A 7 month old girl (body weight 7 kg, length 73 cm) was presented with tachypnoea, hepatomegaly, vomiting, decreased peripheral perfusion, systolic heart murmur, and sinus tachycardia of up to 205 beats/min. She had a short history of decreasing activity for about four weeks. Radiography showed an enlarged heart, and echocardiography showed the left ventricular function was depressed with severe mitral regurgitation and mild …