**5. Management of Arrhythmias Encountered in patients with ventricular assist devices**

It is important to note the potential for reversible causes of arrhythmia in pediatric patients with VAD. Electrolyte derangement, consequences of comorbidities, and drug–drug interactions with electrophysiologic effects should be considered. The

identification of reversible causes of atrial or ventricular arrhythmia may allow for management with conventional therapies. Limitation of known QT-prolonging medications and proarrhythmic agents is prudent.

Suction events where the VAD inflow cannula interacts with the ventricular wall can result in ventricular arrhythmia [28]. These events may be avoided by reducing high VAD pump speed and avoiding intravascular volume depletion. Recurrent suction events associated with ventricular arrhythmia may require fluid supplementation.

Studies have demonstrated that some adult patients with continuous-flow VAD remain hemodynamically stable while in ventricular tachyarrhythmia including ventricular fibrillation [40, 42–44]. While patients were symptomatic, there was no evidence of end-organ dysfunction as a result of the ventricular arrhythmia. After restoration of sinus rhythm, there was no recurrence of the ventricular arrhythmia [42]. This suggests that there can be hemodynamic stability with left VAD support during episodes of ventricular arrhythmia. However, prolonged ventricular fibrillation can result in right ventricular failure and subsequent sequela. As such, restoration of sinus rhythm would be prudent.

#### **5.1 Medical management**

#### *5.1.1 Atrial arrhythmias*

Beta blockers are standard first-line therapy for rate control in patients with heart failure. Rate control with beta blockers is usually sufficient for the management of atrial arrhythmias. Digoxin may be a useful adjunct to beta blocker therapy by slowing ventricular response to the atrial arrhythmia. Calcium channel blockers are not typically used in the setting of significant systolic dysfunction.

When rate control is insufficient, then restoration and maintenance of sinus rhythm may be required. Amiodarone and dofetilide are commonly utilized for conversion to sinus rhythm in adult patients. Amiodarone is the most commonly utilized antiarrhythmic as single-agent therapy in pediatric patients with VAD [33]. Refractory cases may require amiodarone in conjunction with beta blockers, certain sodium channel blockers, or digoxin.

#### *5.1.2 Ventricular arrhythmias*

Due to the underlying condition, most patients who have received a VAD likely have an indication for beta-blockade. However, it is unclear in the pediatric population if beta-blockade is adequate for prevention of ventricular arrhythmias. Adult studies are divergent with some studies demonstrating an association with betablocker nonuse and ventricular arrhythmias and others showing no differences [27, 45]. Amiodarone has been identified as protective against ventricular arrhythmias amongst non-LVAD patients with ICDs, however it comes with risks of adverse effects [46]. One adult study showed improved arrhythmia-free survival in LVAD patients with ventricular arrhythmias who were started on amiodarone as secondary prevention [17]. However, when baseline amiodarone use was studied in the LVAD population, there was an increased mortality associated with its use [47]. More data are needed to assess efficacy of antiarrhythmics in the adult LVAD population and there is a near-absence in data in the pediatric population. Therefore, decisions will continue to need to be patient-specific taking into account arrhythmia burden, substrate,

patient hemodynamics, drug–drug interactions, and type of VAD. Should an antiarrhythmic be initiated, as the first month post VAD implantation is reported as the highest risk [48], consideration could be made for discontinuation of antiarrhythmic medication over time in patients with longer-term VAD.
