Heart valve tricuspid valve has anterior, posterior, and septal cusps; and the mitral valve has just anterior and posterior cusps. The valves of the human heart can be grouped in two sets: 1- Two Atrioventricular (AV) valves to prevent backflow of blood from the ventricles into the atria a) Tricuspid valve, located between the right atrium and right ventricle. b) Bicuspid or mitral valve, located between the left atrium and left ventricle. 2- Two Semilunar valves to prevent the backflow of blood into the ventricle a) Pulmonary semilunar valve, located at the opening between the right ventricle and the pulmonary trunk. b)
Heart some from the atrioventricular node (e.g. AV nodal re-entrant tachycardia) whilst others arise from the ventricles (e.g. ventricular tachycardia). Some tachyarrhythmias are caused by scarring within the heart (e.g. some forms of ventricular tachycardia), others by an irritable focus (e.g. focal atrial tachycardia), while others are caused by additional abnormal conduction tissue that has been present since birth (e.g. Wolff-Parkinson-White syndrome). The most dangerous form of heart racing is ventricular fibrillation, in which the ventricles quiver rather than contract, and which if untreated is rapidly fatal. The sack which surrounds the heart, called the pericardium, can become inflamed in a