ECG Wave Research Articles

On the relationship between U waves of the ECG and the transmembrane action potentials of single myocardial cells of the in situ heart

On the relationship between U waves of the ECG and the transmembrane action potentials of single myocardial cells of the in situ heart

Analysis of T-wave abnormalities associated with myocardial infarction using a theoretic model.

The physiological basis of serial T-wave abnormalities associated with myocardial infarction was studied. After coronary artery ligation in dogs, ventricular functional refractory periods (FRPs) were measured at five to eight epicardial, intramural, and endocardial sites. FRPs measured during acute ischemia shortened an average of 26 msec. FRPs measured 24 to 72 hr after coronary ligation were 24 msec longer at ischemic than at nonischemic sites. Alterations of recovery times were analyzed in terms of a repolarization model which related the form of the action potential downstroke to the form of the T wave of the body surface ECG. Observed FRPs were used to infer action potential duration and T waves were derived. Shortening FRPs in the anterolateral wall of the ventricle increased the amplitude of derived T waves in the X lead and caused T-wave inversion in the Z lead. Prolonging FRPs in the same area caused T-wave inversion in lead X and increased T amplitude in lead Z. The form of derived T waves qualitatively corresponded to serial T-wave abnormalities seen in patients with myocardial infarction.

Audio Monitoring of ECG Wave Forms

Audio Monitoring of ECG Wave Forms

A simplified on-line analogue adding device

An on-line adding device was designed to distribute a small periodic signal, masked by a large background noise, to a bank of capacitors for storage. The distribution was performed through reed relays, which were closed successively for a constant duration of 5–20 msec, being activated by two dekatrons. The counting of the dekatrons was initiated by some trigger pulse, such as the R wave of ECG. The circuits were wholly transistorized to make the device both compact and stable. It is shown that the stored voltage is proportional to the number of additions for up to 100 additions. Applications of the device to cardiopulmonary research revealed that a favourable signal-to-noise ratio was obtained by adding between 50 and 100 successive signals.

Automatic Measurement of the Electrocardiogram by Digital Computer

An on-line system for the automatc measurement or diagnosis of ECG was devised, whereby operation for data acquisition and processing of ECG was made in a simpler and more effective way. Twenty-five patients' ECG could be automatically recorded and processed by the system a day. Pattern recognition and measurement of ECG was successfully performed by a parameter of radial velocity of the spatial vectorcardiogram. The beginning and end of ECG waves were accurately estimated in ninety-seven per cent of one hundred subjects with various ECG findings. Consideration on several methods to improve the system was made on hard ware as well as on soft ware.

EFFECTS OF POTASSIUM ON AUTOMATICITY AND CONDUCTION OF CANINE HEARTS.

The action of potassium on cardiac automaticity and conduction was studied in dogs. It was found that idioventricular automaticity is depressed at an early stage of potassium administration. Apparent dissociation between P and QRS waves resulted from various degrees of atrioventricular block, but not complete block. The ventricles were driven by an atrial pacemaker even in absence of P waves in the limb lead ECG, as evidenced by the following findings. First, local atrial activity persisted in absence of P waves. Second, the His bundle electrogram maintained its control pattern. Finally, vagal stimulation inhibited the ventricular activity. Depression of ventricular conduction was found to involve Purkinje fibers, their junction with muscle, and the muscular fibers. Enlargement of the ventricular complexes in the ECG results in part from intermingling of depolarization and repolarization processes. Cardiac arrest results from failure of conduction since atrial activity often persisted after ventricular arrest. Ventricular flutter may occur in presence of reduced idioventricular automaticity; it is precipitated by a supraventricular beat under conditions of depressed ventricular conduction.

On the survival and metabolism of normal and hypothermic pre-viable human foetuses.

SUMMARY A total of twenty-three human pre-viable foetuses (7–400 g.) were removed by abdominal hysterotomy (legal abortions) and studied during survival in an anoxic state at different temperatures. The duration of survival, as judged by ECG waves, at 37° c was about 3 hr.; it was longer for female foetuses than for males, and longer for large foetuses than for small ones. General reduction of the body-temperature to 4° c during periods varying between 30 min. and 6 hr. with subsequent rewarming to and maintenance at 37° c increased the survival time by a further 1–2 hr. The blood sugar did not decrease either during the period of survival or during hypothermia, but the non-protein nitrogen increased, while acidosis and hyperkalaemia developed. The glycogen content of the liver decreased during the anoxic period of survival and diminished further during hypothermia. The adrenal glands produced adrenaline in addition to noradrenaline during the anoxic phase, and this may occur in a very early stage of intrauterine life.

Respiratory and circulatory vagal reflexes in rabbits exposed to high explosive shock waves.

Changes in respiration and heart rate were studied in rabbits which were exposed to high explosive shock waves in a detonation chamber after bilateral cervical vagotomy, or after pulmonary vagal denervation with the innervation of the sinoaortic region and heart left intact. The rapid shallow breathing occurring after the detonation in nondenervated animals was almost completely absent after cervical vagotomy or pulmonary vagal denervation. Sometimes an often very long period of apnea preceded the tachypnea after the detonation in the control animals. In the denervated animals, especially in the pulmonary vagally denervated ones, apnea was rare or of only very short duration. The bradycardia that can be prevented by bilateral cervical vagotomy, was not elicited by reflexes from the lungs, as the heart rate was lowered to the same extent in the lung vagus denervated as in the control animals. A cardiac standstill or severe distortions of the ECG waves during the first 1–3 seconds after the detonation were common in the nondenervated and in the lung vagus denervated animals but were rare in animals in which bilateral cervical vagotomy had been made.

Effect of malononitrile upon the electrocorticogram of the rabbit

The effect of malononitrile injection on ECG, evoked visual response and steady potential across the cortex was studied in 14 rabbits carried under minimal anesthesia. 1. 1. After injecting 10 to 25 ml. of 1 per cent malononitrile intravenously the first changes noted in cortical activity included the development of slow waves in ECG, loss of the negative phase of the evoked visual response, and exaggeration of its positive after-effect component. Thereafter the steady potential across the cortex underwent a gradual positive shift, the ECG became isoelectric, and the positive phase of the evoked response diminished in amplitude progressively until the animal died 5 to 8 min. later. 2. 2. Sodium thiosulfate can reverse this process, attributable to cellular anoxia, if its injection is commenced sufficiently early. The injection must be started at the time when slow waves are commencing to appear in ECG, the negative phase of evoked response has just disappeared, and the positive after effect component has become exaggerated. The reversal of effect takes time, and in one or another aspect, further deterioration is to be expected after the injection of sodium thiosulfate is started. Eventually, however (5–8 min.), with injection of about 20 ml. of 5 per cent sodium thiosulfate, the preinjection state for malononitrile may be completely restored.

The Experimental Study on the Change in Elektrocardiogram caused by Exposure to the Centrifugal Acceleration (VIII)

The depression of ST wave below the isoelectric line is most frequently found in Experiment I (head→tail×10") and hardly in Exp. II and III (tail→head & along the transverse axis × 10"). According to its form, ST depression can be classified in the 4 forms (M, C, V & r-form). ST begins to depress in the former half stage of exposure to the constant centrifugal acceleration, and indicates the maximal depression in the latter half stage of it. In many cases ST elevates gradually since the stage of the decrease of acceleration, but in some cases it maintains the max. depression till the cessation of centrifugalization and then begins to elevate. In general, ST depression returns to the isoelectric line within 10" alter the cessation of centrifugalization. It seems that the greater the acceler. is, the greater the frequency of appearance of ST depression and the depth of it are. Some supplemental experiment necessiated for the discussion on the experimental results were excuted. These results showed, I) In this experiment the Rabyrinth-Reflex seemed to have little influence on the changes in the pulse rate and in the height of P_II, R_II, T_II wave and the position of ST_II wave. II) In this experiment the change in the tone of Extracardiac Nerve was the most important factor for the change in pulse rate and the appearance of any arrhythmia, but the change of each wave of ECG seemed to have little concern with this factor. III) By application of the Abdomen Bandaging (30mm Hg Press.) to the guinea pig in this experiment, the change in pulse rate, the appearance of arrhythmia and the change of each wave, especially P & ST wave vanished or diminished in general. This was chiefly due to the prevention of the centrifugal stagnation of blood in the vessels of abdomen area. III) It was found that the Electric Axis whose direction was expressed by the angle θ_R in Maekawa's Orthogonal Isosceles Triangle Coordinates rotated clockwisely during the centrifugalization from head to tail, and it rotated anticlockwisely during the centrifugalization from tail to head. It was seemingly the chief causative agent for the former result that the heart position became more standing, and for the latter result that the heart position became more lying.

Report on R. E. Monaghan's apparatus for recording the ayes and nays in legislative assemblies

The modelling of ECG wave is one of the essential tools in explaining the activity of the heart ECG voltage vector. In the present paper a mathematical model of the ECG wave has been proposed, assuming the human body to be equivalent to a cylindrical composite dielectric and conducting medium and the heart to be a harmonic bio-signal generator located in this medium. This model has been utilised to explain the harmonic amplitude orientation pattern at a number of electrode locations on the frontal plane of a normal human body. It has been observed that there exists a close proximity of the nature of the mathematically predicted data with that of the experimental data.