Influence of changes in myocardial contractility on the height and slope of the calibrated apex cardiogram

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).

Identification of patients with coronary artery disease by assessing diastolic abnormalities during isometric exercise

BACKGROUND

Previous clinical studies using invasive and noninvasive methods have shown handgrip-induced diastolic abnormalities in patients with coronary artery disease (CAD).

HYPOTHESIS

The study was undertaken to determine the utility of Doppler echo- and pressocardiography during hand-grip in discriminating patients with coronary artery disease (CAD) and in those with normal coronary arteries.

METHODS

Both methods were obtained in 96 patients with suspected CAD within 24 h before coronary angiography. An abnormal handgrip-Doppler was defined by an early (E) to late (A) transmitral flow velocities ratio (E/A) < 1 during handgrip and a positive handgrip pressocardiographic test (HAT) by an abnormal increase in the A wave/total excursion or prolongation of the absolute or relative (heart-rate corrected) total relaxation time during isometric exercise.

RESULTS

Of the 96 patients studied, 23 had normal coronary arteries and 73 showed CAD. In patients with normal coronary arteries, handgrip-Doppler showed an abnormal average E/A at rest and during handgrip, whereas all variables of HAT were within normal limits. In patients with CAD, handgrip-Doppler showed only a moderate handgrip-induced increase in average A (+ 19%, p < 0.001), whereas HAT showed a significant (p < 0.001) increase in mean A wave/total excursion (+ 60%) and decrease in the relative total relaxation time (- 17%). Furthermore, handgrip-Doppler and HAT were abnormal in 15 of 23 (65%, specificity 35%) and the HAT in 5 of 23 (22%, specificity 78%) patients with normal coronary arteries, as well as in 57 of 73 (sensitivity 78%) and 69 of 73 (95%) patients with CAD.

CONCLUSIONS

Our study demonstrates that these noninvasive stress tests can become a useful new diagnostic modality for detecting patients with unknown or suspected CAD.

Noninvasive detection of coronary artery disease by assessing diastolic abnormalities during low isometric exercise

The handgrip-apexcardiographic test (HAT) is a simple low-level (40% of maximal voluntary handgrip during 2 min) stress test which can detect left ventricular (LV) diastolic abnormalities. To determine whether it contributes to the diagnosis of coronary artery disease (CAD), HAT was obtained in 68 patients--47 with and 21 without angina pectoris--who prospectively underwent coronary arteriography. According to the highest or lowest individual values of diastolic apexcardiographic indices in 255 healthy volunteers, a pathologic or positive HAT was defined by the presence of at least one of the following new criteria: (1) A wave relative to total height of apexcardiogram during and/or after handgrip > 21%, (2) total apexcardiographic relaxation time (TART) during handgrip > TART at rest > 143 ms and/or TART corrected for the duration of diastole (TARTI) during handgrip < 0.14, or (3) diastolic amplitude time index (DATI), given by dividing TARTI and A wave relative to total diastolic amplitude of apex tracing during handgrip < 0.27. HAT was positive in 20 of 21 patients with single-vessel disease (sensitivity 95%), 21 of 24 patients with double-vessel disease (sensitivity 88%), and in 22 of 23 patients with triple-vessel disease (sensitivity 96%). Furthermore, HAT was positive in 20 of 21 (95%) patients without symptoms. Thus, the overall sensitivity of HAT for detecting CAD was 93%. This study is the first to demonstrate the high sensitivity of HAT in identifying patients with CAD with or without symptoms by assessing diastolic apexcardiographic abnormalities during low-level isometric stress. Thus, HAT potentially could become an additional simple diagnostic tool for noninvasive detection of patients with CAD.

The mechanism of disappearance of the physiologic third heart sound with age

To study the mechanism of disappearance of the physiologic third heart sound (S3) with advancing age, combined phonoechocardiographic and phonomechanocardiographic recordings from 165 normal subjects between 6 and 62 years old were quantitatively analyzed. Nearly all individuals under 40 years old had a recordable S3. Although recordable in 38.6% of the 44 subjects over 40 years old, the physiologic S3 found in adults was less intense and occurred later in diastole when compared with that in children and adolescents. Marked changes in left ventricular filling hemodynamics were observed with aging, including an increase in left ventricular wall thickness and mass, a prolongation of the left ventricular isovolumetric relaxation period, a decrease in left ventricular early diastolic filling and wall thinning rates, and a reduction in the height and steepness of the rapid filling wave measured on the calibrated left apexcardiogram (linear correlation with age significant at p less than .001 for all parameters). Although less pronounced, these changes were very similar to the diastolic abnormalities found in patients with pressure overload left ventricular hypertrophy. Therefore, the higher pressure load imposed on the left ventricular wall due to the well-known gradual increase in blood pressure that occurs during normal growth and adulthood appears to be the most likely explanation for the observed changes in diastolic filling. It is concluded that the later occurrence, the diminishing amplitude, and the eventual complete disappearance of the physiologic S3 with age results from a decrease in early diastolic left ventricular filling and subsequent deceleration of inflow caused by the development of relative left ventricular hypertrophy in adulthood as compared with childhood.

The apical impulse in coronary heart disease

Forty patients (36 with coronary artery disease), who had angiographic assessment of left ventricular function were studied using apexcardiography with a new method of standardization, the objective being to define the parameters of the apical impulse which reflect changes in the left ventricular function and correlate them with clinical assessment of the apical impulse. Based on measurements from patients with normal left ventricular function, abnormalities in apexcardiograms were identified. An increase in amplitude of percent A wave alone (greater than 13.3%) (palpable as an atrial kick in approximately half of these patients) was not associated with significant left ventricular dysfunction. An isolated abnormality in isovolumic slopes, although associated with mild left ventricular dysfunction, could not be detected clinically. Moderate to severe left ventricular dysfunction was always associated with abnormal ejection phase slopes and all had sustained apical impulses. The additional presence of a palpable atrial kick or an increased percent A wave on the apexcardiogram was more indicative of moderate rather than severe dysfunction. Thus this study clearly establishes that left ventricular function does in fact affect the nature of the apical impulse in patients with coronary artery disease and these can be easily defined.

Relationship between apexcardiogram, left ventricular pressure and wall stress

Simultaneous measurement of left ventricular dimension and wall thickness by M-mode echocardiography, of left ventricular pressure by a tip-transducer manometer, and of the calibrated apexcardiogram with a pixie beam transducer, were made during acute experiments on anaesthetized dogs. Instantaneous values for chamber dimensions and wall thickness were obtained throughout the heart cycle by digitizing the echo-mechanocardiograms. From these data myocardial stresses, derived from a thick shell theory (meridional and circumferential components) and from Laplace's law, were computed. Laplace stress if shown to be an adequate expression for average wall stress. Its value was correlated with the calibrated apexcardiogram. The present investigation suggests that to a certain extent, the apexcardiogram not only reflects pressure changes but also dimensional changes of the left ventricle.

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.

Mechanocardiographic assessment of left ventricular function in coronary artery disease

Images

Use of apexcardiography to evaluate left ventricular diastolic compliance in human beings

The relation between various relative amplitude measurements of the left apexcardiogram and internally derived indexes of diastolic compliance of the left ventricle was studied in 29 patients. Simultaneous high fidelity recordings of the left apex tracing and left ventricular pressure were obtained in 11 patients without left ventricular disease (group I) and 18 patients with congestive cardiomyopathy (group II). In 204 normal subjects the ratio of the A wave amplitude to the total diastolic deflection (A/D ratio) of the left apexcardiogram was 31.4 +/- 11.4 (mean +/- standard deviation) percent, the ratio of the A wave amplitude to the total height (A/H ratio) 8.9 +/- 4.3 percent and the D/H ratio 30.4 +/- 14.7 percent. The A/D and A/H ratios were significantly (P less than 0.001 and P less than 0.005) increased in group II (69.2 +/- 12.2 percent and 16.8 +/- 8.2 percent, respectively); they were within normal limits in group I. In contrast, the D/H ratio was within normal limits in both groups of patients. The A/D ratio correlated significantly better with specific compliance (deltaV/deltaP.V) (r = -0.87) than did the A/H ratio (r = -0.53), whereas similar correlations were obtained with end-diastolic volume compliance (dV/dPV) (r = -0.61 and r = - 0.64, respectively). In contrast, the D/H ratio correlated significantly only with end-diastolic distensibility index (dV/dP) (r = -0.52). It is concluded that A wave amplitude/total diastolic deflection (A/D) ratio and, to a lesser degree, the A wave amplitude/total height (A/H) ratio of the left apexcardiogram correspond best to diastolic compliance and are useful noninvasive measurements of this property of the left ventricle.

Ejection phase indexes by invasive and noninvasive methods: an apexcardiographic, echocardiographic and ventriculographic correlative study

A new noninvasive method of measuring ejection fraction and the mean velocity of circumferential fiber shortening from the apexcardiogram and carotid pulse tracing is described and compared with the echocardiographic and angiographic measurement of these values in 35 patients with coronary artery disease. The correlations of the apexcardiographic derived values with the angiographic measurements were excellent (r = 0.89 and 0.96, respectively, P less than 0.001) even though asynergy was present in 14 of the 35 patients. Only 6 percent of the derived ejection fractions and none of the mean velocity measurements were discordant with the angiographic data. In contrast, correlations of the echocardiographic measurements of the ejection phase indexes with the same angiographic data were poorer (r = 0.75 and 0.66, respectively, for ejection fraction and mean velocity, P less than 0.01). Twenty-eight percent of echocardiographic ejection fraction measurements and 20 percent of the echocardiographic mean velocity measurements were discordant with the angiographic data. It is concluded that the apexcardiogram is a dependable bedside test for estimating left ventricular function and is superior to the echocardiogram for measuring ejection phase indexes.

Clinical assessment of calibrated jugular pulse recording

Calibrated jugular pulse tracings and cardiac catheterisation were performed on 50 consecutive patients with organic heart disease. Twenty normal adults had calibrated jugular pulse tracings and served as controls. The height of the jugular 'A' and 'V' waves was quantified as a percentage of a known displacement, rendering measurements independent of the amplification used in recording technique. A close correlation existed between the size of the calibrated jugular 'A' and 'V' waves and the actual magnitude of the right intra-atrial pressure changes (A wave, r = 0.72; V wave, r = 0.80). Patients who were free of pulmonary hypertension or tricuspid disease had calibrated 'A' and 'V' waves similar in height to the control population. An enlarged 'A' wave was usually associated with conditions restricting flow into the right ventricle. An enlarged 'V' wave generally indicated tricuspid regurgitation. These changes are often subtle and are not apparent in conventional venous tracings or at the bedside. We conclude that the calibrated jugular pulse tracings can accurately separate normal from abnormal venous waves and expand the diagnostic potential of the jugular pulse.

Normalized first derivative ofthe left apex cardiogram in assessment of left ventricular function

The relation between the left displacement apex cardiogram and the left ventricular pressure during isovolumic contraction was studied in 30 patients with cardiac disease. Using the instantaneous relation between the first time derivative and the magnitude of both the left apex cardiogram and the left ventricular pressure, normalized derivatives were obtained. These noramized velocities were correlated with each other and with several indexes of left ventricular function. The normalized derivatives of the left apex cardiogram (dD/dt/D) and the left ventricular pressure (dP/dt/P) were similar in magnitude, standard deviation and variation coefficient. No such similarity was present when the first time derivatives of each tracing (dD/dt and dP/dt) were compared. A highly significant relation was found between normalized displacement velocity and normalized pressure velocity using both total (r = 0.76, P less than 0.001) and developed (r = 0.75, P less than 0.001) displacement and pressure. Significant correlations with several other indexes of left ventricular function (end-diastolic pressure, peak dP/dt, maximal velocity of the contractile elements at zero load[Vmax]) were also observed. It is concluded that the index dD/dt/D of the left apex cardiogram is an important noninvasive tool for assessing left ventricular function in man.

First derivative of the apex cardiogram and systolic time intervals in evaluation of myocardial contractility in man

The sensitivity of various systolic ... myocardial contractility.

On the clinical value of calibrated displacement apexcardiography

A new type of displacement transducer for recording the calibrated left apexcardiogram (QLAC) has been evaluated in 69 normal subjects and 99 cardiac patients. Total displacement of QLAC (TD), its peak first derviative (peak dD/dt (t-peak dD/dt). A strong corretation exists between peak dD/dt and TD in normal subjects (r=0.95) and the deviation from the normal relationship allows a separation between normal and abnormal ventricular function. In normal subjects (dD/dt/Dt) max averaged 34.2 plus or minus 5.7 sec-1; it was signigicantly lower in patients with congestive cardiomyopathy (26.5 plus or minus 6.3 sec-1 p greater than 0.005). This index correlates with left ventricular end-diastolic pressure (LVEDP) (R = - 0.69) and with ejection fraction (R - 0.66) and behaves as expected during positive and NEGATIVE INOTROPIC interventions. The index (dD/dt/Dt) max is superior to TD and peak dD/dt, being less variable independent of thorax circumference and better correlated with hemodynamic parameters. The index t-peak dD/dt was 53.9 plus or minus 9.5 msec in normal subjects and 81.6 plus or minus 18.9 msec in patients with congestive cardiomyopathy (p greater than 0.001). This time-interval correlates weakly with LVEDP (R = 0.04) and with ejection fraction (R = - 0.66). It is concluded that the normalized first derivative of QLAC provides useful information on left ventricular function.