Key result
During late pregnancy in rats, cardiac hypertrophy is associated with a significant decrease in passive tension developed by the right and left ventricular walls compared to nonpregnant rats, which reverses postpartum.
Why the study?
Does pregnancy alter the passive mechanical properties and myocyte size of cardiac tissues in rats?
Does pregnancy alter the passive mechanical properties and myocyte size of cardiac tissues in rats?
Absolute Event Rate: 5.39% vs 9.02%
p-value: p=<0.05
Pregnancy induces a reversible decrease in ventricular rigidity and passive tension, which may act as a compensatory mechanism to handle blood volume overload.
We evaluated changes in passive mechanical properties in cardiac tissues during rat pregnancy. Left and right ventricular free walls were dissected from hearts of nonpregnant, late-pregnant, and postpartum rats. Mechanical experiments in ventricular strips were done by stretch-release cycles using a step motor. The results show that during pregnancy, there is cardiac hypertrophy associated with (1) an increase in myocyte size, particularly of augmented myocyte length, (2) a decrease in passive tension developed by the myocardial walls, and (3) a decrease in both elastic modulus and hysteresis. All changes observed during rat pregnancy were reversed during postpartum. In conclusion, a heart with less ventricular rigidity could contribute to facilitating the ventricular filling in conditions of a greater circulating volume characteristic of pregnancy.
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Virgen‐Ortiz et al. (2009) studied Pregnancy-induced cardiac hypertrophy (n=24). Pregnancy vs. Nonpregnant state was evaluated on Passive tension developed by right ventricular free walls at 10% stretch (mN/mm2) (p=<0.05). During late pregnancy in rats, cardiac hypertrophy is associated with a significant decrease in passive tension developed by the right and left ventricular walls compared to nonpregnant rats, which reverses postpartum.
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