The feeling of a racing, fluttering, or “skipped” heartbeat, often called a palpitation, is a common experience. While the heart generally maintains a steady rhythm, extra beats occasionally interrupt this pattern. The two most frequent types of these premature heartbeats are Premature Atrial Contractions (PACs) and Premature Ventricular Contractions (PVCs). Both PACs and PVCs are extra heartbeats that occur earlier than the heart’s natural rhythm dictates, but they originate from different locations within the heart’s electrical system.
Understanding Premature Atrial Contractions (PACs)
Premature Atrial Contractions are extra heartbeats that originate in the upper chambers of the heart, known as the atria. Normally, the heart’s electrical signal begins at the sinus node, the natural pacemaker. In a PAC, an electrical impulse fires from a different spot in the atria before the sinus node is scheduled to fire, causing the atria to contract prematurely.
This early beat disrupts the regular rhythm, often leading to a pause before the next normal beat. The sensation is often described as a brief fluttering in the chest or a skipped beat. PACs are common and frequently occur in healthy individuals with no underlying heart disease.
Understanding Premature Ventricular Contractions (PVCs)
Premature Ventricular Contractions are extra beats that originate in the lower pumping chambers of the heart, called the ventricles. These occur when an electrical impulse spontaneously fires from an ectopic focus within the ventricles, bypassing the normal conduction pathway. This premature firing causes the ventricle to contract before its normal time, disrupting the regular sequence of the heartbeat.
The sensation of a PVC is often described as a hard “thump” or a pounding in the chest. This stronger sensation occurs because the premature beat is usually followed by a longer compensatory pause, allowing the ventricles to fill with more blood. This results in a more forceful contraction on the subsequent normal beat. While PVCs are common in healthy hearts, frequent occurrences or certain patterns can indicate a more serious underlying issue.
Lifestyle and Medical Triggers
A variety of factors can trigger or increase the frequency of both PACs and PVCs, many related to daily habits and body chemistry. Stimulants are common culprits, including high intake of caffeine and nicotine from tobacco products. Alcohol consumption is another well-documented trigger that increases the likelihood of premature beats.
Emotional and physiological states also play a significant role. Stress, anxiety, and a lack of adequate sleep often lead to an increase in palpitations. Dehydration is a frequent non-cardiac trigger because it can lead to an imbalance of electrolytes necessary for stable heart electrical activity. Certain over-the-counter medications, particularly decongestants, can also increase the heart’s excitability, as can medical conditions like thyroid disorders, anemia, and high blood pressure.
Diagnosis and When to Seek Treatment
The first step in evaluating premature heartbeats is an accurate diagnosis to determine their type and frequency. A healthcare provider typically begins with a standard electrocardiogram (ECG or EKG), which records the heart’s electrical activity. Since these beats are often intermittent, a short-term or long-term heart monitor may be necessary, such as a Holter monitor or an event recorder, to capture the irregular rhythm. An echocardiogram, an ultrasound of the heart, may also be used to rule out any underlying structural heart disease.
For individuals with structurally normal hearts and infrequent, asymptomatic PACs or PVCs, the condition is usually considered benign and requires no specific treatment beyond avoiding triggers. If the premature beats are frequent, cause significant symptoms, or occur alongside other heart conditions, further intervention is necessary. Frequent PVCs, especially more than 2,000 per day, may be associated with a risk of weakening the heart muscle over time.
Treatment often begins with lifestyle modifications, such as reducing stimulant intake and managing stress. If symptoms persist or the beats are deemed a risk factor, medication may be prescribed. Beta-blockers and calcium channel blockers are common first-line treatments to help regulate the heart rhythm. In rare cases, a minimally invasive procedure called catheter ablation may be used to eliminate the specific electrical focus causing the premature beats.