Pulmonary hypertension is a pathophysiological disorder that may involve multiple clinical conditions and can complicate the majority of cardiovascular and respiratory diseases. Moreover, it results from restricted flow through the pulmonary arterial circulation resulting in increased pulmonary vascular resistance and ultimately right heart failure. Today, there is a wide variety of researches in cardiopulmonary medicine for pulmonary hypertension. The aim of this book is to give detailed information about right ventricular dysfunction diagnosis by echocardiography and also the current treatment of pulmonary hypertension.