Premature Ventricular Contraction (PVC)

A premature ventricular contraction is also called an extra systole. PVCs are originated inside the heart below the Atrio-ventricular node (A-V node), more specifically in the lower chambers area, known as ventricles. In there, a condition of abnormal irritability of an area of the soft ventricular tissue causes the interruption of the normal heart beating and leads to an irregular pumping rhythm.

Premature ventricular contractions are usually harmless if they occur as isolated incidents, but if they happen frequently a treatment must be applied, because the repetition of episodes of PVCs can cause much more serious heart rhythm anomalies, particularly if there is an underlying cardiac disease present.

Pathophysiology Of Premature Ventricular Contraction

A premature ventricular contraction can be activated by several types of mechanisms, being the main three: enhanced automaticity of the muscle, triggered activation and electricity re-entry.

Enhanced automaticity often suggests an ectopic group of pacemaker cells in the ventricle area that can fire a muscle contraction. Normal heart beating causes these cells to fire an extra beat. This whole process is the underlying cause of arrhythmias due to hyperkalemia and other electrolyte deficiencies, as well as those produced by an excess of catecholamines.

Triggered activation of a premature ventricular contraction happens as a result of the action of medications, particularly digoxyn. This is frequent in people who were treated for myocardial infarction.

Reentry usually happens on patients with an underlying heart disease (often ischemia) that creates an extra path of slow electricity conduction to the ventricle area. After a normal beat, when the ventricle recovers, an extra electric pulse reaches and activates the area, which results in a premature ventricular contraction.

Causes Of Premature Ventricular Contraction

This heart disease has several causes, most of them related to previous diseases. Causes of premature ventricular contraction (PVC) include: Acute myocardial infarction, ischemia, myocarditis, dilated or hypertrophic cardiomyopathy, myocardial contusion, prolapse of the mitral valve, hypoxia, hypercapnia, various types of medications (for instance aminophylline, digoxin, tricyclic antidepressants and sympathomimetics, like ephedrine), harmful substances (for instance, cocaine, amphetamines, nicotine and alcohol) and several electrolytic deficiencies, like hypomagnesemia, hypercalcemia and hypokalemia, among others. Prevention of these causes by a healthy diet and a healthy lifestyle also helps in preventing PVCs.

Symptoms And Treatment Of Premature Ventricular Contraction

Although patients usually don’t show symptoms, there are some that experience chest or neck pain, palpitations and even dizziness and lightheadedness, which indicates hemodynamic compromise.

As said above, premature ventricular contraction usually doesn’t require treatment. However, when it does, the treatment is focused on solving the underlying cause of the PVC. Also, as an ECG can detect the problem easily, it is recommended for everyone to include an ECG in their regular routine medical checks, in order to detect every possible heart problem early.

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