Pregnancy is a feat of endurance comparable to running an ultra-marathon and has a huge impact on the heart.
Dr Stephanie Curtis, Consultant Cardiologist at University Hospitals Bristol NHS Foundation Trust said what happened to the body during pregnancy was “incredible”.
During pregnancy, the feto-placenta unit needs access to oxygen, glucose, and other nutrients from the blood. To this end, systemic vascular resistance decreases, while heart rate, cardiac output, and stroke volume increases. “These changes happen early on and continue to relentlessly climb,” said Dr Curtis, adding that cardiac output significantly increases in the run up to and during labour. “It stands to reason that the heart is going to have to adapt to this,” she said.
Expected changes
Pregnancy puts as much strain on the heart as an endurance sporting event, but there is comparatively less data in this patient group.
In the small number of studies that have been published, there is evidence of increases in diastolic diameter and volume, and LV mass, while hypertrabeculation appears to affect around 25% of pregnant women. All these tend to resolve post-partum. Ejection fraction can decrease, rather than increase, during pregnancy.
Interestingly, the heart appears to become more spherical during pregnancy, and studies are ongoing to understand the reasons for this.
The data is mixed on diastolic function, said Dr Curtis. “Regardless of what changes have been reported, they all seem to return to normal post-partum, so I think it is safe to say it doesn’t change overall in the normal heart.” In women with comorbidities, however, such as hypertension, diabetes, or preeclampsia, diastolic dysfunction may be a marker of future LV disease.
In terms of the right heart, fractional area change and RV strain tend to decrease, particularly towards the end of the pregnancy, and return to normal afterwards.
Regurgitation
“Most valves leak in pregnancy because there’s a lot more blood volume,” said Dr Curtis, adding that 90% of pregnant women will experience tricuspid regurgitation. She suggested that sonographers request to see the patient six months post-partum to observe the valve under normal loading conditions if they are unsure of the significance of mild valvular regurgitation.
Mild pulmonary regurgitation is “pretty much the norm” and mild mitral regurgitation is common. Any aortic valve disease, however, is not pregnancy relate, as the aortic annulus does not dilate in pregnancy.Concluding her talk, Dr Curtis reiterated the fact that pregnancy was “an act of endurance”, and that echo findings were often similar to those consistent with athlete’s heart.
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