Assessment of ventricular relaxation in the developing chick embryo using a monoexponential model

Area of Science:

• Cardiovascular Physiology
• Developmental Biology
• Biomedical Engineering

Background:

• Ventricular relaxation is crucial for diastolic filling.
• Understanding early cardiac mechanics is vital for developmental studies.
• Previous models may not fully capture embryonic heart dynamics.

Purpose of the Study:

• To model ventricular pressure decline during isovolumic relaxation in embryonic chick hearts.
• To evaluate computational models for approximating pressure decline.
• To investigate the role of diastolic suction in early cardiac filling.

Main Methods:

• Analysis of 330 ventricular pressure waveforms from chick embryos (stages 17, 23, 26).
• Application of a monoexponential formula: P(t) = P infinity+P0e-t/tau.
• Utilized least-squares nonlinear regression to estimate relaxation parameters (tau and P infinity).

Main Results:

• A monoexponential model best approximated ventricular pressure decline when both P infinity and tau were estimated.
• Negative P infinity values were observed in early developmental stages.
• Cardiac cycle length perturbation did not alter the fundamental modeling approach.

Conclusions:

• Isovolumic pressure decline in the embryonic heart is accurately described by a monoexponential model.
• Negative diastolic suction is implicated in ventricular filling during early cardiac morphogenesis.
• The findings provide insights into the mechanical properties of the developing heart.