| NAC | N-acetylcysteine; National Asthma Center; National Audiovisual Center; Noise Advisory Council |
|---|---|
| NC | nasal cannula; nasal clearance; neck complaint; neonatal cholestasis; neural crest; neurologic check... |
| NDT | neurodevelopmental treatment; noise detection threshold; nondestructive test, nondestructive testing... |
| NF | nafcillin; National Formulary; nephritic factor; neurofibromatosis; neurofilament; neutral fraction;... |
| NI | neuraminidase inhibition; neurological improvement; neutralization index; no information; noise inde... |
| third sound | Occurs in early diastole and corresponds with the end of the first phase of rapid ventricular filling; normal in children and younger people but abnormal in others. Synonym: third sound. (05 Mar 2000) |
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| to-and-fro sound | Doubling of an abnormal murmur usually in systole and diastole and formerly applied to pericardial rubs. (05 Mar 2000) |
| Jewett sound | A short straight sound for dilating the anterior urethra. (05 Mar 2000) |
| first heart sound | Occurs with ventricular systole and is mainly produced by closure of the atrioventricular valves. (05 Mar 2000) |
| fourth heart 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) |
| friction sound | The sound, heard on auscultation, made by the rubbing of two opposed serous surfaces roughened by an inflammatory exudate, or, if chronic, by nonadhesive fibrosis. Synonym: friction murmur, friction rub. (05 Mar 2000) |
| Le Fort sound | A curved sound threaded for a filiform bougie, used for dilation of urethral strictures in the male when small caliber or presence of false passages prevents safe passage of a standard sound or catheter. (05 Mar 2000) |