Premature Ventricular Contractions (cont.)

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What happens during a premature ventricular contraction?

During a premature ventricular contraction, the ventricle electrically discharges (and contracts) prematurely before the normal electrical discharges arrive from the SA node. These premature discharges are due to electrical "irritability" of the heart muscle of the ventricles and can be caused by heart attacks, electrolyte imbalances, lack of oxygen, or medications. Immediately after a premature ventricular contraction, the electrical system of the heart resets. This resetting causes a brief pause in heartbeat, and some patients report feeling the heart briefly stopping after a premature ventricular contraction.

How common are premature ventricular contractions?

Premature ventricular contractions are common. Many people have premature ventricular contractions without any symptoms. Premature ventricular contractions may be more common among older patients, patients with high blood pressure, and patients with heart disease. Premature ventricular contractions can also occur in young healthy individuals without heart disease or high blood pressure.

What causes premature ventricular contractions?

There are many causes of premature ventricular contractions, which include:

  • heart attack;
  • high blood pressure;
  • cardiomyopathy, including congestive heart failure;
  • disease of heart valves such as mitral valve prolapse;
  • hypokalemia (low blood levels of potassium), and hypomagnesemia (low blood levels of magnesium) -- hypokalemia and hypomagnesemia can occur, for example, in patients taking diuretics (water pills);
  • hypoxia (low amounts of oxygen in the blood), for example, hypoxia occurs with lung diseases such as emphysema or chronic obstructive pulmonary disease (COPD);
  • medications such as digoxin (Lanoxin), aminophylline (Phyllocontin, Truphylline), tricyclic antidepressants, and ephedrine-containing, decongestants;
  • excessive intake of alcohol;
  • excess caffeine intake;
  • stimulant drug use such as cocaine, and amphetamines;
  • myocarditis (heart muscle inflammation) and cardiac contusion (heart muscle injury), and
  • premature ventricular contractions also occur in healthy individuals without heart diseases.
Medically Reviewed by a Doctor on 11/13/2013

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