Premature ventricular contraction

Premature ventricular contraction (PVC), also known as ventricular premature beat (VPB) or extrasystole, is a form of irregular heartbeat in which the ventricle contracts prematurely. This is mistakenly felt as a "skipped beat", although this is a misnomer. The premature beat merely increases the refractory period and the following beat is stronger due to increased intake of blood into the ventrical during the extended period. Individuals with the condition may also report feeling that his or her heart "stops" after a symptom. This is also false as the heart does not "stop". PVCs are also called heart palpitations (although there are many other forms of arrhythmia). The depolarization begins in the ventricle instead of the usual place, the sinus node. PVCs can be a useful natural probe, since they induce Heart rate turbulence whose characteristics can be measured, and used to evaluate cardiac function.

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Frequency

PVCs are the most common form of arrhythmia, and can occur in both individuals with and without heart disease. They can also occur in otherwise healthy athletes (e.g. in the days following a major effort such as a marathon). Estimates of the prevalence of PVCs vary greatly.

In children, PVCs occur less frequently than in adults, although healthy children are known to have episodes of PVC. In fact, on routine monitoring of children aged 10-13 years with a Holter monitor, about 20% of healthy boys had occurrences of PVC. In otherwise healthy newborns, PVCs will often resolve on their own by the 12th week of life, and almost never require treatment.

In people who work swing shifts and nights, studies have shown as high as 40% have PVCs. Most people over 40 years of age have PVCs whether they realize it or not.

Causes

For benign PVCs, anxiety is the most common cause. Increased levels of adrenaline are thought to play a role, often caused by caffeine, exercise or anxiety. Some other possible causes of PVC in adults include the use of cocaine, amphetamines, alcohol, and tobacco. Medicines including digoxin, sympathomimetics, tricyclic antidepressants, and aminophylline have also been known to trigger attacks of PVC. ^[1]

Heart conditions or a previous history of heart attack, ischemia, myocarditis, dilated or hypertrophic cardiomyopathy, myocardial contusion, atrial fibrillation and mitral valve prolapse may cause PVC. Patients with hypomagnesemia, hypokalemia, and hypercalcemia may also present with PVC.

PVCs in young children are thought to be associated with developmental factors of the autonomic nervous system. In older children, sympathomimetic drugs, such as cold or asthma medication may cause PVCs, along with mild cases of viral myocarditis.

Diagnosis

PVCs are diagnosed by an ECG or a TMT but some patients will need to wear a Holter monitor to record PVCs that occur outside the doctor's office or hospital. PVCs are often benign but may be a sign of a heart condition. PVCs may be unifocal (coming from the same part of the heart and having the same shape on the ECG) or multifocal (coming from several parts of the heart and having various shapes on the ECG). On the ECG, PVCs are diagnosed by: 1. prematurity 2. wide QRS 3. the presence (usually) of a compensatory pause.

In healthy individuals, PVCs can often be resolved with continuous rehydration and by repleting the balance of magnesium, calcium and potassium within the body.

Possible triggers

• Anxiety/Stress
• Chocolate
• Caffeine
• Calcium/magnesium imbalance
• Dehydration
• Exercise
• Hormonal imbalance
• Hypercapnia (CO₂ poisoning)
• Hyperstimulation of the Vagus nerve
• Lack of sleep/exhaustion
• Overeating
• Low copper
• MSG

Treatment

If asymptomatic, no treatment may be necessary

• Medicinal/supplements
  • Magnesium supplements (e.g. magnesium citrate, orate, etc.)
  • Calcium supplements (e.g. citrate, etc.)
  • Hawthorn extract
  • CoQ10
  • Fish oil
  • Potassium citrate
  • Beta blockers (Propranolol, Atenolol, Toprol XL)
  • Maalox
  • Xanax
  • Kava

• Lifestyle/other
  • Avoiding the triggers
  • Exercise
  • Aerobic exercises
  • Frequent aerobic exercise
  • Deep breathing
  • Hands in ice water
  • Coughing (while holding breath)
  • Losing weight
  • Good support group
  • Burping^{[citation needed]}

See also

• Bigeminy
• Heart rate turbulence
• Premature atrial contraction

References