wave
[wāv] 1. a uniformly advancing disturbance in which the parts undergo a change in direction, such as a progressing disturbance on the surface of a liquid.
2. variation in the transmission of electromagnetic energy, especially the periodic change in direction of a reading on a monitoring device.
A wave the wave on a His bundle electrogram that represents atrial activation.
alpha w's brain waves having a frequency of 8 to 13 per second, typical of a normal person awake in a quiet resting state; they occur primarily in the occipital region.
B wave a sharp rhythmic oscillation with a sawtooth pattern, occurring every 30 seconds to two minutes during
intracranial pressure monitoring, associated with unstable increases in pressure.
beta w's brain waves having a frequency of 18 to 30 per second, typical during periods of intense central nervous system activity; they occur primarily in the parietal and frontal regions.
brain w's changes in electric
potential of different areas of the brain, as recorded by
electroencephalography. See also
alpha,
beta,
delta, and
theta waves.
delta w's 1. brain waves having a frequency below 3½ per second, typical in deep sleep, in infancy, and in serious brain disorders.
dicrotic wave the second portion of the tracing of a
sphygmograph of the arterial pulse or arterial pressure after the
dicrotic notch, attributed to the reflected impulse of closure of the aortic valves. Called also
recoil wave electromagnetic w's the entire series of ethereal waves, which are similar in character and move at the speed of light but vary enormously in wavelength. The unbroken series is known from
radio waves that may be many kilometers in length through
light waves,
ultraviolet rays,
x-rays, and
gamma rays, to the cosmic rays, whose wavelength may be as short as 40 femtometers (4 × 10
−14 m).
P wave a positive deflection in the normal surface electrocardiogram produced by the wave of excitation passing over the atria; it represents atrial
depolarization, an intrinsic atrial event.
papillary wave (
percussion wave) the chief ascending portion of the tracing of a
sphygmograph.
pulse wave the elevation of the pulse felt by the finger or shown graphically in a recording of pulse pressure.
Q wave in the QRS complex, the initial electrocardiographic downward (negative) deflection, related to the initial phase of
depolarization.
R wave in the normal surface electrocardiogram, the initial upward deflection of the QRS complex, following the Q wave; it represents ventricular
depolarization. In
cardiac pacing, it may be the entire native or intrinsic QRS complex.
radio w's electromagnetic waves of wavelength between 10
−1 and 10
6 cm and frequency of about 10
11 to 10
4 hertz.
S wave a downward deflection of the QRS complex following the R wave in the normal surface electrocardiogram.
sonic w's audible sound waves.
sound w's longitudinal waves of mechanical energy that transmit the vibrations interpreted as
sound (def. 2).
T wave the second major deflection of the normal surface electrocardiogram, reflecting the potential variations occurring with
repolarization of the ventricles.
theta w's brain waves having a frequency of 4 to 7 per second, occurring mainly in children but also seen in adults under emotional stress.
ultrasonic w's waves similar to
sonic waves but of such high frequency (20,000 hertz or higher) that the human ear does not perceive them as sound; see
ultrasonics. Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.