Prospective echocardiographic characterization of postnatal cardiac development in C57BL/6 mice: Strain analysis between birth and adulthood

Q: What are the key findings of this study?

During murine postnatal development, structural maturation was accompanied by lower ejection fraction (from 69% at birth to 60% at 8 weeks), whereas myocardial strain remained stable with males developing greater longitudinal and radial strain than females by adulthood.

Q: What is the clinical evidence from this study?

Study design: Observational. Population: Normal cardiac development (wild-type C57BL/6 mice) (n=30). Intervention: Postnatal development vs. Baseline (Postnatal day 0 or 8). Primary outcome: Trajectories of cardiac structure, function, and myocardial strain.

Q: What does this research mean for the field?

During murine postnatal development, structural maturation is accompanied by a decline in ejection fraction, while intrinsic myocardial strain remains stable with sex-specific divergence emerging by adulthood characterized by greater longitudinal and radial strain magnitudes in males. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

Sehjin Jo; George Spyropoulos; Logan G. Hart; Taylor A. Covington; Arvind K. Pandey; Thomas M. Michel; Fotios Spyropoulos

doi:10.14814/phy2.71113

September 1, 2026Physiological ReportsOpen Access

Prospective echocardiographic characterization of postnatal cardiac development in C57BL/6 mice: Strain analysis between birth and adulthood

View Full Paper

Ask AI

Bookmark

Share

Key result

Murine postnatal cardiac maturation shows an absolute ~9% LVEF decline alongside sex-divergent strain by adulthood.

n=30

Figures

Why the study?

Normative echocardiographic data including advanced myocardial strain metrics for early postnatal cardiac development in mice remain undefined, limiting interpretation of preclinical congenital and neonatal heart disease models.

Key Points

To define normative, sex-specific trajectories of cardiac structure and function using advanced high-frequency echocardiography and myocardial strain analysis from birth through adulthood in mice.
Prospective high-frequency echocardiography was performed on wild-type C57BL/6 mice (N=30) across four developmental time points: postnatal day 0 (P0), P8, P21, and week 8 (Wk8).
Assessed left ventricular dimensions, conventional systolic and diastolic Doppler indices, and speckle-tracking myocardial deformation parameters (circumferential, longitudinal, and radial strain) stratified by sex.
Structural maturation was marked by progressive left ventricular growth alongside declining ejection fraction (69 ± 5% at P0 to 60 ± 8% at Wk8, p < 0.001) and fractional shortening (35.8 ± 4.15% to 31.84 ± 5.69%, p = 0.017).
Intrinsic myocardial deformation remained stable across development for myocardial global circumferential strain (p = 0.12) and global radial strain (p = 0.051), whereas myocardial global longitudinal strain increased from −8.79 ± 2.64% at P8 to −11.88 ± 2.38% at P21 (p < 0.001).
Sexual dimorphism emerged between P21 and Wk8; by Wk8, males exhibited significantly higher systolic annular velocity (21.52 ± 3.65 vs. 17.33 ± 1.62 mm/s, p = 0.002) and greater longitudinal and radial strain magnitudes than females.

Study Design

Type

Observational (n=30)

Structured PICO

P

Population

30 wild-type C57BL/6 mice followed prospectively from birth to 8 weeks of age to establish normative, sex-specific trajectories of echocardiographic parameters and cardiac function.

E

Exposure

Serial high-frequency echocardiographic assessments at postnatal Day 0 (P0), Day 8 (P8), Day 21 (P21), and Week 8 (Wk8)

O

Outcome

Normative, sex-specific trajectories of cardiac structure and function between birth and adulthood, including myocardial strainsurrogate

This study establishes normative, sex-specific developmental trajectories for advanced echocardiographic metrics, including myocardial strain, in murine models from birth to adulthood, providing a crucial framework for preclinical research in pediatric and congenital heart disease.

Limitations

Anesthesia significantly influences cardiac hemodynamics, which may confound functional measurements.
Short-axis M-mode systematic bias overestimates ejection fraction compared to long-axis B-mode.
The Teichholz formula assumes a spherical left ventricular geometry, which may overestimate true volumes.
Different myosin heavy-chain isoform expression and heart rates between mice and humans limit direct translation of sex-dependent strain patterns.
Technical constraints of neonatal cardiac imaging at P0 prevented apical four-chamber view acquisition, precluding mitral valve Doppler, tissue Doppler, speckle-tracking strain analysis, and right ventricular assessment at birth.

Implication

Normative murine trajectories show declining EF with stable strain and adult male predominance; extends preclinical benchmarks while leaving clinical translation open.

Abstract

Echocardiography is critical for characterizing murine models of cardiovascular disease, yet normative data for the early postnatal period, particularly advanced functional metrics like myocardial strain, remain undefined. This developmental window features rapid cardiac maturation and is central to modeling congenital and neonatal heart disease. To establish normative, sex-specific trajectories of cardiac structure and function between birth and adulthood, we performed prospective high-frequency echocardiography in C57BL/6 mice at postnatal day 0 (P0), P8, P21, and week 8 (Wk8). Somatic growth and left ventricular structural dimensions increased progressively from P0 to Wk8. This structural maturation was accompanied by lower ejection fraction and fractional shortening, attributable to geometric remodeling. In contrast, speckle-tracking strain analysis revealed that intrinsic myocardial deformation, including global circumferential and radial strain, remained stable throughout postnatal development. Importantly, we identified sexual dimorphism emerging during late adolescence; by Wk8, males exhibited significantly greater longitudinal and radial strain magnitudes than females. This study provides the first prospective, myocardial strain-based echocardiographic characterization of murine cardiac development between birth and adulthood, identifying P21-Wk8 as a critical window for sex-specific cardiac mechanics. These normative trajectories provide a translational framework for interpreting cardiac phenotypes in preclinical models of congenital, pediatric, and developmental cardiovascular disease.

Discussion

No takes yet. Share an insight, caveat, or question.

Cite This Study

Jo et al. (2026) conducted an observational in Normal cardiac development (wild-type C57BL/6 mice) (n=30). Postnatal development vs. Baseline (Postnatal day 0 or 8) was evaluated on Trajectories of cardiac structure, function, and myocardial strain. During murine postnatal development, structural maturation was accompanied by lower ejection fraction (from 69% at birth to 60% at 8 weeks), whereas myocardial strain remained stable with males developing greater longitudinal and radial strain than females by adulthood.

synapsesocial.com/papers/6ad0fd553afa093ea9ad03f8 https://doi.org/10.14814/phy2.71113

Topics

Echocardiography

View Full Paper

Ask AI

Bookmark

Share

Prospective echocardiographic characterization of postnatal cardiac development in C57BL/6 mice: Strain analysis between birth and adulthood

Figures

Key Points

Study Design

Structured PICO

Limitations

Implication

Abstract

Discussion

Cite This Study

Topics

Prospective echocardiographic characterization of postnatal cardiac development in C57BL/6 mice: Strain analysis between birth and adulthood

Figures

Key Points

Study Design

Structured PICO

Limitations

Implication

Abstract

Discussion

Cite This Study

Keep reading

Topics

Keep reading