Heart palpitations and heart pounding at 24 weeks?

Hi all, I'm currently 24 weeks pregnant with our second child. I have been experiencing heart palpitations and occasionally the sensation that my heart is racing and pounding really hard, even when I'm doing absolutely nothing. I do currently have borderline high blood pressure brought on by the pregnancy (around 138/96) for which I'm being very closely monitored. My OB-GYN had me get checked out by a cardiologist and everything looks great with my heart. I am just wondering if anyone else had similar symptoms while pregnant? I had a few episodes of a racing heart rate with my first pregnancy, but nothing compared to this time around.