Bipolar Lead Research Articles

Aimed electrocardiography with simple bipolar leads. Experimental study of a new concept: surface search for unweighted leads which record the ECG from limited cardiac areas.

All currently employed ECG and VCG leads vectorially record added contributions from all cardiac regions. Aimed leads, if feasible, would yield information cancelled during addition. Three artificial dipoles (µ 1 , µ 2 , µ 3 ) are placed within a torso model in the approximate right ventricular free wall, posterobasal wall of left ventricle, and inferior cardiac surface, respectively. Dipoles are excited in turn and torso surface potential fields are mapped for each dipole. A bipolar lead connecting any pair of points on the same equipotential of the field produced by µ 1 does not show a deflection when µ 1 is excited, but responds to µ 2 and µ 3 . If this lead is now so placed that its two electrodes, while remaining on the µ 1 equipotential, are on the same equipotential of the µ 2 field as well, then it will respond to µ 3 alone; it is aimed at the latter. Superimposing the three field maps and searching for those equipotential lines of one map which cross the same equipotential line of another map twice, provides a large number of suitable leads, each aimed at one of the three dipoles. Five leads are described and tested in detail.

Electrocardiogram changes in prolonged automobile driving.

Numerous observations suggest that the cardiovascular system is affected by the complex physiological stress of driving an automobile. In view of the general importance both in regard to automobile accidents and health protection of the driver, the number of observations is still small, and more information is needed. Particularly, there does not seem to be any information about electrocardiogram (ECG) changes during long distance driving. It must be assumed that, like other phys~olog~cal stress situations, accumulation of stress occurs during prolonged activity. Thc,refote, exploratory work investigated changes on the ECG during nearly continuous (without sleep) driving over distances from 200 to 700 miles. Data were obtained for a total of 6000 miles of driving. A, male (26 yr.); B, male (40 yr.); and C, male (77 yr.) were clinically healthy; D, male (32 yr.) had nephrosis with chronic albuminuria, with otherwise negative clinical findings. The resting conventional 12-lead ECGs of all four Ss were within normal limits. The ECG was taken with a bipolar lead (manubrium-C-5 position) at intervals of approximately 20 min., using a commercially available portable instrument modified for automobile use. The start of each driving session was preceded by a resting ECG taken in the same position. Experimental cars were equipped with power steering and brakes and automatic transmission. A logbook was kept of driving events and conditions. The total distances driven by each S were as follows: A drove 2600 miles in four days; B drove 970 miles in two days; C drove 200 miles in one day; and D drove 2500 miles in four days. The electrical activity of the heart was noted to respond distinctly to duration of driving and critical road siruations. For example, in C, the T wave decreased after 4 hr. of driving to half its original size. In A, transient flattening of the previously positive T wave developed after 4 hr. of driving and some correlation to road events appeared; in B transient inversion developed after 1 hr. As driving continued, the periods of T wave flattening or inversion became more frequent and more prolonged. After interruption of driving, the T wave recovered to approximately rwo-thirds its original size but became flat or inverted shortly after resumption of driving. It appears that significant ECG changes may occur in healthy Ss during long distance driving which would be considered as abnormal in response to other stress situations. Although it would be premature to generalize, it may be inferred that there is a significant myocardial involvement in the stress of driving an automobile, even in some apparently healthy drivers. Most likely, the changes found in ECG during driving are due to emotional stress, mediated through the autonomic nervous system and hormonal system, particularly the adrenal system. More elaborate investigations, using both physiological and behavioral measures, are being conducted in our laboratories.

Synchronized recording of electroureterogram and urometrogram.

Experiments were undertaken with the purpose of developing a method for synchronized recording of urometrograms and electroureterograms. An electrode was constructed for synchronized recording of electroureterogram and urometrogram from the same region of the ureter. Electroureterography was made either by the unipolar lead or by the bipolar lead method. It was found that insertion of this electrode into the ureter did not exert any artificial effect on peristalsis of the ureter. The contraction phase was shown to be closely related to the action potential, while the pre-contraction phase merely represented secondary changes in intra-ureteral pressure which is related to urinary volume.

Experimental comparison of “parallel grid leads” with simple bipolar, and the SVEC-III, Frank, and McFee-Parungao systems. I. Sagittal leads

A performance comparison of the following five leads is made in the homogeneous torso model: The sagittal leads of the Frank, Schmitt-Simonson SVEC-III, and McFee-Parungao lead systems, a simple bipolar lead consisting of a precordial and dorsal electrode, and a 7-by-5 parallel grid sagittal lead. The criteria of uniformity, orthogonality, and ability to measure the total outward dipole moment of the heart are used in judging lead quality. A point of reference corresponding to the approximate center of gravity of the ventricles, and concentric “large”, “normal”, and “reduced” heart areas, are defined within the model and on maps placed on a drawing board near the model. A current source able to deliver x, y, and z-directed current, is three directionally movable within the model and its position is transmitted to the drawing board by means of a rigid arm. The source, z directed at the point of reference within the torso, is excited to deliver current which is sufficient to cause a 100-mv. reference voltage in the lead under study. Lead voltages obtained when the source is x, y, or z directed at 177 points within the cardiac area of the torso, are then read directly as percentages of the reference voltage. In an ideally uniform lead, 177 readings of 100 mV. are obtained when the source is z directed. In an ideally orthogonal lead, two sets of 177 zero readings are obtained when the source is x and y directed, respectively. 1. 1. By inspection alone of graphs which show the frequency distribution of individual voltage readings around these standards of ideal accuracy, and of torso maps which show lines of percentage deviation from the reference voltage, leads are grouped as follows: (i) the least accurate group, containing the Frank, McFee-Parungao, and bipolar sagittal leads; (ii) the SVEC-III sagittal lead, intermediate between the first and third classes; and (iii) the grid, showing greater uniformity and orthogonality than the four other leads. 2. 2. Nonuniformity expressed as arithmetic standard deviation of measured lead voltages supports the division into three classes. It is 30 to 50 per cent in group (i), 16 to 24 per cent in the SVEC-III sagittal lead, and 4 to 9 per cent in the sagittal grid. The standard deviation on a logarithmic scale of millivolts again separates the three groups (p = 0.001), and within the least accurate group (i) there is, in most of the sets analyzed, no significant difference in uniformity between the Frank, McFee-Parungao, and bipolar leads. 3. 3. The means of sagittal lead voltages when the current source is x or y directed, respectively, used as a measure of nonorthogonality, are 12 to 25 per cent in the Frank, McFee-Parungao, and bipolar group, 12 to 30 per cent in SVEC-III, and 4.3 to 5.7 per cent in the grid. The differences between the grid, on the one hand, and the 4 other leads, on the other, are significant (p = 0.001) in all heart sizes. Differences in orthogonality between leads other than the grid are statistically not significant in most of the samples. 4. 4. The equation M z = A z V z ϱ , derived previously in this laboratory, is accurate within an error of ±5 per cent in measuring the dipole moment of z-directed current source in the homogeneous torso model, if A z is the area of the 7-by-5 grid, V z is the sagittal lead voltage, and ϱ is the torso resistivity. By the performance standards used in this study, the sagittal leads of the Frank and McFee-Parungao systems are not more uniform or orthogonal than is a simple bipolar sagittal lead. The SVEC-III sagittal lead is more uniform but not more orthogonal. The parallel grid sagittal lead is more uniform and more orthogonal than any of the other leads tested.

Bipolar Esophageal Electrocardiography in Unusual Cardiac Mechanisms.

Excerpt During the past 5 years, the salt-bridge bipolar esophageal lead has proved, in our hands, superior to the unipolar esophageal lead and to body surface leads in the diagnosis of complex and...

Diaphragm contraction as a limiting factor to maximum expiration.

Electrical activity of the diaphragm has been studied by means of a bipolar esophageal lead to investigate the high abdominal thoracic pressure difference found at the end of maximum expiration. An esophageal balloon, placed alongside the electrodes and moderately inflated, overcomes the difficulty previously found in using an esophageal lead to study diaphragm activity at small lung volume. At the end of maximum expiration, intense activity of the diaphragm has been recorded. Contraction of the diaphragm at the end of maximum expiration balances the muscle action of the abdominal wall, preventing further reduction of lung volume. Analysis of factors that may set the lower volume limit suggests that contraction of antagonist muscles is the main factor, at least on the abdominal boundary of the thorax. The possible afferent impulses leading to a reflex contraction of the diaphragm at full expiration are discussed. Submitted on December 18, 1961

Electromyography of the diaphragm in man and transdiaphragmatic pressure.

The electrical activity of the vertebral part of the diaphragm in man has been studied in physiological conditions through an esophageal bipolar lead; the spirogram and/or the intrathoracic and gastric pressure were simultaneously recorded. Electrical activity has been found during inspiration; it is approximately related to the transdiaphragmatic pressure as the activity found during graded inspiratory efforts at relaxation volume. At minimum lung volume the electrical activity during maximum inspiratory efforts is small notwithstanding the high transdiaphragmatic pressure. Electrical activity may persist at the beginning of expiration, showing that the diaphragm does not relax completely at the onset of expiration. At the end of maximum expiration a small electrical activity may appear, the transdiaphragmatic pressure is high and it is not clear to what extent the diaphragm is passively distended or contracted. At relaxation volume during expiratory efforts electrical activity appears only when the effort is high, while during expulsive efforts, even moderate, the activity is marked. Submitted on May 2, 1960

Clinical evaluation of a new esophageal electrode, with particular reference to the bipolar esophageel electrocardiogram part II. Observations in cardiac arrhythmias

1. 1. The application of the salt-bridge method of esophageal electrocardiographic registration to the development of a simple and clinically reliable bipolar esophageal lead has been outlined. The results of multichannel, multilevel esophageal lead surveys made with this device upon 26 subjects with normal sinus mechanism and 74 with various cardiac arrhythmias are reported here. The leads which were routinely recorded simultaneously in these surveys include unipolar registration from the proximal and distal members of the lead assembly (VE P and VE D), the difference in potential between these two members (Lead BE), and a conventional extremity lead (usually Lead II). 2. 2. A careful and extensive analysis of the group of subjects with normal sinus rhythm confirms that both the unipolar and bipolar esophageal leads greatly exceed the capability of conventional body surface leads in depicting the forces of atrial depolarization and repolarization. In this group the bipolar esophageal leads appeared to have certain advantages as compared to the unipolar leads, and in no instance did they prove inferior to the unipolar leads. 3. 3. In our evaluation of the group of subjects with cardiac arrhythmias the esophageal leads offered unsurpassable diagnostic superiority as compared to the conventional leads. In a number of cases the bipolar esophageal lead was decidedly better than the unipolar leads, although this was not invariably so. 4. 4. Our clinical observations of the unipolar and bipolar esophageal electrocardiograms appear to confirm the theoretical principles which were previously developed in this laboratory. As anticipated, the bipolar lead has proved to be particularly sensitive to alterations in the time course of atrial depolarization. It also provides a ready means for sorting atrial from ventricular deflections, especially in situations in which they occur concomitantly. 5. 5. On the basis of the experiences reported here, we believe that no complicated or perplexing arrhythmia will have been studied adequately without the benefit of esophageal tracings. The relative technical simplicity of the salt-bridge principle as applied to unipolar and bipolar esophageal registration greatly minimizes the demands which such a procedure would ordinarily impose upon the physician's time and energy.

CONTRIBUTION TO THE CONFIGURATION OF ACTION POTENTIAL DEPENDING THE LEADING METHOD

The A. P. of N. ishiadicus which was separated from a toad was recorded by means of monopolar or bipolar lead, and then the distance between two electrodes was changed on each experiment.By monopolar lead, the configuration of A. P. led at a central part is large and abrupt (Fig. 8 a), and that at the peripheral is small and gentle (Fig. 8 d). By bipolar lead, if the distance of two electrodes is short, the configuration of A. P. is small, but if the distance is long, it is very large and a plateau. between two deflections appears.This configuration of A. P. (bipolar lead) may be able to be composed of each A. P. of monopolar lead, considering its distance and direction.Some results of the first reports which inquired into the nerve were proved logically, by means of the Model (The Yamagiwa-Lillie's and the Matumoto' s Model)

The principles of esophageal electrocardiography

Our recent experiences with unipolar and bipolar esophageal leads have impressed us with the need for developing and clarifying the heart-lead relationships which apply to that particular area of clinical electrocardiography. Accordingly, we undertook such a study in the light of modern concepts, and report here the fundamental principles which were found to underlie esophageal electrocardiography. Largely on the basis of the lead-field and lead-vector concepts, together with a consideration of effects produced by the intracardiac phase-inhomogeneity, this study offers a rational explanation of why P waves appear in greatly amplified form in esophageal leads as compared to the relatively minor amplification of QRS complexes. The bipolar esophageal lead is shown to possess at least three unique properties, the latter two of which have already proved to be of special clinical value: (1) In the registration of atrial depolarization it is more truly a proximity lead than the unipolar connection. (2) In recording from the level of atrial transition it is strikingly sensitive to even minor variations in the time-course of atrial depolarization. (3) It greatly facilitates determination of the timing and direction of atrial activation in situations in which such information would ordinarily be obscured by the concomitant occurrence of ventricular depolarization. It is hoped that the theoretical principles developed here will eventually prove to be a reliable foundation for the clinical evaluation of present and future studies in esophageal electrocardiography.

Relation between S-T segment elevation and experimental myocardial oxygen gradient.

Myocardial oxygen gradient was altered variously by means of gas mixture inhalation in acute coronary artery occlusion in dog. This was correlated with the S-T segment elevation in electrocardiograms recorded in a bipolar subepicardial lead across the pink area and cyanotic area of the myocardium. The electrocardiograms revealed a positive relation between them, that is, the S-T segment increased in height with the increasing of oxygen gradient, and decreased in height with the decreasing of gradient. Occasionally there were also observed S-T segment electrical alternans and the merging of the S-T segment. Implications were briefly discussed.

Ventricular fibrillation studied by the microelectrode method.

Capillary ultramicroelectrodes were inserted into ventricular muscle fibers of dogs in ventricular fibrillation and action potentials obtained were compared with deflections of unipolar direct lead, adjoining bipolar direct lead or other electrocardiograms taken simultaneously. In most stages of ventricular fibrillation neither synehronism nor any other regular time relationship could he found between them. Microelectrodes inserted at two points variously distant on various regions of the ventricular surface also failed to show any regular time relationship. Total incoordination of ventricular muscle fibers was thus supported.

Relationship between the Intrinsic or Intrinsicoid deflection and Time of Arrival of Activation by Unipolar Lead Ecg

In clinical diagnosis of ventricular hypertrophy, bundle branch brock, premature heart beat, tricuspidal- and aortic valvular insufficiency, it is of great significance to determine the time of arrival of activation in ECG. However, there still remains a contraversy as to the point indication it. For example, the onset of ingrinsic or intrinsicoid deflection is regarded as the point marking this by Lewis, Wilson in early stage and many other authors, while the end of this deflection is considered to mark it by Wilson. This report was made to elucidate the accurate relationship between it and intrinsicoid deflection. According to our results in calculation, the actual instant of arrival of activation could be reperesented by cross point of tracing with zero-line when the equivalent double layer, perpendicular to the ling axis of straight muscle strip, was moved from one end to another. The time interval between the onset of the int. defl. and the cross point was variablw according to the transmission rate of activation and the distance from electode to muscle strip. When the equivalent double layer, oblique to hte long axis of the muscle strip,w was moved from one end to another, it could not be reperesented by cross point, differing from above mentioned case. Consequently, the onset of intrinsicoid deflection or the cross point of this deflection with zero-line could not be regarded as the representative point of arrival of activation even in simple activation process like above mentioned cases. Since the activation process in human heart is notso simple as that applying to above cases, we want to calculate the potential variation arising in more complicated activation process. When we calculated the potential change at a given point without a hollow polaraized sphoere in a certain process of activation, the time of arrival of activation was somewhre within the duration of intrinsicoid deflection. Moreover, when we calculated the potential variation at many points without heart in a feew process og activation, the arrival of activation occurred some where during the intrinsicoid deflection and was not upon a specific point like the onset or the end of the deflection. These caliculations were made on the schema of heart quoted from the atlas of anatomy by Toldt Hochstetter, assuming the every equivalent double layer in each stadium of activation as a disk. It must be noted that the intrinsicoid deflection is not necessarily sharp and large deflection but sometimes smaller than the deflection due to the extrinsic effect, and it is not always easy to point out the intrinsicoid deflection in ECG. Comparing these results of calculation with those of experiments pwerformed on toad heart, recording the contiguous bipolar lead ECG and unipolar lead ECG simultaneously, we could observe that the both results coincident very well. We may conclude that the onset or the end ofthe intrinsicoid deflection can not be interpreted as the point indicating the arrival of activation as Lewis Wilson and others say, and that ingrinsicoid deflection is not neccessarily a large and sharp deflection but sometimes smaller then the deflection due to extrinsic effect. In general, the time of arrival of activation lies somewhere during the intrinsicoid deflection, bu can not be defined on a specific point.

On the significance of the bipolar chest lead in ECG between apex cordis and the left posterior axillary line.

On the significance of the bipolar chest lead in ECG between apex cordis and the left posterior axillary line.

A method for recording spatial vectorcardiograms

Three perpendicular bipolar axes which constitute a spatial reference system have been described. The electrodes comprising the reference system are remote or equidistant. The angle subtended to the force measured in each instance was as great as the body would accommodate and not violate the distance necessary for remoteness. This reference system was compared in one hundred instances with the rectangular cube method used by Grishman and others. The chief difference in the two reference systems was found in the measurement of the anterior-posterior electromotive force. In each instance, using our modification, the anterior-posterior component was greater. We believe this change is due to the difference in the angle subtended by electrodes comprising this bipolar lead in the two systems. It is recognized that the electrode placement of this system, as with other spatial reference systems, may not always be considered remote. However, this factor is not inherently greater in the suggested reference system than other currently employed methods. Therefore, we suggest that the method described here may more closely reflect the true potential manifested in the heart.

Cortical response to intermittent stimulation with colored light in the cat.

The effects of spectral lights of various wave-lengths upon the electrical activity of the cat's cortex were investigated. The light was interrupted at various frequencies by means of an episcotister driven by a motor. The horizontal sweep of a cathode ray oscillograph was made to synchronize with the rhythm of stimulation, so that a standing image of responses was established on the screen.1. At lower frequencies of flicker, evoked potentials consisted of on-and offresponses. The latter, however, disappeared above a certain frequency between 10 and 15 cps. The critical fusion frequency seemed to lie between 25 and 35 cps.2. No pattern characteristic of the wave-length could be found. However, the amplitude of response was altered in a characteristic manner as the wavelength was systematically varied. The spectral distribution of amplitude was found closely similar to the scotopic luminosity curve.3. When strong colored lights were used, some difference in wave form could be found, but it was shown that the difference was chiefly due to the difference in luminosity.4. Responses obtained with bipolar lead were restricted to the striate and extra-striate areas. When monopolar lead was used, responses appeared over much wider regions, including the so-called auditory areas. A systematic phase difference was seen between records obtained from two neighboring areas, and this fact suggests that excitation spreads from the visual cortex into surrounding areas through some intracortical pathways.

Relationship between the intrinsic deflection and subepicardial activation: An experimental study

1. 1. The morphology and significance of the curves obtained by the method of adjoining bipolar leads, as described by Harris, 5 is studied. 2. 2. It is proved experimentally that the greatest deflection of bipolar leads corresponds to the activation of the small muscular region in contact with the electrodes; indeed, it does not change in shape if right bundle branch block is produced or if premature contractions of right or left ventricle occur. On the contrary, the greatest deflection disappears or is reduced if the subepicardial muscular tissue in contact with the electrode is injured. 3. 3. Reasons are given why the apex of the greatest deflection of the bipolar lead is chosen as the moment corresponding to the arrival of the activation wave at the subepicardial muscle. 4. 4. Through the use of a simultaneously recorded Lead II the apex of the major deflection of the bipolar curve is referred to the intrinsic deffection of a unipolar curve. It is found that the lowest part of the intrinsic deflection or its lower third conesponds with the arrival of the wave to the subepicardial muscle.