Figure 1.

Histopathology and echocardiography characterization of HCM cats. Histopathology sections from HCM cat H11: (a) Myofibre disarray and sarcoplasmic fragmentation (H+E). (b) Intramural fibrosis with myofibre disarray and fragmentation of sarcoplasm (Masson's Trichrome). (c) Fibrosis in a papillary muscle (Masson's Trichrome). (d) Arteriosclerosis (H+E). Echocardiography of cat hearts N4 and H14. NON-HCM Cat (e). Right parasternal long axis view of cat N4 at end diastole. Note normal sized LA (green arrow) and LV wall thickness (red arrows) measuring <6 mm (see accompanying movie S1). (f) Right parasternal short axis view at the level of the papillary muscles of cat N4 at end diastole. Note normal LV wall thickness (red arrows) measuring <6 mm. HCM Cat (g) Right parasternal long axis view of cat H14 at end diastole. Note severe hypertrophy of the LV free wall measuring >6 mm (double headed arrow) and a small volume pericardial effusion secondary to heart failure (green arrow). An incidental false tendon (single headed red arrow) is also present (see accompanying movie S2). (h) Right parasternal long axis view of cat H14 at end systole. Note the severely enlarged LA (double headed arrow). Further echocardiography plots and movies in supplementary Data.