Ventricular Arrhythmias

Ventricular arrhythmias manifest clinically with palpitations, or episodes of ventricular tachycardia (VT) associated with syncope, and are frequently the first manifestations of the disorder. There is evidence that ARVC/D is a common cause of sudden cardiac death in young people [6]. Patients with VT who have associated hemodynamics impairment or those who had ventricular fibrillation have a worse prognosis than patients with hemodynamically stable VT [7]. They usually also have more advanced right ventricular disease, as described by Turrini et al. [7] who demonstrated the association between sustained VT and reduced RV ejection fraction.

Dalal et al. [8] compared the incidence of induced or spontaneous ventricular arrhythmias in patients with plakophilin-2 (PKP2) gene mutation with those who did not have an identified form of the disease. There was no significant difference between the two groups, suggesting that the PKP2 mutation is not as

Table 13.1 • ECG-Based Task Force criteria for Diagnosing ARVC/D [4]

Minor

Major

III. Repolarization Abnormalities

Inverted T waves in precordial leads (V2 and V3) in absence of right bundle block

IV. Depolarization/Conduction Abnormalities

Late potentials in signal-averaged ECG

Epsilon waves/Localized prolongation (>110 ms) of QRS in right precordial leads (V1-V3)

V. Arrhythmias

Left bundle branch block type ventricular tachycardia (sustained & nonsustained) by ECG, Holter, or exercise testing Frequent ventricular extrasystoles in Holter (>1000/24 h)

Fig. 13.1 • Holter-detected episode of nonsustained VT of left bundle branch block morphology in a patient with ARVC/D

sociated with a more pronounced susceptibility to ventricular arrhythmias.

Ventricular tachyarrhythmias occurring in ARVC/D patients originate in the right ventricle (Fig. 13.1). The morphology of the ventricular ectopic beats is of LBBB morphology and has either an inferior or superior QRS axis [9]. The inferior morphology could indicate idiopathic or right ventricular outflow tachycardia (RVOT). It is important to differentiate between this relatively benign arrhythmia and ARVC/D, which carries a more serious prognosis. RVOT tachycardia is a primary electrical disease, most likely related to intracellular calcium overload precipitated by catecholamines. The ventricular arrhythmias are inhibited by intravenous adenosine. In contrast to patients with ARVC/D, those who have RVOT tachycardia do not have structural changes of the right ventricle. However, it is difficult to be certain that the right ventricle is normal by all of the imaging modalities in patients who may have an early form of ARVC/D. Some patients thought to have RVOT tachycardia may eventually show progression to ARVC/D.

In a large number of patients with ARVC/D, Holter recordings show frequent ventricular premature beats (PVB), which are defined as >1,000 PVBs per 24 h in probands [4] and >200 PVBs per 24h in family members [10]. In preliminary data from the North American ARVC/D Registry, 61% of probands had frequent PVBs on Holter; however, in only 10% were Holter-detected ventricular arrhythmias the exclusive basis for classification of a minor criterion. In 60%, the criterion for Task Force criteria for ventricular arrhythmias was met based on the presence of such arrhythmia recorded in a nonstudy prior Holter recordings or emergency visit ECGs. These percentages may not reflect the actual contribution of Holter recordings to the diagnosis of ARVC/D. In the North

American ARVC/D Registry, Holter recordings were obtained by a standardized protocol after enrollment. Numerous probands had out-of-study Holter recordings that met the criteria of PVB frequency by Holter prior to their official enrollment.

Was this article helpful?

0 0

Post a comment