Nightshade, "Solanine", is a vining plant with heart shaped leaves and purple berries.

Pipevine also has heart-shaped leaves, and I had to get rid of mine because it suckered everywhere. Can you give us a picture of the vine so the ID can be established? You are going to have to find the main stem at some point, though.

I don't know of, and can't find, any plant called Solanine. If you mean one of the Solanums, they don't have heart shaped leaves.

A picture would be really useful. It could even be a morning glory.

Or bindweed. Get a teenager with an Iphone to take a picture and post it. In the mean time you can just cut it as low as you can around the yew and at least the portion above the cuts will die. What a monster!

The leaves on Solanum dulcamara can sometimes be heart shaped, more arrow, but can also be thought of a broadly heart shaped. This vine is very common as a strangler of evergreens here in PA, especially if the branches grow to the ground, or in a hedge situation. In a situation like that, the people don't see it take root, and it is more likely to explode after about 3 years. The vine is whitish or greyish, with fleshy wood. A small vine the size of a pencil at the ground can cover a good sized shrub with leaves.

Poaky, you're a regular on here. You know the drill. Tell us about any flowers, what the stems look like, anything. You sound like somebody doing a drive by for ID. You know if ken finds this post he'll likely come on and harangue you.

Nightshade, "Solanine".

Here is a link that might be useful: Solanine

The plant at that link isn't being called solanine (and isn't the same plant being discussed here as nightshade.)

The very first paragraph:
"The chemicals contained within deadly nightshade (or atropa belladonna) have been used throughout history and still have valuable uses in today's society. The most pronounced chemical (the compound that is responsible for most of the nightshade's more unusual properties), is solanine."

Although some of the leaves on Solanum dulcamara can be narrowly heart shaped they are variable and I don't think that heart-shaped would be an obvious description for that plant. We also don't have any idea of the scale of these leaves. They could be huge like Vitis coignetiae. We really need a picture.

Just from the fact that the OP is in PA, I'd guess Polygonum convolvulus or relative if no pic is forthcoming. So many vines have truly heart-shaped leaves.

what is this plants name and does it bloom?

Whatever it is, I think I have it too. When we first bought our house in Massachusetts it was a dark green vine that had completely overtaken a screen porch. I don't know if the previous owners had planted it or not, but it was hell on earth to get rid of it. It took a lot of digging, a lot of round up, and at least three years to just get it under control. It was gone "for good" after we tore down the screen porch and built an addition.

Now I think it's back, though more delicate with lighter green leaves. I assume that's because it's young. I've searched high and low, but every similar vine I've found flowers, and this stuff doesn't seem to.

I'm stumped.

The best solution is to pull it out as often as needed. It weakens the plant to have to keep replacing the leaves and eventually it will decline. If you can't reach the base,just keep wacking the plant as far down as you can reach. By all means, do not let it flower.
Plants reproduce several ways-through seed or root. Preventing it from flowering by cutting it off before it matures,stops some weeds. Others that reproduce through roots as well, like dandelions,need a more vigorous approach. I've even cut off some weeds and sprayed vinegar on them so that it would affect the root. You need to be careful if this would affect some of your other plants but it can be very effective at managing weeds.