Regular Supraventricular Tachycardia - ECG

Regular supraventricular tachycardia (SVT) has two most known forms - AVRT and AVNRT. In AVRT, the electric impulse cycles between the atrium and ventricle. In AVNRT, the electric impulse circulates quickly within the AV node. It is quite difficult to distinguish AVRT and AVNRT for a non-cardiologist (including me) but for a basic evaluation and treatment, this is luckily not so important.

ECG of a regular SVT has regularly positioned narrow QRS complexes; the tachycardia is usually above 150 beats per minute. There are no P waves visible among the QRS complexes.
The QRS complexes can be wide when there is present a simultaneous bundle branch block.

 

Regular Supraventricular Tachycardia - ECGThis is an ECG of a classic regular SVT – The QRS complexes are narrow, their distances are regular and the heart rate is about 150 per minute (less than two large squares between two QRS complexes). P waves can not be distinguished.
 

Conclusion: These types of arrhythmia can be removed by administration of a special substance (adenosine) that for a very short time blocks the atrioventricular transmission and thus blocks the vicious circle.