What is a pacemaker? What are it's type?

Dear Student,Sino-atrial node is known as the natural pacemaker of the heart. It is a bundle of fibres that is located in the upper part of the right atrium. It helps in regulating the heart beat. Pacemaker is also inserted into the heart artificially known as artificial pacemaker. Types of pacemaker are Single chamber pacemaker,Dual chamber pacemaker, Biventricular pacemaker.Regards