Pregnant, shortness of breath, high pulse rate. Heart scan showed enlarged right chamber, goes away on child birth. Cause of concern?

I am 33 wks + with my second baby and was admitted to hosp with shortness of breath and high pulse rate, test where done for blood clots,leg scan and ct scan and that was ruled out, heart scan was done and came back that the lower right chamber was slightly enlarged, medicle team and cardiologist double checked it and where happy to let me go home as 25% of pregnant women get this duering pregnancy and it goes away once baby is born, they told me the name of this but for the life of me i cant remember. Was wondering if someone could tell what this is called? Im sure they said something like hyperchia