There may be cystic medial necrosis of the media which is due to fragmentation of elastic laminae with an accumulation of myxoid material in aortic media leading to aortic dissection
About
- Autosomal Dominant inherited connective tissue disease
- Risk of death from aortic disease and heart failure
- Incidence of around 1 in 9800
- 27% of cases arise from new mutation.
Genetics
- Autosomal dominant disease
- Mutation in the gene FBN1 for fibrillin 1 on chromosome 15
- Over 800 distinct mutations exist
- Fibrillin 1 is a component of elastin
- Diagnosis is based on clinical criteria
- Variable phenotypes within affected families
Clinical
- Babies/Infants - severe MR and heart failure
- Tall think wide arm span:long thin arms and legs called dolichostenomelia
- Arm span to height > 1.05
- Arachnodactyly - long spidery fingers
- Pectus excavatum and high arched palate
- Eyes - Ectopia lentis - lens dislocation upwards, myopia, (fibrillin in suspensory ligament of the eye)
- Aortic aneurysm formation and possible dissection (fibrillin in Aorta)
- Mitral valve prolapse - mid-systolic click murmur syndrome
- Aortic regurgitation - early diastolic murmur
- Type A aortic dissection just above the valve
- Spontaneous pneumothorax and apical blebs in 5%
- Unstable joints, dislocation of the patella, progressive kyphoscoliosis
- Liver and kidney cysts on scanning
- Inguinal and femoral herniae
Differential with Marfanoid Habitus
- Homozygous Homocystinuria
- Familial aortic aneurysm
- Lujan-Fryns syndrome
- MEN2B
Investigations
- Assessment of family history, affected relatives Fibrillin 1 mutation testing if indicated
- Transthoracic echo
- Diagnosis by Ghent diagnostic nosology
- Echocardiography to assess mitral valve and Aortic root
- Genetics for FBN1 mutation
Management
- Annual review by specialist/cardiologist with echocardiogram of aortic root
- Prophylactic Beta blockade from early age reduces aortic dilatation
- Prophylactic Surgical repair of the Aorta reduces aortic dilatation when aortic root > 50 mm. A history of dissection in the family should encourage earlier surgery.
- Acute Surgery for dissection - some may need insertion of a Dacron graft to the aortic valvular ring after excision of a terminally dilated aorta when diameter reaches 5 cm. This also requires reimplantation of the coronary arteries
- Life expectancy approaches that of normal
References