An<unk>  can reside within a part of the electrical conduction system of the heart, or within the muscle cells of the atria or ventricles. When an<unk>  initiates a beat, premature contraction occurs. A premature contraction will not follow the normal signal transduction pathway, and can render the heart refractory or incapable of transmitting the normal signal from the SA node. Location of the<unk>  can also change its effect on the SA node and its rhythm. An<unk>  located in the atria is known as an atrial<unk>  and can cause the atrial contraction to be faster. An<unk>  situated near the AV node and the septum is known as a junctional<unk> . The<unk>  that is operating in the ventricles is known as the ventricular. Other such<unk> s can even lie within the pulmonary vein and thoracic vein walls.
Ectopic pacemaker
Wandering atrial pacemaker
Ectopic beat
Junctional ectopic tachycardia
Pre-excitation syndrome
Sinus arrhythmia
Benign early repolarization
Supraventricular tachycardia