When you take your pulse, you are actually measuring the beats of your heart. Each time your heart contracts, blood is forced into the aorta, creating a wave of pressure that moves swiftly through all the arteries. At the pulse points – the sites where large arteries lie near the surface of your body – you can feel the regular throbbing in the blood caused by the contractions of your heart.
These pulse points, which are shown in the drawings at left, are found in arteries at the temples and jaw, in the neck and arms, at the wrists, groin, and insteps, and behind the knees. Normally, pulse rates at rest range from 60 to 90 per minute, but they may be higher or lower and still be healthy.
To find your own pulse, place the fingertips of one hand lightly on the opposite wrist near the base of your thumb, and move them around until you can feel the throb of the artery.
Special Tests That May Reveal Cardiovascular Disease
The treadmill test is important because some abnormalities in the heart’s electrical activity show up only when the heart muscle is pumping hard. In this test, the subject paces on a motorized treadmill while an electrocardiogram monitors his heart. Another diagnostic technique is the coronary arteriograph, or angiogram, in which a thin plastic tube, or catheter, is inserted into a blood vessel and pushed through to the heart.
The tube delivers a dye to the heart, and X rays record the progress of the dye n the blood, producing a precise reading of congenital defects, heart leaks, arterial blockages, and valve malfunctions.
Sometimes nuclear scanning is used instead, to provide the same information without the need for a catheter. In this case, radioactive thallium is injected into the blood and traced by camera. A computer then converts the data into an image of the beating heart on a screen. Still another technique, the echocardiogram, uses methods rather like underwater sonar also to project an image of the heart on a screen.
The heart of a Masai warrior shows great strength in a treadmill test. Researchers credit his active life-style.
Bleeding as a Remedy
For hundreds of years, draining blood was the remedy for ailments as diverse as amnesia, deafness, and stroke. It was theorized that in disease blood stagnated in certain parts of the body and that letting blood out revitalized patients. In practice, these “cures” often bled patients white, weakening them and sometimes killing them. The techniques included applying leeches, cutting open a blood vessel, using suction cups to form blood blisters.
In the 1860s, bleeding was discredited, but now doctors are reinvestigating bloodletting. In certain micro surgery, leeches have removed excess blood from tissue that would otherwise clot and impede repair. And some disorders are caused by too-thick blood – in one technique, blood is drawn and replaced with plasma, to dilute it.
In medieval times, bloodletting was accomplished by barber-surgeons, who frequently would cut open a vein at the site of the disorder.