[L. valva, leaf of a folding door, half of a hinged shell, (membranous) fold]
Any of various membranous structures in a hollow organ or passage that temporarily close to permit the flow of fluid in one direction only.

aortic valve

ABBR: AoV The valve at the junction of the left ventricle and the ascending aorta. It is composed of three semilunar cusps and prevents regurgitation.
SEE: cardiac valve for illus

bicuspid valve

SEE: Mitral valve.

Bjork-Shiley heart valve

SEE: Bjork-Shiley heart valve

cardiac valve

Any of the four valves that prevent the backflow of blood as it passes into, through, and out of the heart. In order of the entry of the venous blood into the right atrium, they are the tricuspid, pulmonary, mitral, and aortic.

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CARDIAC VALVES With ventricles relapsed

Carpentier-Edwards valve

SEE: Carpentier-Edwards valve.

check valve

A valve that permits fluids or gases to flow in just one direction. Check valves are used in infusion sets to prohibit backflow of fluids during intravenous therapy.

coronary valve

SEE: Thebesian valve.

coronary sinus valve

SEE: Thebesian valve.

eustachian valve

The valve at the entrance of the inferior vena cava.

external nasal valve

The outermost opening of the nose (the alar rim).

flutter valve

1. A one-way valve used in chest tube drainage systems that allows fluids or gases to flow out of the chest, but does not let them reenter the body
SYN: SEE: Heimlich flutter valve; SEE: Heimlich valve
2. A unidirectional valve used in respiratory care that allows air to move in one direction but not back in the other. It is used, e.g., to improve the clearance of mucus from an airway.
SYN: SEE: Heimlich valve.

high-pressure relief valve

A safety device built into a ventilator circuit that protects the patient from excessively high airway pressures by venting excess pressure into the atmosphere.

ileocecal valve

A projection of two membranous folds of the ileum of the small intestine into the cecum of the colon. It prevents backup of fecal material into the small intestine.
SYN: SEE: Bauhin valve; SEE: valvula coli

inspiratory impedance threshold valve

ABBR: ITV A valve placed between a patient's airway and his or her source of respiratory gas, e.g., ambient air or, in the case of critically ill patients, a ventilator or bag-valve mask. It lowers tracheal and intrathoracic pressure and as a result increases blood pressure and blood flow to the brain and coronary arteries. It is used in cardiopulmonary resuscitation and advanced cardiac life support to support the circulation in the absence of volume resuscitation. It can also be used to prevent hypotension and syncope in patients with hypovolemia or reduced stroke volumes. The device works by allowing air to escape during chest compressions but not to re-enter the lungs until pressure is > −10 cm H2O. This negative intrathoracic pressure increases venous return.
SYN: SEE: inspiratory impedance threshold device

internal nasal valve

SEE: Nasal valve.

left atrioventricular valve

SEE: Mitral valve.

mitral valve

The valve that closes the orifice between the left cardiac atrium and the left ventricle during ventricular systole.
SYN: SEE: bicuspid valve; SEE: left atrioventricular valve

nasal valve

The site of greatest obstruction to airflow through the nasal passages. It extends from the bony cave near the piriform aperture into part of the cartilaginous vestibule of the nose.
SYN: SEE: internal nasal valve

pop-off valve

A safety valve that releases gas into the atmosphere from a ventilator circuit when the pressure in the circuit exceeds a known, safe level.

prosthetic heart valve

A substitute valve used to replace a diseased valve. There are two main types of prostheses: those made from biological tissues, e.g., the heart valves of animals, esp. pigs, and those made from biocompatible materials, e.g., metals or polymers. Biocompatible mechanical valves may be constructed in a variety of ways, e.g., from a ball that moves up and down in a cage; with bileaflet valves that close in the midline; or with a single leaflet (which tilts to open and close).

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TYPES OF MECHANICAL HEART VALVES A. caged ball valve; B. monoleaflet. C. bileaflet

pulmonary valve

The valve at the junction of the right ventricle and pulmonary artery. It is composed of three semilunar cusps and prevents regurgitation of blood from the pulmonary trunk into the right ventricle.
SEE: cardiac valve for illus.

pyloric valve

The prominent circular membranous fold at the pyloric orifice of the stomach.
SYN: SEE: valvula pylori

rectal valve

One of the horizontal folds of the mucosa of the rectum.
SYN: SEE: Houston valve; SEE: Kohlrausch fold

reducing valve

A device to reduce the pressure of gas that has been compressed in a cylinder.

right atrioventricular valve

SEE: Tricuspid valve.

semilunar valve

The type of valve separating the heart and aorta and the heart and pulmonary artery.
SEE: cardiac valve for illus.

thebesian valve

The valve at the entrance of the coronary sinus into the right atrium.
SYN: SEE: coronary valve; SEE: coronary sinus valve

tissue valve

A heart valve constructed from animal tissue, such as porcine tissue.

tricuspid valve

ABBR: TV The valve that closes the orifice between the right cardiac atrium and right ventricle during ventricular systole.
SYN: SEE: right atrioventricular valve; SEE: valvula tricuspidalis
SEE: cardiac valve for illus