The E-wave delayed relaxation pattern to LV pressure contour relation: model-based prediction with in vivo validation
Wei Zhang1, Leonid Shmuylovich, Sándor J Kovács
1Cardiovascular Biophysics Laboratory, Department of Physics, College of Arts and Sciences, St. Louis, MO, USA.
Ultrasound in Medicine & Biology
|February 23, 2010
Summary
The pressure recovery ratio (PRR) may identify diastolic dysfunction (DD) by analyzing left ventricular (LV) pressure during the E-wave. This new hemodynamic marker differentiates delayed relaxation patterns, even when other measures like time-constant of isovolumic relaxation (tau) are normal.
Area of Science:
- Cardiology
- Biomedical Engineering
- Physiology
Background:
- The transmitral Doppler E-wave delayed relaxation (DR) pattern is a recognized indicator of diastolic dysfunction (DD).
- A prolonged time-constant of isovolumic relaxation (tau) is typically expected with DR patterns.
- Simultaneous observation of DR patterns and normal tau occurs, highlighting a need for alternative diagnostic methods.
Purpose of the Study:
- To derive and validate a hemodynamic parameter, the pressure recovery ratio (PRR), reflecting left ventricular (LV) pressure contour features during E-wave.
- To establish the PRR as a potential hemodynamic equivalent of the DR pattern.
- To assess the PRR's ability to differentiate between normal and abnormal E-wave patterns, particularly in the presence of normal tau.
Main Methods:
- Kinematic and fluid mechanics principles were applied to derive the PRR, defined as [PRR=(P(Diastasis)-P(Min))/(P(Fiducial)-P(Min))].
- Analysis included 354 cardiac cycles from 40 normal sinus rhythm (NSR) subjects and 113 beats from nine atrial fibrillation (AF) subjects.
- Simultaneous transmitral flow and micromanometric LV pressure recordings were utilized, with specific definitions for fiducial pressure in NSR and AF.
Main Results:
- The PRR demonstrated a strong linear relationship with a model-based relaxation parameter associated with the DR pattern (R² = 0.77 in NSR, R² = 0.83 in AF).
- The PRR effectively distinguished subjects with a DR pattern from those with partial DR or normal E-wave patterns (p < 0.05).
- These findings suggest PRR is a robust indicator of diastolic function related to LV relaxation.
Conclusions:
- The pressure recovery ratio (PRR) is a novel hemodynamic parameter causally related to the transmitral Doppler E-wave DR pattern.
- PRR can differentiate subjects with a DR pattern from those with normal E-waves, offering value even when tau measurements are inconclusive.
- This parameter holds potential for improved non-invasive assessment of diastolic dysfunction.
