| echo | Origin: L. Echo, Gr. Echo, sound, akin to, sound, noise; cf. Skr. Va to sound, bellow; perh. Akin to E. Voice: cf. F. Echo. 1. A sound reflected from an opposing surface and repeated to the ear of a listener; repercussion of sound; repetition of a sound. "The babbling echo mocks the hounds." (Shak) "The woods shall answer, and the echo ring." (Pope) 2. Sympathetic recognition; response; answer. "Fame is the echo of actions, resounding them." (Fuller) "Many kind, and sincere speeches found an echo in his heart." (R. L. Stevenson) 3. A wood or mountain nymph, regarded as repeating, and causing the reverberation of them. "Sweet Echo, sweetest nymph, that liv'st unseen Within thy airy shell." (Milton) A nymph, the daughter of Air and Earth, who, for love of Narcissus, pined away until nothing was left of her but her voice. "Compelled me to awake the courteous Echo To give me answer from her mossy couch." (Milton) Echo organ, a stop upon a harpsichord contrived for producing the soft effect of distant sound. To applaud to the echo, to give loud and continuous applause. "I would applaud thee to the very echo, That should applaud again." (Shak) Source: Websters Dictionary (01 Mar 1998) |
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| echo beat | Extrasystole produced by the return of an impulse in the heart retrograde to a focus near its origin which then returns antegradely to produce a second depolorization. (05 Mar 2000) |
| echo planar | A method of magnetic resonance imaging that allows rapid image acquisition during free induction decay, using technically difficult rapidly oscillating radiofrequency gradients. (05 Mar 2000) |
| echo reaction | A disorder of speech where there is an involuntary repetition several times of the same word. (27 Sep 1997) |
| echo speech | A disorder of speech where there is an involuntary repetition several times of the same word. (27 Sep 1997) |
| echo-free | The property of appearing echo-free or without echoes on a sonographic image; a clear cyst appears anechoic. See: transonic. Synonym: echo-free. Origin: G. An-priv. + echo + ic (05 Mar 2000) |
| echo-planar imaging | A type of magnetic resonance imaging that uses only one nuclear spin excitation per image and therefore can obtain images in a fraction of a second rather than the minutes required in traditional mri techniques. It is used in a variety of medical and scientific applications. (12 Dec 1998) |
| echoacousia | A subjective disturbance of hearing in which a sound appears to be repeated. Origin: echo + G. Akouo, to hear (05 Mar 2000) |
| echoaortography | Application of ultrasound techniques to the diagnosis and study of the aorta. Origin: echo + aortography (05 Mar 2000) |
| echocardiogram | <investigation, radiology> A test which uses high-frequency sound waves to image the heart and surrounding tissues. (27 Sep 1997) |
| echocardiographic differentiation | The processing of a signal so that the output depends upon the rate of change of the input; e.g., it will display changes in amplitude but will reduce the duration of the waveform. (05 Mar 2000) |
| echocardiography | Echocardiography is a diagnostic test which uses ultrasound waves to make images of the heart chambers, valves and surrounding structures. It can measure cardiac output and is a sensitive test for inflammation around the heart (pericarditis). It can also be used to detect abnormal anatomy or infections of the heart valves. (12 Dec 1998) |
| echocardiography, doppler | Measurement of intracardiac blood flow using an m-mode and/or two-dimensional (2-d) echocardiogram while simultaneously recording the spectrum of the audible doppler signal (e.g., velocity, direction, amplitude, intensity, timing) reflected from the moving column of red blood cells. (12 Dec 1998) |
| echocardiography, doppler, colour | Echocardiography applying the doppler effect, with the superposition of flow information as colours on a gray scale in a real-time image. (12 Dec 1998) |
| echocardiography, doppler, pulsed | Echocardiography applying the doppler effect, with velocity detection combined with range discrimination. Short bursts of ultrasound are transmitted at regular intervals and the echoes are demodulated as they return. (12 Dec 1998) |
| atrial echo | Electrical reactivation of the atrium by a retrograde impulse returning from the A-V node while the antegrade impulse continues to the ventricle; characterised electrocardiographically, by a pair of P waves enclosing a QRS complex, the second P wave being inverted, indicating that it is the reverse (the retrograde pathway) of the pathway of the first P wave (the antegrade pathway). (05 Mar 2000) |
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| spin echo | A commonly used technique to recover T2 relaxation signals in magnetic resonance imaging, by using a 180 |
| nodus sinuatrialis echo | A postectopic sinus beat occurring earlier than would be expected from the preceding sinus node discharge interval; i.e., the interval following a premature beat of supraventricular origin is less than the ordinary cycle length between sinus beats, whereas ordinarily the interval would be expected to exceed cycle length. (05 Mar 2000) |