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Amplitudes, durations, and timings of apically directed left ventricular myocardial velocities: I. Their normal
1Section of Cardiology, Jerry L. Pettis VA Medical Center and Loma Linda University School of Medicine, California 92357, USA.
Insights
Left ventricular long-axis myocardial velocities were investigated in healthy volunteers. Significant regional variations were observed, with the posterior wall showing the highest shortening velocity and the lateral wall exhibiting favorable early diastolic properties.
Area of Science:
- Cardiology
- Echocardiography
- Physiology
Background:
- Left ventricular (LV) major axis shortening is crucial for global function.
- Long-axis dynamics are less characterized than minor-axis dynamics.
- Understanding regional LV long-axis function is essential.
Purpose of the Study:
- To investigate amplitudes, durations, and timings of LV long-axis myocardial velocities.
- To relate these velocities to LV filling and ejection in healthy individuals.
- To characterize regional differences in LV long-axis function.
Main Methods:
- Spectral Doppler tissue imaging used to record myocardial velocities from LV walls in 20 normal individuals.
- Analysis of velocity timings, amplitudes, and durations.
- Comparison of longitudinal and circumferential velocities, and relation to mitral inflow and LV ejection.
Main Results:
- Identified three principal myocardial velocities: apically directed systolic, and early/late atrially directed diastolic.
- Posterior wall exhibited highest shortening velocity; lateral wall showed greatest early diastolic lengthening.
- Circumferential synchrony observed; velocities decreased distally, with the apex being stationary.
- Myocardial velocities preceded and ended before blood flow velocities, suggesting inertial factors.
Conclusions:
- Apically directed myocardial velocities provide valuable insights into regional myocardial function.
- Significant regional variations in myocardial velocities exist in healthy individuals.
- Analysis of regional myocardial velocities may aid in diagnosing early myocardial disease.
Background:
The left ventricular (LV) major axis shortening is an important determinant of its global function. But unlike the LV minor axis dynamics, the long-axis dynamics have not been well characterized. We investigated the amplitudes, durations, and timings of LV long-axis myocardial velocities and related them to LV filling and ejection in normal healthy volunteers.
Methods And Results:
Myocardial velocities from the basal, mid, and distal portions of the four LV walls were recorded from the apical window with spectral Doppler tissue imaging in 20 normal individuals. The timings, amplitudes, and durations were measured and compared both longitudinally and circumferentially. These were also related to mitral inflow and LV ejection. Analysis of the recordings indicated that there were three principal myocardial velocities: apically directed systolic velocity and atrially directed early and late diastolic velocities. The LV posterior wall had the highest shortening velocity and the amount of shortening. The lateral wall had the greatest amplitude of early diastolic lengthening velocity, amount of lengthening, and early to late lengthening velocity and integral ratios, probably indicating most favorable early diastolic properties. There was a striking synchrony in the myocardial velocities circumferentially. The myocardial velocities dropped progressively as the sampling site was moved distally and the LV apex was practically stationary. Although the onsets of the velocity profiles were simultaneous in the meridional orientation, their durations were shorter distally. All myocardial velocities preceded the corresponding blood flow velocities. They also ended before the corresponding blood flow velocities, this being more pronounced in the distal myocardial segments, indicating the presence of inertial factors responsible for the terminal portions of mitral and aortic flows.
Conclusions:
Recording of apically directed myocardial velocities gives valuable insights into the regional myocardial function. These velocities show significant regional variations in healthy normal individuals. It is speculated that analysis of regional myocardial velocities may have a role in the diagnosis of early myocardial disease.