-
• Mechanism-based categorisation: Outpatient ventricular fibrillation in paediatric left ventricular assist device recipients may arise from structural, mechanical, or endocrine mechanisms, each requiring a distinct management approach.
-
• Clinical implication: Mechanism-guided strategies combining antiarrhythmic, mechanical, and metabolic correction are essential to improve survival and prevent recurrence.
-
• Programmatic relevance: Continuous rhythm surveillance and readiness for immediate defibrillation are key to improving survival in this vulnerable group.
Introduction
Ventricular assist devices have become an essential component of paediatric end-stage heart failure management, offering durable circulatory support as a bridge to transplantation, recovery, or, in selected cases, destination therapy. Reference Frigerio1–Reference Castrodeza, Ortiz-Bautista and Fernández-Avilés3 As device technology and long-term survival have improved, attention has shifted toward late complications, among which ventricular arrhythmias have emerged as clinically significant and potentially fatal events. Reference Kadado, Akar and Hummel4,Reference Gordon, Maynes and Choi5
In paediatric ventricular assist device recipients, the incidence of ventricular arrhythmias is lower than in adults but remains clinically relevant, ranging from 10% to 15% in recent cohorts. Reference Pompa, Beerman and Feingold6,Reference Refaat, Chemaly and Lebeche7 Ventricular fibrillation represents the most catastrophic manifestation, capable of compromising systemic perfusion despite ongoing pump flow. Continuous-flow support may sustain partial haemodynamics during ventricular fibrillation; however, ineffective native contraction predisposes to suction events, inflow cannula obstruction, and eventual pump malfunction. Reference Mehra, Uriel and Naka8,Reference Załucka, Świerżyńska and Orczykowski9 The pathophysiology of ventricular fibrillation in this context is complex and multifactorial, encompassing residual myocardial scar, ischaemia, mechanoelectrical interaction, electrolyte imbalance, and drug- or endocrine-induced proarrhythmia. Reference Vollkron, Voitl and Ta10–Reference Bedi, Kormos and Winowich12
Although adult studies provide most of the existing data, paediatric patients differ substantially in myocardial geometry, device–heart proportionality, and autonomic regulation, all of which influence arrhythmogenic mechanisms and treatment response. Reference Shi, Yu and Liu13 Paediatric-specific guidance for ventricular fibrillation management is therefore lacking, and therapeutic strategies are often extrapolated from adult practice. Reference Doğan, Ergin and Beyter14 Moreover, ventricular fibrillation events occurring outside the hospital present unique challenges, as continuous-flow physiology can maintain partial consciousness and delay recognition, while limited access to defibrillators and caregiver inexperience impede timely intervention. Reference Kozik and Alsoufi15,Reference Burki and Adachi16
To date, reports describing out-of-hospital ventricular fibrillation in paediatric left ventricular assist device recipients remain exceedingly rare, with most literature focused on perioperative or inpatient arrhythmias. Reference Throckmorton, Allaire and Gutgesell17,Reference Shinkawa, Ichihara and Saito18 The present study describes three paediatric left ventricular assist device patients who developed outpatient ventricular fibrillation, each representing a distinct mechanistic substrate: structural, mechanical, and endocrine. Through these cases, we aimed to characterise the mechanistic diversity, diagnostic challenges, and management strategies of outpatient ventricular fibrillation in paediatric left ventricular assist device recipients, emphasising the need for continuous rhythm surveillance and mechanism-guided therapy.
Case presentations
Case 1 – structural mechanism (Arrhythmogenic right ventricular dysplasia)
A 16-year-old male with end-stage dilated cardiomyopathy underwent implantation of a left ventricular assist device as a bridge to cardiac transplantation (Figure 1). Histopathological examination of myocardial tissue obtained at implantation revealed fibrofatty replacement of the right ventricular myocardium, confirming the diagnosis of arrhythmogenic right ventricular dysplasia.
Postoperative chest radiographs of three paediatric patients supported with left ventricular assist devices (LVADs).
Figure 1 Long description
Three postoperative chest X-rays of pediatric patients with left ventricular assist devices. Each radiograph shows the placement of the LVAD within the chest cavity. The devices are visible as distinct, opaque structures positioned near the heart. The lungs, ribs, and other anatomical features are also discernible in the images. The orientation of the scans provides a clear view of the thoracic region, highlighting the integration of the assist devices with the patients' anatomy.
Several months after discharge, the patient presented to the paediatric cardiology outpatient clinic with palpitations, dizziness, and near-syncope. Continuous-flow left ventricular assist device parameters were within normal limits; however, a 12-lead electrocardiogram showed ventricular fibrillation (Figure 2). Immediate biphasic defibrillation (200 J) restored sinus rhythm, but recurrent ventricular fibrillation episodes occurred within hours, requiring multiple defibrillations despite stable haemodynamic parameters and normal device flow.
Electrocardiographic tracing demonstrating ventricular fibrillation (VF) in a paediatric patient supported with a left ventricular assist device (LVAD). The tracing shows a chaotic, rapid, and irregular waveform without discernible QRS complexes, consistent with VF morphology.
Figure 2 Long description
A line graph displays a chaotic, rapid, and irregular waveform without discernible QRS complexes, consistent with ventricular fibrillation morphology in a pediatric patient supported with a left ventricular assist device. The x-axis represents time, while the y-axis represents electrical activity of the heart. The waveform appears disorganized and lacks the typical P waves, QRS complexes, and T waves seen in a normal electrocardiogram. This tracing indicates a life-threatening arrhythmia where the heart's ventricles quiver ineffectively, impairing blood circulation. All values are approximated.
Antiarrhythmic therapy with intravenous amiodarone, lidocaine, flecainide, and β-blockers failed to achieve sustained rhythm control. Echocardiography demonstrated adequate left ventricular unloading with no suction or cannula contact, confirming that the arrhythmia was intrinsic to the underlying arrhythmogenic right ventricular dysplasia substrate. Given refractory electrical instability and risk of sudden cardiac death, urgent heart transplantation was performed. Post-transplant follow-up showed a stable sinus rhythm without recurrent arrhythmias.
Summary insight
This case illustrates a structural arrhythmogenic mechanism in which intrinsic myocardial disease drives refractory ventricular fibrillation despite optimal left ventricular assist device support and pharmacologic therapy.
Case 2 – mechanical mechanism (Suction-induced VF)
A 15-year-old female with idiopathic dilated cardiomyopathy supported by a continuous-flow left ventricular assist device as a bridge to transplantation presented six months post-implantation with sudden-onset palpitations and lightheadedness. On examination, she was alert, with preserved mean arterial pressure and normal pump parameters. ECG revealed rapid, chaotic ventricular activity consistent with ventricular fibrillation (Figure 3).
Twelve-lead ECG demonstrating ventricular fibrillation in a paediatric LVAD recipient. The tracing shows rapid, disorganised baseline oscillations without discrete QRS morphology, consistent with ventricular fibrillation.
Figure 3 Long description
The ECG tracing shows rapid, disorganised baseline oscillations without discrete QRS morphology, consistent with ventricular fibrillation. The graph features multiple lines representing different leads, each showing erratic and irregular waveforms. The x-axis represents time, while the y-axis represents electrical activity. All values are approximated.
Transthoracic echocardiography performed immediately before defibrillation demonstrated transient left ventricular suction with inflow cannula contact against the interventricular septum and spontaneous echocardiographic contrast in the right ventricle, indicating near-cessation of native contraction (Supplementary Video 1). These findings identified a mechanical suction event as the precipitating mechanism of ventricular fibrillation.
A 150 J biphasic shock restored sinus rhythm. The patient received intravenous fluids to optimise preload, and left ventricular assist device rotational speed was reduced to relieve suction. After these adjustments, both haemodynamics and rhythm stabilised. No further arrhythmias occurred during the following 10 days of monitoring, and she remained free of ventricular fibrillation recurrence during 12 months of follow-up with optimised speed settings.
Summary insight
This case demonstrates a reversible mechanoelectrical coupling mechanism, where suction-induced septal deformation triggered ventricular fibrillation that resolved after haemodynamic optimisation and left ventricular assist device speed adjustment.
Case 3 – endocrine mechanism (Amiodarone-induced thyrotoxicosis)
A 15-year-old male with advanced dilated cardiomyopathy and severe left ventricular systolic dysfunction was implanted with a left ventricular assist device as a bridge to transplantation. He had been receiving long-term amiodarone therapy for frequent premature ventricular contractions, with previously normal thyroid function.
Two years later, at age 17, he presented with ventricular fibrillation during a routine outpatient visit and underwent immediate electrical defibrillation, successfully restoring sinus rhythm. Laboratory tests revealed severe thyrotoxicosis (TSH < 0.01 µIU/mL, FT4 > 7.7 ng/dL, FT3 15.7 pg/mL). Thyroid ultrasonography showed heterogeneous parenchyma consistent with destructive thyroiditis. A diagnosis of amiodarone-induced thyrotoxicosis was established. Amiodarone was discontinued, and methimazole plus metoprolol were initiated.
Two weeks later, recurrent ventricular fibrillation prompted intensive care admission. The patient exhibited thyroid storm with multi-organ stress and inotrope dependence. High-dose methimazole, intravenous hydrocortisone, Lugol’s iodine, and plasmapheresis were administered to reduce circulating thyroid hormones. Despite these measures and multi-agent antiarrhythmic therapy (esmolol, lidocaine, intermittent amiodarone infusion, mexiletine, and sotalol), recurrent polymorphic ventricular tachycardia and ventricular fibrillation persisted (Figure 4).
Twelve-lead electrocardiogram showing sustained monomorphic ventricular tachycardia (VT) in a paediatric patient with amiodarone-induced thyrotoxicosis and left ventricular assist device (LVAD) support.
Figure 4 Long description
A twelve-lead electrocardiogram displays sustained monomorphic ventricular tachycardia in a pediatric patient. The graph includes multiple lines representing different leads, with each line showing distinct patterns of electrical activity. The x-axis represents time, while the y-axis represents electrical voltage. The analysis indicates excessive alternating current noise, as noted by the error message. The leads are labeled as I, II, III, aVR, aVL, aVF, V1, V2, V3, V4, V5, and V6, showing varying waveforms and amplitudes. The device speed is set at twenty-five millimeters per second, with limb and chest measurements at ten millimeters per millivolt. The frequency range is set between sixty and one hundred fifty hertz.
Progressive renal dysfunction and infection precluded surgical thyroidectomy. The patient succumbed to intractable electrical storm and multi-organ failure secondary to uncontrolled thyrotoxicosis.
Summary insight
This case highlights an endocrine-metabolic mechanism, where thyrotoxicosis potentiated ventricular excitability and rendered antiarrhythmic therapy ineffective, emphasising the systemic dimension of ventricular fibrillation pathogenesis in left ventricular assist device recipients.
Discussion
Ventricular assist devices have revolutionised paediatric heart failure management by providing durable circulatory support and improving survival as a bridge to transplantation or recovery. Reference Frigerio1–Reference Castrodeza, Ortiz-Bautista and Fernández-Avilés3 However, as survival extends, late complications such as ventricular arrhythmias, particularly ventricular fibrillation, have gained increasing importance. Reference Kadado, Akar and Hummel4,Reference Gordon, Maynes and Choi5 Although continuous-flow physiology may sustain partial systemic perfusion during ventricular fibrillation, delayed recognition and inadequate intervention in outpatient settings can lead to irreversible end-organ injury or death. Reference Pompa, Beerman and Feingold6
The mechanisms underlying ventricular fibrillation in left ventricular assist device recipients are multifactorial, encompassing intrinsic myocardial abnormalities, device-heart interaction, and systemic metabolic factors. Reference Hui, Mauermann and Stulak19–Reference Galand, Flécher and Auffret21 The three cases presented here exemplify these mechanistic categories: structural, mechanical, and endocrine, highlighting the need for individualised management strategies based on the underlying substrate rather than uniform antiarrhythmic protocols.
The first case demonstrated a structural arrhythmogenic mechanism in a patient with biopsy-proven arrhythmogenic right ventricular dysplasia. Despite stable left ventricular assist device performance, recurrent ventricular fibrillation episodes occurred, refractory to multiple antiarrhythmic agents. This reflects the intrinsic arrhythmogenicity of arrhythmogenic right ventricular dysplasia, in which fibrofatty replacement and desmosomal disruption cause conduction heterogeneity and re-entry, independent of loading conditions. Reference Towbin, McKenna and Abrams22 Such patients may require definitive management through transplantation rather than prolonged pharmacologic therapy.
The second case illustrated a mechanical mechanism in which suction-induced septal deformation precipitated ventricular fibrillation. Mechanical suction activates stretch-sensitive ion channels and disrupts local repolarisation, leading to mechanoelectrical coupling and arrhythmia initiation. Reference Vollkron, Voitl and Ta10,Reference Tavazzi, Dammassa and Colombo11 Recognition of suction events through echocardiography and haemodynamic assessment is critical, as prompt adjustment of left ventricular assist device speed and preload optimisation can restore normal geometry and terminate arrhythmia without further pharmacologic intervention.
The third case emphasised a systemic or endocrine mechanism, where amiodarone-induced thyrotoxicosis triggered electrical instability. Excess thyroid hormone shortens repolarisation, increases β-adrenergic sensitivity, and enhances ventricular automaticity. Reference Souza, Campagnolo and Martins23,Reference Salzberg, Lachat and Zünd24 Despite aggressive endocrine management and multiple antiarrhythmics, refractory electrical storm developed, underscoring the lethal synergy between metabolic dysregulation and arrhythmogenesis in advanced heart failure. In such cases, early thyroid function surveillance and multidisciplinary coordination between cardiology, endocrinology, and critical care teams are crucial.
Continuous-flow left ventricular assist devices may paradoxically mask malignant arrhythmias by maintaining partial perfusion during ventricular fibrillation. Reference Salzberg, Lachat and Zünd24,Reference Ratman, Biełka and Kalinowski25 Patients may remain conscious, delaying recognition and defibrillation. Structured outpatient rhythm surveillance, caregiver education, and access to portable defibrillators are therefore essential components of paediatric left ventricular assist device programmes. In selected patients, remote ECG monitoring could provide early detection of unrecognised ventricular fibrillation episodes.
The role of implantable cardioverter-defibrillators in paediatric left ventricular assist device recipients remains debated. While implantable cardioverter-defibrillators may reduce sudden cardiac death risk in adults, paediatric data are inconclusive, and device interference or lead-related complications may outweigh benefits. Reference Ahmed, Amin and Boilson26,Reference Duncker, König and Müller-Leisse27 Implantable cardioverter-defibrillator implantation should thus be individualised, guided by arrhythmia mechanism, recurrence risk, and transplant timing.
Collectively, these cases highlight that outpatient ventricular fibrillation in paediatric left ventricular assist device recipients represents a spectrum of mechanisms rather than a uniform entity. Experimental studies have also explored potential cardioprotective and antiarrhythmic mechanisms in animal models, providing additional insights into the electrophysiological basis of ventricular arrhythmias. Reference Sharma, Kishore and Sharma28,Reference Sharma, Bhat and Singh29 Structural myocardial disease can produce arrhythmias independent of device function; mechanical suction events are reversible with prompt haemodynamic optimisation; and endocrine or systemic factors can amplify electrical vulnerability beyond standard antiarrhythmic control. Mechanism-guided therapy integrating electrophysiologic, mechanical, and metabolic perspectives is therefore essential.
Future multicentre registries focusing on paediatric left ventricular assist device-related arrhythmias are warranted to establish mechanism-based diagnostic algorithms and standardised management protocols. By integrating continuous rhythm surveillance, caregiver training, and multidisciplinary coordination, outcomes in this vulnerable population can be substantially improved.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/S1047951126112165.
Financial support
No funding was received for this study.
Competing interests
The authors declare that they have no conflicts of interest to disclose.
Ethical standard
This study was conducted in accordance with the principles of the Declaration of Helsinki and was approved by the Ege University Faculty of Medicine Ethics Committee (Approval No: 23-6T/47). Written informed consent for participation and data use was obtained from the legal guardians of all paediatric patients included in this report.
Consent for publication
Written informed consent for publication of clinical details, images, and supplementary video material was obtained from the legal guardians of the patients. Identifying information has been omitted to ensure patient confidentiality.
