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Computer processing of transaortic valve blood pressures in the horse using the first derivative of the left
Insights
This study introduces a new method for analyzing equine transaortic valve pressures using left ventricular pressure derivatives. The LVEDP 150 method accurately determines systolic complex timing and ejection duration, improving cardiovascular analysis in horses.
Area of Science:
- Cardiovascular Physiology
- Equine Medicine
- Biomedical Engineering
Background:
- Accurate processing of transaortic valve pressures is crucial for understanding equine cardiovascular function.
- Existing methods may lack precision in defining key systolic events.
Purpose of the Study:
- To develop and validate a novel method for processing transaortic valve pressures in horses.
- To precisely define the beginning and end of systolic complexes using left ventricular pressure derivatives.
Main Methods:
- Utilized the first derivative of left ventricular pressure (LVdP/dt) to identify systolic complex boundaries.
- Evaluated three definitions of left ventricular end-diastolic pressure (LVEDP) based on diastolic pressure rise rates (100, 150, 200 mmHg/sec).
- Defined the optimal LVEDP (LVEDP 150) as the point preceding a sustained LVdP/dt ≥ 150 mmHg/sec over 44 msec; estimated ejection end at -LVdP/dtmax.
Main Results:
- The LVEDP 150 definition effectively determined systolic complex timing and isovolumic contraction time.
- Left ventricular ejection time (LVET) calculated to -LVdP/dtmax showed excellent agreement with measurements to the aortic incisura (r = 0.991).
Conclusions:
- The proposed method, particularly LVEDP 150, offers a reliable approach for processing equine transaortic valve pressures.
- Accurate determination of systolic intervals like LVET is achievable using LVdP/dtmax.
- Visual inspection of pressure waveforms is recommended prior to automated analysis to ensure accuracy.
Abstract:
A method is described of processing transaortic valve pressures in the horse using the first derivative of the left ventricular pressure to define the beginning and end of each systolic complex. To determine the beginning of each systole three definitions of left ventricular end diastolic pressure (LVEDP), based on a 100, 150 or 200 mmHg/sec rate of left ventricular diastolic pressure rise, were evaluated. These definitions were also evaluated for their ability to determine isovolumic contraction time (ICT) and pulse interval. The best of these, LVEDP 150, was defined as the last point in diastole before a rate of rise of left ventricular pressure (LVdP/dt) equal to or exceeding 150 mmHg/sec sustained over 44 msecs. The end of left ventricular ejection was estimated from the left ventricular pressure trace as the point at which--LVdP/dtmax occurred. There was good agreement between the values of left ventricular ejection time (LVET) measured to the incisura of the aortic pressure trace and LVET calculated to the time of--LVdP/dtmax (r = 0.991). The importance of visually examining the waveforms before committing them to automatic processing is emphasised.