: With report of two cases

1. 1. Myxedema heart is characterized by an enlargement of all four chambers, slow pulse rate, a normal blood pressure, and electrocardiographic changes. 2. 2. The myxedema heart was first described in 1918 by Zondek, who observed the cardiac hypertrophy and demonstrated the reduction in size after giving thyroid substance. 3. 3. Not all cases reported in the literature are typical examples of myxedema heart. Many authors omit electrocardiographic and x-ray studies. It is possible that certain patients were suffering from coronary artery disease. 4. 4. A case is reported of a fifty-eight-year-old man who presented the typical signs and symptoms of thyroid insufficiency. In this case the teleroentgenogram showed an enlargement of the right and left ventricles. The basal metabolism rate was minus 20 per cent. The electrocardiogram revealed a low voltage in all three leads, a left ventricular preponderance, and a notching and prolongation of the QRS complexes in all leads. After treatment with thyroid substance there was clinical improvement in the myxedema, but no demonstrable changes were observed either in the x-ray outline of the heart or in the electrocardiograms. The second case reported was that of a young man of twenty-six years, whose basal metabolism rate was minus 18 per cent. The electrocardiogram was not characteristic in this case. 5. 5. Many electrocardiographic studies have been made in hypothyroidism. Absent P- and T-waves are well known. Widening and notching of the QRS complexes, and negative T-waves have been described. Low-voltages are known to occur. All these characteristics usually disappear after thyroid medication. 6. 6. Theories which explain the above changes are discussed. 7. 7. Methods of safe administration of thyroid gland products and dosage are recorded. 8. 8. There are probably two groups of cases of myxedema heart: those which respond to thyroid therapy, and those in which a long standing myxedema and other factors produce permanent changes in the myocardium which do not permit of a response to thyroid medication.

CONGENITAL HEART BLOCK

Marked bradycardia in persons in middle or later life was first described by Morgagni in 1761. It is only in recent years, however, that accounts of the condition in children have appeared. In nineteen instances, the bradycardia apparently was due to congenital heart block. This disorder in infants is sufficiently rare to warrant the recording of an additional case. It is evident that the diagnosis of congenital heart block can rarely be proved because of the lack of exact observations on fetal heart rates. This condition, however, must be seriously considered in a child with a slow pulse rate when a history of acquired disease, such as diphtheria, rheumatic fever, syphilis or severe pyogenic infection is not obtained. The accepted cases were proved by electrocardiograms or pulse tracings. Graphic proof of heart block was delayed until later years in several instances, but in these a history of some circulatory disorder,

POSTINFLUENZAL BRADYCARDIA

Slowing of the pulse rate during the course and convalescence of certain acute infectious diseases has been a clinical observation for many years. Osler's classical description of post-typhoidal bradycardia was made in 1898; he was the first to record pulse rates as low as 30 a minute following this disease.¹Morison²noted the slow pulse rate in certain types of pneumonia. In 1922, Cowan and Ritchie³were among the first to describe its development following influenzal infections. During a recent study of postinfluenzal disturbances of the heart⁴and postinfluenzal heart block,⁵a rather definite type of bradycardia was discovered with certain associated irregularities of rhythm; this type, though apparently common, has not been discussed in the available literature. The rather frequent occurrence of bradycardia during the recent outbreak of influenza and the apprehension aroused by its detection prompted a closer investigation of these bradycardial irregularities. What constitutes pathologic bradycardia, so

IN POSTINFECTIOUS STAGES AND IN DISEASES CHARACTERIZED BY SLOW PULSE RATE

From clinical observation, we learn that several diseases at a certain period in their course have a retarded pulse rate. This slow pulse rate is perhaps best seen in cases of tuberculous meningitis in the stage of irritation, attributed to the increased intracranial pressure. Similarly, we frequently observe a low pulse rate in other forms of meningitis, in brain tumors, in hydrocephalus and in intracranial hemorrhage. The slow pulse rate in these conditions has usually been assigned to an irritation of the vagus nerve or vagus center, for we know that stimulation of the vagus nerve causes a slowing of the heart beat. Very remarkable also is the slow pulse rate we sometimes see in the postcritical period of lobar pneumonia and in diseases characterized by icterus. The number of examples can easily be increased. Frequently, this slow pulse rate is associated with a subnormal temperature. Is irritation of the

Dengue Fever in Australia. Its History and Clinical Course, its Experimental Transmission by Stegomyia fasciata, and the Results of Inoculation and other Experiments

1. Dengue Fever in Australia is undoubtedly an introduced disease. It has been existent from time to time in epidemic form since 1885.2. The clinical description of the disease agrees with that of the Dengue described in text-books, the only departure noted being the distinct tendency to a relatively, and sometimes absolutely, slow pulse rate as compared with the temperature.3. It is possible that under the single term “Dengue” more than one disease is at present included.4. Epidemic Dengue in Australia is approximately co-extensive with the known distribution of Stegomyia fasciata. It does not extend beyond the area in which this mosquito is prevalent.5. Stegomyia fasciata mosquitoes caught in a dengue infected district in the surroundings of cases of the disease, and some of them known to have fed on a dengue patient on the first and second days of his illness, transported to a non-dengue district, reproduced the disease in four out of seven persons on whom biting experiments were conducted.6. Blood taken from three of these four cases reproduced the disease when injected into further persons. The blood of one case was not tested.7. The incubation period of the four cases was found to be possibly between five and nine and a half days, probably between six and a half and nine and a half days, counting from the bitings to the definite onsets.8. No known case of contagion occurred from any of the above four cases.9. No evidence was obtained from two cases, one of which was heavily and repeatedly bitten with Culex fatigans, that Culex fatigans is capable of acting as a transmitter of dengue fever.10. The blood of patients suffering from an attack of dengue can reproduce the disease when inoculated subcutaneously into healthy persons.11. The disease thus inoculated is typical in every way of dengue fever naturally contracted. The inoculated disease may or may not shew marked skin rashes and double phases in the temperature charts, and presents a relatively and sometimes absolutely slow pulse; such variations occur in the natural disease. The incubation period of the inoculated disease varies from five to nine days corresponding with the incubation period of the mosquito-transmitted disease.12. Results of the inoculations shew that:(a) The virus of dengue is present in the blood as a whole.(b) The serum of clotted infective blood may contain the virus.(c) With washed corpuscles one apparently positive result was obtained out of three experiments.(d) The fluid part of citrated infective blood may contain the virus.(e) With Pasteur-Chamberland filtrates of infected serum and corpuscles, one positive result was obtained out of five experiments.In considering these results failure to convey tne disease must not necessarily be interpreted as meaning that the menstruum employed never does contain the virus, as in some of the cases the blood may no longer have been infective at the time at which it was withdrawn.(f) The presence of the virus in the blood has been demonstrated on the second and third days of the disease. Two experiments made may possibly be interpreted as shewing that infective material may still be present on the eighth day of the disease.(g) One experiment appears to indicate that the virus is no longer present in the blood on the fourteenth day from' the beginning of the illness.(h) Immunity to the inoculation of infective blood appears to be complete twenty-four days after recovery from a typical attack of dengue.(i) Infected blood may maintain its infectivity outside the body if kept in a cool place for seven days at least.(j) In two instances two individuals inoculated with the same material on the same day exhibited incubation periods practically identical in duration.(k) The infection of dengue can be conveyed by sub-inoculations from individual to individual at least to the fourth generation without the resultant disease departing from the type of the natural disease.(I) The disease has not been conveyed by the application of infective serum to a scarified area; nor apparently has it been conveyed by the application of infective material by swabbing to the nostrils.(m) A very doubtful and probably negative result followed the gargling of the throat with infective material followed by swallowing of the same.(n) Dengue fever has close analogies with yellow fever.

HEART-BLOCK

The following two cases of complete heart-block are considered worthy of report because of several unusual features shown by electrocardiograms. <h3>REPORT OF CASES</h3><h3>Case 1.</h3> —Mrs. E. P., an American housewife, aged 39, had been under observation in the Washington University Dispensary for two years. She first came to the dispensary because of various gynecologic complaints associated with retroversion of the uterus. At that time it was found that she had an unusually slow pulse rate, and electrocardiograms revealed the presence of complete heart-block. This condition had been constantly present since, but in spite of this fact she had had no cardiac symptoms aside from slight dyspnea on exertion. She had never had a syncopal attack. Physical examination of her heart had constantly shown moderate enlargement of the cardiac dulness, the presence of an apical systolic murmur transmitted to the axilla, and a faint aortic systolic murmur poorly transmitted. The