One useful app I recently came across is the Insight Heart app.  It is an augmented reality app that is made by ANIMA RES GmBH that is available in iOS, android, and windows.  One of the challenges on teaching the cardiac cycle is to describe a dynamic process such as breaking the cycle down into multiple phases;  these details are important to know but I find students having difficulties putting the phases together.  Thus I appreciate software such as Insight Heart that does an excellent job showing the systole and diastole with blood flow and valvular activities.

There are other functions as well, such as showing the names of the parts of the heart and the vascular tree:

However, some of the missing details that stood out to me are the mesenteric arteries in the abdominal aorta (which will be neat to see), but understandbly so for the sake of clarity.  As long as one keeps that in mind, I think the app is useful for review and for the cardiac cycle animation.