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Premature Ventricular Contractions (PVCs)
Palpitations are feelings that your heart is skipping a beat, fluttering, or beating irregularly, too hard or too fast. Some will be diagnosed by your doctor as Premature Ventricular Contractions (PVCs). PVCs are an arrhythmia and relatively common. Some people are very sensitive and feel every abnormal heart beat; others are blissfully unaware of them.
PVCs are extra electrical impulses arising from one of the cardiac ventricles, usually the left ventricle. They are easily detected on an EKG. Sometimes the presence of PVCs indicates an inherent electrical instability in the heart, and therefore indicates an increased risk of sudden death. These “dangerous” PVCs are generally limited to patients with significant underlying heart disease, such as coronary artery disease or valve disease.
More often, PVCs do not indicate any inherent problem with electrical stability, and are completely benign.
PVCs may indicate the presence of underlying heart disease. If a patient has NO significant underlying heart disease, PVCs are probably not dangerous. Most "anti-arrhythmic" drugs are relatively poor at treating PVCs (though they often reduce their frequency.) and can make dangerous arrhythmias more likely. Doctors and patients should thus be very reluctant to treat PVCs with drugs other than Beta blockers (drugs that block the effect of adrenaline). Since Beta-blockers are generally well tolerated and do not make the arrhythmia worse, they are often worth a try. However, patients with NEW palpitations should be checked because that may indicate something serious may have happened to their heart.
In general, patients should try to eliminate caffeine, tobacco and alcohol usage, as it may reduce the frequency of PVCs.
Thus, PVCs sometimes are a marker for underlying cardiac diseases that may be dangerous!
- A variety of underlying cardiac conditions, including coronary artery disease, cardiomyopathy, mitral valve prolapse, etc.
- Abnormal levels of "electrolytes" (minerals) in the blood. Decreased potassium and/or magnesium are the most common associated abnormalities of electrolytes. Both may be caused by the use of diuretics (water pills), among other reasons.
- There are unusual congenital (familial) causes of ventricular arrhythmias.
- Abnormal conditions such as increased thyroid hormones, and others.
- Toxins, including alcohol.
- Stimulants including Caffeine, Nicotine, Cocaine and some over-the-counter medications and herbal/natural formulations contain important stimulants.
- Infection, inflammation or degeneration of the heart muscle.
- Infections at other sites in the body.
- They are often worse with lack of sleep, or stress.
Tests of electrolyte levels, thyroid levels, and other blood tests are frequently done.
An electrocardiogram is necessary to make the diagnosis of PVCs. Since PVCs don’t always occur when one is looking for them, several other means have been developed to assess the frequency and severity of the process in some cases. Holter monitors and event monitors may be useful.
An echocardiogram can assess the function and structure of the heart muscle and it’s valves.
Stress ECHO testing can be completed to assess not only for the possible presence of blockage of the heart arteries (coronary artery disease), but also to see whether more arrhythmias occur with exercise.
Cardiac catheterization, utilizing catheters to measure the pressures in the heart and inject dye in some of its structures, can be very useful in determining the presence of possible associated heart diseases. This is not a routine part of the evaluation, however.
Electrophysiology testing (EPS) can be very informative in some cases. It can be utilized in certain circumstances where the results of the above tests are unrevealing. These studies are performed in the hospital in a suite similar to a heart cauterization lab. Catheters are inserted in veins and/or arteries and advanced to the heart where very precise recordings of the electrical activity can be obtained. In some cases, catheters are also used to stimulate the electrical system to see if abnormal beats can be "induced".
Beta-blockers (there are many of them) have been shown to cut down both on symptomatic PVC’s in some patients, as well as decrease the risk of sudden death in high-risk patients. In terms of treatment for the palpitations associated with PVC’s, they can often be quite effective but do have side effects that may require their discontinuation.
Specific anti-arrhythmic drugs are designed to cut down on the number of PVC’s by altering the electrical properties of the cardiac muscle. Every "anti"-arrhythmic however, has its own "pro"-arrhythmic properties which have the potential to make the rhythm worse, sometimes dangerously worse. Many trials of medications designed to improve the survival of some types of patients with ventricular arrhythmias actually did the opposite. These drugs have to be used carefully in selected patients who will also need to be monitored closely.
Ask Doctor T. Blog
My 12 yr old son (140cm, 38kg) had a recent episode last month of sudden fainting, hit the back of his head on the concrete at high speed. Was unconscious for under a minute. Went to emergency via ambulance and his ECG showed QT prolonged 492ms. Question 1.Could the knock on his head of caused this ? (he did have a previous episode of unconsciousness but it was...