Premature ventricular contractions are essentially heartbeats that occur before they should. If they happen frequently or if you have a preexisting heart condition, they are a cause for concern.

Overview of how the heart works

To fully understand premature ventricular contractions, it is important to know the basics of how a healthy heart functions.

The heart has two sides, separated by an inner wall called the septum, according to the National Heart, Lung, and Blood Institute. The right side of the heart pumps blood to the lungs and that blood is infused with oxygen. The left side of the heart receives the oxygen-rich blood from the lungs and pumps it throughout the rest of the body.

The heart contains four chambers: the upper two chambers are the atria, and the lower two, where premature ventricular contractions originate, are the ventricles. The chambers work together, alternately contracting and relaxing to pump blood through your heart.

The rhythm of your heart is controlled by a natural pacemaker, the sinus node, located in the right atrium. The sinus node produces electrical impulses that trigger the heartbeat. From the sinus node, electrical impulses travel across the atria and cause the atria muscles to contact and pump blood into the ventricles.

The electrical impulses then arrive at a cluster of cells called the atrioventricular node (AV node), which is the pathway for signals to travel from the atria to the ventricles.

The AV node slows down the electrical signals before sending them to the ventricles. This slight delay allows the ventricles to fill with blood. When electrical impulses reach the muscles of the ventricles, they contract, causing them to pump blood to the lungs or to the rest of the body.

Without this electrical system in place, the heart would not contract and would not pump blood. When the heart’s electrical system malfunctions, arrhythmias such as premature ventricular contractions occur.

What is a premature ventricular contraction?

Premature ventricular contractions (PVCs) are also called extrasytoles or ectopic heartbeats. They are extra, abnormal heartbeats that begin in one of your heart’s two lower pumping chambers (ventricles). These additional heartbeats are often followed by a pause, then a stronger, quicker heartbeat.

Because they disrupt your normal heart rhythm, PVCs can sometimes cause you to feel a flip-flop or skipped beat in your chest, according to Mayo Clinic. During a PVC, less oxygen is delivered to the body because the heart pumps blood less effectively.

It’s important to know that PVCs are very common and will occur at some point in most people, even those who have healthy hearts. Because of this, they are not an immediate cause for concern and usually require no treatment. People who experience the occasional PVC usually do not develop any complications or problems. Frequent PVCs, however, are a more serious sign, especially if you have a known heart issue or history of heart disease.

An extra heartbeat can also occur in the upper chambers of the heart (atria). When it does, it is called a premature atrial contraction.

Other terms related to PVCs are bigeminy and trigeminy. Bigeminy is the occurrence of a PVC with every other heartbeat. Similarly, trigeminy is every third beat. Doctors look for such patterns to help them assess the severity of the abnormal heartbeat.

People with three or more consecutive PVCs have ventricular tachycardia, a more serious arrhythmia that will likely require treatment.

Causes

Healthy people of any age can experience PVCs, although they are more common in people over the age of 50. The cause of a PVC is not always identifiable, but there are certain factors that increase your risk.

Some of the more common risk factors for PVCs include:

• Underlying cardiac conditions, including coronary artery disease, cardiomyopathy, mitral valve prolapse, and others
• Previous heart attack
• Scarring after a heart attack (myocardial infarction)
• Abnormal levels of electrolytes in the blood. Low potassium and magnesium levels are common causes of abnormal electrolyte levels.
• Unusual congenital (familial) defects in the heart
• High blood pressure
• Toxins, including alcohol
• Certain medications such as stimulants and asthma medications
• Inflammation or degeneration of the heart muscle
• Caffeine consumption
• Drug use, particularly cocaine
• Smoking

PVCs that occur frequently or for longer periods of time are more likely to be related to heart disease, an injury to the heart, or conditions such as a chemical imbalance in the body, according to Cleveland Clinic.

PVCs can also be triggered by low blood oxygen, which could happen if you have chronic obstructive pulmonary disease or pneumonia. High levels of adrenaline due to stress or exercise can also cause PVCs.

Many of the causes of PVCs, such as medications, alcohol, high blood pressure, or stress, can be managed and adjusted.

Thyroid problems can also have an impact on your heart. Hyperthyroidism, or the presence of excessive thyroid hormone, can cause the heart to beat harder and faster and may trigger abnormal heart rhythms, according to Harvard Health. Other symptoms of hyperthyroidism include sleeplessness, heat intolerance, excess sweating, weight loss, extreme hunger, and loose bowels.

If you’re at risk of, or already have, heart disease and have symptoms of hyperthyroidism, ask your primary care provider or cardiologist to consider testing your thyroid function, Harvard Health suggests. A simple blood test is usually all that’s needed.

Symptoms

Premature ventricular contractions often cause no symptoms. But, you may experience the following:

• Flip-flops in your chest
• Fluttering heartbeat
• Pounding or jumping heartbeat
• Skipped beats or missed beats
• Increased awareness of your heartbeat
• Fatigue
• Dizziness
• Pressure or a pulsing sensation in your neck

Generally, PVCs cause dangerous symptoms only if you have another heart problem, according to Saint Luke’s Health System. For example, dangerous symptoms might only occur in someone whose ventricle already squeezes poorly.

Treatments and when to see a doctor

Again, in people who have healthy hearts, occasional PVCs are typically nothing to worry about. They usually go away on their own and do not require treatment.

But, you should talk to your doctor if you have other symptoms along with PVCs, such as dizziness, lightheadedness, or fainting. If you have a known heart problem, such as heart failure or heart disease, PVCs may be a sign that a dangerous heart rhythm could occur.

So, if you experience frequent PVCs or even if you experience infrequent PVCs but have a known heart issue or family history of heart disease, it’s a good idea to see your doctor.

Your doctor will do a complete physical exam to make sure there are no underlying reasons for your PVCs, according to Dartmouth-Hitchcock.

He or she may initiate the following tests:

Electrocardiogram (ECG). This test measures electrical activity of your heart to show if it is working normally. The ECG shows the heart’s electrical activity as line tracings on paper. The spikes and dips in the tracings are called waves. If each wave peak on the ECG has a different shape, you may have multifocal PVCs, which means multiple sites on your ventricles are responsible for the PVCs.

Echocardiogram. An echocardiogram uses high frequency sound waves, or ultrasound, to make a picture of your heart. This test can help the doctor determine your heart’s pumping strength and if the heart valves are working correctly, among other things. An echocardiogram doesn’t hurt and has no side effects.

Coronary Angiography. This test uses a catheter to measure the blood flow and pressure in the heart chambers. The catheter is placed in an artery, usually in the groin or the arm, and then moved until it is in the heart. A special dye is then pumped into the catheter and monitored through X-ray images, allowing doctors to observe how blood is flowing through your heart.

Holter monitor. Because PVCs may not be occurring at the exact moment your doctor is administering an ECG, a Holter monitor may be necessary because it provides a continuous reading of your heart rate and rhythm as you go about your daily activities outside of the hospital. The Holter monitor is a portable device that you wear for 24 hours or more.

You may also be prescribed certain medications to control your heart rhythm. Beta blockers decrease the heart rate and lower blood pressure by blocking the effects of adrenalin. Digitalis medicines control irregular heart rhythms by slowing the signals that start in the sinus node.

Some lifestyle changes may also help control PVCs. These could include limiting caffeine, avoiding tobacco, limiting alcohol, and managing stress and anxiety more effectively.

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