Their presence, especially in a patient with syncope, requires expert evaluation. However, short-coupled VEs, those occurring less than 400 ms after the preceding QRS, have the potential to trigger life threatening ventricular rhythms. Isolated VEs are an extremely common finding in healthy individuals. This report describes a patient with a structurally normal heart in whom short-coupled ventricular ectopy led to cardiac arrest. Sudden arrhythmic death syndrome (SADS) affects more than 500 people in the UK each year. The varying morphology that is exhibited is due to a single intrapapillary focus, most commonly closer to the tip of the muscle, that has different exits towards the base. They are more likely to produce slightly variable QRS complexes and would usually have an R wave greater than the R’ wave in V1. Įctopics arising from left ventricular papillary muscles produce a more atypical RBBB appearance. A QRS feature that distinguishes an ectopic of fascicular origin from other left ventricular ectopics is the presence of an R prime wave (R’) of greater amplitude than the R wave in leads V1 and V2, as would also be observed in a typical RBBB pattern. įascicular QRS complexes have a relatively narrow QRS (< 130 ms) with a sharp initial deflection, consistent with utilization of the rapidly-conducting fascicular tissue. The resulting QRS complexes have a RBBB-like morphology, but may have either a superior or inferior axis, depending on whether they originate from the posterior or anterior fascicles, respectively. Īrrhythmias arising from the His-Pukinje conduction system, typically the terminal arborizations of the left bundle branch fascicles, can also cause both ventricular ectopy and sustained ventricular tachycardia. There are different patterns to outflow tract arrhythmia they can present as isolated beats, couplets, non-sustained and sustained monomorphic ventricular tachycardia. Classically benign, outflow tract ectopics have an inferior axis (positive QRS in the inferior leads) and a left bundle branch block pattern if of right ventricular outflow tract origin and an atypical RBBB pattern if from the left ventricular outflow tract. VE beats most commonly arise from the outflow tracts of both ventricles, with a greater preponderance of right ventricular beats. ![]() The QRS morphology of ventricular ectopy on a 12-lead ECG helps to identify their anatomical origin, as well as their clinical significance. By studying the morphologies and axes of the QRS complexes produced by VEs, we can identify their likely origins and ascertain their clinical significance. Short-couped VEs that are superimposed onto the preceding T wave (R-on-T) are indicative of electrical instability of the heart and should prompt urgent investigation. The patient made a good recovery and was discharged from hospital with a secondary prevention implantable cardioverter-defibrillator (ICD) in situ. The patient underwent electrophysiological mapping and catheter ablation of her ectopy. A cardiac MRI revealed late gadolinium enhancement of the posterior papillary muscle (indicative of focal scarring). Anti-arrhythmic therapy was initiated in the form of hydroquinidine, but the patient continued to have frequent VEs of right bundle branch block (RBBB) morphology with a relatively narrow QRS complex and a variation in frontal axis. The dysrhythmia had been initiated by a short-coupled (R-on-T) ventricular ectopic (VE) beat. Review of her cardiac monitoring revealed an episode of polymorphic ventricular tachycardia which had degenerated into ventricular fibrillation. ![]() In the context of syncope, ventricular ectopy should be carefully assessed for coupling interval and morphology.Ī 39-year-old woman, who had presented with recurrent syncope, had a cardiac arrest shortly after admission that required emergency defibrillation. This case report highlights the importance of recognizing that ventricular ectopy may be a cause for syncope and sudden cardiac death, through triggered disorganized arrhythmia.
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