Differential Diagnosis of Tachycardias

Differential diagnosis of broad complex tachycardias Criteria for the diagnosis of the presence of a broad complex tachycardia: QRS >120ms = Broad Complex Tachycardia QRS <120ms = Narrow Complex Tachycardia

Tachycardias Broad QRS Ventricular tachycardia Narrow QRS SVT with abnormal conduction Bundle branch block Rate related Ventricular pre- excitation Narrow QRS Sinus tachycardia Atrial tachycardia Atrial fibrillation Atrial Flutter AVRNT AVRT SVT

Differential diagnosis of broad complex tachycardias The rhythm strip taken from a single lead is generally insufficient to make a differential diagnosis between an SVT with aberrancy or VT. A 12 lead ECG is required for making an accurate diagnosis.

Differential diagnosis of broad complex tachycardias The presence of anyone of the following confirms the diagnosis of VT: Evidence of A.V.Dissociation….in the form of independent atrial activity. Presence of fusion beats Presence of capture beats

AV dissociation Atrioventricular dissociation in monomorphic ventricular tachycardia (note P waves, arrowed)

Capture beat Capture beat

Fusion Beat Fusion beat

Differential diagnosis of broad complex tachycardias In patients with IHD…. …. 90% of broad complex tachycardias will be ventricular in origin

QRS Contours Favouring Ventricular Tachycardia Wellens Gulamhusein V1 15/15 (100%) 84/86 (98%) V1 7/7 (100%) 177/187 (95%) V6 27/31 (87%) 189/190(100%) V6 17/17 (100%) 38/40(94%) Wagner (2001) Marriotts Practical Electrocardiography 10th Ed.

Differential diagnosis of broad complex tachycardias QRS Contours Favouring Ventricular Aberration Wellens Gulamhusein V1 38/41 (93%) 55/55 (100%) V6 44/47 (94%) 27/27 (100%) Wagner (2001) Marriotts Practical Electrocardiography 10th Ed.

Tachycardias presenting with a basically RBB pattern Differential diagnosis of broad complex tachycardias Tachycardias presenting with a basically RBB pattern R’ SVT is more the likely diagnosis where there is a triphasic QRS…rSR’; with the R’ wave taller than the initial r. V1 Professor A.J Camm: “A Master Class in The Differential Diagnosis of Broad Complex Tachycardias.

Tachycardias presenting with a basically RBB pattern Differential diagnosis of broad complex tachycardias Tachycardias presenting with a basically RBB pattern If the ‘S’ wave at least reaches the isoelectric line (or goes beyond it) the tachycardia is most likely to be supra- ventricular in origin. S V1 Professor A.J Camm: “A Master Class in The Differential Diagnosis of Broad Complex Tachycardias.

Tachycardias presenting with a basically RBB pattern Differential diagnosis of broad complex tachycardias NB: Proviso: If the ‘S’ wave is not much more than a notch on the down-stroke, then the tachycardia is less likely to be supraventricular in origin. S V1 Professor A.J Camm: “A Master Class in The Differential Diagnosis of Broad Complex Tachycardias.

Tachycardias presenting with a basically RBB pattern Differential diagnosis of broad complex tachycardias R:S >1 SVT R:S <1 VT V6 Professor A.J Camm: “A Master Class in The Differential Diagnosis of Broad Complex Tachycardias.

Tachycardias presenting with a basically LBB pattern Differential diagnosis of broad complex tachycardias Tachycardias presenting with a basically LBB pattern V1 Kinwall Criteria: The Presence of any one of these characteristics points to the diagnosis of VT. Initial ‘r’ wave in V1 > 30ms in duration. Presence of a ‘notch’ on the down-stroke of the ‘S’ wave. The duration of the complex from the start of the ‘r’ wave to the nadir of the ‘S’ wave = 60ms or more.

Tachycardias presenting with a basically LBB pattern Differential diagnosis of broad complex tachycardias 30ms ‘notch’ V1 60ms Professor A.J Camm: “A Master Class in The Differential Diagnosis of Broad Complex Tachycardias.

Tachycardias presenting with a basically LBB pattern Differential diagnosis of broad complex tachycardias The presence of any ‘q’ wave points to the likelihood that the tachycardia is ventricular in origin. ‘q’ V6 Professor A.J Camm: “A Master Class in The Differential Diagnosis of Broad Complex Tachycardias.

Differential diagnosis of broad complex tachycardias Brugarder et al Criteria: ‘rS’ patterns are usually present in one or more precordial leads therefore: A no ‘rS’ pattern most likely suggests that the tachycardia is ventricular in origin. If there are any ‘rS’ complexes; if the distance from the start of the ‘r’ wave to the ‘nadir’ of the ‘S’ wave is 100ms or more it indicates that the tachycardia is most likely to be ventricular in origin.

V1 V6 Differential diagnosis of broad complex tachycardias 100ms Professor A.J Camm: “A Master Class in The Differential Diagnosis of Broad Complex Tachycardias.

Differential diagnosis of broad complex tachycardias Concordance of The QRS complexes in The Precordial Leads “When all of the ventricular complexes from leads V1 to V6 are either negative (concordant precordial negative) or positive (concordant precordial positive), the diagnosis is most likely VT, since these patterns would be atypical of either RBBB or LBBB.” Wagner (2001) Marriotts Practical Electrocardiography 10th Ed.

Differential diagnosis of broad complex tachycardias Negative Concordance Positive Concordance Wagner (2001) Marriotts Practical Electrocardiography 10th Ed.

Cardiac Axis: If the Cardiac axis is between -1500 and -/+ 1800, this is clearly abnormal and is a useful clue to the tachycardia being ventricular in origin since the electrical axis of neither RBBB or LBBB produce such extreme axis deviation.

Broad complex Tachycardia yes Independent p waves visible VT no no Are QRS in V1 and V6 typical for left or right BBB VT yes SVT a possibilty