Can you explain the mechanism of heart muscle contraction?

Can you explain the mechanism of heart muscle contraction?

Heart muscle contraction occurs due to the sliding in of actin and myosin myofilaments so that the length of the sarcomere decreases. Sarcomere is the basic unit of the heart muscle and each muscle fibre has multiple sarcomeres. Excitation contraction coupling is mediated by release of calcium from the sarcolemma, when a stimulus transmitted through the Purkinje fibre depolarizes the muscle fibre.