Dysplastic conditions of the right ventricular myocardium: Uhl's anomaly vs arrhythmogenic right ventricular dysplasia.
Comparison of Uhl's anomaly, right ventricular outflow tract ventricular tachycardia (RVOT VT) & arrhythmogenic right ventricular dysplasia/cardiomyopathy (AC) with an insight into genetics of AC.
Uhl's anomaly, arrhythmogenic right ventricular dysplasia / cardiomyopathy (ARVD/C) and right ventricular outflow tract ventricular tachycardia (RVOT VT) involve pathogenic changes in the right ventricular (RV) myocardium.
Since then, the term ARVD/C has been used increasingly and references to the Uhl's anomaly have decreased raising the question whether the two conditions are different entities or are variants of a single underlying disorder (3).
Uhl's anomaly and RVOT VT, severe and mild forms of ARVD/C?
ARVD/C and Uhl's anomaly are considered as different manifestations of the same disease (34).
In Uhl's anomaly the apoptotic process may be incessant and starts early in infancy or childhood with complete destruction of RV wall, whereas in ARVD/C there may be episodic apoptosis beginning in adolescence (36).
The mechanism involved in Uhl's anomaly would probably involve the factors that would either trigger apoptotic pathways or fail to protect from apoptosis leading to complete loss of right ventricular myocardium.
A similar process might be expected in Uhl's anomaly where the Wnt ligands fail to suppress the apoptosis leading to complete loss of RV myocardium.
Mallat et al (40) showed that apoptosis could be the primary process that precedes fibrofatty replacement of myocardial tissue in ARVD/C unlike in Uhl's anomaly where the only process of apoptosis is reported.
The mechanism operating in ARVD/C should be essentially different from the apoptosis triggered in Uhl's anomaly as in the later condition there is complete loss of RV myocardium unlike in ARVD/C where it is assumed that apoptosis process not being continued incessantly but being only episodic both spatially and temporally and result in the focal loss of myocardium in a few limited regions or may be more diffused.