The RSR' pattern in right chest leads in hypertrophic cardiomyopathy: vectorcardiographic analysis

Vectorcardiogram (VCG) was studied in four patients with hypertrophic cardiomyopathy (HCM) with RSR' pattern in right chest leads. In these patients there ws an anterior QRS loop with a slow inscription in the initial part of the QRS loop, the pathognomonic initial pig-tail curl pattern was also observed in two patients. Though mid-terminal conduction delay was also observed in two patients, the slowly inscribed terminal QRS vector oriented anteriorly and to the right, thus characteristic of right, thus characteristic of right bundle branch block (RBBB), was not observed. The initial conduction delay was attributed to the conduction disturbance as the result of hypertrophy and disarray of the muscle fiber, particularly in the septal area. The recognition of this VCG pattern provides a pertinent clue in the clinical detection of HCM.