Most<unk><unk> s have a narrow QRS complex on the EKG.  It is not infrequent, however, for aberrant conduction to be be present, sometimes as a result of the more rapid rate of conduction.  This widening of the QRS complex yields<unk><unk>  with aberrant conduction <unk> AC) which produces a wide-complex<unk>  that may mimic ventricular<unk>  <unk> .  In the clinical setting, it is important to determine whether a wide-complex<unk>  is an<unk>  or a ventricular<unk> , since they are treated differently.  Ventricular<unk>  has to be treated appropriately, since it can quickly degenerate to ventricular fibrillation and death. A number of different algorithms have been devised to determine whether a wide complex<unk>  is<unk>  or ventricular in origin.
In general, a history of structural heart disease, ischemic heart disease or congestive heart failure increases the likelihood that the<unk>  is ventricular in origin.
Supraventricular tachycardia differentiating SVT from VT
Second degree AV block echocardiography
Third degree AV block echocardiography
Stress cardiomyopathy electrocardiogram
Sick sinus syndrome electrocardiogram
First degree AV block echocardiography
Pacemaker syndrome electrocardiogram
Ventricular fibrillation electrocardiogram