Apex Cardiogram Research Articles

Hall effect transducer for apexcardiography and sphygmography

Recording of mechanograms (Recording of mechanical activity of internal organs and vessels, often non-invasively eg. apex cardiogram) can be performed by applying different kinds of mechano-electric transducers. In this paper the idea and construction of a new transducer with Hall-generator are presented. This transducer is self-adjusting in the range of its linear characteristics, and exerts practically constant touching pressure independent of the configuration of the patients thorax. This facilitates the measuring process and allows for calibration of the obtained records. The sensitivity of the transducer is 250 mV/mm, frequency bandwidth 0–45 Hz and it has a linearity of ± 1.5% in the range of displacements ± 1.5 mm. The transducer also generates the signal of the first derivative of the investigated vibrations. Assessment of the transducer was carried out in a cardiology clinic on 27 patients with a normal heart and with different kind and degree of heart damage. The mechanograms obtained from different transducers for each patient were compared in respect of the essential time intervals and morphological elements. The comparison shows a good detecting capability, correctness and reproducibility of the data obtained by means of the Hall-effect transducer. Some recordings of mechanograms (apexcardiograms and different kinds of pulse) from patients with normal heart, valvular aortic stenosis and atrial heart defect are shown and discussed in the paper.

Influence of acute hemodynamic changes on the normalized negative peak of the first derivative of the apex cardiogram and time constant of ventricular relaxation in dogs.

The effect of various alterations in preload, afterload and inotropic state of the left ventricle on two non-invasive indices of myocardial relaxation was studied in anesthetized dogs, in an attempt to clarify some of the determinants of myocardial relaxation. The first derivative of the displacement left apex cardiogram (dA/dt), the apex cardiogram, left ventricular pressure, the first derivative of left ventricular pressure, electrocardiogram and phonocardiogram were recorded simultaneously. The following mechanocardiographic parameters of myocardial relaxation were investigated: (1) normalized negative peak of dA/dt for simultaneous isovolumic apex cardiographic amplitude (min dA/dt/Ar). and (2) time constant of myocardial relaxation T. The non-invasive time constant was derived from a logarithmic isovolumic calibrated apex cardiographic amplitude v. time plot subsequent to min dA/dt. The indices min dA/dt/Ar and T compared with analogue parameters of left ventricular catheterization (min dP/dt/Pr and T) showed similarity in magnitude and standard deviation during various acute hemodynamic interventions. The min dA/dt/Ar was related to the level of afterload; furthermore isoprenaline accelerated relaxation as determined by the two investigated indices. During the various hemodynamic changes a high correlation existed between invasive and non-invasive indices. The results presented indicate that the apexcardiographic time constant of myocardial relaxation may be a reliable index for ventricular relaxation since it is independent of pre- and afterload, whereas min dA/dt/Ar are load-dependent.

Assessment of left ventricular function by synchronous echocardiography and apex cardiography.

The relationship between left ventricular dimension measured using M-mode echocardiography and simultaneous apex cardiography has been studied in 69 normal subjects (2 groups) and 159 patients with heart disease (6 groups). A loop was formed by plotting the apex cardiogram, which is related to ventricular wall stress, against ventricular dimension. Abnormalities in ventricular function due to shape or volume changes in the isovolumic phases of the cardiac cycle produced characteristic alterations in the loop pattern. These changes were measured and the results for different groups compared. Normal subjects were divided into two age groups (13-38, 40-78) and no significant differences were found between them. In the heart-disease, patients, 25% had an abnormal decrease in dimension during isovolumic contraction and 25% had an abnormal increase during isovolumic relaxation. When the downstroke of the apex cardiogram was differentially analysed, it was possible to show that 60% of heart-disease patients lay outside the normal range. By using these techniques it is possible (a) to show abnormal ventricular response to pressure changes during the isovolumic periods, (b) to quantify the abnormality and, (c) to detect early abnormal muscle behaviour before it becomes visible on conventional ultrasound recordings.

Influence of acute hemodynamic changes on the peak velocity of contractile element shortening and maximum velocity obtained by the calibrated apex cardiography in dogs.

The effect of various alterations in preload, afterload and inotropic state of the left ventricle on the noninvasive peak velocity of contractile element shortening (Vpm) and maximum velocity of contractile element shortening (Vmax) was studied in the anesthetized dogs in an attempt to test the methods and clarify some of the determinants of these parameters. Calibrated displacement left apex cardiogram obtained with time constant 3 sec and calibrated first derivative of apex cardiogram were recorded simultaneously with left ventricular pressure and its first derivative, electrocardiogram and phonocardiogram. The values of Vpm obtained from catheterization and calibrated apex cardiography were similar in magnitude and standard deviations under various hemodynamic interventions. A highly significant relation was found between these invasive and noninvasive parameters of myocardial contractility. Both Vpm and Vmax were elevated during the administrations of isoprenaline and strophanthin, where only Vpm showed a decrease after extreme volume or pressure load. In conclusion, the results from this study suggest that Vpm and Vmax of the calibrated apex cardiography are a reliable noninvasive tool for assessing left ventricular function; furthermore, Vpm is relatively load independent, whereas Vmax is virtually unchanged over a broad range of loading conditions.

Part 2. The Appreciation of Apex Cardiograms and Clinical Studies

Part 2. The Appreciation of Apex Cardiograms and Clinical Studies

The use of the first derivative of apex cardiogram and echocardiographic dimensions for assessing left ventricular relaxation and mean velocity of circumferential fibre lengthening in cardiomyopathy.

Eleven patients with hypertrophic obstructive cardiomyopathy (HOCM) and nine patients with congestive cardiomyopathy (COCM) were studied to determine the usefulness of relaxation time and mean velocity of circumferential fibre lengthening (VCFJ obtained from the first derivative of apex cardiogram and echocardiographic left ventricular dimensions. Twenty-two normal patients were ± investigated by echo and apex cardiography and served as controls. In HOCM both early apex cardiographic relaxation time interval (ERT) and total apex cardiographic relaxation time interval (TRT) were increased (ERT: 16 ±9 ms v. 5 ± 4 ms in controls, P<O.001; TRT: 127 ± 22 ms v. 94 ± 21 ms in controls, P<O.01) and VCFL was decreased (0.87 ± O.08 circs v. 1.21± O.09 circ/s for controls, P<0.02). In COCM both ERT and TRT were diminished (ERT: 1 ± 3.5 ms v.7±4 ms in controls, P<O001; TRT: 53 ± 14 ms v. 94 ± 21 ms for controls, P<O.01) and VCFL was decreased (0.69 ± 0.08 circ/s v. 1.21 ±0.09 circ/s in controls, P<O.01). There was a significant correlation between min dp/dt determined at catheterization and both ERT (r = O.86) and TRT (r=O.81). These findings indicate that alterations in relaxation and mean velocity of circumferential fibre a lengthening take place in cardiomyopathy and they may be detected non-invasively by the first derivative of the apex cardiogram and the left ventricular echocardiogram.

Evaluation of contractile state of the left ventricle from the peak of the first derivative of the apexcardiogram

Simultaneous records of the electrocardiogram, phonocardiogram, apexcardiogram (ACG), and the first derivative of the apexcardiogram ( dA dt ) were obtained in 50 normal subjects and in 38 patients with ischemic heart disease. This allowed us to measure the ratio of peak dA dt to total amplitude of the first derivative in percent and the interval from electrical stimulation to peak dA dt (R to peak dA dt ). In 16 additional normal subjects the effects of pharmacological agents with positive and negative inotropic action were studied with the above parameters. During isoprenaline infusion the ratio of peak to total amplitude dA dt was increased and the interval R to peak dA dt was shortened, while after propranolol the ratio of peak dA dt diminished and the interval R to peak dA dt showed elongation. In normal subjects the ratio of peak dA dt averaged 48 ± 14% and it is significantly lower in patients with ischemic heart disease (32 ± 13%, p < 0.001). In controls the interval R to peak dA dt was 73 ± 15 msec., whereas in ischemic heart disease it showed elongation (121 ± 15 msec., p < 0.01). It is concluded that the ratio peak dA dt and the interval R to peak dA dt , expressing noninvasively the rate of pressure changes and the duration of the development of maximum tension during isovolumic contraction, provide useful information on left ventricular function.

Evaluation of left ventricular function by apex cardiography comparison of "t(dA/dt)/A" with hemodynamic indexes and with myocardial perfusion scintigraphy.

Left apex cardiograms (ACGs) were recorded in a total of 112 subjects; 32 normal individuals, 36 patients with ischemic heart disease, 19 patients with idiopathic cardiomyopathy and 25 patients with other cardiovascular diseases. The apex cardiographic index t(dA/dt)/A showed a good, positive correlation with t(dp/dt)/p (r = 0.81), p < 0.001) and also a positive correlation with Vmax (r = 0.76) as well as with ejection fraction (r = 0.65). It was weakly correlated with cardiac index and LV max dp/dt (r = 0.60 and r = 0.57, respectively) and had inverse correlations with LV end-diastolic pressure (r = -0.40) and LV end-diastolic volume (r = -0.59). There was no significant correlation between t(dA/dt)/A and LV peak systolic pressure. The t(dA/dt)/A value was significantly lower in the congestive cardiomyopathy group than in any other group investigated: ischemic heart disease, hypertrophic cardiomyopathy, occlusive thromboaortopathy or atrial septal defect (p < 0.001). Of the patients with ischemic heart disease examined by thallium-201 myocardial scintigraphy, those with imaging defects displayed significantly lower values for t(dA/dt)/A than those without imaging defects (p < 0.001), and the index tended to be lower in the patients with moderate to large imaging defects than in those with small defects. The results of the present study indicate potential usefulness of the ACG index of t(dA/dt)/A in noninvasive evaluation of the LV function and presumably of the mode of myocardial contraction.

Blue Plans Medical Necessity Program

ADOLPH et al (JAMA 241:799-800,1979), in their COMMENTARY, protest the policy of the Blue Cross and Blue Shield associations as it applies to phonocardiography, pulse tracings, and apex cardiograms. The writers fear that patients will be denied these procedures when they might be of specific benefit to the patient. The policy they protest denies nothing. It recommends to Blue Cross and Blue Shield plans that payment be made only when the claim is accompanied by a report from the physician stating the indications in the given case. There is nothing in the policy that recommends abandonment of phonocardiography, as implied in the title, and nothing that denies any of the procedures when indicated. Nine of the 11 cardiologists protesting the policy might protest the need to submit a claim by report, but there is no justification for the implication that the policy recommended to the associations by the American College

Should Phonocardiography Be Abandoned?

IN JUNE 1977, the Blue Shield Association announced that Blue Shield plans would discontinue routine payment for several diagnostic procedures because they were considered generally unnecessary. Phonocardiography was listed among those procedures, along with pulse tracings and apex cardiograms. This Program on Medical Appropriateness is already being implemented by most carriers, including Medicare and insurance companies. Thus, many patients may be deprived of the use of this method although they may be studied by means of other procedures, some of which are more costly or more dangerous. An official letter of disagreement with this policy on phonocardiography was drafted by the officers of the Laennec Society, passed by the membership, and sent to the Council on Clinical Cardiology of the American Heart Association with a recommendation that the association petition Blue Shield to reevaluate their decision with the advice of experts. Several noninvasive methods of study of the cardiac function,

Left ventricular relaxation and filling in hypertrophic cardiomyopathy. An echocardiographic study.

Echocardiograms showing left ventricular cavity and mitral valve cusps simultaneously were recorded in 36 patients, apex cardiograms being obtained in 26 of them. These were digitised and continuous plots made of left ventricular dimension, its rate of change, and anterior mitral leaflet velocity, and were compared with those in 20 normal subjects. Peak mitral diastolic closure rate was reduced to 120 +/- 80 mm/s, compared with normal (250 +/- 60 mm/s). Peak rate of increase of dimension was normal (13.4 cm/s), though the pattern of filling was disturbed, with the duration of rapid filling prolonged in 5, and shortened in 15, suggesting restriction. Mitral valve opening, normally synchronous with minimum dimension, was delayed by a mean of 76 ms, and during this period there was an abnormal increase in dimension. Dimension also increased by 50 +/- 25 per cent of the total diastolic excursion before the 'O' point of the apex cardiogram compared with 21 +/- 7 per cent in normals, and the timing of peak rate of increase of dimension was delayed by 50 +/- 20 ms instead of being synchronous with the 'O' point as normal. None of these findings correlated with the reduction in peak mitral diastolic closure rate. Noninvasive methods thus show that relaxation may be abnormal in hypertrophic cardiomyopathy. Delay in mitral valve opening and disturbances in the rate, duration, and co-ordination of wall movement during filling suggest the presence of segmental abnormalities of left ventricular function.

Noninvasive study of early diastole in mitral stenosis.

Cardiac events of early diastole were studied in 50 normal subjects and 46 patients with mitral stenosis (MS) by simultaneous recordings of the mitral valve echogram (MVE), phonocardiogram, and apexcardiogram (ACG). Left ventricular isovolumic relaxation time (IRT), measured between A2 and onset of the MVE opening motion, had almost the same values in normals 54 +/- 7 msec, and MS 51 +/- 16 msec. The interval between A2 and the ACG "O" point was approximately double that of IRT: 99 +/- 11 msec in normal subjects, 109 +/- 20 msec in MS. The normal MVE opening motion had a velocity 293 +/- 76 mm/sec and duration 45 +/- 6 msec, values significantly different (P less than 0.001) from 536 +/- 271 mm/sec, 23 +/- 7.5 msec found in MS patients. In atrial fibrillation the length of the cardiac cycle did not affect A2-O interval or mitral valve opening movement duration; however cycle length was clearly related to isovolumic relaxation time. This resulted in a variation in the interval between completion of the mitral valve opening (opening snap) and O point. This interval was longer after a short diastole and vice versa.

Apex-carotis diagram as related to systolic and diastolic time intervals in myocardial infarction.

Simultaneous recordings of the electrocardiogram, phonocardiogram carotid pulse tracing and left apex cardiogram were obtained in 32 patients with myocardial infarction and 62 normal subjects. This allowed to measure systolic and diastolic time intervals and to construct the apex-carotis diagram (ACD), a new mechanocardiographic method which integrates the carotid pulse tracing and the apexcardiogram in an orthogonal coordinate system. In myocardial infarction, the ACD showed a decrease of the field of ventricular filling, a decrease of the field of ventricular ejection and an increase of the diastolic subsegment. A. The measurement of time intervals showed statistically significant information in those which were directly related to the deformation of the ACD in patients with myocardial infarction.

Distortion of non-invasive cardiac pulse curves. A capillary-damped pick-up and a calibration unit forapex cardiograms and other pulse curves.

A calibration unit and a capillary-damped pick-up, of funnel type, intended for apex cardiograms and other non-invasive cardiac pulse curves are presented. The physical properties of a recording system, suitable for non-invasive cardiac diagnostic techniques, are reviewed. In 4 identical recording units consisting of a funnel with and without capillary damping, connected via air transmission to a transducer, the overamplification in the underdamped systems varied between 2-4 and 4-3, and in the capillary-damped systems between 1-1 and 1-2. The capillary damping gave an approximately linear relation between phase shift and frequency in the high frequency range with a calculated delay of about 4ms. The low frequency time constant in the systems varied between 1-9 and 4-6 s, depending on the amplifier setting used, which for sine curves of frequency 0-5 and 2 Hz means an apparent prematurity for their maxima and minima varying between 53 and 1 ms, this being larger with lower frequency time constants and lower frequency curves.

Effects of Nitroglycerine Ointment On the Apexcardiogram and Systolic Time Intervals

Ten patients with angina pectoris and a previous myocardial infarction were administered nitroglycerine (NTG) ointment, sublingual NTG, and a placebo ointment in a double-blind study. Left ventricular function was monitored noninvasively over 3 hours. Two patients showed no response to any of the NTG preparations and were excluded from the results. Left ventricular function improved in all remaining patients after both the sublingual NTG and the NTG ointment, but not the placebo ointment. This improvement was evidenced by a redution in a wave amplitude and duration of the apexcardiogram (ACG). At the same time the isovolumic relaxation time increased significantly and indicated a reduction in left atrial pressure. Also, a simultaneous improvement in the slope of the systolic wave indicated improved wall motion. The ΔLVET decreased, presumably because of a decrease in venous return due to peripheral pooling. None of these parameters changed significantly during the con trol period or after application of the placebo ointment. The onset of the effect after sublingual NTG was 3-5 minutes with a duration of 15-30 minutes. The NTG ointment had its onset of action at 20-30 minutes, a peak effect at 90 minutes, and a still significant effect at 3 hours. These findings clearly demonstrate the improvement in left ven tricular function that occurs in patients with ischemic heart disease in the absence of chest pain, and suggests that continual usage would be benefi cial even in patients with infrequent angina.

Relation between apex cardiogram and changes in left ventricular pressure and dimension.

The relation between the apex cardiogram and changes in left ventricular pressure measured by micromanometer, and dimension measured by echocardiography, was studied in 12 normal subjects and 64 patients with heart disease. In 12 patients, the apex cardiogram was delayed with respect to simultaneous left ventricular pressure by 17 +/- 18 ms during the upstroke and 28 +/- 16 ms during the downstroke. In the normal subjects, changes in left ventricular dimension during the upstroke and downstroke of the apex cardiogram were small, amounting to 6 +/- 5 and 21 +/- 7 per cent total excursion, respectively. In 10 patients with mitral regurgitation, there was significant inward wall movement during the upstroke and in 10 patients with aortic regurgitation, significant outward movement during the downstroke, both reflecting valvular regurgitation. In 20 patients with ischaemic heart disease and segmental abnormalities on left ventricular angiography, apex cardiogram-echo dimension relations were abnormal in all, because of inward or outward wall movement during the upstroke, increased outward movement before the 'O' point, or abnormal inward movement during the downstroke. These disturbances were displayed by constructing apex cardiogram-echo dimension loops, which appear to be a sensitive means of detecting incoordinate left ventricular contraction, analogous to those between pressure and dimension.

End-diastolic amplitude of mitral valve echogram in mitral stenosis.

By using simultaneous recordings of the mitral valve echogram and apex cardiogram, the mitral echogram amplitude was measured at the onset of left ventricular isovolumic contraction (MAIC). Twenty normal subjects and 68 patients with a reduced diastolic closure rate in the mitral valve echogram were studied. Of these patients, 53 had mitral stenosis, 6 aortic valvar stenosis, and 9 hypertrophic obstructive cardiomyopathy. In the normal subjects the MAIC ranged between 2 and 4 mm, average 2-7 mm, in the patients with aortic valvar stenosis or hypertrophic obstructive cardiomyopathy between 2 and 4 mm, average 2-9 mm, and in the patients with mitral stenosis between 6 and 17 mm, average 11-3 mm. The DE/MAIC ratio, where DE represents the opening amplitude of the mitral valve in early diastole, was between 3-3 and 6-5, average 5-1, in normal subjects; in the patients with aortic stenosis or hypertrophic obstructive cardiomyopathy the DE/MAIC ratio was between 2-7 and 6-5, average 4-2, and in the patients with mitral stenosis between 0-7 and 1-5, average 1-1. An excellent correlation was found between the DE/MAIC ratio and mitral valve area in the patients with mitral stenosis (r = 0-84, P less than 0-01) while the correlation between the diastolic closure rate and valve area was less satisfactory (4 = 0-62, P less than 0-01). These findings suggest that in cases with a reduced diastolic closure rate for reasons other than mitral stenosis, error can be avoided by using the DE/MAIC ratio.

An electrooptical sensor for cardiac sound and vibrations.

An electrooptical sensor for long-term recording of the apex cardiogram in a clinical environment is reported here. The active elements of the sensor include three red light-emitting diodes (LED's) and eight phototransistors. These function by detecting the change in light reflection from the chest wall caused by the mechanical vibrations and motions of the heart. The advantages of this sensor over the existing microphone include wide bandwidth (3.1 Hz-9.0 kHz), small physical size, and ease of attachment to patients in all positions.

Non-invasive assessment of left ventricular function after correction of severe aortic regurgitation.

Twenty patients were studied with simultaneous left ventricular cavity echocardiograms and apex cardiograms during the first two weeks after correction of severe aortic regurgitation. Endocardial echoes and apex cardiograms were digitized, so that left ventricular dimensions, their rates of change, and echo dimension-apex cardiogram relations could be studied. After aortic valve replacement, there was an early reduction in end-diastolic dimension, within 2 days, from 7-0 +/- 0-8 cm to 5-7 +/- 1-0 cm (P less than 0-001), while peak normalized shortening rate (peak Vcf) dropped from 1-9 +/- 0-6 to 1-4 +/- 0-6 S-1 (P less than 0-01), and remained unchanged for the remainder of the study. Immediately after operation, striking abnormalities of isovolumic contraction and, to a lesser extent, of early relaxation, could be seen, which regressed over 4 to 7 days, except in 2 patients who developed a low output state. These changes in left ventricular dimension, Vcf, and isovolumic contraction could not have been described by an single "measure" of left ventricular function.

Studies on the Myocardial Contractile State by the First Derivative of the Apex Cardiogram

Pediatrics InternationalVolume 18, Issue 2 p. 30-30 Studies on the Myocardial Contractile State by the First Derivative of the Apex Cardiogram Yoshiro Takeuchi, Yoshiro Takeuchi Department of Pediatrics, School of Medicine, Tokushima University, Tokushima (Director: Prof. Masuhide Miyao)Search for more papers by this author Yoshiro Takeuchi, Yoshiro Takeuchi Department of Pediatrics, School of Medicine, Tokushima University, Tokushima (Director: Prof. Masuhide Miyao)Search for more papers by this author First published: December 1976 https://doi.org/10.1111/j.1442-200X.1976.tb01489.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume18, Issue2December 1976Pages 30-30 RelatedInformation