A blockage to the heart can be a few things, but mostly it is blocked arteries.

The arteries are either constricted from smoking or a genetic defect or from high blood pressure or high cholesterol. When your arteries are restricted close to the heart, you may have a heart attack. If your arteries are clogged or restricted in other parts of your body if left alone you could have a stroke.

These can be detected by your doctor doing a simple blood test.

The symptoms of a heart blockage are as follows:
Pain in the shoulders, neck or arms. This may feel like pressure, tightness, burning, or a heavy weight
.
Pain in the chest, upper abdomen, neck, jaw
Chest discomfort or tightness in the chest
Lightheadedness or fainting
Sweating
Nausea

Shortness of breath

Increased Heart rate

If you are experiencing any of these please call 911 right away.