The left side of the heart is much more prone to develop a faulty valve than the right side. The left side valves operate under higher pressure to pump blood out to the body. The left side valves are the mitral valve (for incoming blood) and the aortic valve (for outflowing blood).
Both the mitral valve and the aortic valve can become tight or leaky, so we essentially have four major valve problems:
Tight valves or leaky valves can create problems that have unique effects on the heart. Each condition should be checked for likely signs that the problem is progressing or causing damage to the heart.