Also known as throbbing. An appearance seen or felt naturally below the fourth and ?fth ribs on the left side, where the heart lies, and also at every point where an artery lies close beneath the surface. In other situations, it may be a sign of ANEURYSM. In thin people, pulsation can often be seen and felt in the upper part of the abdomen, due to the throbbing of the normal abdominal AORTA.
Areas on the head on which bone has not yet formed. The chief of these is the anterior fontanelle, situated on the top of the head between the frontal and two parietal bones. In shape it is four-sided, about 25 mm (1 inch) square at the time of birth, gradually diminishing until it is completely covered by bone, which should happen by the age of 18 months. The pulsations of the brain can be readily felt through it. Delay in its closure is particularly found in cases of RICKETS, as well as in other states of defective development. The fontanelle bulges in raised intracranial pressure from HYDROCEPHALUS and MENINGITIS, and depressed in DEHYDRATION.... fontanelle
If the tip of one ?nger is laid on the front of the forearm, about 2·5 cm (one inch) above the wrist, and about 1 cm (half an inch) from the outer edge, the pulsations of the radial artery can be felt. This is known as the pulse, but a pulse can be felt wherever an artery of large or medium size lies near the surface.
The cause of the pulsation lies in the fact that, at each heartbeat, 80–90 millilitres of blood are driven into the AORTA, and a ?uid wave, distending the vessels as it passes, is transmitted along the ARTERIES all over the body. This pulsation falls away as the arteries grow smaller, and is ?nally lost in the minute capillaries, where a steady pressure is maintained. For this reason, the blood in the veins ?ows steadily on without any pulsation. Immediately after the wave has passed, the artery, by virtue of its great elasticity, regains its former size. The nature of this wave helps the doctor to assess the state of the artery and the action of the heart.
The pulse rate is usually about 70 per minute, but it may vary in health from 50 to 100, and is quicker in childhood and slower in old age than in middle life; it is low (at rest) in physically ?t athletes or other sports people. Fever causes the rate to rise, sometimes to 120 beats a minute or more.
In childhood and youth the vessel wall is so thin that, when su?cient pressure is made to expel the blood from it, the artery can no longer be felt. In old age, however, and in some degenerative diseases, the vessel wall becomes so thick that it may be felt like a piece of whipcord rolling beneath the ?nger.
Di?erent types of heart disease have special features of the pulse associated with them. In atrial FIBRILLATION the great character is irregularity. In patients with an incompetent AORTIC VALVE the pulse is characterised by a sharp rise and sudden collapse. (See HEART, DISEASES OF.)
An instrument known as the SPHYGMOGRAPH registers the arterial waves and a polygraph (an instrument that obtains simultaneous tracings from several di?erent sources such as radial and jugular pulse, apex beat of the heart and ELECTROCARDIOGRAM (ECG)) enables tracings to be taken from the pulse at the wrist and from the veins in the neck and simultaneous events in the two compared.
The pressure of the blood in various arteries is estimated by a SPHYGMOMANOMETER. (See BLOOD PRESSURE.)... pulse
n. the destruction of a fetus in the uterus by injection of potassium chloride into the fetal heart to stop any pulsation and other signs of life before induced abortion and following premedication to the mother. This is usually performed to achieve a late-stage termination of pregnancy (after 21 weeks), for example because of major abnormalities in the fetus.... feticide
Health Encyclopedia