The paroxysmal atrial supraventricular tachycardia
The paroxysmal atrial supraventricular tachycardia Paroxysmal atrial supraventricular tachycardia (PSVT) is a common form of arrhythmia characterized by sudden episodes of rapid heart rate originating above the ventricles, specifically in the atria or the atrioventricular (AV) node. These episodes begin and end abruptly, often lasting from a few seconds to several hours, and can be quite alarming for those experiencing them. Understanding the mechanisms, symptoms, diagnosis, and treatment options of PSVT can help patients and healthcare providers manage this condition effectively.
The primary feature of PSVT is its paroxysmal nature, meaning it occurs in sudden, unpredictable bursts. During an episode, the heart rate can soar between 150 to 250 beats per minute, leading to symptoms such as palpitations, chest discomfort, shortness of breath, dizziness, or even fainting. Many individuals with PSVT report that episodes are triggered by factors like stress, caffeine intake, alcohol consumption, fatigue, or certain medications. While PSVT is generally not life-threatening, its episodes can cause significant discomfort and anxiety, especially if they recur frequently.
The underlying mechanism involves abnormal electrical circuits within the atria or AV node. In most cases, PSVT results from a reentrant circuit—a loop of electrical activity that causes rapid, repetitive firing. This reentrant circuit allows impulses to travel in a circular manner, overriding the normal sinus rhythm. The most common type of PSVT is atrioventricular nodal reentrant tachycardia (AVNRT), which involves reentry within or near the AV node. Other types include orthodromic atrioventricular reentrant tachycardia (AVRT), often associated with accessory pathways, and focal atrial tachycardia, originating from a localized area within the atria.
Diagnosis begins with a detailed medical history and physical examination, but the definitive diagnosis relies on electrocardiogram (ECG) recordings. During an episode, an ECG can reveal characteristic features such as narrow QRS complexes with rapid, regular atrial and ventricular activity. Sometimes, the episodes may be infrequent, making ambulatory monitoring with Holter or event recorders necessary to capture episodes when they occur. In certain cases, electrophysiological studies involving intracardiac catheterization are performed to pinpoint the precise location and nature of the abnormal circuit, especially if ablation therapy is considered.
Treatment options for PSVT aim to terminate episodes promptly and prevent future occurrences. Vagal maneuvers, such as the Valsalva maneuver or carotid sinus massage, are first-line interventions that stimulate the vagus nerve, slowing conduction through the AV node and potentially terminating the episode. If these are unsuccessful, medications like adenosine are administered intravenously; adenosine has a rapid onset and is highly effective in restoring normal rhythm. For recurrent or refractory cases, catheter ablation—a procedure that destroys the abnormal electrical pathway—is often curative and considered the definitive treatment. Antiarrhythmic drugs may also be prescribed for long-term management when ablation is not suitable.
Overall, while PSVT can be disruptive, most patients respond well to treatment, and the prognosis is excellent. Education about triggering factors and appropriate management strategies can significantly improve quality of life. Regular follow-up with a cardiologist ensures optimal care, and advances in electrophysiology continue to enhance treatment success rates.
