The normal myocardium of the right ventricle becomes replaced by a chaotic mix of fibrous tissue and fat interspersed within myocardium. The myocardium becomes extremely thinned. The left ventricular may also be involved, but often to a lesser extent. These pathologic changes usually become evident by the time the patient is 20-30 years old.
The effect of these morphologic changes is right ventricular failure and rhythm abnormalities. Ventricular tachycardia and ventricular fibrillation is common, and unfortunately can result in sudden cardiac death (SCD). Structural remodelling of the myocardial wall progresses with the course of the disease, and this generates more and more foci for initiating arrhythmias.
The diagnosis can be challenging due to nonspecific clinical features. It is important to gather structural, functional, and electrophysiologic information about the patient’s heart to make the diagnosis. The first diagnostic criteria were laid out in 1994 by the International Task Force, and revised in 2010. However, it is usually arrhythmia (especially ventricular tachycardia), that first brings the healthy patient medical attention.
Simplified diagnostic criteria of ARVD (2 required). Adopted from Circulation 2010;121:1533.
- Structural. Regional RV akinesia, dyskinesia, or aneurysm with either dilated RVOT or decreased EF by echo, MRI, or angiography.
- Tissue. Residual myocytes <50% of RV free wall by biopsy.
- Repolarization abnormalities. Inverted T waves in the right precordial leads (V1-v#) in the absence of complete RBBB
- Depolarization/conduction abnormalities. Epsilon wave in the right precordial leads (V1 – V3)
- Arrhythmias. Nonsustained or sustained ventricular tachycardia of LBBB morphology with superior axis.
- Family history. First degree relative diagnosed with ARVD.
The ECG changes in ARVD include:
- Epsilon wave (most specific finding, seen in 30% of patients). From Slow RV.
- T wave inversions in V1-3 (85% of patients)
- Prolonged S-wave upstroke of 55ms in V1-3 (95% of patients)
- Localised QRS widening of 110ms in V1-3
- Paroxysmal episodes of ventricular tachycardia with a LBBB morphology
Therapies are directed at preventing heart failure, malignant arrhythmias, and sudden cardiac death. Treats can include:
- Avoid strenuous sports and activity.
- ICD implantation after episode of sustained VT.
- Class III antiarrhythmic (sotalol, amiodarone) therapy if there are unacceptable number of ICD discharges.
- Consideration of radiofrequency ablation (RFA).
- Bilateral cardiac sympathetic denervation via thoracoscopy if refractory to all other therapy
- Heart transplantation
Conventional treatment begins with avoidance of high-intensity activity that can precipitate arrhythmias. ICD implantation is recommended once evidence of ventricular tachycardia has occurred for the patient. Medical antiarrhythmic therapy is usually added as the disease progresses and the ICD discharges are either intolerable or unsuccessful.
If patients are not tolerate of antiarrhythmic treatment or do not achieve unsuccesful clinical improvement, RFA has been the standard backup therapy. However, because of the progressive nature of the disease, even if the original arrhythmia foci are ablated, further remodelling can produce additional initiated sites. Recurrence rates of ventricular arrhythmias after RFA are 50-75% after ablation.
Standard ablation is performed by transvenous approach and performed on the endocardial surface. However, patient’s have a higher success rate for RFA if ablation is performed on epicardial foci also. This requires pericardial access, usually obtained percutaneously with a micropuncture needle. Once confirmed that the pericardial space has been entered, and that there are not interfering adhesions, the tract can de dilated for a sheath insertion. The mapping and ablation catheter can then act on the epicardial surface of the heart. With this endo-epicardial combined approach, there are reports that up to 85% of patients may remain free of arrhythmias.
End-stage heart failure or refractory arrhythmias may require that the patient is considered for heart transplantation.