Abstract
Left ventricular (LV) pressure–volume (P–V) loop analysis is the gold standard for chamber function assessment. To advance beyond traditional P–V and pressure phase plane (dP/dt‐P) analysis in the quest for novel load‐independent chamber properties, we introduce the normalized P–V loop. High‐fidelity LV pressure and volume data (161 P‐V loops) from 13 normal control subjects were analyzed. Normalized LV pressure (P N) was defined by 0 ≤ P(t) ≤ 1. Normalized LV volume (VN) was defined as V N=V(t)/V diastasis, since the LV volume at diastasis (V diastasis) is the in‐vivo equilibrium volume relative to which the LV volume oscillates. Plotting PN versus VN for each cardiac cycle generates normalized P‐V loops. LV volume at the peak LV ejection rate and at the peak LV filling rate (peak −dV/dt and peak +dV/dt, respectively) were determined for conventional and normalized loops. V N at peak +dV/dt was inscribed at 64 ± 5% of normalized equilibrium (diastatic) volume with an inter‐subject variation of 8%, and had a reduced intra‐subject (beat‐to‐beat) variation compared to conventional P‐V loops (9% vs. 13%, respectively; P < 0.005), thereby demonstrating load‐independent attributes. In contrast, V N at peak −dV/dt was inscribed at 81 ± 9% with an inter‐subject variation of 11%, and had no significant change in intra‐subject (beat‐to‐beat) variation compared to conventional P‐V loops (17% vs. 17%, respectively; P = 0.56), therefore failing to demonstrate load‐independent tendencies. Thus, the normalized P‐V loop advances the quest for load‐independent LV chamber properties. V N at the peak LV filling rate (≈sarcomere length at the peak sarcomere lengthening rate) manifests load‐independent properties. This novel method may help to elucidate and quantify new attributes of cardiac and cellular function. It merits further application in additional human and animal physiologic and pathophysiologic datasets.
Highlights
The pressure–volume loop (PVL) is widely used in cardiovascular physiology and cardiology for the assessment of cardiac chamber function
The key findings based on our preliminary data are: (1) the new method can reveal and quantify novel chamber properties at the organ system level; and (2) PVL normalization revealed that the volume at the peak rate of left ventricular (LV) filling and, by analogy, the myocyte length at the peak rate of myocyte lengthening may possess load-independent attributes
Our results reveal that LV volume at the peak rate of chamber filling is generated at 64 Æ 5% of the equilibrium LV volume
Summary
The pressure–volume loop (PVL) is widely used in cardiovascular physiology and cardiology for the assessment of cardiac chamber function. PVL analysis is the “gold standard” for left ventricular (LV) chamber function assessment, since it facilitates characterization of the load-dependence versus load-independence of various physiologic measures in humans and animals (Suga et al 1973; Cingolani and Kass 2011). Suga et al (1973) pioneered the familiar conceptual framework for quantitative assessment of LV chamber properties by analyzing hemodynamics in the P–V plane. They observed that peak systolic elastance (Emax), the (nearly constant) linear slope of the end-systolic P–V a 2017 The Authors.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
