A very unusual wide QRS tachycardia: VT or SVT?

INTRODUCTION

A 13 old girl presented with recurrent wide QRS tachycardia since she was 4.

METHODS

An electrophysiologic study was performed.

RESULTS

The electrophysiologic study showed that QRS complexes identical to those of the tachycardia could be elicited with premature atrial extrastimuli but with a shorter atrioventricular (AV) delay when the QRS was wide compared with narrow QRS complexes. The tachycardia was ablated at 9 o'clock on the tricuspid annulus demonstrating the presence of an atriofascicular fiber.

CONCLUSION

We believe that this atypical behavior can be explained by AV nodal like longitudinal dissociation of a slowly conducting accessory pathway.

Lacosamide Intoxication-induced Wide QRS Tachycardia Successfully Treated with Veno-arterial Extracorporeal Membrane Oxygenation

Lacosamide is an antiepileptic drug that acts on voltage-gated sodium channels and was approved as an antiepileptic by the Food and Drug Administration in 2008. Although the efficacy and safety of lacosamide have been established in many previous trials, some case reports have shown that it may lead to cardiovascular side effects, especially in patients with electrical conduction system disorders. We herein report a case of life-threatening cardiac arrhythmia caused by lacosamide intoxication that was successfully treated with veno-arterial extracorporeal membrane oxygenation.

An Incessant Tachycardia with Alternating QRS Complexes: What Is the Mechanism?

We present a patient with ischemic cardiomyopathy who had ventricular tachycardia (VT) with QRS morphology alternans. The electrophysiological findings, in this case, supported the occurrence of antegrade activation of the proximal His–Purkinje system during VT, with the ultimate electrocardiogram morphology dependent on fusion from intramyocardial and His–Purkinje activations.

[ECG pearl: Valsalva maneuver terminated ventricular tachycardia]

Összefoglaló. Egy 78 éves férfi széles-QRS-tachycardiás esetét mutatjuk be. A betegnél a pitvar-kamrai disszociáció igazolta a ritmuszavar kamrai eredetét, amelyet a Valsalva-manőverrel több alkalommal is átmenetileg meg lehetett szüntetni. A szerzők ismertetik a manőver lehetséges patomechanizmusait, illetve felhívják a figyelmet arra, hogy a vagusmanőverre megszűnő reguláris tachycardia nem jelent feltétlenül supraventricularis eredetet. Orv Hetil. 2021; 162(12): 468-470. Summary. A 78-year-old man is presented with wide QRS tachycardia (WQRST). The ventricular origin of WQRST was confirmed by atrioventricular dissociation. The Valsalva maneuver terminated the tachycardia repeatedly. The authors discuss the possible mechanisms of Valsalva maneuver in the arrhythmia termination. This case highlights that Valsalva maneuver or carotid massage terminated tachycardia are not necessarily supraventricular tachycardia. Orv Hetil. 2021; 162(12): 468-470.

Time-dependent antiarrhythmic effects of flecainide on induced atrial fibrillation in horses

Background

Pharmacological treatment of atrial fibrillation (AF) in horses can be challenging because of low efficacy and adverse effects. Flecainide has been tested with variable efficacy.

Objective

To test whether the efficacy of flecainide is dependent on AF duration.

Animals

Nine Standardbred mares.

Methods

Factorial study design. All horses were instrumented with a pacemaker and assigned to a control or an AF group. On day 0, all horses were in sinus rhythm and received 2 mg/kg flecainide IV. Atrial fibrillation subsequently was induced in the AF group by pacemaker stimulation. On days 3, 9, 27, and 55, flecainide was administered to all horses, regardless of heart rhythm.

Results

All horses in AF cardioverted to sinus rhythm on days 3 and 9. On day 27, 5/6 horses cardioverted, whereas only 2/6 cardioverted on day 55. The time from the start of flecainide infusion to cardioversion (range, 3–185 min, log transformed) showed linear correlation with the cumulative duration of AF (r² = .80, P < .0001). Flecainide induced abnormal QRS complexes in 4/6 AF horses and 1/3 controls. A positive correlation was found between heart rate before flecainide infusion and number of abnormal QRS complexes (0.14, P < .05). One horse suffered from cardiac arrest and died after flecainide infusion.

Conclusions and Clinical Importance

Flecainide is effective for cardioversion of short‐term induced AF, but the effect decreases with AF duration. Controlling heart rate may minimize adverse effects caused by flecainide, but the drug should be used with great caution.