A premature heart beat or extrasystole is a heart rhythm disorder corresponding to a premature contraction of one of the chambers of the heart. Premature heart beats come in two different types:

premature atrial contraction Premature atrial contraction (PAC), also known as atrial premature complexes (APC) or atrial premature beats (APB), are a common arrhythmia characterized by premature heartbeats originating in the atria. While the sinoatrial node typically re ...

s and

premature ventricular contraction A premature ventricular contraction (PVC) is a common event where the heartbeat is initiated by Purkinje fibers in the ventricles rather than by the sinoatrial node. PVCs may cause no symptoms or may be perceived as a "skipped beat" or felt as ...

s. Often they cause no symptoms but may present with fluttering in the chest or a skipped beat. They typically have no long-term complications. They most often happen naturally but may be associated with caffeine, nicotine, or stress. Usually no treatment is needed. They are the most common

arrhythmia Arrhythmias, also known as cardiac arrhythmias, are irregularities in the cardiac cycle, heartbeat, including when it is too fast or too slow. Essentially, this is anything but normal sinus rhythm. A resting heart rate that is too fast – ab ...

Physiopathology

The normal heart contraction comes from a cyclic membrane

depolarization In biology, depolarization or hypopolarization is a change within a cell (biology), cell, during which the cell undergoes a shift in electric charge distribution, resulting in less negative charge inside the cell compared to the outside. Depolar ...

(reversal of the electrical polarity of the cell membrane) of a group of cells located on the upper part of the right atrium, the

sinoatrial node The sinoatrial node (also known as the sinuatrial node, SA node, sinus node or Keith–Flack node) is an ellipse, oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of Cell (biology), cells known as pa ...

. This depolarization spreads to the whole heart and causes muscle cells to contract. It is followed by a "refractory period", a short time when the cells are no longer stimulable. The heart rate is controlled by this node.

Diagnosis

Premature heart beat revealed by laser Doppler holography of the eye fundus

Premature heart beats can be asymptomatic (the patient does not complain about anything). The subject may experience

palpitations Palpitations occur when a person becomes aware of their heartbeat. The heartbeat may feel hard, fast, or uneven in their chest. Symptoms include a very fast or irregular heartbeat. Palpitations are a sensory symptom. They are often described as ...

, a feeling of cardiac "pause". Taking (prolonged)

pulse In medicine, the pulse refers to the rhythmic pulsations (expansion and contraction) of an artery in response to the cardiac cycle (heartbeat). The pulse may be felt ( palpated) in any place that allows an artery to be compressed near the surfac ...

may result in a rhythm that seems irregular.

Electrocardiography Electrocardiography is the process of producing an electrocardiogram (ECG or EKG), a recording of the heart's electrical activity through repeated cardiac cycles. It is an electrogram of the heart which is a graph of voltage versus time of t ...

and

laser Doppler imaging Laser Doppler imaging (LDI) is an imaging method that uses a laser beam to image live tissue. When the laser light reaches the tissue, the moving blood cells generate Doppler components in the reflected ( backscattered) light. The light that comes ...

allow to visualize premature heart beats. From their appearance, their location can be assessed. The

Holter monitor In medicine, a Holter monitor (often simply Holter) is a type of ambulatory electrocardiography device, a portable device for cardiac monitoring (the monitoring of the electrical activity of the cardiovascular system) for at least 24 hours. ...

allows to quantify them, to specify their characteristics and their repetition.

Types

Premature atrial contraction Premature atrial contraction (PAC), also known as atrial premature complexes (APC) or atrial premature beats (APB), are a common arrhythmia characterized by premature heartbeats originating in the atria. While the sinoatrial node typically re ...

(PAC) ** Supraventricular extrasystoles (SVES) *

Premature ventricular contraction A premature ventricular contraction (PVC) is a common event where the heartbeat is initiated by Purkinje fibers in the ventricles rather than by the sinoatrial node. PVCs may cause no symptoms or may be perceived as a "skipped beat" or felt as ...

(PVC) ** Ventricular extrasystoles (VES) * Premature junctional contraction

References

{{Authority control Cardiac arrhythmia