Can Supraventricular Tachycardia (SVT) have a P wave?

From the Guidelines

Supraventricular tachycardia (SVT) can indeed have P waves, though they may appear differently than normal sinus P waves. In typical SVT, P waves are often hidden within the QRS complex or T wave due to the rapid heart rate, making them difficult to visualize on an ECG. According to the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1, the presence and appearance of P waves in SVT can help electrophysiologists determine the specific mechanism of the arrhythmia. For instance, in atrioventricular nodal reentrant tachycardia (AVNRT), retrograde P waves may appear immediately after the QRS complex, creating a pseudo-R' wave in lead V1 or a pseudo-S wave in inferior leads. Atrioventricular reentrant tachycardia (AVRT) typically shows retrograde P waves within the ST segment.

Some key points to consider when evaluating SVT with P waves include:

• The morphology and axis of the P waves, which may be abnormal compared to sinus P waves
• The location of the P waves in relation to the QRS complex, which can help determine the type of SVT
• The presence of retrograde P waves, which can indicate AVNRT or AVRT
• The importance of a 12-lead ECG in evaluating the etiology of tachycardia, as stated in the 2015 ACC/AHA/HRS guideline 1.

It's also worth noting that, as mentioned in the guidelines for the interpretation of the neonatal electrocardiogram 1, in 60% of cases, the P waves are visible in SVT, but they almost always have a different morphology from sinus. However, the most recent and highest quality study, the 2015 ACC/AHA/HRS guideline 1, provides more detailed information on the evaluation of SVT with P waves.

From the Research

SVT and P-Wave Association

• SVT (Supraventricular Tachycardia) is characterized by an abnormal rapid cardiac rhythm that involves atrial or atrioventricular node tissue from the His bundle or above 2.
• The presence of a P-wave during SVT can be related to the underlying mechanism of the tachycardia, such as atrial tachycardia, where the site of the atrial focus can be determined by the polarity of the P-wave 3.
• In some cases of SVT, the P-wave can be obscured or hidden in the T-wave, making it difficult to detect 3.
• The ECG findings associated with SVT can help distinguish between different types of tachycardia, including atrioventricular nodal re-entrant tachycardia and atrioventricular re-entrant tachycardia 3.

ECG Diagnosis and Anatomy

• The normal anatomy of the supraventricular conducting system is complex, with conduction proceeding along preferential pathways determined by the anisotropic properties of the atrial myocardium 3.
• The ECG findings associated with SVT can be related to the anatomical substrates responsible for the induction and maintenance of the tachycardia 3.
• The presence of a delta wave during sinus rhythm can be highly suggestive of atrioventricular re-entrant tachycardia as the mechanism of SVT 3.

Clinical Implications

• The diagnosis and management of SVT can be challenging, and a comprehensive history and physical examination, electrocardiography, and laboratory workup may be necessary to confirm the diagnosis 2, 4.
• The treatment of SVT can range from conservative management to catheter ablation, depending on the frequency and severity of symptoms, as well as patient preference 2, 4, 5.