Calcium channels have a unique functional role, because not only do they participate in this activity, they form the means by which electrical signals are converted to responses within the cell. Calcium channels play an integral role in excitation in the heart and shaping the cardiac action potential. In addition, calcium influx through calcium channels is responsible for initiating contraction. Abnormalities in calcium homeostasis underlie cardiac arrhythmia, contractile dysfunction and cardiac remodelling.