TY - JOUR
T1 - The quest for load-independent left ventricular chamber properties
T2 - exploring the normalized pressure–volume loop
AU - Kohli, Keshav
AU - Kovács, Sándor J.
N1 - Funding Information:
Funding Information This work was supported by: The Alan A. and Edith L. Wolff Charitable Trust and The Barnes-Jewish Hospital Foundation. We acknowledge helpful discussions with Erina Ghosh. We also acknowledge the assistance of the staff of the Cardiovascular Procedure Center at Barnes-Jewish Hospital at Washington University Medical Center during data acquisition.
Publisher Copyright:
© 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.
PY - 2017/3/1
Y1 - 2017/3/1
N2 - 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 (PN) was defined by 0 ≤ P(t) ≤ 1. Normalized LV volume (VN) was defined as VN=V(t)/Vdiastasis, since the LV volume at diastasis (Vdiastasis) 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. VN 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, VN 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. VN 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.
AB - 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 (PN) was defined by 0 ≤ P(t) ≤ 1. Normalized LV volume (VN) was defined as VN=V(t)/Vdiastasis, since the LV volume at diastasis (Vdiastasis) 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. VN 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, VN 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. VN 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.
KW - Catheterization
KW - hemodynamics
KW - load-independence
KW - pressure–volume loops
UR - http://www.scopus.com/inward/record.url?scp=85016239461&partnerID=8YFLogxK
U2 - 10.14814/phy2.13160
DO - 10.14814/phy2.13160
M3 - Article
C2 - 28351966
AN - SCOPUS:85016239461
SN - 2051-817X
VL - 5
JO - Physiological Reports
JF - Physiological Reports
IS - 6
M1 - e13160
ER -