Estrogen-induced left ventricular chamber enlargement in ewes

Area of Science:

• Cardiovascular Physiology
• Endocrinology

Background:

• Estrogen's chronic effects on cardiac structure and function are not fully understood.
• Previous research suggests potential cardiovascular impacts of sex hormones.

Purpose of the Study:

• To investigate the chronic impact of a single large intramuscular dose of 17 beta-estradiol on left ventricular chamber size and output in ewes.
• To assess changes in cardiac dimensions and performance following estrogen administration.

Main Methods:

• Oophorectomized ewes were instrumented to measure cardiac pressures, stroke volume, and left ventricular dimensions.
• Ewes received either 17 beta-estradiol or a placebo, with measurements taken pre-treatment and at 1, 2, and 3 weeks post-treatment.
• Left ventricular function was assessed using pressure-dimension and pressure-volume relationships during hemodynamic challenges.

Main Results:

• Estrogen administration led to a significant increase in left ventricular end-diastolic diameter.
• The left ventricular end-diastolic pressure-end-diastolic dimension relationship shifted rightward, indicating chamber enlargement.
• Stroke volume increased in the estrogen group, while the placebo group showed no significant changes.

Conclusions:

• A single large intramuscular dose of 17 beta-estradiol causes chronic left ventricular chamber enlargement in ewes.
• Estrogen administration also resulted in an increased stroke volume, suggesting enhanced cardiac output.
• These findings highlight the significant impact of estrogen on cardiac remodeling and function.