If ventricular tachycardia occurs in an Implantable Cardioverter Defibrillator (ICD) wearer, the ICD can combat this with 2 different forms of therapy, provided these are activated (which can be done using a programming device). First, the ICD attempts to override the tachycardia. The fastest pacemaker gets control of the heart. If this is not successful, the defibrillator function is used. Here you can see the limb leads. Initially there is a relatively slow ventricular tachycardia with a heart rate of approx. 125 bpm.

Atrial flutter and atrial fibrillation are two different cardiac arrhythmias, but occur frequently side by side in the same patient. Here is an example of how atrial flutter degenerataes into atrial fibrillation. The initially ordered atrial activity (left in the picture) with 2 flutter waves/1 QRS complex changes into irregular atrial activity (right in the picture) and the RR intervals become completely irregular.

Many people are considerably unsettled by ECG recordings from smart watches. However, smartwatch ECGs can be helpful in the diagnosis of paroxysmal atrial fibrillation. Here. you can see an example. It is a 1-channel ECG that corresponds to lead I. Initially there is an irregular fast pulse without P waves, which corresponds to a tachyarrhythmia in atrial fibrillation. At the end of the first line, after a very short pause, there is sinus rhythm. In the third line you see a short SVT over 3 beats, then SR again. The QRS complex is widened to over 120 ms.

There are several differential diagnoses in the presence of broad-complex tachycardia. The most common cause of wide-complex tachycardia is ventricular tachycardia. In 2nd place is sinus tachycardia/supraventricular tachycardia with aberrant conduction or preexisting bundle branch block.