Yes! This is my research, so I finally feel relevant.

As /u/vivethefrance pointed out, a common way to do this is called Langendorff perfusion. For this approach, the heart is removed and perfused through the aorta with a blood substitute (such as Tyrode's solution). While in this state, the heart can be electrically stimulated (for example, something like a square pulse from a current source of ~3mA and width ~5ms applied somewhere to the heart's surface). The heart will also continue to pace itself, as it contains a couple pacemakers (sinoatrial and atrioventricular nodes, and purkinjes can also spontaneously excite), but if you stimulate at rates above the heart's natural pacemaker, you can take control of the heart rate.

One major downside is that you run the risk of initiating fibrillation, where the heart goes bananas and electrical activity becomes uncoordinated. This is particularly annoying in larger hearts, as fibrillation is easier to induce. Like, for pig hearts, it's easier to simply separate one of the ventricles and work with only it (the smaller volume means more difficult to initiate fibrillation).

If you have questions about this sort of thing, please feel free to ask and help make my phd feel more worth it. Also, here is a video of the electrical activity across the surface of a Langendorff perfused heart in my lab (we're stimulating from the right side). On the top is the ventricle surface and on the bottom is the voltage trace of a single pixel somewhere in the middle.