| dis- | 1. <prefix> A prefix from the Latin, whence F. Des, or sometimes de-, dis-. The Latin dis- appears as di- before b, d, g, l, m, n, r, v, becomes dif- before f, and either dis- or di- before j. It is from the same root as bis twice, and duo, E. Two. See Two, and cf. Bi-, Di-, Dia-. Dis- denotes separation, a parting from, as in distribute, disconnect; hence it often has the force of a privative and negative, as in disarm, disoblige, disagree. Also intensive, as in dissever. Walker's rule of pronouncing this prefix is, that the s ought always to be pronounced like z, when the next syllable is accented and begins with "a flat mute [b, d, v, g, z], a liquid [l, m, n, r], or a vowel; as, disable, disease, disorder, disuse, disband, disdain, disgrace, disvalue, disjoin, dislike, dislodge, dismay, dismember, dismiss, dismount, disnatured, disrank, disrelish, disrobe." Dr. Webster's example in disapproving of Walker's rule and pronouncing dis- as diz in only one (disease) of the above words, is followed by recent orthoepists. See Disable, Disgrace, and the other words, beginning with dis-, in this Dictionary. 2. A prefix from Gr. Twice. See Di-. (29 Oct 1998) |
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| artificial heart valve | <cardiology> A synthetic or porcine (pigskin) valve surgically placed into the heart to replace a defective or malfunctioning valve. The aortic and mitral valves are the most frequently replaced with artificial valves. (27 Sep 1997) |
| heart valve | <anatomy> A term used to describe anyone of the main 4 valves of the heart: tricuspid, mitral, aortic or pulmonic valves. Mitral valve separates left atrium and left ventricle, pulmonic valve separates pulmonary vein and left atrium, tricuspid valve separates right atrium and right ventricle, aortic valve separates left ventricle and the aorta (27 Sep 1997) |
| heart valve prolapse | Displacement of the valves of the heart. (12 Dec 1998) |
| heart valve prosthesis | An artificial substitute for a heart valve. It may be mechanical or composed of tissue. (12 Dec 1998) |
| heart valve prosthesis implantation | Surgical insertion of synthetic material to repair injured or diseased heart valves. (12 Dec 1998) |
| abnormal cleavage of cardiac valve | Congenital malformation of a valve leaflet with a defect extending from the free margin. (05 Mar 2000) |
| Amussat's valve | A series of crescentic folds of mucous membrane in the upper part of the cystic duct, arranged in a somewhat spiral manner. Synonym: plica spiralis ductus cystici, Amussat's valve, Heister's valve, spiral valve of cystic duct, valvula spiralis. (05 Mar 2000) |
| anterior cusp of atrioventricular valve | The anterior leaflet or valvule of either the tricuspid or mitral valves. Synonym: cuspis anterior valvae atrioventricularis dextrae/sinistrae. (05 Mar 2000) |
| anterior urethral valve | A crescentic horizontal fold in the proximal spongy urethra. (05 Mar 2000) |
| aortic valve | The heart valve that divides the left ventricle and the aorta. The aortic valve opens during left ventricular contraction and then closes to prohibit the backwash of oxygenated blood from the aorta into the ventricle. The aortic valve has 3 valve cusps. (27 Sep 1997) |
| aortic valve insufficiency | Backflow of blood from the aorta into the left ventricle, owing to imperfect functioning of the aortic semilunar valve. (12 Dec 1998) |
| aortic valve prolapse | The downward displacement of the cuspal material (misalignment of the cusps) below a line joining points of attachment of the aortic valve leaflets. The prolapsed cusp may occlude the ventricular septal defect during ventricular diastole. (12 Dec 1998) |
| aortic valve stenosis | Narrowing of the orifice of the aortic valve or of the supravalular or subvalvular regions. (12 Dec 1998) |
| ball valve | Any of a variety of prosthetic cardiac valve's comprised of a ball within a retaining cage affixed to the orifice; when appropriately sized, used in aortic, mitral, or tricuspid position. (05 Mar 2000) |