Author,Title,Journal,ISSN,Publisher,Date,Volume,Number,Page,URL,URL(DOI) NIWANO S,Prognostic significance of frequent premature ventricular contractions originating from the ventricular outflow tract in patients with normal left ventricular function,Heart,,,2009,95,,1230-1237,https://cir.nii.ac.jp/crid/1570291226323241984,