Paroxysmal Atrial Tachycardia (PAT) is an abnormal heart rhythm causing the heart to beat unusually fast. This condition involves episodes that begin and end suddenly, with the rapid heart rate originating in the atria, the heart’s upper chambers. During a PAT episode, the heart rate can increase significantly, sometimes reaching between 150 and 250 beats per minute. This quickened pace prevents the heart from properly filling with blood between beats, which can lead to various uncomfortable symptoms. While the term PAT is still recognized, it is now largely integrated into the broader classification known as Paroxysmal Supraventricular Tachycardia (PSVT).
Defining Paroxysmal Atrial Tachycardia
The term Paroxysmal Atrial Tachycardia is descriptive, explaining the nature of the condition through three components. “Paroxysmal” means the rapid heart rate episodes start and stop abruptly, often without warning. “Atrial” specifies that the electrical abnormality is located in the atria, the heart’s upper chambers. “Tachycardia” is the medical term for an abnormally fast heart rate, typically exceeding 100 beats per minute.
A normal heart rhythm is regulated by the sinoatrial (SA) node, the heart’s natural pacemaker. In PAT, atrial tissue outside the SA node begins to fire electrical impulses rapidly, overriding the heart’s normal rhythm. This rapid firing is caused either by enhanced automaticity in a specific focal area or by a re-entry mechanism where an electrical impulse gets caught in a continuous loop. Because this abnormal electrical activity originates above the ventricles, PAT is categorized as a form of Supraventricular Tachycardia (SVT).
Symptoms and Common Triggers
The experience of a PAT episode ranges from mildly bothersome to alarming, depending on the severity and underlying health. The most common symptom is a sudden onset of strong, rapid palpitations, often described as a fluttering or pounding sensation in the chest. This rapid beating can be accompanied by shortness of breath, lightheadedness, or dizziness. In severe cases, when the heart rate significantly reduces the amount of blood pumped, symptoms may include chest pain or fainting (syncope).
PAT episodes are often unpredictable but can be initiated by various non-cardiac factors. Common triggers include the excessive consumption of stimulants such as caffeine or alcohol, which heighten the heart’s excitability. Episodes can also be precipitated by intense emotional stress, anxiety, or extreme physical fatigue. Underlying health issues, such as an overactive thyroid or pulmonary disease, are also known to trigger or increase the frequency of these rapid heart rhythms.
How Doctors Identify the Condition
Identifying PAT relies on capturing the brief, intermittent electrical event while it is actively occurring. The primary diagnostic tool is the Electrocardiogram (ECG or EKG), which records the heart’s electrical activity. An ECG performed during an episode reveals a regular, rapid rhythm with a characteristic narrow QRS complex, indicating the impulse originates above the ventricles.
Since episodes are paroxysmal, a standard in-office ECG often misses the event. Doctors frequently use ambulatory monitoring devices to record the heart rhythm over an extended period. A Holter monitor is a portable ECG device worn continuously for up to seven days. For less frequent episodes, an event recorder or mobile cardiac telemetry device may be used for a month or more, allowing the patient to manually trigger a recording when symptoms occur. In complex cases, an Electrophysiology (EP) study may be recommended, which is an invasive procedure using catheters to map the exact location and mechanism of the abnormal electrical circuit.
Treatment Strategies
Treatment for PAT focuses on two main goals: immediately stopping an acute episode and preventing future occurrences. During a sudden episode, patients may perform non-invasive maneuvers that stimulate the vagus nerve to slow the heart rate. These vagal maneuvers include bearing down (Valsalva maneuver) or splashing cold water on the face.
If vagal maneuvers are ineffective, pharmacological treatment is utilized, often involving intravenous medications in a hospital setting to restore a normal rhythm. Adenosine is frequently used because it quickly interrupts the abnormal electrical circuit. For long-term management, medications such as beta-blockers or calcium channel blockers may be prescribed to control the heart rate and reduce episode frequency. A definitive option for recurrent PAT is catheter ablation. This minimally invasive procedure uses a catheter to destroy the small area of heart tissue responsible for generating the abnormal electrical impulses, eliminating the problematic pathway.