**4. Arrhythmias encountered in patients with ventricular assist devices**

#### **4.1 Atrial tachyarrhythmia**

Atrial arrhythmias are common on patients with heart failure. Atrial fibrillation is the most frequently encountered atrial arrhythmia. However, ectopic atrial tachycardia and atrial flutter are seen as well. Persistent atrial flutter can result in loss of AV synchrony and impaired ventricular filling. In certain patients with left VADs, atrial arrhythmias, particularly atrial flutter with rapid ventricular response, have been associated with hemodynamic compromise secondary to decompensated right heart failure [29, 30]. Improvement in right heart failure has been demonstrated after catheter ablation of the atrial flutter [29].

The pathophysiology of heart failure results in structural changes and electrical remodeling that encourage the development of atrial fibrillation. The frequency of atrial fibrillation increases with heart failure severity, reaching approximately 50% of patients with New York Heart Association (NYHA) Class IV classification [31]. In adult patients, atrial fibrillation may be encountered in over 40% of patients on VAD therapy [32]. There are conflicting results regarding the risk of thromboembolic events patients with atrial arrhythmia on VAD therapy; however, the presence of atrial fibrillation prior to VAD therapy has been shown to predict the occurrence of ventricular arrhythmia after VAD implantation [23].

*Arrhythmia Management in Pediatric Patients with Ventricular Assist Devices DOI: http://dx.doi.org/10.5772/intechopen.107061*

It has been demonstrated that pediatric patients undergoing VAD therapy for cardiomyopathy or myocarditis have an increased risk of developing arrhythmia [10]. In a cohort of pediatric patients with VAD, 38% experienced an atrial arrhythmia [11]. The majority of the tachyarrhythmia episodes were non-sustained with a median rate of 150 bpm. There was no correlation between presence of arrhythmia and mortality [11]. In pediatric patients with VAD for primary diagnosis of arrhythmia, it has been demonstrated that nearly 70% have supraventricular tachycardia, of which nearly 40% are ectopic atrial tachycardia or atrial flutter [33].

#### **4.2 Ventricular tachyarrhythmia**

Before discussing the risks of ventricular arrhythmias in the context of pediatric VAD use, it is important to recognize the risks of these arrhythmias in patients with heart failure in general. Regardless of whether the reason for heart failure is secondary to cardiomyopathy or congenital heart disease, risks have been well described [24, 34]. Guidelines and consensus statements include recommendations for management, including the use of anti-arrhythmics as well as indications for implantation of implantable cardioverter-defibrillators (ICDs) [35, 36]. For this reason, many patients who present for VAD implant are already receiving anti-arrhythmics, have ICDs, or both. In fact, there are a handful of pediatric patients who have received VADs specifically for intractable ventricular arrhythmias [33, 37].

Early in the era of adult VAD use, it became clear that there was an association of new onset monomorphic ventricular tachycardia in the months following implant [38]. While the majority of arrhythmias tend to occur during the initial hospitalization at implant, later onset arrhythmias have also been documented [17]. In addition, given that most patients have significant heart failure, many will already have primary or secondary prevention ICDs with a history of ventricular arrhythmias [39]. Pediatric arrhythmia data in VADs are quite scarce. A 2015 study found over half of patients in a single center study developed ventricular arrhythmias [11]. A more recently published single center study found that patients with cardiomyopathy and myocarditis were more likely to have non-sustained and sustained ventricular tachycardia than those with congenital heart disease [10]. Additionally, those who had less left ventricular decompression were at a higher risk for having ventricular arrhythmias. Arrhythmia presence prior to VAD implant was associated with increased risk of ventricular arrhythmias and antiarrhythmic therapy was associated with decreased risk.

While isolated ventricular ectopy and often non-sustained ventricular tachycardia do not require significant intervention in patients with heart failure, once a VAD is implanted these will likely become even less hemodynamically significant given the additional support [40]. With more sustained arrhythmias, one would expect decreased flows given the loss of right ventricular contribution to cardiac output and if sustained enough, right ventricular failure. For this reason, those patients who receive VAD support specifically for intractable arrhythmias often are given biventricular support [41].
