From the Guidelines
Supraventricular Tachycardia (SVT) and sinus tachycardia are distinct conditions with different underlying mechanisms and ECG characteristics. The primary difference between SVT and sinus tachycardia lies in their origin and the presence of specific ECG features.
Key Differences
- Origin: Sinus tachycardia originates from the sinus node, with a heart rate exceeding 100 bpm, often in response to physiological stimuli or stress 1. In contrast, SVT encompasses various tachyarrhythmias that involve tissue from the His bundle or above, including atrial and atrioventricular nodal tissues 2.
- ECG Characteristics: + Sinus tachycardia is characterized by an upright P wave in leads I, II, and aVF, and a biphasic P wave in lead V1, with the P wave preceding each QRS complex 3. + SVT can present with various ECG patterns depending on the specific type, such as atrial flutter, atrial tachycardia, or AVNRT, each with distinct P wave morphologies and PR intervals 1, 4.
Diagnostic Considerations
Diagnosing SVT versus sinus tachycardia involves careful analysis of the ECG, including the assessment of P wave morphology, PR interval, and the relationship between P waves and QRS complexes. The presence of AV dissociation or fusion complexes can indicate ventricular tachycardia rather than SVT 4. Algorithms like the Brugada criteria and the Vereckei algorithm can aid in differentiating wide-complex tachycardias as either ventricular or supraventricular in origin 3.
Clinical Implications
Understanding the difference between SVT and sinus tachycardia is crucial for appropriate management, as treatment strategies vary significantly between these conditions. While sinus tachycardia often resolves with addressing the underlying cause, SVT may require specific interventions, including vagal maneuvers, pharmacological conversion, or catheter ablation, depending on the type and severity of the arrhythmia 2, 4.
From the Research
Definition and Characteristics
- Supraventricular Tachycardia (SVT) is a rapid dysrhythmia that originates at or above the level of the His bundle of the atrioventricular (AV) conduction system 5
- SVT encompasses subclasses of tachycardias such as atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reciprocating tachycardia (AVRT), atrial tachycardia, and atrial flutter 6
- Sinus tachycardia, on the other hand, is a rapid heart rhythm that originates from the sinus node, with a rate typically between 100-180 beats per minute
Differentiation
- SVT can be differentiated from sinus tachycardia using electrocardiogram (ECG) recordings, with a sensitivity of 89% and a specificity of 91% for the detection of SVT using smartphone-based one-lead ECG monitors 7
- The QRS complex during SVT is typically identical to that seen in sinus rhythm, except for tachycardia-related bundle branch block 5
- In contrast, sinus tachycardia has a normal P wave axis and a 1:1 atrioventricular (AV) relationship, whereas SVT often has an abnormal P wave axis and an AV relationship that is not 1:1
Clinical Implications
- Accurate differentiation between SVT and sinus tachycardia is crucial for proper management and treatment, as SVT can be treated with radiofrequency ablation or pharmacotherapy 8, 6
- Misdiagnosis or delayed diagnosis can lead to unnecessary electrophysiology procedures or inappropriate treatment, highlighting the importance of accurate ECG interpretation and diagnosis 7, 9