| posterior cusp of atrioventricular valve | The posterior leaflet of either the tricuspid or mitral valves. Synonym: cuspis posterior valvae atrioventricularis dextrae/sinistrae. (05 Mar 2000) |
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| discordant atrioventricular connections | Connections in which each atrium is connected with a morphologically inappropriate ventricle. (05 Mar 2000) |
| double inlet atrioventricular connections | Connections in which both atrial chambers connect to the same ventricle. (05 Mar 2000) |
| incomplete atrioventricular dissociation | A-V dissociation interrupted by ventricular captures. (05 Mar 2000) |
| tachycardia, atrioventricular nodal reentry | A tachycardia characterised by rates between 150 and 250 beats per minute and a qrs complex of supraventricular origin. (12 Dec 1998) |
| trunk of atrioventricular bundle | The singular initial portion (stem) of the atrioventricular bundle which passes from the atrioventricular node into the right trigone of the fibrous skeleton of the heart and along the periphery of the membranous interventricular septum; upon reaching the muscular interventricular septum, the trunk terminates by dividing into the right and left crura of the atrioventricular bundle. Synonym: truncus fascicularis atrioventricularis. (05 Mar 2000) |
| left atrioventricular valve | <anatomy, cardiology> The heart valve that divides the left atrium and left ventricle. During left atrial contraction, the mitral valve opens to allow blood to flow into the left ventricle. Upon closure, the mitral valve prohibits the regurgitation of blood back into the left atrium. The mitral valve is the only heart valve that has only 2 valve cusps (all others have 3). (13 Nov 1997) |
| left crus of atrioventricular bundle | The left leg or branch of the atrioventricular bundle which separates from the atrioventricular bundle just below the membranous portion of the interventricular septum to descend the septal wall of the left ventricle and begins to ramify subendocardially. Synonym: crus sinistrum fasciculi atrioventricularis. (05 Mar 2000) |
| alveolocapillary block | The presence of material that impairs the diffusion of gases between the air in the alveolar spaces and the blood in alveolar capillaries; block can be caused by oedema, cellular infiltration, fibrosis, or tumour, and results in undersaturation of peripheral arterial blood with oxygen. (05 Mar 2000) |
| anterograde block | Conduction block of an impulse traveling anywhere in its ordinary direction, for example, from the sinoatrial node toward the ventricular myocardium. (05 Mar 2000) |
| arborization block | Intraventricular block supposedly due to widespread blockage in the Purkinje ramifications and manifested in the electrocardiogram by a pattern similar to bundle-branch block but with complexes of low amplitude. (05 Mar 2000) |
| autonomic nerve block | Interruption of sympathetic pathways, by local injection of an anaesthetic agent, at any of four levels: peripheral nerve block, sympathetic ganglion block, extradural block, and subarachnoid block. (12 Dec 1998) |
| A-V block | <cardiology> A conduction disturbance that results in the inappropriate delay (or complete inability) of a electrical impulse, generated in the atria, to reach the ventricles (via the atrioventricular node). Clinical types are divided into first (nonserious), second and third degree (most serious). Some drugs may precipitate atrioventricular block (for example clonidine, methyldopa, verapamil). A permanent pacemaker may be required for a third degree (complete) heart block. (02 Jan 1998) |
| block | An obstruction or stoppage. (18 Nov 1997) |
| block anaesthesia | Regional anaesthesia in which local anaesthetic solution is injected about nerves to inhibit nerve transmission; includes spinal, epidural, nerve block, and field block anaesthesia, but not local or topical anaesthesia. Synonym: block anaesthesia. (05 Mar 2000) |