Supraventricular tachycardia (SVT) is a rapid heart rhythm originating above the ventricles. Understanding the different types of SVT and their characteristic ECG features is crucial for accurate diagnosis and effective management. This article delves into the various forms of SVT, exploring their underlying mechanisms, ECG patterns, and associated symptoms, offering a comprehensive resource beyond the basics.
Understanding Supraventricular Tachycardia (SVT)
SVT encompasses a range of heart conditions characterized by a rapid heartbeat that originates in the atria or atrioventricular (AV) node. This abnormal electrical activity disrupts the regular heart rhythm, leading to a variety of symptoms. It’s important to differentiate SVT from ventricular tachycardia, which is a more serious condition arising from the ventricles.
Types of Supraventricular Tachycardia (SVT)
Atrioventricular Nodal Reentrant Tachycardia (AVNRT)
AVNRT, the most common type of SVT, occurs due to a re-entry circuit within the AV node. This circuit causes the electrical impulses to cycle repeatedly, leading to a rapid heartbeat. ECG features of AVNRT typically include a narrow QRS complex and buried or retrograde P waves.
Atrioventricular Reciprocating Tachycardia (AVRT)
AVRT involves an accessory pathway, an extra electrical connection between the atria and ventricles. This pathway creates a loop that facilitates rapid electrical conduction, resulting in tachycardia. ECG findings in AVRT may show a short PR interval and a delta wave, a slurred upstroke at the beginning of the QRS complex.
Atrial Tachycardia (AT)
Atrial tachycardia originates from an ectopic focus within the atria, firing rapidly and overriding the normal sinus rhythm. AT can present with various ECG patterns, including regular or irregular rhythms, and P waves that may differ in morphology from sinus P waves.
Sinus Tachycardia
While not strictly an SVT, sinus tachycardia is a rapid heart rate originating from the sinus node, the heart’s natural pacemaker. It’s important to distinguish sinus tachycardia from other SVTs as the causes and management differ. ECG findings in sinus tachycardia reveal a normal sinus rhythm with a rate exceeding 100 beats per minute.
ECG Features of Supraventricular Tachycardia
Accurate interpretation of ECGs is vital in diagnosing SVT. Key features to look for include:
- Heart rate: Typically above 100 beats per minute.
- QRS complex: Usually narrow, but can be wide in certain cases.
- P waves: May be visible, hidden, or retrograde.
- Rhythm: Can be regular or irregular.
Symptoms and Management of SVT
Symptoms of SVT can vary from mild to severe, including palpitations, chest pain, shortness of breath, dizziness, and lightheadedness. Treatment options range from vagal maneuvers and medications to catheter ablation for more persistent cases.
Further Exploration of Supraventricular Tachycardia
This overview provides a foundational understanding of SVT. Deeper exploration can involve learning about the different mechanisms of each SVT subtype, the specific ECG criteria for diagnosis, and the various treatment strategies employed. Consulting with a cardiologist or electrophysiologist is essential for personalized diagnosis and management.
What are your experiences with understanding or managing supraventricular tachycardia? Share your insights and questions in the comments below. We’ll also explore related topics like atrial fibrillation and other heart rhythm disorders in future posts.