Anatomic variations of the cardiac valves and papillary muscles of the right heart

This article reviews the right atrioventricular and pulmonary valves, along with their anatomic variations as well as the papillary muscles and chordae tendineae of the right ventricle of the human heart. A brief anatomical background is given for every structure, as well as a gross review of their embryological basis. Although the normal morphology of the right atrioventricular valve is tricuspid, this is not always the case; its anatomic variations involve, firstly, the number of cusps and accessory leaflets. Anatomic variations of the right atrioventricular valve may occur in association with other congenital anomalies and syndromes. Also the number, length and shape of the papillary muscles and chordae tendineae are variable. This can be of clinical significance since the papillary muscles play an important role in the contraction of the right ventricle and in the closure of the tricuspid valve so as to prevent ventricular blood from passing back into the right atrium. The pulmonary valve may present variations in the number of cusps, stenosis or atresia, either as isolated clinical findings or in association with congenital syndromes.