This book presents an overview on the challenges and concerns posed by the clinical condition known as tachycardia. Generally, heart rates are kept in check by a natural pacemaker, the sinus node, and normal heart rhythm is known as sinus rhythm. Tachycardia can be described as a heart rhythm occurring at a faster pace than sinus rhythm. It can result in palpitations, chest pain, shortness of breath and fatigue, all of which deteriorate the quality of life. Fast tachycardias can be a reason of hemodynamic collapse and sudden cardiac death. Diverse factors, mechanisms, and sources are responsible for tachycardias. The identification of tachycardias is made by electrocardiograms and electrophysiological tests. They can be handled and cured by both pharmacological and non-pharmacological methodologies. This book presents an overview on a myriad of facets related to tachycardia; varying from fundamental challenges to clinical viewpoints. It will help readers in gaining a greater comprehension and advancement in the clinical results of tachycardias.