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Coronary artery pressure development and wave transmission characteristics in the horse
Insights
Pressure wave patterns in horse coronary arteries change distally, with oscillations masking initial signals. These changes are linked to wave reflections and heart motion, affecting pressure and wave speed.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
- Hemodynamics
Background:
- Coronary artery pressure waveforms are crucial for understanding myocardial perfusion.
- Wave transmission characteristics in coronary arteries are not fully elucidated.
- Previous studies have not comprehensively analyzed distal pressure waveform development.
Purpose of the Study:
- To investigate the development of pressure waveforms in the left extramural coronary arteries of horses.
- To characterize wave transmission and reflection phenomena in these vessels.
- To determine the relationship between pressure, flow, and wave speed in the coronary circulation.
Main Methods:
- Measurements of pressure waveforms, centerline velocity, and phasic flow in equine left coronary arteries.
- Analysis of pressure waveform changes from the ostium to distal locations.
- Estimation of wave speeds and their dependence on pressure and location.
Main Results:
- Coronary pressure waveforms initially resemble aortic root waveforms but develop dominant low-frequency diastolic oscillations distally.
- These oscillations mask the incisura and are observed in velocity and flow signals, suggesting wave reflection.
- Peak systolic pressure remained stable, while end-diastolic pressure decreased distally, increasing pulse pressure and decreasing mean pressure.
Conclusions:
- Distal pressure waveform changes in coronary arteries are influenced by wave reflections and potentially cardiac motion.
- Wave speeds in coronary arteries vary (4-11 m/s) and depend on intralumenal pressure and location.
- Understanding these dynamic pressure transmission characteristics is vital for coronary circulation research.
Abstract:
Measurements of the pressure waveform development and the wave transmission characteristics in the left extramural coronary arteries of the horse have been carried out. Near the ostium the left coronary pressure waveforms are seen to be virtually identical to the corresponding aortic root waveforms; however, the present of low frequency, relatively large amplitude pressure oscillations (on the order of 5 to 10 Hz) gradually become the dominant diastolic feature as one proceeds distally from the left ostium, and these eventually completely mask the incisura. In a limited number of experiments, these oscillations have been simultaneously observed on both centerline velocity and phasic flow signals. These are felt to be primarily due to wave reflection phenomena, but may represent a combined effect of wave reflections and the natural oscillatory motion of the heart mass. Peak systolic pressures were found to remain relatively unchanged as one proceeds distally; however, the end-diastolic pressures were found to decrease steadily, thus giving rise to an increasing pulse pressure and a gradually decreasing mean pressure. Wave speeds in the coronary arteries were found to range between 4 and 11 m.s-1, and the data obtained indicate the wave speed to be highly dependent on both local intralumenal pressure and spatial location.