Apex Cardiogram Research Articles

Extraction of apex beat waveform from acoustic pulse wave by sound sensing system using stochastic resonance

With a sound sensing system using stochastic resonance (4SR), it became possible to obtain an acoustic pulse wave (APW)—a waveform created via a mixture of apex beat and heart sound. We examined 50 subjects who were healthy, with no underlying cardiovascular diseases. We could determine boundary frequency (BF) using APW and phonocardiogram signals. APW data was divided into two bands, one from 0.5 Hz to BF, and a second one from BF to 50 Hz. This permitted the extraction of cardiac apex beat (CAB) and cardiac acoustic sound (CAS), respectively. BF could be expressed by a quadratic function of heart rate, and made it possible to collect CAB and CAS in real time. According to heart rate variability analysis, the fluctuation was 1/f, which indicated an efficient cardiac movement when heart rate was 70 to 80/min. In the frequency band between 0.5 Hz and BF, CAB readings collected from the precordial region resembled apex cardiogram data. The waveforms were classified into five types. Therefore, the new 4SR sensing system can be used as a physical diagnostic tool to obtain biological pulse wave data non-invasively and repeatedly over a long period, and it shows promise for broader applications, including AI analysis.

Stretchable E-Skin Apexcardiogram Sensor.

A new strategy to measure the apex cardiogram with electronic skin technology is presented. An electronic skin apexcardiogram sensor, which can compensate the conventional electrocardiogram for cardiac diagnosis, is demonstrated through a highly sensitive and stretchable strain sensor with gold-nanoparticle composites.

Ultrasensitive, passive and wearable sensors for monitoring human muscle motion and physiological signals

Flexible sensors have attracted more and more attention as a fundamental part of anthropomorphic robot research, medical diagnosis and physical health monitoring. Here, we constructed an ultrasensitive and passive flexible sensor with the advantages of low cost, lightness and wearability, electric safety and reliability. The fundamental mechanism of the sensor is based on triboelectric effect inducing electrostatic charges on the surfaces between two different materials. Just like a plate capacitor, current will be generated while the distance or size of the parallel capacitors changes caused by the small mechanical disturbance upon it and therefore the output current/voltage will be produced. Typically, the passive sensor unambiguously monitors muscle motions including hand motion from stretch–clench–stretch, mouth motion from open-bite-open, blink and respiration. Moreover, this sensor records the details of the consecutive phases in a cardiac cycle of the apex cardiogram, and identify the peaks including percussion wave, tidal wave and diastolic wave of the radial pulse wave. To record subtle human physiological signals including radial pulsilogram and apex cardiogram with excellent signal/noise ratio, stability and reproducibility, the sensor shows great potential in the applications of medical diagnosis and daily health monitoring.

Diastolic flow velocity pattern of the left anterior descending coronary artery in hypertrophied heart, with special reference to the difference between hypertrophic cardiomyopathy and hypertensive left ventricular hypertrophy

This study aimed to clarify the characteristics of diastolic flow velocity pattern of the left anterior descending coronary artery (LAD) in patients with left ventricular hypertrophy (LVH), and the difference in diastolic LAD flow velocity pattern between hypertensive LVH and hypertrophic cardiomyopathy (HCM). The flow velocity pattern was recorded at the mid-portion of the LAD by high-frequency transthoracic Doppler echocardiography in 22 patients with HCM, 10 hypertensive patients with LVH [LVH(+)HT], and 9 hypertensive patients without LVH [LVH(-)HT]. The diastolic flow pattern was analyzed. Standard two-dimensional echocardiogram and apexcardiogram (ACG) were also recorded. The interventricular septal thickness (IVST) and the sum of the IVST and LV posterior wall thickness (PWT) (IVST+PWT) were greater in HCM than in HT (p<0.01) patients. Early diastolic upstroke time (D-UT) of the LAD flow velocity wave was longest in HCM, and was longer in LVH(+)HT than in LVH(-)HT (p<0.01) patients. Direct correlation was found between D-UT and IVST, IVST+PWT in patients with LVH(+)HT and LVH(-)HT (r=0.80, 0.79, respectively; p<0.01), but no correlation was found between these parameters in HCM. Late-diastolic step (LDS) formation of the LAD flow velocity wave was observed in 68% of HCM, 20% of LVH(+)HT, but none of the LVH(-)HT patients. The A wave ratio of ACG was higher in patients with LDS than in those without (p<0.01). The LDS occurred coincidently with the A wave of ACG. The diastolic LAD flow velocity pattern in hypertrophied heart is characterized by slow acceleration and LDS formation, reflecting impaired relaxation and increased stiffness of the LV, respectively. These abnormalities correlate with the degree of hypertrophy in hypertensive heart, but do not correlate with that in HCM.

Nicht-invasive Untersuchung der systolischen linksventrikulären Funktion bei Patienten über 65 Jahre*

Left ventricular functions were assessed in 96 patients (26 men, 70 women aged over 65 years; mean age 74.6 +/- 6.3 years) with various cardiovascular diseases (arterial hypertension, coronary heart disease, cardiomyopathy, various cardiac defects) by comparing various left-ventricular time intervals obtained from resting ECGs, apex cardiograms, carotid-pulse curves and phonocardiograms with left-ventricular ejection fractions by echocardiography. The correlations were strongest with the Weissler index (ratio of pre-ejection and left-ventricular ejection times), PEP/LVET (r = -0.76; P less than 0.001), with PEP itself (r = -0.65; P less than 0.001), as well as with rate-corrected PEP (r = -0.71; P less than 0.001). The plain chest X-ray did not make it possible to assess quantitatively patients with diminished cardiac pump function, despite radiological signs of congestion.

Myocardial contractility in chickens ( Gallus gallus): Analysis of systolic time intervals

The avian cardiovascular system is of special interest because avian hearts are relatively larger than mammalian hearts, and activation of ventricular myocardium in birds has a “flash” pattern. Systolic time intervals and indices of myocardial contractility were examined in anaesthetized open-chest chickens by polycardiography, including synchronous recordings of electrocardiogram, phonocardiogram, and apex cardiogram. The asynchronous contraction time, isometric contraction time, pre-ejection period and ejection time were 26 ± 3 (Mean ± SD), 21 ± 9, 47 ± 12, and 83 ± 23 ms, respectively, for heart rates of 260 ± 57 bpm. The myocardial tension index, isometric contraction index and the pre-ejection period/ejection time ratio were 0.39 ± 0.11, 0.42 ± 0.10, and 0.54 ± 0.14, respectively. A “flash” pattern of ventricular myocardial depolarization causes more rapid excitation and as a consequence shorter asynchronous contraction time of relatively larger chicken hearts compared with rabbit hearts. Inverse relation ( P < 0.05) of the asynchronous contraction time to the heart rate in chickens is probably associated with the specific activation pattern of avian ventricles. Establishment of the values of systolic time intervals will facilitate a better understanding of cardiac function in birds. The obtained results are discussed in comparison with the rabbit. The indices calculated from the systolic time intervals show disadvantageous contractile function of chicken heart compared to rabbit heart.

Simple, noninvasive system for measuring the heart rate of avian embryos and hatchlings by means of a piezoelectric film

Using a flexible piezoelectric film, the authors developed a simple system to determine noninvasively the heart rate of chicken embryos and hatchlings. The film was piezoelectric polyvinylidene fluoride (PVDF), which is sensitive enough to detect cardiogenic ballistic movements of the egg (ballistocardiogram (BCG)) and precordial movements of the hatchling attributable to cardiac contractions (apexcardiogram (ACG)). The BCG could be detected, during the second half of incubation, by placing the egg on the PVDF film on a soft substrate. The detected signal was found to be a measure of movement velocity. The ACG could be measured when the hatchling's chest wall made contact with the PVDF film installed in a box in which the hatchling was confined. The heart rate was counted from the lag time of autocorrelation calculated for a certain time segment (e.g. 2 s) of the BCG and ACG recordings.

Relation of filling pattern to diastolic function in severe left ventricular disease.

M mode and Doppler echocardiograms, apex cardiograms, and phonocardiograms were recorded in 50 patients with severe ventricular disease of varying aetiology to examine how left ventricular filling is disturbed by cavity dilatation. The size of the left ventricular cavity was increased in all with a mean (SD) transverse diameter of 7.2 (0.8) cm at end diastole and 6.3 (0.8) cm at end systole. All were in sinus rhythm and 35 had functional mitral regurgitation. In nine patients, in whom filling period was less than 170 ms, transmitral flow showed only a single peak, representing summation. In the remainder there was a strikingly bimodal distribution of filling pattern. In 12 the ventricle filled dominantly with atrial systole (A fillers). Isovolumic relaxation was long (75 (35) ms) and wall motion incoordinate; mitral regurgitation was present in only one. In most (29) the left ventricle filled predominantly during early diastole (E fillers). Mitral regurgitation, which was present in 26, was much more common than in the A fillers, while the isovolumic relaxation time (10 (24) ms) was much shorter and the normal phase relations between flow velocity and wall motion were lost. In 24 E fillers no atrial flow was detected. In four there was no evidence of any mechanical activity, suggesting "atrial failure". In 20, either the apex cardiogram or the mitral echogram showed an A wave, implying that atrial contraction had occurred but had failed to cause transmitral flow, showing that ventricular filling was fundamentally disturbed in late diastole. A series of discrete abnormalities of filling, beyond those shown by Doppler alone, could thus be detected in this apparently homogeneous patient group by a combination of non-invasive methods. The presence and nature of these abnormalities may shed light on underlying physiological disturbances.

Influence of preload on apex cardiogram and mitral Doppler in the assessment of diastolic left ventricular (LV) function in dilated cardiomyopathy

Influence of preload on apex cardiogram and mitral Doppler in the assessment of diastolic left ventricular (LV) function in dilated cardiomyopathy

Effect of Abana on ventricular function in ischemic heart disease.

Mechanocardiography has been in use to evaluate ventricular function and the cardiac effect of drugs. Twenty-five patients with ischemic heart disease (IHD) and 25 patients with IHD and mild hypertension (HTN) were enrolled in a double-blind, placebo controlled study of Abana. Half the patients in each group received Abana--a formulation based on Ayurvedic principles--and the other half received a placebo in a randomized manner. The effect of Abana was evaluated by means of LV apex cardiogram (ACG), phonocardiogram and carotid pulse tracing and ECG (mechanocardiography) before and at the end of 8 weeks of treatment. As compared to placebo, Abana significantly reduced the frequency and severity of anginal episodes, as judged by clinical improvement and nitrate consumption. Significant improvement in ventricular function was observed as reflected by a decrease in ACG A amplitude and A wave duration, along with a significant increase in LV ejection fraction and VCF. The decrease in double and triple products reflected decreased MVO2. A significant fall in diastolic blood pressure was noted in patients with mild hypertension. Abana seems to reduce preload and afterload and improve diastolic function and pump function, which may be responsible for the beneficial effects of Abana in ischemic heart disease.

Left ventricular systolic and diastolic time intervals in familial amyloid polyneuropathy.

To determine left ventricular (LV) systolic and diastolic properties in patients with familial amyloid polyneuropathy (FAP), we analyzed simultaneous recordings of the electrocardiogram, phonocardiogram, carotid arterial pulse, and apex cardiogram in 14 patients and 21 normal subjects. LV systolic and diastolic time intervals were measured. Correlations between the intervals and neurologic disabilities, duration of illness, and age were examined. We found that in patients with FAP, 1) LV relaxation was impaired, especially in early diastole, whereas systolic function was generally preserved, 2) abnormal LV relaxation could be seen before the development of both clinically identifiable heart disease and the abnormalities in systolic function, 3) indexes of LV systolic function and relaxation decreased in parallel with the progress of the disease, duration of illness, and age, and 4) electromechanical delay was markedly increased.

Dyspnoea of cardiac origin in 67 year old men: (1). Relation to systolic left ventricular function and wall stress. The study of men born in 1913.

The relation between dyspnoea of presumed cardiac origin and disturbed left ventricular systolic function was studied in a group of 67 year old men from the general population of Gothenburg, Sweden. Forty two men with cardiac dyspnoea were identified and 45 controls were randomly selected from a screened cohort of 644 men. Dyspnoea was graded according to the World Health Organisation standard, and M mode echocardiography, carotid pulse tracing, an apex cardiogram, and phonocardiography were used to evaluate the grade of dyspnoea and its relation to systolic time intervals, left ventricular ejection indices, and wall stress. The dyspnoea grade was significantly related to the left ventricular end systolic dimension, to septal and posterior wall fractional thickening, and to ejection indices such as fractional shortening. The dyspnoea grade was also significantly correlated with the ratio of end systolic wall stress to end systolic volume index. There was a close relation between end systolic wall stress and mean velocity of circumferential fibre shortening adjusted for heart rate. This relation did not clearly show reduced inotropy in the dyspnoeic men. There was no relation between the degree of dyspnoea and the systolic time intervals. Among the systolic variables obtained by echocardiography the only abnormal finding in mild to moderate dyspnoea was an increased end systolic dimension. The grade of cardiac dyspnoea seemed to be related to the degree of systolic left ventricular dysfunction, which was considerably impaired in severe dyspnoea. In population studies left ventricular end systolic dimension and fractional shortening may provide sufficient information on systolic function without the need to assess variables that are independent of load.

Quantitative assessment of myocardial mechanical activity

The use of computer technology makes it possible to increase diagnostic capabilities of traditionally used methods of cardiovascular system investigation and significantly reduce the examination time. Methods of automatic processing of ECG, sphygmograms and rheograms are most developed. The aim of this work is to use computer processing of apexcardiograms (ACG) to develop a set of quantitative indices characterizing mechanical activity of myocardium.

Phonoechocardiography and intracardiac phonocardiography in hypertrophic cardiomyopathy.

The salient phonoechocardiographic features of patients having hypertrophic cardiomyopathy (HCM) with or without left ventricular outflow tract (LVOT) gradients are reviewed. Intracardiac sound and pressure recordings from high fidelity catheter-tipped micromanometers have documented that the precordial murmur is the summation of both the systolic ejection murmur (SEM) arising from the LVOT, as well as the mitral regurgitant murmur recorded from the left atrium. The intensity of the precordial murmur varies directly with the LVOT gradient, which in turn is determined primarily by the contractility and loading conditions of the left ventricle. Reversed splitting of the second heart sound (S2) with paradoxical respiratory movement is a common finding in HCM, and when present, almost always denotes a significant LVOT gradient. It is due to marked lengthening of the left ventricular ejection time secondary to prolongation of the contraction and relaxation phases of left ventricular systole. The presence of a fourth heart sound (S4) is the rule in HCM when normal sinus rhythm is present, and is a reflection of a forceful left atrial contraction into a hypertrophied noncompliant left ventricle. A third heart sound (S3) is also common in HCM, and often the initial vibrations occur before the 0 point of the apexcardiogram (ACG) and continue giving the auscultatory impression of a diastolic rumble. When associated with a loud S1, which is frequently present, the clinical presentation may mimic mitral stenosis. This is particularly true when the patient has chronic atrial fibrillation. Careful attention to evidence of marked left ventricular hypertrophy as well as the typical echocardiographic findings of HCM preclude this diagnosis. In conclusion, phonoechocardiography is a simple non-invasive technique which almost always makes the definitive diagnosis of HCM.

Mitral valve closure and left ventricular filling time in patients with VDD pacemakers. Assessment of the onset of left ventricular systole and the end of diastole.

The effect of mitral valve closure on left ventricular filling time and its relation to the onset of systole were assessed from mitral valve echocardiograms and simultaneous apex cardiograms in 21 normal subjects, 11 patients with left bundle branch block, and 19 patients with VDD pacemakers programmed for atrioventricular intervals of 50, 150, and 250 ms. The interval between the electrocardiograph Q wave and the apex cardiogram upstroke was similar in normal subjects and patients with left bundle branch block, but was significantly longer in patients with VDD pacemakers at all atrioventricular intervals. Similarly there was little difference in the time interval between the Q wave and mitral valve closure in normal individuals and patients with left bundle branch block but this was considerably delayed in VDD pacemaker patients with the atrioventricular interval set at 50 ms. With increasing atrioventricular intervals the mitral valve closed significantly earlier, whereas the onset of left ventricular systole and the timing of mitral valve opening remained unchanged. Thus as a result of earlier mitral valve closure left ventricular filling time decreased progressively as the atrioventricular interval was increased. Since the onset of left ventricular systole, with respect to left ventricular stimulation, is considerably delayed in VDD pacemaker patients a short atrioventricular interval is required in these patients to maintain the normal time relations between atrial and ventricular contraction and hence maximise left ventricular filling.

Mechanocardiography in evaluation of left ventricular function. Relevance of combined study of apex cardiogram and systolic time intervals in diagnosis of cardiomyopathies.

The study of left ventricular performance by means of systolic time intervals, especially represented by the PEP/LVET ratio and indices drawn from the first derivative of the apex cardiogram, makes possible a good approach to the functional anomalies of patients suffering from hypokinetic cardiomyopathies or hyperkinetic conditions of obstructive or unobstructive hypertrophic cardiomyopathies and of patients with hyperthyroid conditions. In hypokinetic states, the sensitivity and the specificity of the PEP/LVET ratio proved to be good, as was the case for indices taken from the first derivative of the apex cardiogram. However, the sensitivity and the specificity of the cardiogram were much better in the detection and evaluation of hyperkinetic conditions, hypertrophic cardiopathies or hyperthyroiditis. By providing the elements required for analysis of isometric contraction through indices drawn from the first derivative of the apex cardiogram and from the ejection phase, through the PEP/LVET ratio, and by adding exploitation of the diastolic phase, in particular through the A/H ratio exploring diastolic compliance, mechanocardiograms allow an all-round, quasi-physiopathological approach to disorders of left ventricular function during cardiomyopathies.

Cardiopulmonary Function following Post-cardiac Surgical Mediastinitis

Eleven survivors of bacterial mediastinitis, which followed cardiac surgery through a median sternotomy approach, underwent noninvasive cardiopulmonary evaluation to determine whether clinically apparent mediastinal fibrosis had developed. Compared to preoperative values, forced vital capacity was reduced by 9.75 percent of predicted; the greatest reduction occurred in those patients with Gram-negative mediastinitis. In one patient, an abnormal jugular venous wave form and apex cardiogram were consistent with constrictive cardiac physiology, but this was not associated with an abnormal echocardiogram or impaired functional status. In this small series, no serious abnormalities in cardiopulmonary function were detected which could be attributed to prior mediastinal infection.

Assessment of left ventricular filling pressure in myocardial infarction using the first derivative of the apexcardiogram.

We recorded the apexcardiogram (ACG) and its first derivative (dA/dt) in 24 patients with acute or recent myocardial infarction. From dA/dt, an index I = X 10 dRFW/dS was defined (dRFW and dS = peaks of dA/dt corresponding to the rapid filling wave and to the systolic upstroke of the ACG). A significant correlation was found between I and pulmonary capillary wedge pressure (PCW, mmHg). PCW = 2.3 X I + 6.5 (r = 0.80, p less than 0.001). Normal PCW was found in 15 patients who all had an I less than 2.8. Elevated PCW was found in 9 patients who all had an I greater than 2.8. Thus the ability of I to predict elevated PCW was 100% (95% confidence limit greater than 66.4%). The ability to predict normal PCW was 100% (95% confidence limit greater than 76.2%). No significant correlation was found between I and cardiac index (r = 0.29, p greater than 0.1).

Combined echo-apexcardiographic assessment of left ventricular function in cardiomyopathy.

Eleven patients with hypertrophic obstructive cardiomyopathy (HOCM) and 9 patients with congestive cardiomyopathy (COCM) were studied to determine the usefulness of mean normalized velocity of circumferential fiber shortening (VCFS), mean normalized velocity of circumferential fiber lengthening (VCFL) and left ventricular diastolic distensibility obtained noninvasively from combined recordings of simultaneously calibrated left apex cardiogram and M-mode echogram. Twenty-two normal subjects were similarly investigated and served as a control. In HOCM VCFS were increased (1.83 +/- 0.2 s-1 versus 1.22 +/- 0.1 s-1 for controls, p less than 0.02) and both VCFL and diastolic distensibility were decreased (VCFL: 0.50 +/- 0.1 s-1 versus 1.32 s-1 in controls, p less than 0.001; diastolic distensibility: 0.03 +/- 0.004 cm/mmHg-1 compared with 0.18 +/- 0.003 cm/mmHg-1 for controls, p less than 0.001). In COCM all investigated indexes were diminished (VCFS: 0.49 +/- 0.1 s-1 versus 1.22 +/- 0.1 s-1 for controls, p less than 0.001; VCFL: 0.70 +/- 0.1 s-1 versus 1.32 +/- 0.1 s-1 in controls, p less than 0.01 and diastolic distensibility: 0.05 +/- 0.003 cm/mmHg-1 compared with 0.18 +/- 0.003 cm/mmHg-1 for controls, p less than 0.01). The echo-apexcardiographic indexes were significantly correlated with many analogous invasive indexes. It is concluded that the value of both M-mode echocardiography and calibrated apex cardiography is enchanced by a combination of the two methods which opens the possibility of a fresh approach to the noninvasive study of cardiac performance in cardiomyopathy.

Beta-blockers in dilated cardiomyopathies: they work.

Prognosis in congestive cardiomyopathy (COCM) with marked dilatation and heart failure is poor. A low rate of spontaneous recovery was observed. A high level of circulating catecholamines is often found, which may explain the common finding of resting tachycardia. An early series of COCM patients with tachycardia responded surprisingly well when chronic beta-blockade was added to the conventional treatment of failure. Later, even patients without tachycardia were included with a period of placebo preceding beta-blocker treatment in order to exclude patients with spontaneous recovery. Acute beta-blockade was surprisingly well tolerated, possibly because the reduction in contractility was compensated for by an increase in myocardial compliance. After long-term beta-blockade, improvement was observed after 6 months and further improvement was seen after 24 months. In patients improving functionally, there was reduction in heart size and left ventricular end diastolic diameter and increase in working performance. For the whole group, there was a decrease in rapid filling wave in apex cardiogram, reduction in third heart sound and increase in ejection fraction. Changes in the reverse way were seen in these three variables after beta-blocker withdrawal and relapse into heart failure occurred in 6/15 patients. Changes in diastolic function may be an early important effect of beta-blockade in COCM. Increase in survival was seen when beta-blocker-treated patients with COCM were compared to well matched COCM controls. It is suggested that increased sensitivity to sympathetic stimulation contributes to the pathogenesis in some patients with COCM and that improvement in myocardial function explains prolonged survival.