Automated method for calculation of a load-independent index of isovolumic pressure decay from left ventricular pressure data.

Diastolic heart failure (DHF) is present in over 50% of hospitalized heart failure patients, and diastolic dysfunction is known to play a critical pathophysiologic role. Measurement of left-ventricular pressure (LVP) via catheterization is the gold standard for diastolic function (DF) evaluation, but current methods fail to fully capitalize on the complete information content of the pressure contour. We have previously demonstrated that a kinematic model of isovolumic pressure decay (IVPD), which accounts for restoring force (stiffness) and resistance (viscoelasticity/relaxation), provides mechanistic insight into IVPD physiology and provides an accurate fit to the recorded contour.

Frequency dependence of acoustic backscatter from 5 to 65 MHz (0.06 < ka < 4.0) of polystyrene beads in agarose.

Attenuation and compensated backscatter from suspensions of random distributions of polystyrene beads in agarose are reported across a broad, continuous range of frequencies including frequencies which are currently of interest in the emerging fields of acoustic backscatter microscopy and intravascular imaging. Data are reported over the range of ka from 0.06 to 4, where k is the magnitude of the ultrasonic wave vector and a is the radius of the beads.

Anisotropy of ultrasonic velocity and elastic properties in normal human myocardium.

Measurements of ultrasonic quasilongitudinal velocity were made in the muscle fiber plane of excised human myocardium. Multiple adjacent planes across the left ventricular wall were interrogated to assess the transmural dependence of velocity. For each measurement plane, data were obtained in 2-deg increments through the full 360 deg relative to the myofibers.