Obligatory medical device diagnostics.
- Electrocardiogram (ECG; recording of myocardial electrical activity) [rate ≥ 100/min; due toDD: supraventricular tachycardia (SVT) shows a QRS complex with normal width (QRS width ≤ 120 ms); ventricular tachycardia: QRS complex > 120 msec]Note:
- On 12-lead ECG, ventricular tachycardia (VT) can never be reliably differentiated from supraventricular tachycardia (SVT) in the presence of preexcitation or aberration → In an emergency situation, therefore, always tend to assume VT!
- The resting ECG is unremarkable in most patients with supraventricular tachycardia (SVT).
- SVT due to thigh block is associated with widened QRS complex (= wide-complex tachycardia of non-ventricular origin).
Optional medical device diagnostics – depending on the results of the history, physical examination and obligatory laboratory parameters – for differential diagnostic clarification.
- Echocardiography (echo; cardiac ultrasound) – for suspected structural heart disease.
- X-ray of the thorax (X-ray thorax/chest), in two planes.
Note: Tachycardia with a widened QRS complex is found in:
- A ventricular tachycardia (VT; ventricular tachycardia).
- A supraventricular tachycardia (SVT) with a branch block (preexisting or tachycardia-related) about 30% of all SVT).
- An antegrade conduction via an accessory bundle or retrograde with bundle branch block (rare)
- Electrolyte disturbances or medications that widen SVT (very rare).
