Right ventricular injection study in a dog with supravalvular and subvalvular pulmonic stenosis. Note the large right ventricular papillary muscles (PM) and marked infundibular hypertrophy of the right ventricular outflow tract (arrow) which almost closes the outflow tract in systole. Post stenotic dilation of the pulmonary trunk (PT) extends into the left pulmonary artery (LPA). Opacification of the right atrium (RA) indicates tricuspid regurgitation. Persistent tricuspid valve immobility and non-opacification suggests tricuspid valve dysplasia.