Simultaneous narrow and wide QRS complex tachycardia: Misdiagnosis or missed diagnosis?

Wide complex tachycardia with negative precordial concordance: All that glitters is not gold

“…1-8 Double tachycardia is uncommon but should always be in differential diagnosis in the presence of CL or QRS morphology change. Three possibilities should be considered: (1) the narrow and WCTs are related to a single mechanism (SVT with transient aberrancy), (2) preexcited tachycardia with ventricular activation over an AP, or (3) an inducing VT. [9][10][11][12][13][14][15][16][17][18][19][20][21][22] The most common explanation for alternating narrow and wide QRS tachycardia with identical heart rates is SVT with alternating bundle branch block. 20 Evaluation with a 12-lead ECG can support the differential diagnosis of the underlying mechanism, and several ECG criteria have been proposed.…”

A wide QRS tachycardia with the short and long ventriculoatrial interval in the presence of an atriofascicular pathway: What is the mechanism?

“…The differential diagnosis of a regular WCT with 1:1 AV association includes (1) orthodromic atrioventricular reentrant tachycardia (AVRT) with aberrancy; (2) atrial flutter or atrial tachycardia (AT) with ventricular pre-excitation; (3) antidromic AVRT with retrograde conduction through bundle branch-His-AV node axis; (4) pre-excited tachycardia due to pathway-to-pathway (duodromic) conduction (5) atrioventricular nodal reentrant tachycardia (AVNRT) with bystander AP conduction; (6) AVRT with bystander activation of ventricles using another pathway; (7) ventricular tachycardia (VT) or bundle brunch reentry tachycardia; (8) junctional tachycardia with aberrancy or fasciculoventricular connection; and (9) antidromic AF, nodofascicular or nodoventricular reentrant tachycardia. [1][2][3][4][5][6][7][8][9][10][11][12] Advancement of ventricular activation by an APC at a time when the septal atrium (proximal coronary sinus) has been already (retrogradely) depolarized followed by resetting of the tachycardia in patients with decremental conducting AF (Figure 1) is a helpful maneuver to prove AP existence and participation in the circuit, 5,13,14 and also rules out a myocardial VT. It is also important in WCT to identify accurately the retrograde limb of the circuit, often requiring placement of VPC (Figure 2) in addition to APC to define the antegrade limb during the tachycardia.…”

“…The differential diagnosis of a regular WCT with 1:1 AV association includes (1) orthodromic atrioventricular reentrant tachycardia (AVRT) with aberrancy; (2) atrial flutter or atrial tachycardia (AT) with ventricular pre‐excitation; (3) antidromic AVRT with retrograde conduction through bundle branch–His–AV node axis; (4) pre‐excited tachycardia due to pathway‐to‐pathway (duodromic) conduction (5) atrioventricular nodal reentrant tachycardia (AVNRT) with bystander AP conduction; (6) AVRT with bystander activation of ventricles using another pathway; (7) ventricular tachycardia (VT) or bundle brunch reentry tachycardia; (8) junctional tachycardia with aberrancy or fasciculoventricular connection; and (9) antidromic AF, nodofascicular or nodoventricular reentrant tachycardia 1–12 …”