Heart arrhythmias are incredibly common. Most people have experienced heart palpitations or the sensation of a skipped heartbeat at some point in their lives.
Two common types of heart rhythm disturbances are premature ventricular contractions (PVCs) and premature atrial contractions (PACs). But what exactly are PVCs and PACs, and how are they different?
While usually harmless, frequent PVCs and PACs, especially if they cause noticeable symptoms, should be evaluated by a doctor. This article will help you understand the difference between PVCs vs PACs, as well as when to seek medical advice.
What’s a Premature Ventricular Contraction (PVC)?
A premature ventricular contraction, or PVC, is an extra heartbeat that starts in one of the ventricles, or lower chambers, of your heart. The beat happens sooner than it should, which throws off your regular heart rhythm for a moment.
Here’s how a PVC shows up on an electrocardiogram, or EKG:
- PVCs show up early, before the next expected beat.
- The QRS complex looks wide and odd.
- Notably, there’s no P wave before the QRS complex. That’s a key difference between PVCs and PACs.
What’s a Premature Atrial Contraction (PAC)?
Like PVCs, PACs are a type of premature heartbeat. But while PVCs originate in the ventricles, PACs start in the atria, the upper chambers of the heart.
The “premature” part of the name means that the atria contract sooner than they should, causing an early atrial beat.
How PACs appear on an ECG
On an electrocardiogram, PACs show up as early P waves followed by a QRS complex and a compensatory pause. The P wave will occur earlier than expected.
That early P wave is what distinguishes PACs from PVCs on an ECG.
What’s the difference between PVCs and PACs?
Although both PVCs and PACs are types of heart arrhythmias, they originate in different parts of the heart and have different characteristics.
Where they start
PVCs start in the ventricles, the lower chambers of your heart, while PACs start in the atria, the upper chambers.
What they look like on an EKG
On an electrocardiogram (EKG), a PVC will show up as a wide QRS complex without a P wave beforehand. A PAC, on the other hand, will have a premature P wave, followed by a QRS complex.
What causes them
PVCs can be caused by heart disease, low blood oxygen, medications, adrenaline surges, high blood pressure, alcohol, anemia, and tobacco use. PACs are often asymptomatic, but they can cause skipped beats and palpitations, especially at night or when you’re relaxing.
For both PVCs and PACs, lifestyle factors like caffeine, stress, and lack of sleep can make them worse.
Symptoms, Diagnosis, and Treatment
Symptoms
PVCs sometimes feel like a fluttering or pounding in your chest. You might notice a skipped beat or heart palpitations.
PACs also tend to show up as skipped beats or heart palpitations.
However, you might not notice any symptoms at all. Many people have PACs or PVCs and don’t even know it.
Diagnosis
An electrocardiogram (ECG) can detect both PVCs and PACs. Another test, called a Holter monitor, can record your heart’s activity over a longer period of time.
Some smartwatches can take an ECG and may detect heart irregularities. However, these aren’t a substitute for a full medical evaluation.
Treatment
If you’re otherwise healthy, occasional PVCs may not need to be treated. Lifestyle modifications, like cutting back on caffeine or alcohol, can sometimes help manage symptoms.
If you have them frequently, your doctor may prescribe medications like beta blockers or calcium channel blockers. In severe cases, catheter ablation may be an option.
Your treatment plan will depend on how often you’re having these extra heartbeats, how severe your symptoms are, and whether you have any underlying heart conditions.
Frequently Asked Questions
What is the most common cause of PACs?
PACs, or premature atrial contractions, are often caused by lifestyle factors like caffeine or alcohol consumption, stress, or lack of sleep. Sometimes, they can also be related to underlying medical conditions such as heart disease, thyroid problems, or electrolyte imbalances. It’s best to consult a healthcare professional to determine the specific cause in your case.
Is PVC or PAC more concerning?
Generally, neither PVCs (premature ventricular contractions) nor PACs are inherently more concerning than the other. Both are common and often benign. However, the significance depends on the frequency, underlying heart health, and presence of any associated symptoms. Frequent PVCs or PACs in someone with existing heart disease might warrant closer evaluation and management.
Does anxiety cause PVCs and PACs?
Anxiety can certainly trigger or exacerbate PVCs and PACs. When you’re anxious, your body releases stress hormones like adrenaline, which can affect the heart’s electrical activity and lead to these extra beats. While anxiety itself might not be the sole cause, managing stress and anxiety can often help reduce the frequency and severity of PVCs and PACs.
In Summary
Premature ventricular contractions (PVCs) originate in the ventricles, while premature atrial contractions (PACs) start in the atria. Knowing the difference between these two common types of heart palpitations can help you feel more confident and empowered about your heart health.
If you have frequent or bothersome palpitations, it’s important to talk with a healthcare professional for diagnosis and treatment. A doctor can interpret the signals your heart is sending and help you address any irregularities.