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Reduced high harmonic power spectra in patients with old myocardial infarction
M Maeshima1, M Hiroe, K Taniguchi
1Department of medicine, Hokushin General Hospital, Nakanoshi, Japan.
Insights
Old myocardial infarction (OMI) significantly reduces hydraulic power ratios (Rh) and left ventricular contractility indicators in patients. This suggests impaired cardiac function due to asynchronous or depressed left ventricular contractions in OMI patients.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
- Cardiac Mechanics
Background:
- Left ventricular contraction abnormalities, such as asynchronous or depressed function, can impact blood flow dynamics in the aorta.
- Arterial impedance plays a crucial role in modulating the relationship between ventricular ejection and aortic blood flow characteristics.
Purpose of the Study:
- To evaluate the effect of old myocardial infarction (OMI) on the hydraulic power state of blood flow in the aorta.
- To assess the relationship between left ventricular contractility and aortic hemodynamics in healthy individuals and OMI patients.
Main Methods:
- Simultaneous recordings of pulsatile aortic pressure and flow velocity at the aortic root were obtained from normal controls and OMI patients.
- Aortic input impedance and hydraulic power spectra were calculated.
- Ratios of hydraulic power in high harmonics to the fundamental harmonic (Rh) and products of Rh and characteristic impedance (Zc) were determined.
Main Results:
- Patients with OMI, with or without aneurysm, exhibited significantly lower hydraulic power ratios (Rh) compared to normal controls (p < 0.001).
- The product of Rh and characteristic impedance (Zc), an indicator of left ventricular contractility, was significantly reduced in OMI groups (p < 0.005).
- Depressed Rh and Zc products correlated with asynchronous or locally depressed left ventricular contractions.
Conclusions:
- Analysis of aortic blood flow power spectra provides valuable insights into left ventricular contractility.
- OMI is associated with altered hydraulic power dynamics and reduced left ventricular contractility, likely due to impaired ventricular function.
- The study highlights the utility of hemodynamic analysis in assessing cardiac function post-myocardial infarction.
Abstract:
Acceleration of blood flow ejected from the ventricle into the aorta and the hydraulic power state of blood flow in the aorta may be affected by asynchronous or locally depressed contraction of the left ventricle as well as by arterial impedance. In order to evaluate the effect of an infarcted heart on the hydraulic power state of blood flow, the aortic input impedance spectrum and the hydraulic power spectrum were calculated from simultaneous recordings of pulsatile aortic pressure and flow velocity at the aortic root in 6 normal controls (group 1), 6 patients with old myocardial infarction (OMI) without aneurysm (group 2), and 6 patients of OMI with aneurysm (group 3). The ratios (Rh) of power in high harmonics to that of fundamental harmonics, that is, Rh = (E2 + E3 + ...E10)/E1, where E represents hydraulic power and the numbers represent harmonic numbers, were 0.64 +/- 0.17, 0.23 +/- 0.09, and 0.22 +/- 0.10 in groups 1, 2, and respectively (p less than 0.001 between groups 1 and 2; p less than 0.001, between groups 1 and 3). As the acceleration of ejecting flow of blood by the left ventricle is inversely related with arterial impedance, Rh will be also inversely related with arterial impedance. Then, the product of Rh and the characteristic impedance (Zc) would be an indicator of the left ventricular contractility. In fact, the products were 64 +/- 15, 32 +/- 14, and 31 +/- 13 dyne.sec.cm-5 in groups 1, 2, and 3 respectively (p less than 0.005, between groups 1 and 2; p less than 0.005, between groups 1 and 3). These results suggest that asynchronous or locally depressed contractions of the left ventricular wall are closely related to depressed Rh and further to depressed values of the products of Rh and Zc. It is concluded that analysis of the power spectrum of blood flow in the root of the aorta provides information of the left ventricular contractility in connection with arterial impedance.