Atrial tachycardia is an abnormal heart rhythm, or arrhythmia, originating in the heart’s upper chambers (atria). This condition causes the atria to beat faster than normal, typically ranging from 100 to 250 beats per minute. This article explores the heart’s electrical system and the primary causes of atrial tachycardia.
Understanding Atrial Tachycardia
The heart’s electrical system regulates its pumping action, ensuring coordinated contractions of its four chambers. A small group of specialized cells in the right upper chamber, the sinoatrial (SA) node, acts as the heart’s natural pacemaker. The SA node generates electrical impulses that spread throughout the atria, causing them to contract, before traveling to the lower chambers (ventricles). This organized electrical pathway ensures blood is efficiently pumped through the heart and to the rest of the body.
In atrial tachycardia, an abnormal electrical signal originates within the atria, overriding the SA node’s pacing function. This faulty signal causes the atrial chambers to contract rapidly and sometimes irregularly. This rapid rate can prevent the heart chambers from filling properly between beats, potentially affecting blood flow.
The Most Common Origin
The most common mechanism leading to atrial tachycardia is re-entry. Re-entry occurs when an electrical impulse, instead of dissipating, finds a path to re-excite the same heart tissue. This typically involves two adjacent electrical pathways with different conduction properties, allowing an impulse to circulate continuously.
Scar tissue or areas of slowed electrical conduction within the atria frequently provide the necessary conditions for these re-entry circuits to form. These altered tissue regions create electrical “obstacles” that redirect impulses, enabling the circular pathway. Previous heart conditions like coronary artery disease, heart failure, or prior heart attacks can lead to such scarring. Individuals who have undergone cardiac surgery, especially involving the atria, often develop arrhythmogenic scar tissue.
Age-related changes in the heart’s electrical properties can also contribute to these re-entry pathways. The continuous cycling of the electrical signal within a re-entry loop results in the rapid and often regular heart rate characteristic of atrial tachycardia.
Other Contributing Factors
While re-entry circuits are a frequent cause, several other factors can contribute to or directly trigger atrial tachycardia. Excessive consumption of stimulants, such as caffeine, alcohol, and nicotine, can increase the heart’s excitability. These substances heighten the sympathetic nervous system’s activity, making the heart more prone to abnormal electrical impulses.
Certain medications can also influence heart rhythm. Some cold remedies and asthma medications, for instance, contain ingredients that can stimulate the heart and potentially induce a rapid heartbeat. Drug toxicities, like from digoxin, can also be a cause.
Underlying medical conditions play a role in developing atrial tachycardia. Thyroid disorders, particularly an overactive thyroid, can accelerate heart rate and predispose individuals to arrhythmias. Lung diseases, such as chronic obstructive pulmonary disease (COPD), and electrolyte imbalances, like those affecting sodium, potassium, or calcium, can disrupt the heart’s electrical stability. Structural heart disease or conditions like hypertension leading to a stretched atrium, can also increase risk.
Emotional stress and anxiety can also impact heart rhythm. Stress triggers the body’s fight-or-flight response, releasing hormones like adrenaline that increase heart rate and contribute to palpitations. While anxiety may not directly cause atrial tachycardia, it can exacerbate symptoms or trigger episodes in susceptible individuals.
Identifying Atrial Tachycardia
Identifying atrial tachycardia often begins with recognizing its common symptoms. Individuals may experience heart palpitations, feeling their heart beating much faster or stronger than usual. Other symptoms can include dizziness, lightheadedness, or shortness of breath. Some people might also report chest pain or fatigue during episodes.
Diagnosis typically involves an electrocardiogram (ECG or EKG), which records the heart’s electrical activity. An ECG can capture the rapid heart rate and the abnormal electrical signals originating from the atria. For symptoms that occur intermittently, healthcare providers might use portable devices like Holter monitors or event recorders, which record heart rhythms over extended periods.
In more complex cases, an electrophysiology (EP) study may be performed. This invasive procedure involves guiding thin wires into the heart to precisely map its electrical pathways and pinpoint the origin of the abnormal rhythm. An EP study helps confirm the diagnosis, differentiate atrial tachycardia from other arrhythmias, and guide potential treatment strategies. Anyone experiencing symptoms of a rapid or irregular heartbeat should consult a healthcare professional for an accurate diagnosis and appropriate management.