This diagram depicts a hypoplastic left heart. In this condition, there can be a spectrum of hypoplasia ranging from mild reduction in size of the left ventricle to virtual absence of the left ventricle, with just a microscopic slit for a chamber. The worse the hypoplasia, the worse the prognosis. The mitral and aortic valves show varying degrees of hypoplasia to atresia. The left atrium is also small. The foramen ovale and/or ductus remain patent.