Tuesday, April 17, 2007

When the Heart Skips, Flips, Flops or Flies

Oh, I've got rhythm, I've got music,
I got my girl, who could ask for anything more?
I've got rhythm, I've got rhythm ...

- George Gershwin

So your heart does not have perfect rhythm? You're not alone. It seems I’ve been seeing lots of folks recently with the unpleasant sensations of a racing, irregular or forceful beating of the heart in their chest, commonly called palpitations.

The diagnosis of palpitations can be perplexing if they occur very infrequently. It seems many doctors I work with almost always initially order a HOLTER MONITOR to evaluate an irregular or rapid heart rhythm. A Holter monitor records every heartbeat over (usually) a 24-hour period. The newer Holter monitors record the electrocardiogram signal digitally and are less prone to artifact caused by variations in tape speed seen with older monitors that recorded the electrocardiogram signals to recording tape. Patients are asked to record the time of any symptoms they experience on a diary to include with the recording. Unfortunately, if you do not have symptoms the day the Holter is connected, a diagnosis for your symptoms is unlikely to be identified.

More often, I have found that an EVENT RECORDER (this example: Del Mar Reynolds Medical) is more reliable at capturing the cause of intermittent palpitations. This device is about the size of a pager and continuously records your electrocardiogram from two small electrodes attached to your chest in a continuous loop-like fashion. Your heart rhythm activity is recorded in a memory buffer that continuously refreshes new heart rhythm information over old information, thereby always haveing the last minute of heart rhythm in its memory. When a symptom strikes, you can push a button on the top of the device to lock the preceding minute of the heart rhythm in the memory of the device while it records an additional minute of the electrocardiogram. Later, at a time that is convenient, the signal can be transmitted via any phone line to a reading site. The nice thing about event recorders is they ae usually issued for a month at a time, making them especially useful for intermittent rhythms. Some newer companies have event recorders that are even disposable, eliminating the administrative overhead of retrieving the devices and reducing the number of trips the patient needs to make to the office.

HEART CARDS (First Call Medical), a small credit-card sized device with four electrodes on the back of it, are not my favorite recording device. While its advantages are that it is small, it only records what the heart is doing at the time the device is held to the skin over the chest. Women are not likely to use this device for obvious reasons. While patients complain to be that this can be embarrassing to use in a public space since the device emits a tone as it records, their problems are offset, to some extent, by their simplicity.

If these devices are ineffective and the diagnosis remains elusive, a rarely used device can often succeed where other devices fail: an IMPLANTABLE LOOP RECORDER (Medtronic, Inc.). This device is surgically implanted beneath the skin in a minor same-day surgical procedure under local anesthesia. Like the event recorder, it continuously records the electrocardiogram from two small electrodes on the device. If the patient feels a rhythm, they can place a small “actuator” over the device and lock the rhythm occurring before and after the symptom within the device’s computer memory. Perhaps the best feature of this device is that it can be set to “auto-trigger” for heart rhythms above or below a set cut-off value, making the need for a patient to have to capture the rhythm unnecessary. This is particularly useful for older patients. One drawback to this device is that monthly visits to your doctor should be performed to check the memory of the device to see if there is was a rhythm stored within its memory that was not perceived. Since the device only holds the last 5 episodes in its memory, heart rhythm abnormalities not perceived by the patient might be missed otherwise. Battery life of the device typically lasts 14 months and most people opt to have the device surgically removed after that time.

So next time you feel your heart doesn't have rhythm, you can always "ask for anything more."

Like one of the devices above.

-Wes

1 comment:

Coimbatore Ramakrishna said...

Those are interesting medical instruments. Sadly not available or affordable by our people in India.

Good and nice to see a cardiologist finding time to write here. My heart stays warm :-)