Mitral valve regurgitation means that one of the valves in your heart-the mitral valve-is letting blood leak backward into the heart.

Mitral valve stenosis, or mitral stenosis is a condition in which the mitral valve narrows. This narrowing causes the valve to not open properly and to obstruct blood flow between the left upper and lower chambers of your heart.

Myocarditis refers to an inflammation of the heart that usually results from an infection within the heart muscle itself. It is most often caused by a virus but can be caused by some bacteria (including the bacteria that causes Lyme Disease), fungi, autoimmune disorders like SLE (Systemic Lupus Erythematosis), and a host of medical drugs.