Muscle injuries and dehydration can also trigger cramps. Dehydration is the excessive loss of fluids in the body. Low levels of any of the following minerals that contribute to healthy muscle function may also cause muscle cramps: calcium.
The heart is a part of the cardiovascular system in fact its the main part so if you have heart disease another way of saying this is you have cardiovascular disease.
Myocardial muscle contains less connective tissue than does skeletal muscle. Specially modified fibers of myocardial muscle constitute the conduction system of the heart, including the sinoatrial node, the atrioventricular (AV) node, the AV bundle, and the Purkinje fibers.