a membranous fold in a canal or passage that prevents backward flow of material passing through it.
a semilunar valve
that separates the left ventricle and the aorta; it opens with end diastole, causing the second heart sound
bicuspid aortic valve a congenital anomaly of the aortic valve, caused by incomplete separation of two of the three cusps; it is generally asymptomatic early in life but is predisposed to calcification and stenosis later on.
cardiac v's valves that control flow of blood through and from the heart.
coronary valve a valve at the entrance of the coronary sinus into the right atrium.
flail mitral valve
a mitral valve
having a cusp that has lost its normal support (as in ruptured chordae tendineae) and flutters in the blood stream.
Heimlich valve a small one-way valve used for chest drainage, emptying into a flexible collection device; the valve prevents return of gases or fluids into the pleural space. The Heimlich valve is less than 13 cm (5 inches) long and facilitates patient ambulation; it can be used in many patients instead of a traditional water seal drainage system.
ileocecal valve (ileocolic valve) the valve guarding the opening between the ileum and cecum.
the cardiac valve
between the left atrium and left ventricle, usually having two cusps (anterior and posterior). Called also bicuspid valve
Valves of the heart. The right heart pumps the venous blood into the lungs. The oxygenated blood returns from the lungs into the left atrium and is propelled by the left ventricle into the aorta. The insets show closed valves: the tricuspid valve has three leaflets, whereas the mitral valve has two leaflets. The aortic and pulmonary artery valves have three leaflets and resemble one another except for the fact that the coronary arteries originate from behind the cusps in the aorta. From Damjanov, 1996.
posterior urethral valve
any of various types of congenital folds across the proximal part of the male urethra
near the seminal colliculus
, the most common cause of urethral obstruction in male infants.
) the pocketlike cardiac valve
that protects the orifice between the right ventricle and the pulmonary artery.
pyloric valve a prominent fold of mucous membrane at the pyloric orifice of the stomach.
the cardiac valve
guarding the opening between the right atrium and right ventricle.
valve of vein (venous v's) any of the small cusps or folds found in the tunica intima of many veins, serving to prevent backflow of blood.
pertaining to or emanating from the aorta. See also aortic arch
occurs most often in dogs, where it is caused by Spirocerca lupi
larvae, turkeys and primates, causing dyspnea, cyanosis and coughing. May be congenital affecting the aortic trunk and the arch sometimes associated with aneurysm of an aortic sinus. See also copper
aortic aneurysm, inherited aortic annulus fibrosus
the fibrous ring in the wall of the root of the aorta. In the bovine heart the ring carries the ossa cordis (see os2
aortic base rupture
rupture of the vessel just above the semilunar valves.
small neurovascular structures on either side of the aorta in the region of the aortic arch. The left body is located at the angle between the left subclavian artery and the aorta, and the right at the junction of the right subclavian and right common carotid arteries. They contain chemical receptors which send impulses through the afferent branches of the vagus nerve and are involved in regulating respiration so as to ensure an appropriate partial pressure of oxygen in the arterial blood.
aortic body tumors
single or multiple nodules within the pericardial sac near the base of the heart. Malignant tumors may invade the anterior mediastinum. Called also heart base tumor.
the dilated part of the aorta at its origin, caused by the swellings of the aortic sinuses.
constriction of the aorta at the site of entry of the ductus arteriosus causing a syndrome similar to that of stenosis of the aortic valve.
aortic cystic medionecrosis
pools of ground substance within the elastic media of the aorta. May predispose to arterial aneurysm but this material is present in the aortas of normal horses.
aortic depressor nerve
pressure receptors in the aortic arch and thoracic aorta which assist in maintaining circulatory equilibrium by communicating pressure changes through the aortic depressor nerve, an afferent branch of the vagus nerve; stimulation causes heart slowing and vasodilation.
the aorta receives blood from the right ventricle. There are a number of variations of the basic defect. The common one is the aorta overriding the septum, which is defective, so that the aorta receives blood from both ventricles. The clinical syndrome includes dyspnea and cyanosis from birth, usually with a loud systolic murmur. Affected animals are not viable.
occurs in cats in association with feline cardiomyopathy
and rarely in dogs. Acute pain with paresis to paralysis in the hindlegs, cold, cyanotic feet and no femoral pulse are signs of the condition.
an opening in the diaphragm through which the aorta, thoracic duct, the right and/or left azygos veins pass.
is one of the early lesions in poisoning by plants that induce mineralization of tissues, e.g. solanummalacoxylon
. In combination with lesions in the myocardium causes a syndrome of congestive heart failure.
the aorta is easily palpable per rectum in cattle and horses; valuable as a clinical sign only in cases of thrombosis at the bifurcation; incision at this point has been used as a means of euthanasia in an emergency.
an anomaly of the aorta in which there is an opening between the ascending portion of the aorta and the pulmonary artery; clinical signs are similar to those of patent
ductus arteriosus, but surgical correction is much more difficult.
the part of the aorta attached to the atrioventricular fibrous rings and myocardium.
1. in horses is caused by weakening of the wall of the aorta by migrating strongyle larvae. In cattle the cause may be onchocerciasis, in pigs experimental diets deficient in copper. Sudden death results from cardiac tamponade or dissecting aneurysm into the ventricular muscle.
2. sudden death in growing turkeys due to dissecting aneurysmal rupture of the aorta and death due to internal hemorrhage; the cause is unknown. Copper deficiency is suspected as a cause in several animal species.
the merged ventral aortae of the embryo which supplies blood to the aortic arches.
aortic septal defect
a congenital anomaly in which there is abnormal communication between the ascending aorta and the pulmonary artery just above the semilunar valves.
the three pouch-like dilatations of the aortic bulb which carry the cusps of the aortic valve. The coronary arteries arise from the left caudal and the cranial sinuses.
aortic subvalvular stenosis
in dogs and pigs is possibly an inherited defect. Characterized by stenosis of the aorta just below the semilunar valves. In pigs, it causes congestive heart failure in the newborn, but in affected dogs severity increases with age so that clinical effects may not be apparent until the patients are older.
thrombosis is the usual forerunner of embolism, pieces of the thrombus breaking off the main mass and lodging in more distal parts of the vascular system. See also aortic embolism (above), verminous
mesenteric arteritis, iliac
Aortic thromboembolism in a cat. By permission from Nelson RW, Couto CG, Small Animal Internal Medicine, Mosby, 2003
the valve at the entrance to the aorta from the left ventricle made up of three semilunar leaflets or valvulae.
aortic valve rupture
rupture of the medial cusp is recorded as a cause of sudden death in horses usually as a sequel to endocarditis.
aortic valvular disease
stenosis is rarely an acquired disorder, but may be an inherited defect in several species. In cats and rarely dogs, restrictive cardiomyopathy
may be a cause of subvalvular aortic obstruction. Valvular incompetence may be congenital or acquired and results in diastolic overloading of the left ventricle with a characteristic water-hammer pulse
and diastolic murmur. See also aortic stenosis
, aortic subvalvular stenosis (above).
the cranial part of the left ventricular cavity leading to the root of the aorta in the avian heart.
1. a membranous fold in a canal or passage that prevents backward flow of material passing through it.
2. a mechanical device to regulate the flow of liquid or gas from an area of higher pressure to one of lower pressure.
3. automatic valve which maintains a steady vacuum in the system of a mechanical milking machine.
Adam's pressure reducing valve
see reducing valve (below).
the valves between the right atrium and right ventricle (tricuspid valve) and the left atrium and left ventricle (mitral valve).
a valve at entrance of the coronary sinus into right atrium.
a cardiac valve having a cusp that has lost its normal support (as in ruptured chordae tendineae) and flutters in the bloodstream.
ileocecal valve, ileocolic valve nonreturn valve
in anesthetic circuits, it prevents exhaled gas from returning to the patient.
regulates the amount of venous blood entering the kidney.
pressure reducing valve
see reducing valve (below).
a prominent fold of mucous membrane at the pyloric orifice of the stomach.
a special valve used on anesthetic machines and which reduces the pressure of the gas reaching the exit valve so that control of the flow is made easier. Called also regulator.
valves made up of semilunar segments or cusps (valvulae semilunares), guarding the entrances into the aorta and pulmonary artery.
a thermionic diode that permits the flow of electric current in an x-ray machine in only one direction.