Ecg of paroxysmal supraventricular tachycardia
Ecg of paroxysmal supraventricular tachycardia Paroxysmal supraventricular tachycardia (PSVT) is a common arrhythmia characterized by episodes of rapid heart rate originating above the ventricles. Its hallmark is the sudden onset and termination of a rapid, regular heartbeat, often causing symptoms such as palpitations, dizziness, or shortness of breath. The diagnosis of PSVT relies heavily on electrocardiogram (ECG) findings, which provide crucial insights into the arrhythmia’s mechanism and assist in guiding appropriate management.
Ecg of paroxysmal supraventricular tachycardia On an ECG, PSVT typically presents with a narrow QRS complex tachycardia, usually at rates ranging from 150 to 250 beats per minute. The rapid heart rate and regular rhythm are key features, but the most defining characteristic is the abrupt onset and offset, often described as a “paroxysmal” event. In many cases, P waves are difficult to identify because they are either buried within the QRS complex or appear as retrograde P waves following the QRS, especially in atrioventricular nodal reentrant tachycardia (AVNRT), a common type of PSVT.
The classic ECG pattern of AVNRT involves a nearly instantaneous onset with a sudden increase in heart rate. During episodes, the P waves may be inverted in the inferior leads (II, III, aVF) and appear shortly after the QRS complex, creating a pseudo R’ wave in V1 or a pseudo S wave in the inferior leads. This retrograde P wave is a hallmark of reentrant circuits involving the AV node and helps distinguish AVNRT from other supraventricular tachycardias. Ecg of paroxysmal supraventricular tachycardia
Ecg of paroxysmal supraventricular tachycardia Another form of PSVT, orthodromic atrioventricular reentrant tachycardia (AVRT), involves an accessory pathway that allows electrical conduction outside the AV node. On ECG, AVRT often appears similar to AVNRT—narrow QRS complexes with rapid rates—but there may be subtle differences in the P wave morphology or timing, especially if pre-excitation (Wolff-Parkinson-White syndrome) is involved. In pre-excitation, a delta wave appears during sinus rhythm, and during tachycardia, the QRS complex may be wide, adding complexity to diagnosis.
Differentiating PSVT from other tachyarrhythmias, such as atrial fibrillation or flutter, is crucial because management strategies differ significantly. Unlike atrial fibrillation, PSVT maintains a regular rhythm, which is evident on the ECG. The abrupt initiation and termination of the arrhythmia also help distinguish it from other long-standing arrhythmias.
Ecg of paroxysmal supraventricular tachycardia In terms of treatment, vagal maneuvers are often the first-line approach during an acute episode and can transiently increase vagal tone, potentially terminating the arrhythmia. If unsuccessful, pharmacologic interventions like adenosine are highly effective; the characteristic ECG response includes a transient AV block followed by the return to normal sinus rhythm. The ECG during adenosine administration often shows a sudden pause or slowing of the heart rate, confirming the diagnosis.
Understanding the ECG features of PSVT is essential for clinicians to quickly identify and differentiate it from other cardiac arrhythmias. Accurate interpretation can facilitate prompt treatment, alleviate symptoms, and reduce the risk of complications, especially in patients with recurrent episodes or underlying cardiac disease. Ecg of paroxysmal supraventricular tachycardia
