You are practising for your ultrasound exams when someone asks you to look at the following picture of a 17 year old patient. Describe the findings, and suggest a differential diagnosis…….
This clip shows a TTE parasternal long axis of the heart. The obvious finding is the extreme thickening of the LV, with the septum >2.5cm. The LV is at least mildly dilated, and myocardial function is at least moderately reduced. The basal and mid inferolateral walls are severely hypokinetic. The RV also appears thickened, though contraction appears to be preserved (within the limits of PLAX view). The Aortic and Mitral valves appear to be normal. The LA appears to be dilated (ratio LA:Aortic root>1). Overall this is consistent with a severe restrictive cardiomyopathy.
The differential diagnosis includes hypertrophic cardiomyopathy (HCM), Fabry’s disease, haemochromatosis, amyloidosis, mucopolysaccharidosis or other restrictive cardiomyopathies . Such extreme changes are unlikely to be the result of more common causes of LVH such as aortic stenosis, athletes heart, or hypertensive cardiomyopathy.
Key features when assessing severe left ventricular hypertrophy include:
- Symmetry of wall thickening (HCM is often asymmetrical, as is Fabry’s disease, while AS and hypertensive CM are more symmetrical)
- Age of patient (genetic disorders more likely to present at a younger age)
- Appearance of the myocardium (speckled in amyloid, endocardium echogenicity is increased in Fabry’s disease)
- Systolic anterior motion of the Mitral valve (SAM) if severe or in a stressed state.
- Other associated conduction defects (seen in amyloid, haemochromatosis)
- LV dilation and function – many conditions may progress to dilated cardiomyopathy, with thinning of the ventricular walls, making diagnosis difficult.
The patient was referred to a geneticist who performed genetic testing. Danon Disease, a rare X-linked genetic lysosomal storage disorder, was eventually confirmed. He was referred to a specialist heart failure unit for ongoing care, which included workup for cardiac transplantation.