Ea/Ees and PWV/GLS demonstrate complementary, context-dependent behavior in assessing ventricular-arterial coupling, with Ea/Ees reflecting volumetric-pressure coupling during exercise and PWV/GLS capturing tilt-related preload changes at rest.
Key Findings
Results
Ea/Ees progressively declined with increasing exercise intensity in healthy young adults.
Main effect of exercise stage P < 0.01, with all stages significantly different from the previous stage (all P < 0.05).
The decline in Ea/Ees reflected increased left ventricular elastance (Ees) relative to arterial load (Ea).
Study included 20 healthy young adults (10 females; 23 ± 2 yr) in a randomized crossover design.
Exercise was performed at 25 W and 75 W at a fixed heart rate of approximately 130 beats/min.
Results
Ea/Ees showed no detectable differences between supine and 20° head-up tilt (HUT) at rest or at any exercise stage.
Interaction P > 0.05 for Ea/Ees between supine and HUT conditions.
HUT induces changes in ventricular volume loading, thereby challenging inherent assumptions underlying Ea/Ees.
This insensitivity to postural stress suggests Ea/Ees does not capture preload-related changes induced by tilt.
Results
PWV/GLS detected a significant difference from supine to head-up tilt at rest.
PWV/GLS showed a statistically significant difference between supine and HUT conditions at rest (P < 0.01).
This responsiveness to tilt suggests PWV/GLS captures fluid shifts and preload changes not detected by Ea/Ees.
The PWV/GLS index directly integrates measures of arterial stiffness (pulse wave velocity) and myocardial deformation (global longitudinal strain).
Results
PWV/GLS showed dampened sensitivity to exercise intensity compared to Ea/Ees.
All exercise stages were only significantly different from baseline (P < 0.05), with no progressive stage-to-stage differences detected.
This contrasts with Ea/Ees, which showed significant differences between each successive exercise stage.
PWV/GLS was less responsive to graded increases in exercise intensity at both 25 W and 75 W.
Discussion
Ea/Ees and PWV/GLS demonstrated complementary, context-dependent behavior as ventricular-arterial coupling metrics.
Ea/Ees was responsive to exercise-induced volumetric-pressure changes but insensitive to postural/preload changes.
PWV/GLS was responsive to postural/preload changes but showed dampened responsiveness to graded exercise intensity.
The authors propose that Ea/Ees assumptions regarding negligible volume intercept (V0) are challenged under tilt conditions, which may explain its insensitivity to HUT.
The findings support a context-dependent approach to VAC assessment rather than reliance on a single metric.
Discussion
The novel PWV/GLS index is proposed as a mechanistically grounded alternative to Ea/Ees for assessing ventricular-arterial coupling.
PWV/GLS directly integrates arterial stiffness (PWV) and myocardial deformation (GLS), providing mechanistic grounding compared to the lumped-parameter Ea/Ees ratio.
Ea/Ees is described as 'a convenient but global construct that collapses ventricular and arterial properties into a single lumped parameter.'
PWV/GLS may be particularly useful when the assumption of a negligible volume intercept (V0) underlying Ea/Ees is challenged.
The study supports investigating alternative noninvasive methods to resolve coupling under dynamic physiological conditions.
What This Means
This research suggests that the heart and blood vessels work together as a coupled system, and measuring this 'ventricular-arterial coupling' can reveal how the cardiovascular system responds to physical stress. The study tested two different measurement approaches in 20 healthy young adults who performed cycling exercise at two intensities while lying flat and while tilted head-up (to shift blood away from the heart, mimicking standing). The traditional measure (Ea/Ees, based on heart pressure and volume relationships) responded well to increasing exercise intensity but completely missed the changes caused by tilting the body. The newer measure (PWV/GLS, combining arterial stiffness and heart muscle deformation) detected the body tilt changes at rest but was less sensitive to exercise intensity differences.
This research suggests that neither measurement alone tells the full story about how the heart and arteries are working together. The two measures appear to capture different aspects of cardiovascular function: one is better at tracking how hard the heart works during exercise, while the other is better at detecting changes in how much blood is available to fill the heart. This has practical implications for understanding cardiovascular health assessments, as different tests may be needed depending on whether clinicians are trying to evaluate exercise capacity or how the body handles changes in posture and fluid distribution.
The findings are relevant for developing better noninvasive tools to monitor cardiovascular coupling in real-world conditions, which could ultimately help in assessing patients with heart disease or conditions affecting blood pressure regulation. The study highlights that choosing the right measurement tool depends on the specific physiological question being asked, and that using complementary approaches may provide a more complete picture of heart-vessel interaction.
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Ling S, Nguyen L, Jasiak J, Au J. (2026). Ventricular-arterial coupling during exercise and tilt assessed using a pulse wave velocity-to-global longitudinal strain ratio.. American journal of physiology. Heart and circulatory physiology. https://doi.org/10.1152/ajpheart.00393.2026