P wave(redirected from P-wave)
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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.
the first complex of the electrocardiogram, during sinus and atrial rhythms, representing depolarization of the atria; if the P wave is retrograde or ectopic in axis or form, it is labeled P'.
the component of the cardiac cycle shown on an electrocardiogram as an inverted U-shaped curve that follows the T wave and precedes the QRS complex. It represents atrial depolarization.
P waveCardiac pacing The electrocardiographic representation of atrial depolarization
Waveform in an electrocardiogram tracing representing atrial depolarization.
1. A disturbance, usually orderly and predictable, observed as a moving ridge with a definable frequency and amplitude.
2. An undulating or vibrating motion.
3. An oscillation seen in the recording of an electrocardiogram, electroencephalogram, or other graphic record of physiological activity. See: illustration
1. A venous neck wave produced by atrial contraction.
2. A component of right atrial and pulmonary artery wedge pressure tracings produced by atrial contraction. The a wave just precedes the first heart sound. It is absent in atrial fibrillation and is larger in atrioventricular dissociation and in conditions causing dilation of the right atrium.illustration
The wave produced after the action potential wave passes along a nerve. On the recording of the electrical activity, it will be either a negative or positive wave smaller than the main spike.
An electroencephalographic deflection often generated by cells in the visual cortex of the brain. See: alpha rhythm
An electroencephalographic deflection. Its frequency is between 18 and 30 Hz. See: beta rhythm
A shock wave produced by a blast or explosion. The wave front consists of air under very high pressure that can cause great damage to people, objects, and structures.
The fluctuation, usually rhythmic, of electrical impulses produced by the brain.See: electroencephalography
A component of right atrial and pulmonary capillary wedge pressure waves. It reflects the closing of the tricuspid valve at the beginning of ventricular systole. An abnormal configuration is seen in increased right heart pressure and with abnormalities of the tricuspid valve.
An abnormal deflection seen on the electrocardiogram in patients with pre-excitation syndromes, such as Wolff-Parkinson-White syndrome. It occurs at the beginning of the QRS complex and is classically described as causing the complex to have a "slurred upstroke."
A positive wave following the dicrotic notch.
A wave-form produced by simultaneous oscillation of electric and magnetic fields perpendicular to each other. The direction of propagation of the wave is perpendicular to the oscillations. The following waves, in order of increasing frequency and decreasing wavelength, are electromagnetic: radio, television, microwave, infrared, visible light, ultraviolet, x-rays, and gamma rays.See: electromagnetic spectrum for table
The wave of irritability originating in the sinoatrial node that sweeps over the conducting tissue of the heart and induces contraction of the atria and ventricles.
Flutter waves in atrial fibrillation, detectable on the electrocardiogram at 250 to 350 per minute.
A fibrillatory wave seen as the wavy base line on the electrocardiogram tracing of atrial fibrillation. These waves are caused by multiple ectopic foci in the atria.
An upwardly curving deflection of the J point of the electrocardiogram, found in patients whose body temperature is less than 32°C. This finding is one cardiac effect of hypothermia. The J wave has a particular shape; viewed from above, its surface is convex. Synonym: Osborne wave
An electromagnetic wave that stimulates the retina or other optical sensors.
Mayer waveSee: Mayer wave
Osborne waveJ wave.
P waveSee: electrocardiogram
A recoil or second wave (not always present) in a blood pressure tracing.
The pressure wave originated by the systolic discharge of blood into the aorta. It is not due to the passage of the ejected blood but is the result of the impact being transmitted through the arterial walls. The velocity in the aorta may be as high as 500 cm/sec and as low as 0.07 cm/sec in capillaries. The speed of transmission varies with the nature of the arterial wall, increasing with age as the arteries become less resilient. Thus in arteriosclerosis, the velocity is increased over normal.
A downward or negative wave of an electrocardiogram following the P wave. It is usually not prominent and may be absent without significance. New Q waves are present on the electrocardiogram after patients suffer myocardial infarction.See: electrocardiogram
R waveSee: electrocardiogram
An electromagnetic wave between the frequencies of 1011 and 104 Hz.
S waveSee: electrocardiogram
1. A compression wave produced by a shock such as an earthquake or explosion that is characterized by a sudden change in air pressure, density, and velocity.
2. An electromagnetic or sonic shock wave focused at a specific target (e.g., within the body).
A vibration of a vibrating medium that, on stimulating sensory receptors of the cochlea, is capable of giving rise to a sensation of sound. In dry air, the velocity is 1087 ft (331.6 m)/sec at 0°C; in water, it is approx. four times faster than in air.
The portion of the electrical activity of the heart that reflects repolarization of the ventricles.See: electrocardiogram; interval, Q-T
A brain wave present in the electroencephalogram. It has a frequency of about 4 to 7 Hz.
In the electrocardiogram, a low-amplitude deflection that follows the T wave. It is exaggerated in hypokalemia and with digitalis use, and negative in ventricular hypertrophy.See: QRST complex; electrocardiogram
An arbitrary designation of radio waves of a wavelength of less than 1 m.
A sound wave of greater frequency than 20 kHz. These waves do not produce sound audible to the human ear.
a uniformly advancing disturbance in which the parts undergo a double oscillation, as a progressing disturbance on the surface of a liquid or the rhythmic variation occurring in the transmission of electromagnetic energy.
changes in electric potential of different areas of the brain, as recorded by electroencephalography.
the entire series of ethereal waves which are similar in character, and which move with the velocity of light, but which vary enormously in wavelength. The unbroken series is known from the hertzian waves used in radio transmission, which may be miles in length (one mile equals 1.6 × 105 cm), through heat and light, the ultraviolet, x-rays, and gamma rays of radium to the cosmic rays, the wavelength of which may be as short as 40 femtometers (4 × 10−14 nm).
1. a muscle action potential seen on electromyographs; attributed to antidromically conducted motor nerve action potentials.
2. bidirectional, saw-toothed waves on an electrocardiographic tracing characteristic of atrial flutter.
the electromagnetic waves that produce sensations on the retina. See also vision.
swirling motion in a drop of dense semen when viewed microscopically (100 × magnification). The intensity and rapidity of the swirling is a reflection of the concentration of the spermatozoa and their level of motility. Called also mass activity.
a deflection in the normal electrocardiogram produced by the wave of excitation passing over the atria.
positive sharp wave
an electromyographic tracing associated with denervation and some types of primary muscle disease.
the elevation of the pulse felt by the finger or shown graphically in a recording of pulse pressure.
in the QRS complex, the initial electrocardiographic downward (negative) deflection, related to the initial phase of depolarization.
the initial upward deflection of the QRS complex, following the Q wave in the normal electrocardiogram.
a downward deflection of the QRS complex following the R wave in the normal electrocardiogram.
the second major deflection of the normal electrocardiogram, reflecting the potential variations occurring with repolarization of the ventricles.
T wave abnormalities
a common finding in horses whose racing performance worsens. The cause is not identified but may be related to overtraining and the racing of unfit horses. Most animals recover spontaneously with rest. The validity of these abnormalities is now widely doubted.