Can right ventricular (RV) dilation cause arrhythmias and atrioventricular (AV) node block?

Right Ventricular Dilation and Arrhythmias

Right ventricular (RV) dilation can cause arrhythmias and atrioventricular (AV) node block, with the risk increasing with the severity and chronicity of the dilation. 1

Mechanisms of Arrhythmias in RV Dilation

• RV dilation leads to structural and electrical remodeling that creates an arrhythmogenic substrate, with progressive RV dilation being associated with sustained atrial and ventricular arrhythmias 1
• Ventricular tachycardia and ventricular fibrillation are the most common life-threatening arrhythmias in patients with RV dilation, accounting for approximately one-third to half of late deaths in conditions like repaired tetralogy of Fallot 1
• QRS prolongation (>180 ms), particularly if progressive, is a significant risk factor for ventricular tachycardia and sudden cardiac death in patients with RV dilation 1
• Atrial arrhythmias are common in RV failure and tricuspid regurgitation, which frequently accompany chronic RV dilation 1
• Widespread replacement fibrosis in the dilated RV, combined with Connexin 43 and Nav1.5 disruption, leads to shorter wavelength, conduction slowing, and conduction heterogeneity, resulting in greater vulnerability to arrhythmias 2

AV Node Block in RV Dilation

• Atrioventricular conduction disturbances are rare in patients with RV dilation but can occur as a consequence of progressive hemodynamic problems 1
• In conditions like right ventricular cardiomyopathy (RVC), atrioventricular conduction disturbances are uncommon compared to ventricular arrhythmias 1
• The mechanism of AV node block in RV dilation may involve:
  • Mechanical stretching of the conduction system due to chamber enlargement 1
  • Ventricular interdependence where RV dilation affects LV filling and function, potentially impacting the conduction system 1, 3
  • Fibrosis extending to the conduction system in advanced disease 2

Risk Factors for Arrhythmias in RV Dilation

• Severity of RV dilation - larger RV volumes correlate with increased arrhythmia risk 1
• Progressive RV systolic dysfunction accompanying dilation 1
• Presence of significant tricuspid regurgitation, which often accompanies and exacerbates RV dilation 1
• Diffuse RV involvement rather than localized forms of disease 1
• Left ventricular involvement in addition to RV dilation significantly increases arrhythmia risk 1
• QRS duration >180 ms, particularly if progressive 1
• Late potentials during signal-averaged ECG, which correlate with disease severity and are independent predictors of sustained ventricular tachycardia 1

Clinical Implications in Specific Conditions

Tetralogy of Fallot

• In repaired tetralogy of Fallot, significant pulmonary regurgitation leads to RV dilation, which is associated with atrial and ventricular arrhythmias 1
• Sudden cardiac death is reported in 1-6% of cases, mostly due to ventricular tachycardia/ventricular fibrillation 1
• Pulmonary valve replacement should be considered in asymptomatic patients with severe pulmonary regurgitation and RV dilation when sustained atrial/ventricular arrhythmias are present 1

Heart Failure with RV Involvement

• RV dysfunction is a strong predictor for developing atrial fibrillation in acutely decompensated heart failure patients 4
• Patients with RV dysfunction had more cardiac events (56% versus 38%) and higher all-cause mortality (4.7%/year versus 2.9%/year) compared to those with normal RV function 4
• The combination of atrial fibrillation and RV dysfunction carries the worst prognosis, especially when combined with LV dysfunction 4

Diagnostic Approach

• ECG to evaluate for right bundle branch block, QRS prolongation (>180 ms), and rhythm abnormalities 1
• Holter monitoring to detect non-sustained ventricular arrhythmias, though its predictive value for sustained arrhythmias is limited 1
• Signal-averaged ECG to detect late potentials, which correlate with disease severity and arrhythmia risk 1
• Comprehensive echocardiography to assess RV size, function, and associated abnormalities like tricuspid regurgitation 1
• Cardiac MRI for accurate assessment of RV volumes, function, and tissue characterization to detect fibrosis 1

Management Considerations

• Pulmonary valve replacement in patients with severe pulmonary regurgitation and RV dilation when sustained arrhythmias are present 1
• Programmed electrical stimulation may help risk-stratify patients with RV dilation and identify those at higher risk for sustained ventricular arrhythmias 1
• Patients with unexplained syncope and impaired ventricular function should undergo hemodynamic and electrophysiological evaluation 1
• In the absence of a defined and reversible cause of arrhythmias, ICD implantation should be considered 1
• Biventricular pacing may be beneficial in patients with RV dilation who develop heart failure and dilated cardiomyopathy following RV pacing for AV block 1, 5

Pitfalls and Caveats

• Strenuous exercise and competitive sports should be discouraged in patients with significant RV dilation and arrhythmia risk 1
• The presence of non-sustained ventricular arrhythmias has uncertain prognostic significance and should not be the sole determinant for aggressive intervention 1
• QT dispersion and ST-T wave analysis are of uncertain value in risk stratification 1
• Ventricular interdependence must be considered - RV dilation can impair LV filling and function through septal displacement, potentially exacerbating arrhythmia risk 1, 3, 6
• Strain measurements are strongly influenced by ventricular size, which should be considered when interpreting echocardiographic findings 7