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Tue 2 Oct 2007 04:00 AM

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Skipping a beat — the surprise of palpitations

Palpitations are worrisome and are due to a variety of reasons, but usually aren't dangerous.

Most of us are blissfully unaware of the heart's steady thump as it contracts and relaxes nearly 100,000 times a day. Sometimes, though, we may notice that our heart has unexpectedly started to race or pound, or feels like it has skipped a beat. These sensations are called palpitations (pal-pih-TAY-shunz). For most people, palpitations are a once-in-a-blue-moon occurrence. Others have dozens a day, some so strong that they feel like a heart attack.

Most palpitations are caused by a harmless hiccup in the heart's rhythm. A few reflect a problem in the heart or elsewhere in the body. Sorting out worrisome palpitations from the harmless ones isn't always easy. Doctors can be quick to attribute them to anxiety, depression, or some other emotional or psychological problem. Although sometimes that's exactly right, it's important to first rule out harmful heart rhythms and other physical causes.

Some palpitations appear out of the blue and disappear just as suddenly.

A palpitation primer

Palpitations are extremely common. Although most people shrug them off, they worry many people enough to consult a primary care physician or cardiologist. Different people experience palpitations in different ways. They might feel as though their heart is fluttering, throbbing, flip-flopping, or pounding, or that it has skipped a beat. Some people feel palpitations as a pounding in the neck; others as a general sense of unease.

Some palpitations appear out of the blue and disappear just as suddenly. Others are linked with certain activities, events, or feelings. Exercise and physical activity can generate palpitations, as can anxiety or stress. Some people notice palpitations when they are drifting off to sleep; others, when they stand up after bending over. The list of possible causes is long.

Trouble from above. Some palpitations are the result of premature contractions of the atria. When the heart's upper chambers contract a fraction of a second earlier than they should, they rest an instant longer afterward to get back to their usual rhythm. This feels like a skipped beat, often followed by a noticeably forceful contraction as the ventricles clear out the extra blood they accumulated during the pause. These premature beats are almost always benign, meaning they aren't life-threatening or the sign of a heart attack in the making.

Trouble from below. Early contractions of the ventricles, the heart's lower chambers, can also cause palpitations. Single premature ventricular contractions, or a couple in a row, aren't usually a problem, unless they are accompanied by symptoms such as fainting or shortness of breath. Runs of them one after the other, though, are worrisome because of the possibility that they might degenerate into the deadly cardiac chaos known as ventricular fibrillation.

Other sources. Problems with the heart's timekeeper, called the sinus node, can cause palpitations. Another possible source is a breakdown in synchronisation between the upper and lower chambers.

Scar tissue in the heart from a heart attack or other injury can lead to palpitations, as can valve problems such as mitral valve prolapse.

Finding the source

Palpitations come and go. They are usually gone in the doctor's office. That makes pinning them down a joint effort. One of the most helpful pieces of information is the patient's account of how their palpitations feel, how often they strike, and when. The more details the patient can provide, the better. When a person has palpitations, they should try to gauge their heart's rhythm (is it fast or slow? regular or irregular?). Do they feel lightheaded, dizzy, or out of breath, or do they have chest pain? Are they often doing the same thing when they occur? Do they start and stop suddenly, or fade in and out? The patient's description of their general health, what they eat and drink, the medications they are taking - don't forget to ask about herbs and supplements - and their family history are also essential.

Triggering palpitations

Many things can generate palpitations. These include:

• Stress, anxiety, or panic
• Dehydration
• Low potassium
• Low blood sugar
• Too much caffeine, chocolate, or alcohol
• Nicotine
• Exercise
• Standing up
• Swallowing
• Fever
• Prior heart attack
• Mitral valve prolapse
• Anaemia
• Overactive thyroid
• Pregnancy
• Menopause
• Acid reflux (heartburn)
• Drugs and medications such as cocaine, amphetamines, diet pills, some cough and cold remedies, some antibiotics, thyroid hormone, digoxin, asthma medications, beta blockers, or anti-arrhythmics
• Dietary supplements such as ephedra, ginseng, bitter orange, valerian, or hawthorn

A physical exam can reveal telltale signs. When listening to a patient's heart, you may hear a murmur or other sound suggesting a problem with one of the heart's valves, which can cause palpitations. You may also discover a thyroid imbalance, signs of anaemia, low potassium, or other problems that can cause or contribute to palpitations. An electrocardiogram (ECG) is a standard tool for evaluating someone with palpitations. This recording of the heart's electrical activity shows its rhythm and any overt or subtle disturbances, but only over the course of 12 seconds or so. You may want to record your patient's heart rhythm for longer to identify the cause of the palpitations.

Most of the time, the exam and ECG don't turn up any problems. If palpitations aren't accompanied by dizziness or other symptoms, if the patient doesn't have a valve disorder or other structural problem with their heart, and if sudden death or other problems aren't lurking in their family tree, that usually means the palpitations aren't signs of impending doom.

If palpitations come with chest pain, you may want you to give your patient an exercise stress test. If they come with a racing pulse or dizziness, an electrophysiology study using a special probe inserted into the heart may be in order.

What to do

Searching for an underlying cause of palpitations holds out the possibility of halting them. The solution may be as simple as cutting back on caffeine or correcting anemia or a low potassium level, or as complicated as a procedure to destroy a small patch of cells inside the heart that gives rise to erroneous beats. Often, though, even the most thorough search doesn't turn up a fixable cause.

Drug therapy isn't necessarily required. Sure, there are several medications that beautifully suppress premature atrial or ventricular beats. But they tend to have unwanted side effects, and can cause more serious rhythm problems. Several older studies have shown that they may even shorten life compared with no treatment. For some people, a beta blocker or anti-anxiety medication can ease the problem without causing a new one.

If a person has unexplained palpitations, they should start with the simple things first: Cut back on caffeine, or give it up altogether, to see if it is contributing to the problem. Don't forget that many soft drinks pack a powerful jolt of caffeine. Smoking can cause palpitations, as can alcohol. Beware of over-the-counter decongestant medications that contain pseudoephedrine or phenylephrine. Make sure a person eats regularly (low blood sugar can cause palpitations) and drinks plenty of fluids. Sufficient sleep is essential.

Some people have palpitations when they exercise, especially as they cool down afterwards. This doesn't mean they should stop exercising. Instead, they should have an exercise stress test to look at their heart's response to physical challenges.

Stress and anxiety are two other key triggers of palpitations. A two-step approach can help here. Meditation, the relaxation response, exercise, yoga, tai chi, or other stress-busting activities may help keep palpitations away. If they do appear, breathing exercises or tensing and relaxing every muscle group in the body can ease the panic or anxiety spurred by palpitations that sometimes feeds into creating more of them.

Capturing the problem

Sometimes it's important to identify the source of palpitations. If your patient is at risk for a heart-rhythm problem or if palpitations are interfering with their life or mental health, recordings of the heart's rhythm that last longer than an ECG offer a way to capture an electrical signature of the problem.

A Holter monitor constantly records a person's heart's rhythm for 24 to 48 hours as they go about their daily activities. Small patches called electrodes are stuck onto the chest and attached to a recorder that's carried in a pocket or a pouch worn around the neck or waist. During the test, the patient should keep a diary of what they do (walked the dog, got angry at work) and how they feel (skipped heartbeats, dizziness) together with the time. When the patient returns the monitor to the doctor, he or she will look at the recording and see if there have been any irregular heart rhythms.

Sometimes, even 48 hours isn't long enough to spot the culprit. An event recorder can monitor the heart for weeks. These devices don't record every heartbeat. Instead, they store only the most recent minute or two. When patients notice a palpitation or other symptom, they press a button that freezes the recording, then send it by telephone or computer to your doctor. This information can help determine if palpitations stem from potentially harmful changes in the heart's rhythm.

There's even an implantable recorder that can invisibly monitor the heart for a year or more. It is inserted under the skin of the chest in a simple outpatient procedure. An activator the size of a credit card retrieves several minutes of the heart's electrical activity and sends it to a doctor to be analysed. An Italian study reported in the May 15 Journal of the American College of Cardiology showed that an implantable recorder was highly effective at detecting an underlying heart-rhythm problem in people with unexplained palpitations.

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Christine 8 years ago

Thank you for the excellent article. It's one of the best ones I've seen on palpitations.

anonymous 5 years ago

I agree. Well explained and thoroughly detailed.