Fig. 4

Two-dimensional echocardiograms from the right parasternal short axis view of a male, 1.2-year-old Golden Retriever dog with atrial fibrillation at the level of the left ventricular papillary muscles. a There is systolic flattening of the interventricular septum along with a fibromuscular band (arrowhead) dividing the RV into two separate compartments. b Color flow Doppler imaging demonstrates a turbulent jet between the two right ventricular chambers. IVS, interventricular septum; RV–d, right ventricular distal chamber; RV–p, right ventricular–proximal chamber