Malignant Ventricular Arrhythmic Storm Triggered by Short-coupled Premature Ventricular Contractions Arising from the Anterolateral Papillary Muscle

European Journal of Arrhythmia & Electrophysiology, 2016;2(1):33–6 DOI: http://doi.org/10.17925/EJAE.2016.02.01.33

Abstract:

A case of idiopathic ventricular fibrillation (VF), triggered by ectopic beats originating from the anterolateral papillary muscle, is presented. The arrhythmia was characterised by short-coupled premature ventricular contractions (PVCs), which were resistant to isoproterenol, and ultimately treated with catheter ablation.
Keywords: Idiopathic ventricular fibrillation, papillary muscle, isoproterenol
Disclosure: Peter Kabunga, Caroline Medi, Laura Yeates and Raymond W Sy have nothing to disclose in relation to this article. No funding was received in the publication of this article.
Correspondence: Raymond W Sy, Department of Cardiology, Royal Prince Alfred Hospital, Camperdown, New South Wales 2050, Australia. E: raymond.sy01@gmail.com
Open Access: This article is published under the Creative Commons Attribution Noncommercial License, which permits any noncommercial use, distribution, adaptation, and reproduction provided the original author(s) and source are given appropriate credit.
Compliance with Ethics: All procedures were followed in accordance with the responsible committee on human experimentation and with the Helsinki Declaration of 1975 and subsequent revisions, and informed consent was received from the patient involved in this case study.
Supplementary Information: An accompanying video to this article can be found at www.touchcardio.com/gallery/malignant-ventricular-arrhythmic-storm-triggered-short-coupled-premature-ventricular

Premature ventricular contractions (PVCs) arising from the Purkinje network are rare causes of idiopathic ventricular fibrillation (IVF).1–4Van Herendael and colleagues recently highlighted the importance of triggers from the papillary muscles (PM) and the left ventricular outflow tract in the initiation of ventricular fibrillation.4 In their study, eight of 30 patients had PM triggers which were successfully targeted with catheter ablation. Although acute success was reported in all PM-mediated ventricular tachycardia (VT)/ventricular fibrillation (VF) patients, 38% of patients had a recurrence of PVCs during long-term monitoring, perhaps due to poor catheter stability and presumed intramurality of target sites.

A range of medical therapies – including beta-blockers, amiodarone, verapamil and quinidine – have been variably described in the longterm management of idiopathic VF. In addition, isoproterenol has been acutely used in the setting of idiopathic VF storms associated with early repolarisation syndromes.5–7 However, there are few reports regarding the specific response of PM-mediated VT/VF to pharmacological therapy.

We report a case of a malignant, isoproterenol-resistant VF storm, triggered by short-coupled monomorphic PVCs originating from the anterolateral papillary muscle (APM) successfully treated with catheter ablation.

Case report
A 47-year-old woman presented to her local hospital with recurrent nocturnal seizures. Cardiac monitoring revealed non-sustained polymorphic ventricular tachycardia and ventricular fibrillation preceding seizure activity. Over the ensuing 24 hours, she received 10 shocks, despite a sequential trial of pharmacological therapy with intravenous (IV) amiodarone (300 mg bolus plus 900 mg continuous infusion), 40 mmol of magnesium sulphate (MgSO4), 40 mmol of potassium chloride (KCl) and boluses of IV metoprolol. Isoproterenol was then administered at the peripheral hospital as she continued to get multiple PVCs and non-sustained VT and the patient was transferred to our centre for further evaluation.

She had been previously treated with carbamazepine and valproate for 10 years, with the presumed diagnosis of epilepsy. Notably, the patient’s symptoms pre-dated the prescription of anti-epileptic medications. There was also a family history of premature sudden cardiac death (Figure 1).

Baseline investigations including electrolytes, trans-thoracic echocardiogram (TTE), and electrocardiogram (ECG) (including QT interval) during sinus rhythm were normal. The QRS complexes in leads V1–V3 remained normal in all ECGs, and there was no J-point elevation observed before or after episodes of arrhythmia (Figure 2). Episodes of sustained ventricular arrhythmia appeared to be consistently triggered by monomorphic PVCs with a short coupling interval (240 ms) (Figure 3). Interestingly, we did not observe a critical difference in the coupling intervals between isolated PVCs and those PVCs initiating torsades de pointes/VF (Figures 2 and 3). Coronary angiography, cardiac magnetic resonance, flecainide challenge and signal averaged ECG, were normal.

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Keywords: Idiopathic ventricular fibrillation, papillary muscle, isoproterenol