Mark Fingerle, age 13, of Sarasota, Florida, for his question:
What is an electrocardiograph?
The "cardio" syllable refers to the heart, the "graph" means a diagram and the "electro" indicates that some form of electricity is involved in the operation. When the pieces are assembled properly, they become an electrocardiograph which is capable of reporting the various impulses created by the beating heart. Other attachments record the diagram called the electrocardiogram, the ECG or the EKG.
The electrocardiograph works because the beating heart creates a pattern of electrical impulses and way back in 1903, a Dutch physiologist named Willem Einthoven invented his famous string galvanometer to measure such delicate impulses. In the 1920s, the first model brought to the United States weighed a quarter of a ton. Naturally the electrocardiograph has been refined and improved since that time. Up¬to date models weigh 30 pounds or less.
Doctors and operating rooms use different models to record the impulses on paper or as moving pictures on TV type screens. But the inner workings of the electrocardiograph depend on the same type of sensitive galvanometer. It picks up and relays the electrical impulses that originate in the beating heart. It works because it is super sensitive to the magnetic fields that surround all electric currents and the heart impulses are spurts of electric current. The pulsing pattern is amplified and magnified by a system of mirrors and lenses.
The signature of a healthy heart is a wavy line with steep, high peaks at regular intervals. Several methods are used to report the pattern in readable form. A stylus may write it on paper. A heated stylus may record it on specially coated paper. In an operating room, surgeons need to keep a close eye on the patient's heartbeat. The electrocardiograph may be fitted with an oscillograph to take photographs and other equipment to relay a moving picture to a screen. The surgery team can glance at the oscilloscope screen to watch how the patient's heart is performing.
We often see this dramatic electrocardiograph performing in medical type TV shows. But the more modest models that deliver plain pictures do more of the basic work in clinics and doctors' offices. A doctor or technician can recognize the EKG signature of a healthy heart at a glance. Any slight variation in the normal pattern may indicate heart trouble and sometimes pinpoint where and what the trouble is.
The impulses from the patient are conveyed to the electrocardiogram by electrodes and a system of electrical wiring. An electrode may be placed on each arm, on the legs or certain parts of the chest. From there, the galvanometer measures the fluctuating current that originates in the beating heart and spreads through the muscles. The amplified picture is watched by a technician and regulated by dials.