Assessment of single beat end-systolic elastance methods for quantifying ventricular contractility

Area of Science:

• Cardiology
• Physiology
• Biomedical Engineering

Background:

• Multi-beat end-systolic elastance (E_MB) is a gold-standard measure of ventricular contractility.
• Clinical measurement of E_MB is challenging due to the need for invasive loading interventions.

Purpose of the Study:

• To compare the performance of five single-beat elastance (E_SB) methods in estimating E_MB without loading interventions.
• To evaluate the influence of preload reduction versus afterload increase on E_SB accuracy.

Main Methods:

• Seven instrumented sheep were used to compare E_SB methods with E_MB.
• E_MB was obtained via transient preload reduction or afterload increase.
• Five distinct single-beat methods were assessed under varied physiological conditions.

Main Results:

• The Shishido et al. single-beat elastance method showed the highest correlation with E_MB (R=0.69).
• Accuracy of all single-beat methods was limited and variable.
• Afterload increase yielded higher correlations between E_SB and E_MB compared to preload reduction.
• Within-animal correlations were stronger than pooled data, particularly for the Shishido et al. method with afterload increase.

Conclusions:

• Current single-beat elastance methods show potential for tracking relative changes in individual ventricular contractility.
• Using afterload increase to derive reference E_MB improves the performance of single-beat methods.
• Intra-individual comparisons using single-beat elastance may be more reliable than inter-individual assessments.