Premature Junctional Contractions (PJCs) are extra heartbeats that briefly interrupt the heart’s normal rhythm. These premature electrical impulses begin in the atrioventricular (AV) junction, a specialized area of tissue near the center of the heart. This area acts as a secondary pacemaker, meaning the impulse originates here, rather than from the sinoatrial (SA) node, the heart’s natural pacemaker. PJCs are classified as an arrhythmia because they occur earlier than the next expected normal beat.
How Premature Junctional Contractions Are Often Undetected
The most frequent clinical presentation of Premature Junctional Contractions is the complete absence of any noticeable symptoms. Many people experience occasional PJCs without ever realizing it, making the condition asymptomatic. The heart generally tolerates these isolated beats effectively, and circulation remains unaffected.
These silent contractions are typically discovered incidentally during diagnostic testing for an unrelated reason. PJCs may appear as a random, single extra beat on an electrocardiogram (EKG) or during continuous heart monitoring. Their infrequency is a major reason they go unnoticed, as the heart’s dominant rhythm quickly re-establishes itself. The finding is usually purely a matter of diagnostic chance.
The Primary Sensation: Palpitations and Skipped Beats
For individuals who experience symptoms, the most common complaint is palpitations, often described as a “skipped beat” or “fluttering” in the chest. The patient may feel a pause in their heart rhythm, followed by a noticeable, forceful beat or a thumping sensation. This subjective experience results directly from the electrophysiology of the PJC event.
The premature beat occurs so early that the heart’s chambers have not fully filled with blood, resulting in a weak, ineffective contraction that is rarely felt. This early contraction is followed by a brief, involuntary pause, known as a compensatory pause. During this pause, the heart’s ventricles have extra time to fill completely with a larger volume of blood.
When the heart fires the next normal impulse, the resulting contraction is unusually strong due to the increased blood volume. This powerful beat, rather than the weak premature beat or the pause, is what the patient registers as a distinct “thump in the chest.” This phenomenon explains why the perception is a forceful beat following a brief hesitation.
Related Physical and Emotional Effects
When Premature Junctional Contractions occur at a high frequency, they can lead to a more noticeable set of systemic or emotional complaints. A high burden of PJCs may disrupt the heart’s efficiency enough to cause a slight reduction in cardiac output, leading to physical symptoms. These secondary complaints can include chronic fatigue and general malaise.
Some individuals may report lightheadedness or a dizzy feeling, known as pre-syncope, associated with the transient drop in blood flow. Shortness of breath, or dyspnea, can arise when a high number of PJCs interfere with the heart’s ability to circulate oxygenated blood effectively. Furthermore, the perception of an irregular heart rhythm can lead to significant psychological distress, manifesting as heightened anxiety or panic attacks.