"irregularity of cardiac rhythm; recurrent occurrences can be a precursor of ventricular fibrillation"@en-us . . "0"^^ . . . "113549794"@en-us . . "PVC"@en-us . . "0"^^ . . "14362841-n"^^ . . "114362841"^^ . "premature ventricular contraction"@en-us . . . . . "premature ventricular contraction"^^ .