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Diastolic amplitude time index: a new apexcardiographic index of left ventricular diastolic function in human beings
Insights
A new index derived from apexcardiography effectively measures left ventricular diastolic function. This noninvasive method correlates well with invasively measured parameters, offering a valuable tool for assessing relaxation and distensibility.
Area of Science:
- Cardiology
- Biomedical Engineering
- Physiology
Background:
- Assessing left ventricular (LV) diastolic function is crucial for diagnosing and managing heart conditions.
- Traditional methods often involve invasive cardiac catheterization, posing risks and limitations.
- Noninvasive techniques are needed to accurately evaluate LV relaxation and distensibility.
Purpose of the Study:
- To introduce and validate the Diastolic Amplitude Time Index (DATI) derived from apexcardiography.
- To assess the correlation of DATI with invasive hemodynamic measurements of LV function.
- To establish DATI as a reliable noninvasive indicator of diastolic function.
Main Methods:
- Apexcardiography was performed on 260 normal subjects and 37 patients with various cardiac conditions.
- Simultaneous left ventricular pressure and its derivative (dP/dt) were recorded during cardiac catheterization.
- Key apexcardiographic variables were measured to calculate the DATI: total apexcardiographic relaxation time (TART), A2-C interval, and A/D wave ratio.
Main Results:
- Normal subjects exhibited a mean DATI of 0.82 ± 0.26.
- Patients with congestive cardiomyopathy and idiopathic hypertrophic subaortic stenosis showed significantly decreased DATI values (0.23 ± 0.07 and 0.18 ± 0.05, respectively).
- DATI demonstrated strong correlations with specific LV compliance (r = +0.90), minimal dP/dt (r = +0.79), and contractile element lengthening velocity (r = +0.77).
Conclusions:
- The Diastolic Amplitude Time Index (DATI) effectively differentiates normal diastolic function from impaired function in cardiac patients.
- DATI serves as a valuable noninvasive parameter reflecting both LV relaxation ability and diastolic distensibility.
- This index offers a promising new method for comprehensive, noninvasive evaluation of overall left ventricular diastolic function.
Abstract:
Left ventricular apexcardiography was performed in 260 normal subjects and 37 patients undergoing diagnostic cardiac catheterization: 13 without left heart disease (group 1), 18 with congestive cardiomyopathy (group 2) and 6 with idiopathic hypertrophic subaortic stenosis (group 3). In the patients undergoing catheterization the apexcardiogram was recorded simultaneously with left ventricular pressure (tipmanometer) and its first derivative (dP/dt). The following variables were measured in the apex tracing: (1) the time from the onset of the aortic component of the second heart sound (A2) in the phonocardiogram to the nadir of the apexcardiogram, termed total apexcardiographic relaxation time (TART), (2) the time from A2 to the onset of the systolic upstroke (C point) of the apexcardiogram (A2-C), and (3) the ratio of the A wave (A) to the total diastolic amplitude (D) of the apexcardiogram (A/D). The diastolic amplitude time index (DATI) was calculated according to the following formula DATI = (square root A2-C/TART)/(A/D). In the normal subjects the diastolic amplitude time index was 0.82 +/- 0.26 (mean +/- standard deviation). In group 1 this index was within normal limits; in groups 2 and 3 it was decreased (0.23 +/- 0.07 and 0.18 +/- 0.05, respectively). This index showed excellent correlation with specific compliance of the left ventricle (r = +0.90) and close correlations with the maximal rate of decrease of left ventricular pressure (minimal dP/dt) (r = +0.79) as well as the velocity of lengthening of the contractile elements at minimal dP/dt (r = +0.77); less close correlation was obtained with the end-diastolic volume compliance (r = +0.67). These results demonstrate that the diastolic amplitude time index reflects interpatient differences in both relaxation ability and diastolic distensibility of the human left ventricle. Thus, this measurement provides an important new method for noninvasive evaluation of the overall function of the left ventricle during diastole.