Heart valve in the context of "Great Ormond Street Hospital"

The heart is a muscular organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make up the circulatory system. The pumped blood carries oxygen and nutrients to the tissue, while carrying metabolic waste such as carbon dioxide to the lungs. In humans, the heart is approximately the size of a closed fist and is located between the lungs, in the middle compartment of the chest, called the mediastinum.

In humans, the heart is divided into four chambers: upper left and right atria and lower left and right ventricles. Commonly, the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart. In a healthy heart, blood flows one way through the heart due to heart valves, which prevent backflow. The heart is enclosed in a protective sac, the pericardium, which also contains a small amount of fluid. The wall of the heart is made up of three layers: epicardium, myocardium, and endocardium.

A commissure (/ˈkɒməʃər/) is the location at which two objects abut or are joined. The term is used especially in the fields of anatomy and biology.

• The most common usage of the term refers to the brain's commissures, of which there are at least nine. Such a commissure is a bundle of commissural fibers as a tract that crosses the midline at its level of origin or entry (as opposed to a decussation of fibers that cross obliquely). The nine are the anterior commissure, posterior commissure, corpus callosum, commissure of fornix (hippocampal commissure), habenular commissure, ventral supraoptic decussation, Meynert's commissure, anterior hypothalamic commissure of Gasner, and the interthalamic adhesion. They consist of fibre tracts that connect the two cerebral hemispheres and span the longitudinal fissure. In the spinal cord, there are the anterior white commissure, and the gray commissure. Commissural neurons refer to neuronal cells that grow their axons across the midline of the nervous system within the brain and the spinal cord.
• Commissure also often refers to cardiac anatomy of heart valves. In the heart, a commissure is the area where the valve leaflets abut. When such an abutment is abnormally stiffened or even fused, valvular stenosis results, sometimes requiring commissurotomy.
• The term may also refer to the junction of the upper and lower lips (see labial commissure of mouth).
• It may refer to the junction of the upper and lower mandibles of a bird's beak, or alternately, to the full-length apposition of the closed mandibles, from the corners of the mouth to the tip of the beak.
• It may refer to the nasal and temporal meeting points of the upper and lower eyelids (the medial and lateral canthi).
• In the vulva, the joining points of the two folds of the labia majora create two commissures—the anterior commissure just anterior to the prepuce of the clitoris, and the posterior commissure of the labia majora, directly posterior to the frenulum of the labia minora and anterior to the perineal raphe.

In biology, the meeting of the two valves of a brachiopod or clam is a commissure; in botany, the term is used to denote the place where a fern's laterally expanded vein endings come together in a continuous marginal sorus.

The atrium (Latin: ātrium, lit. 'entry hall'; pl.: atria) is one of the two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular mitral and tricuspid heart valves.

There are two atria in the human heart – the left atrium receives blood from the pulmonary circulation, and the right atrium receives blood from the venae cavae of the systemic circulation. During the cardiac cycle, the atria receive blood while relaxed in diastole, then contract in systole to move blood to the ventricles. Each atrium is roughly cube-shaped except for an ear-shaped projection called an atrial appendage, previously known as an auricle. All animals with a closed circulatory system have at least one atrium.

Valvular heart disease is any cardiovascular disease process involving one or more of the four valves of the heart (the aortic and mitral valves on the left side of heart and the pulmonic and tricuspid valves on the right side of heart). These conditions occur largely as a consequence of aging, but may also be the result of congenital (inborn) abnormalities or specific disease or physiologic processes including rheumatic heart disease and pregnancy.

Anatomically, the valves are part of the dense connective tissue of the heart known as the cardiac skeleton and are responsible for the regulation of blood flow through the heart and great vessels. Valve failure or dysfunction can result in diminished heart functionality, though the particular consequences are dependent on the type and severity of valvular disease. Treatment of damaged valves may involve medication alone, but often involves surgical valve repair or valve replacement.

A gumma (plural gummata or gummas) is a soft, non-cancerous growth resulting from the tertiary stage of syphilis (and yaws).

It is a form of granuloma. Gummas are most commonly found in the liver (gumma hepatis), but can also be found in brain, heart, skin, bone, testis, and other tissues, leading to a variety of potential problems including neurological disorders or heart valve disease.