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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.
C wave in intracranial pressure monitoring, a small rhythmic oscillation in pressure that occurs every four to eight minutes.
1. brain waves having a frequency below 3½ per second, typical in deep sleep, in infancy, and in serious brain disorders.
2. an early QRS vector in the electrocardium in wolff-parkinson-white syndrome.
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.
plateau wave a wave seen during intracranial pressure monitoring in advanced stages of increased pressure, signaling hypoxia of the brain cells.
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.
QRS wave QRS complex.
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 106 cm and frequency of about 1011 to 104 hertz.
recoil wave dicrotic wave.
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.
tidal wave the wave after the percussion wave on a sphygmograph recording; the second elevation of the tracing, preceding the dicrotic wave.
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.
See QRS complex.
QRS complex, QRS wave
a group of waves depicted on an electrocardiogram; it actually consists of three distinct waves created by the passage of the cardiac electrical impulse through the ventricles and occurs at the beginning of each contraction of the ventricles. In a normal electrocardiogram the R wave is the most prominent of the three; the Q and S waves may be extremely weak and sometimes are absent.