Samuel Bellet

The electrocardiogram during exercise as recorded by radioelectrocardiography

Abstract The electrocardiogram during the standard Master two-step test was studied and compared with the postexercise tracings in a total of 296 subjects. A radioelectrocardiograph system based on the principle of broadcasting the electrocardiogram was used. The records obtained with this method show a steady baseline. In addition the method permits the taking of records during various forms of activity performed far from the recording apparatus. The changes during exercise in 127 apparently healthy persons below the age of forty years consisted of a decrease of the amplitude of the T wave to complete flattening (54 per cent), S-T segment depression of the junction type (13 per cent), occasional ischemic S-T segment depression (4 per cent) or T wave inversion (3 per cent) and occasional extrasystoles. Only one subject had persistent ischemic S-T segment depression. The following criteria for abnormality were used: appearance or increase of an ischemic S-T segment depression over 1 mm.; elevation of an isoelectric or previously depressed S-T segment over 1 mm. of the control; T wave inversion; reversion of a negative T wave to an upright position; marked changes in the contour of the QRS complex; or appearance of multiple extrasystoles. Sixty-six patients with hypertensive and/or arteriosclerotic cardiovascular disease with normal resting electrocardiograms or evidence of mild left ventricular hypertrophy showed the following electrocardiographic changes during and after exercise: 19.5 per cent had probably or definitely abnormal records only or chiefly during exercise; 9 per cent had changes only or chiefly after exercise; and 6 per cent had equal changes during and after exercise. Eighty-one patients with hypertensive and/or arteriosclerotic cardiovascular disease with abnormal resting electrocardiograms (ST-T changes in one or more leads) showed the following changes during and after exercise: 33 per cent had abnormalities only or chiefly during exercise; 11 per cent only or chiefly after exercise; and 13 per cent both during and after exercise. Of thirty-eight patients with symptomatic coronary artery disease (included in the 147 patients with hypertensive-arteriosclerotic cardiovascular disease), six had changes only or chiefly during exercise and nine both during and after exercise. Of twenty-two patients with miscellaneous (primarily noncardiac) diseases, seven had abnormalities during exercise and only three after exercise. It is concluded that the electrocardiogram during exercise is an extremely valuable adjunct in the detection of myocardial disease since the information obtained during this period is often unavailable or inadequately shown in the postexercise period.

Effect of Stimulation of Hypothalamus and Reticular Activating System on Production of Cardiac Arrhythmia

Changes in blood pressure and the electrocardiogram were studied before and after the stimulation of the hypothalamus (anterior, lateral, and posterior) and the reticular formation of the pons in anesthetized cats. The stimulation of the anterior hypothalamus produced a rise of blood pressure and usually bradycardia; tachycardia was rarely observed. Arrhythmias were not observed, and the electrocardiographic changes consisted only of slight ST elevation and deepening of the T waves. Stimulation of the lateral hypothalamus produced a rise in blood pressure of a lesser magnitude than that of the anterior hypothalamus but was associated with a transitory phase of A-V dissociation and frequent premature systoles. Stimulation of the posterolateral hypothalamus resulted in the same rise in blood pressure as that of stimulation of the lateral hypothalamus and was accompanied by nodal rhythms, aberrant ventricular conduction, and fusion beats. Stimulation of the reticular formation produced a rise in blood pressure similar to stimulation of the lateral and posterolateral hypothalamus and was associated with slight tachycardia, widening of the QRS complexes, transitory A-V dissociation with nodal escapes and ectopic beats of ventricular origin, and fusion beats. These findings suggest that: (1) the hypothalamus serves as a pathway for cardiac neurovegetative stimuli, probably via the reticular formation, producing predominantly sinus node depression; (2) the posterolateral hypothalamus and reticular formation have similar functions in the production of cardiac arrhythmia.

Radioelectrocardiography during Exercise in Patients with Angina Pectoris Comparison with the Postexercise Electrocardiogram

The electrocardiographic changes during exercise were examined by means of the radio-electrocardiograph and compared with the changes in the postexercise period in 70 patients with coronary artery disease. This method permitted the recording of one-lead tracings during exercise with a stable baseline and minimal interference. In addition, it has the advantage of permitting free exercise because of the absence of wire connections between the patient and the recording machine. Tracings may be taken on patients performing exercise at a distance of up to several hundred feet from the electrocardiograph. The criteria for abnormality based on double Master two-step tests in 127 normal individuals below the age of 40 years were appearance or increase in ischemic S-T-segment depression of 1 mm. or more, appearance or increase of S-T-segment elevation of 1 mm. or more, inversion of a positive or reversion of a negative T wave, frank inversion of the U wave, widening or narrowing (of a previously widened) QRS complex, and appearance of multiple premature beats. Thirty-seven of the 70 patients (53 per cent) showed electrocardiographic abnormalities during the period of exercise (single Master two-step test), while only 24 (34 per cent) had similar changes in the postexercise period. Twenty-three of the 70 patients had normal resting electrocardiograms. Of these, 11 (48 per cent) had abnormal alterations during, and six (26 per cent) after exercise. Forty-seven of the 70 patients had abnormal resting electrocardiograms. Twenty-six of these (55 per cent) had abnormal changes during exercise and 18 (38 per cent) after exercise. The advantage of recording the electrocardiogram during exercise is shown by the fact that in 17 of the 37 patients with abnormal responses, the changes were limited to the actual period of exercise and the immediate postexercise period, and would probably be missed were the postexercise tracing taken alone. Possible improvements in technic aimed at increasing the incidence of positive responses are discussed. It is suggested that the recording of the electrocardiogram both during and after exercise should replace the presently used technic in the Master two-step test.

Radioelectrocardiographic Changes during Strenuous Exercise in Normal Subjects

The effect of strenuous exercise (riding a stationary bicycle at 20 to 25 mph for 3 minutes) on the electrocardiogram was studied in 135 normal subjects, aged 17 to 64 years. Radioelectrocardiography was used to record the tracings during and after the period of exercise. The following electrocardiographic alterations during exercise were interpreted as representing a normal physiologic response; sinus tachycardia (100 per cent of the cases), increased P-wave amplitude (85 per cent), ST-segment depression of the junction type, 1 mm. or more (75 per cent), diminished (68 per cent) or increased (9 per cent) T-wave amplitude. A few ventricular premature beats were observed in only two subjects (1.4 per cent). All these changes were observed, although less frequently, in the period after exercise (1 minute after the cessation of exercise). According to criteria for abnormality described previously,23 34 of the 135 subjects (24.8 per cent) exhibited abnormal responses to the bicycle exercise test. Sixteen of the 34 definitely and probably abnormal responses (47 per cent) occurred only during the period of exercise, 12 were observed both during and after the exercise and six occurred only in the postexercise period. The incidence of abnormalities in the group of subjects in the age group 40 to 64 years was 37 per cent, while that in subjects in the age group 17 to 40 years was 22.5 per cent. A comparison between the Master two-step and the bicycle tests suggests that the latter may be more diagnostic for the detection of latent coronary artery disease and the evaluation of the state of physical fitness in subjects below the age of 40 years.

Indications and Contraindications for the Use of Molar Sodium Lactate

The experience with molar sodium lactate has been extended to include 101 patients. Certain indications and relative contraindications to its use have crystallized. Administration of this agent is shown to be a physiologic and effective method for treating patients with severe hyperpotassemia, multiple Stokes-Adams, attacks, and cardiac arrest, particularly that occurring in the operating room complicating cardiac surgery. For many patients in these categories, sodium lactate was life saving even though it was generally given after other more commonly used drugs and methods of therapy had proved ineffective in restoring cardiac rhythm. In the total group of patients untoward effects were few.

Radioelectrocardiography during Exercise in Patients with the Anginal Syndrome Use of Multiple Leads

The electrocardiographic alterations during the period of and immediately following exercise were studied by means of radioelectrocardiography, in 90 patients with angina pectoris. Three leads (II, V4, and V6) were utilized.The criteria for abnormality were based on the findings of 229 “normal” subjects between the ages of 17 and 39 and 300 “normal” subjects between the ages of 40 and 60.Sixty-eight of the 90 patients (76 per cent) with angina pectoris showed electrocardiographic abnormalities during and after the period of exercise. An additional seven patients (8 per cent) manifested alterations that were considered to be “probably abnormal.” The incidence of false-negative tests was 10 per cent, those patients being excluded in whom the test had to be stopped early because of fatigue, leg pain, or other complaints.The findings indicate that the recording of the electrocardiogram during exercise adds considerably to the value of the test. In some patients (12 per cent), the electrocardiogram was positive only during the period of exercise, and in 30 per cent the abnormal findings were obtained chiefly during this period.The Master two-step test involves various technical and subjective difficulties such as interpretation of the alterations, wandering of the baseline, and lack of cooperation from the patient. In a certain percentage of patients with clinical angina pectoris false-negative tests are obtained. Also positive tests in subjects without definite anginal symptoms are not rare, but not enough long-term follow-up studies have been performed to delineate the significance of these findings.In spite of some limitations, the exercise electrocardiogram, especially that taken during as well as after exercise, is an important adjunct in the diagnosis of angina pectoris.

The electrocardiogram during electroconvulsive therapy as studied by radioelectrocardiography

Abstract Electrocardiographic tracings were obtained by continuous radioelectrocardiographic monitoring in 20 patients with apparently normal cardiovascular systems during and after the convulsive stages of electroconvulsive treatment. Sinus tachycardia was typical during the convulsive stage while sinus bradycardia usually developed in the postconvulsive stage. Ischemie S-T depression was noticed in half of the patients and was more pronounced during the convulsive stage. Premature beats developed in 13 patients and were more frequent in the postconvulsive period. Oxygen administration during electroconvulsive therapy, if anything, tended to increase the depression of the S-T segment and the arrhythmias, probably because of the increased duration and severity of the convulsions. The advantages of radioelectrocardiography in recording electrocardiographic phenomena during the convulsive stage are briefly discussed.

Ventricular arrhythmias in a patient with artificial pacemakers

Abstract The case of a patient is reported whose implanted pacemaker manifested different mal-functions, including the development of ventricular premature beats, tachycardia and fibrillation. The ventricular premature beats were satisfactorily controlled when the catheter pacemaker was turned off and the heart was paced only by the internal pacemaker. Successful emergency treatment of ventricular fibrillation included immediate cardiac massage, division of the internal pacemaker leads and external defibrillation. The cardiac rhythm was restored with the aid of a catheter pacemaker.

The Cardiotoxic Effects of Hyperpotassemia and Its Treatment

Hyperpotassemia is common and its possible presence should be considered in any patient with electrolyte imbalance, particularly in the presence of renal insufficiency. The clinical diagnosis can be established by the characteristic electrocardiographic findings and confirmed by estimation of serum potassium, Hyperpotassemia kills primarily by its cardiotoxic effect, and a vigorous therapeutic regimen can often be lifesaving. Active therapy includes use of alkalizing solutions, especially molar sodium lactate and calcium; use of glucose and insulin; and removal of potassium by gastric or intestinal suction, cation exchange resins, and dialysis with the artificial kidney.

Effect of erythrityl tetranitrate on the electrocardiogram as recorded during exercise by radioelectrocardiography

Abstract The effect of erythrityl tetranitrate administered sublingually in a dose of 15 mg. was evaluated in 43 patients with angina pectoris by means of radioelectrocardiography. Leads ii , V 4 and V 6 were telemetered successively for 10 sec. each throughout the test and one, three and five minutes after cessation of the exercise in the standing position. The type and amount of exercise performed was similar to that of the standardized double (Master) two-step exercise test. Of the 43 patients included in this study, 29 (Group A) showed definite electrocardiographic alterations during the control exercise test, 11 (Group B) revealed minor or equivocal changes, and 3 (Group C) exhibited no electrocardiographic alterations, but severe chest pain developed during the control test. Forty-five minutes after administration of erythrityl tetranitrate the exercise tests were repeated under similar conditions. Twenty-six of the 40 patients (65 per cent) with electrocardiographic changes during the control test showed improvement in their tracings during the repeat test. In 18 of 19 patients (95%) who experienced chest pain during the control test, the pain failed to occur after administration of erythrityl tetranitrate. Nineteen of 25 patients (75%) with definite depressions of the S-T segment during the control exercise test showed improvement after erythrityl tetranitrate; in contrast, only 6 of 11 patients (55%) with minor S-T or T changes were improved. Placebos given to 20 patients had no effect on the electrocardiographic alterations.