Your heart starts beating very fast, with that pounding sensation as if it would jump out of your mouth and break free. When you seek medical advice, or even go to the emergency department, the sensation suddenly is gone.
This is where an exam called holter monitoring can be very useful. This device is also known as an ambulatory electrocardiogram, in the sense that your electrocardiogram, or the electrical signals generated by the heart, is recorded while you are moving around.
The first devices were rather cumbersome and bulky, the electrocardiogram was recorded on a cassette tape. Now everything is fitted into a computer chip, and the battery-operated device is about the size of a postcard or a tiny digital camera. Tiny wires connect the monitor to electrodes placed on your chest, and the monitor is usually attached to a belt. It continuously records the heart's electrical activity for 24 to 48 hours. The newer models can record up to two weeks.
The main disadvantage is that usually you cannot have a bath during that period. Patients are encouraged to write a diary describing all symptoms they experience while wearing the device, when they occurred, and what activities were performed when the symptoms appeared. It is very important to mention chest pain, changes in heartbeat and dizziness.
After the test period, the doctor will download the information to a computer that will analyze the heart rhythm and count the type and number of irregular heartbeats. The results will be compared to the written symptom diary to help diagnose any heart problems.
Some symptoms increase the likelihood of your doctor ordering a holter monitoring, such as a fast, pounding heartbeat, as mentioned in the introduction, a very slow or irregular heartbeat, shortness of breath, dizziness, or chest pain that is not associated to exercise.
The test can also be ordered to know how a pacemaker is working. The test can diagnose fits of atrial fibrillation, a rapid, irregular heartbeat that is a very frequent cause of stroke. It can also reveal bouts of ventricular tachycardia, a very fast heart rate that can degenerate into cardiac arrest and death.
Other findings are cardiac arrhythmias in general, conduction disorders, and heart block (very slow rates leading to faints and blackouts). The test is painless and relatively inexpensive.
Apart from being unable to bathe, shower or swim, it might be a good idea to keep away from magnets, metal detectors, and high-voltage electrical wires. So this particular kind of journal can be very helpful indeed, sometimes even saving lives.
MICHAEL ROY SMITH, M.D.