Bigeminy is an irregular heart rhythm where a normal heartbeat is consistently followed by an extra, or premature, beat. This repeating pattern is one of several variations in the heart’s electrical signaling.
Understanding Bigeminy
Bigeminy describes a specific repeating sequence: a regular heartbeat followed by a premature beat, with this pair then repeating. The term “bigeminy” comes from Latin, meaning “twins,” which aptly describes the paired nature of these heartbeats. Every second beat is an early, extra contraction, interrupting the heart’s usual steady rhythm. These premature beats arise from an electrical impulse firing from a different location than the normal pacemaker, causing an early contraction before the next expected normal beat.
How Bigeminy Appears on an ECG
An electrocardiogram (ECG) records the heart’s electrical signals, providing a visual representation of its rhythm. On an ECG, a normal heartbeat is represented by a P wave, a QRS complex, and a T wave. The QRS complex, signifying the electrical activation of the heart’s main pumping chambers (ventricles), appears as a narrow spike, typically lasting between 80 to 100 milliseconds.
In bigeminy, this normal QRS complex is consistently followed by a premature beat. The appearance of this premature beat depends on its origin. If the extra beat comes from the ventricles, it’s a premature ventricular contraction (PVC), leading to ventricular bigeminy. On an ECG, a PVC is characterized by a wide and often unusual-looking QRS complex, typically lasting 120 milliseconds or more, and usually lacks a preceding P wave. This wide, distorted appearance occurs because the electrical impulse travels through the ventricles in an abnormal, slower pathway. A noticeable pause, known as a compensatory pause, often follows a PVC before the next normal heartbeat.
Alternatively, if the premature beat originates from the upper chambers (atria), it’s a premature atrial contraction (PAC), resulting in atrial bigeminy. On an ECG, a PAC shows an abnormal P wave that appears earlier than expected, but is typically followed by a normal, narrow QRS complex. The abnormal P wave might have a different shape or be hidden within the preceding T wave. The defining characteristic of bigeminy on an ECG is the consistent repetition of one normal beat followed by one premature beat.
Common Symptoms and Sensations
The experience of bigeminy varies significantly among individuals; some people feel no symptoms at all. For those who do notice sensations, the most commonly reported feelings include heart palpitations, described as a fluttering or thumping in the chest. Some individuals perceive a “skipped beat,” often due to the compensatory pause after the premature contraction, followed by a stronger beat when the heart fills more fully.
Other potential sensations include feeling as though the heart is beating too fast, or experiencing a “flip-flop” feeling in the chest. Less common but possible symptoms can include lightheadedness or dizziness. These personal experiences are distinct from the objective electrical patterns observed on an ECG.
When to Seek Medical Advice
Anyone experiencing symptoms suggestive of bigeminy or who has concerns about their heart rhythm should consult a healthcare professional. An evaluation can help determine the underlying cause and assess the significance of the irregular beats. While bigeminy is often considered benign, especially in individuals with an otherwise healthy heart, it can sometimes indicate an underlying medical condition.
Conditions such as electrolyte imbalances, certain heart diseases, or thyroid disorders can contribute to bigeminy. For those with severe or frequent symptoms, or if there is a known history of heart disease, further investigation is often recommended. Immediate medical attention is advisable for severe symptoms, including chest pain, fainting episodes, or persistent shortness of breath. Depending on the diagnosis, management might involve monitoring, lifestyle adjustments, or in some cases, medication or other interventions.