What differentiates supraventricular tachycardia (SVT) from sinus tachycardia?

Supraventricular tachycardia (SVT) is differentiated from sinus tachycardia primarily by the specific characteristics of the heart rhythm and the presence or absence of P waves. In SVT, the heart rate is typically higher than 100 beats per minute, which is a defining feature. Additionally, an important characteristic of SVT is the potential absence of identifiable P waves due to the rapid electrical activity originating from the atria or junctional areas rather than the sinoatrial node.

In contrast, sinus tachycardia is a response to physiological factors such as exercise, fever, or anxiety, where P waves are present and consistent with each QRS complex, indicating that the rhythm is originating from the sinus node, with heart rates usually up to 100-120 bpm. Hence, the higher heart rate over 100 bpm combined with absent P waves in SVT is what distinctly sets this arrhythmia apart from sinus tachycardia. This differentiation is crucial for effective diagnosis and management in clinical practice.