| A1 | aortic first sound |
|---|---|
| A2 | aortic second sound |
| A2-OS | aortic second sound, opening snap |
| ACS | acrocallosal syndrome; acrocephalosyndactyly; acute chest syndrome; acute confusional state; Alcon C... |
| AES | acetone-extracted serum; American Electroencephalographic Society; American Encephalographic Society... |
| sinoatrial conduction time | <cardiology, physiology> The time required for an impulse to travel from the sinoatrial node to the atrium; estimated indirectly during asystole by halving the average interval from the premature beat to the following normal sinus beat of the atrium. (05 Mar 2000) |
|---|---|
| sinoventricular conduction | <cardiology, physiology> A rare form of conduction of the sinus impulse during paralysis of the atrial muscle by hyperkalaemia. The impulse leaves the sinus node and enters the internodal tracts rapidly achieving the junctional tissues but without inscribing a P wave due to the inactivation of the atrial muscle cells. (05 Mar 2000) |
| nerve conduction | The transmission of an impulse along a nerve fibre. (05 Mar 2000) |
| nerve conduction velocity | The rate of impulse conduction in a peripheral nerve or its various component fibres, generally expressed in meters per second. (05 Mar 2000) |
| decremental conduction | Impaired conduction in a portion of a fibre because of progressively lessening response of the unexcited portion of the fibre to the action potential coming toward it; it is manifested by decreasing speed of conduction, amplitude of action potential, and extent of spread of the impulse. (05 Mar 2000) |
| supranormal conduction | Transmission of an impulse during the brief period of the cardiac cycle when it would be expected to fail if it occurred outside this time interval. Compare: supranormal excitability. (05 Mar 2000) |
| delayed conduction | First-degree A-V block. See: atrioventricular block, intraventricular block, bundle-branch block. (05 Mar 2000) |
| synaptic conduction | The conduction of a nerve impulse across a synapse. (05 Mar 2000) |
| intra-atrial conduction | Conduction of the cardiac impulse through the atrial myocardium, represented by the P wave in the electrocardiogram. (05 Mar 2000) |
| intra-atrial conduction time | The total duration of electrical activity of the atria in one cardiac cycle. (05 Mar 2000) |
| intraventricular conduction | Conduction of the cardiac impulse through the ventricular myocardium, represented by the QRS complex in the electrocardiogram. H-R conduction time is from the onset of the first high frequency component of the His bundle electrogram to the onset of the QRS complex of the surface electrocardiogram (normally 43 ± 12 msec); H-V conduction time is from the onset of the first high frequency component of the His bundle electrogram to the onset of the ventricular electrogram (normally approximates the H-R interval but may be a little shorter). Synonym: ventricular conduction. (05 Mar 2000) |
| orthograde conduction | Conduction in the expected normal direction between any cardiac structures. Synonym: antegrade conduction, forward conduction, orthograde conduction. (05 Mar 2000) |
| forward conduction | Conduction in the expected normal direction between any cardiac structures. Synonym: antegrade conduction, forward conduction, orthograde conduction. (05 Mar 2000) |
| anvil sound | In cases of a large pulmonary cavity or of pneumothorax, a clear metallic sound obtained by striking a coin, held against the chest, by another coin, or by flicking the chest wall with one's fingernail; the sound is heard on auscultating the chest wall on the same side anteroposteriorly. Synonym: anvil sound, bell sound, coin test. (05 Mar 2000) |
| atrial sound | The sound produced in late diastole in association with ventricular filling due to atrial systole and related to reduced ventricular compliance. It is a low frequency oscillation that may be normal at older ages owing to a physiologic decline in ventricular compliance but is nearly always abnormal at younger ages if it is of high intensity or palpable. It is common in ventricular hypertrophy, particularly with hypertension, and is almost invariable during acute myocardial infarction. Fourth heart sounds may arise from the right or left ventricle or both. Synonym: atrial sound. (05 Mar 2000) |