Frequency-Based Analysis of Diastolic Function: Detrimental Phase-shift of the Pressure-Flow Relation Characterizes the ' Delayed Relaxation ' Transmitral Flow Pattern

• Published in: Conference proceedings (IEEE Engineering in Medicine and Biology Society. Conf.) Vol. 2; pp. 3650 - 3653
• Main Authors: Wu, Y., Kovacs, S.J.
• Format: Conference Proceeding Journal Article
• Language: English
• Published: United States IEEE 2004
• Subjects: cardiac catheterization; Cardiology; Catheterization; Circuits; Diastole; echocardiography; Filling; Frequency domain analysis; Heart; Image processing; Impedance; Pattern analysis; Reflection
• ISBN: 9780780384392; 0780384393
• ISSN: 1557-170X
• DOI: 10.1109/IEMBS.2004.1404026

Cardiologists assess the filling (diastolic) function (DF) of the heart by visually determining whether Doppler echocardiographic transmitral E-waves appear to have "normalâ€, "delayed-relaxation†or "constrictive restrictive†patterns. To achieve a causal method of quantitative DF assessment we present a frequency-based approach. In analogy to impedance of electrical circuits, we characterize DF by analysis of the left ventricular (LV) diastolic pressure (P) to transmitral flow (Q) relation during the Doppler E-wave in the frequency domain in terms of Z(ω) = P(ω) / Q(ω), characteristic and input impedance. This allows DF to be expressed in terms of a complex reflection coefficient R* =|R*|e iφ . Twenty subjects had simultaneous pressure-flow data recorded during catheterization, were dichotomized according to deceleration time (DT) and had E-waves subjected to model-based image processing (MBIP) to determine model parameter c, related to E-wave deceleration. Results show that phase angle φ is linearly related to c ; that both φ and c were significantly different (p < 0.05) between the short (n=12) and long (n=8) DT group. We conclude that the 'delayed relaxation' pattern is associated with deviation of the phase angle φ from its optimal (π) value that minimizes reflection and maximizes filling, resulting in modification of the optimal pressure - flow relation in early diastole.