The quest for load‐independent left ventricular chamber properties: Exploring the normalized pressure phase plane

Physiological Reports

Erina Ghosh¹ 

[1] Cardiovascular Biophysics Laboratory, Cardiovascular Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri

关键词: Catheterization;    diastolic function;    hemodynamics;    phase plane analysis;   

DOI  :  10.1002/phy2.43

来源: Wiley

【 摘 要 】

Abstract

The pressure phase plane (PPP), defined by dP(t)/dt versus P(t) coordinates has revealed novel physiologic relationships not readily obtainable from conventional, time domain analysis of left ventricular pressure (LVP). We extend the methodology by introducing the normalized pressure phase plane (nPPP), defined by 0 ≤ P ≤ 1 and −1 ≤ dP/dt ≤ +1. Normalization eliminates load-dependent effects facilitating comparison of conserved features of nPPP loops. Hence, insight into load-invariant systolic and diastolic chamber properties and their coupling to load can be obtained. To demonstrate utility, high-fidelity P(t) data from 14 subjects (4234 beats) was analyzed. P_NR, the nPPP (dimensionless) pressure, where –dP/dt_peak occurs, was 0.61 and had limited variance (7%). The relative load independence of P_NR was corroborated by comparison of PPP and nPPP features of normal sinus rhythm (NSR) and (ejecting and nonejecting) premature ventricular contraction (PVC) beats. PVCs had lower P(t)_max and lower peak negative and positive dP(t)/dt values versus NSR beats. In the nPPP, +dP/dt_peak occurred at higher (dimensionless) P in PVC beats than in regular beats (0.44 in NSR vs. 0.48 in PVC). However, P_NR for PVC versus NSR remained unaltered (P_NR = 0.64; P > 0.05). Possible mechanistic explanation includes a (near) load-independent (constant) ratio of maximum cross-bridge uncoupling rate to instantaneous wall stress. Hence, nPPP analysis reveals LV properties obscured by load and by conventional temporal P(t) and dP(t)/dt analysis. nPPP identifies chamber properties deserving molecular and cellular physiologic explanation.

【 授权许可】

CC BY   
© 2013 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

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