THE ELECTROCARDIOGRAM (ECG)

The ECG is used to evaluate the cardiac electrical system.  The ECG is an invaluable tool and provides a wealth of information about the heart and heart function, and it does not require any needles.  Shown here is a short ECG strip that includes 3 heart beats.  Each heart beat is composed of three waves.  The first is a small wave, called the “activation” wave and occurs when the SA node fires.  As the electrical impulse spreads across the atria the atria contracts and sends blood down into the ventricles.  The sharp wave occurs when the ventricles contract, sending blood out into the body.  Third wave is called the “recharge” wave and indicates the heart is ready for the next beat.  I don’t expect anyone to become an ECG reader, but it helps to have a mental picture of an ECG tracing and appreciate how useful it is in the management of the cardiac patient.  Virtually every TV show of the emergency room will include a picture of the monitor showing the ECG.  We like to see a nice regular heart rate on the monitor similar to what is shown here.  A skipping, erratic heart beat may mean the presence of an underlying heart problem requiring further evaluation.

Bradycardia and Tachycardia:  These are two terms that are often confusing.  The normal heart rate is between 60 and 100 beats per minute.  A heart rate below 60 is called Bradycardia (slow heart) and over 100 is called Tachycardia (like Tachyometer).   Bradycardia and tachycardia are technically abnormal, but not necessarily an indication of underlying heart disease.  For example a heart rate of a normal person may drop below 60 during sleep and greater than 100 during exercise, but we consider these to be normal physiologic responses.  However, persistently high or low heart rates should be evaluated by the doctor.

Taking the Pulse:  All of us should know how to find and count our pulse rate or heart rate.   We should also be able to find and take the pulse of another person to determine if the heart is pumping.  When you take a pulse you are feeling the pulsation of an artery (there is no pulse in veins) so you need to know the easiest place to find the pulse.  Large arteries are found on both sides of the neck beside the voice box, and in the groin between the hip joint and the pubic bone.  You should find these arteries on yourself while lying quietly in bed and count your pulse.  Use your watch and count the number of beats in 10 seconds and multiply by 6.  The artery in the wrist is found just above the base of the thumb in a groove next to a tiny bone in the wrist.  Use one or two fingers to feel for the pulse and not your thumb because our thumbs have a pulse of their own.