Ivemark Syndrome
Ivemark Syndrome
Ivemark syndrome, also known as right atrial isomerism or asplenia syndrome, is a rare congenital disorder characterized by:
- Absence of the spleen (asplenia)
- Complex cardiovascular malformations
- Abnormal arrangement of internal organs (situs ambiguus)
First described by Swedish pathologist Björn Ivemark in 1955, this syndrome is part of the heterotaxy spectrum disorders.
Key Points:
- Incidence: Approximately 1 in 10,000 to 40,000 live births
- Inheritance: Usually sporadic, but familial cases with autosomal recessive inheritance have been reported
- Associated with mutations in genes involved in left-right patterning during embryonic development (e.g., CFC1, NODAL, ACVR2B)
- More common in males (male to female ratio of 2:1)
Clinical Features
The clinical presentation of Ivemark syndrome can vary widely, but typically includes:
Cardiovascular Abnormalities:
- Complex congenital heart defects:
- Common atrioventricular canal
- Double outlet right ventricle
- Pulmonary stenosis or atresia
- Total anomalous pulmonary venous return
- Transposition of the great arteries
- Bilateral superior vena cava
- Right atrial isomerism (both atria have right atrial morphology)
Visceral Abnormalities:
- Asplenia (absence of spleen)
- Symmetric liver (liver tissue present on both sides of the abdomen)
- Malrotation of the intestines
- Bilateral bilobed lungs (absence of normal lung lobation)
Other Features:
- Increased susceptibility to infections (due to asplenia)
- Cyanosis (due to complex heart defects)
- Failure to thrive
- Developmental delays (in survivors)
Diagnosis
Diagnosis of Ivemark syndrome involves a combination of clinical, imaging, and laboratory findings:
Prenatal Diagnosis:
- Fetal echocardiography: Can detect complex cardiac anomalies
- Fetal MRI: May identify visceral abnormalities and situs ambiguus
Postnatal Diagnosis:
- Physical examination:
- Signs of cyanosis
- Heart murmurs
- Abdominal abnormalities
- Imaging studies:
- Echocardiography: To evaluate cardiac structure and function
- Chest and abdominal X-rays: May show dextrocardia, abnormal bronchial branching, and visceral malposition
- CT or MRI: To assess thoracic and abdominal organ arrangement
- Laboratory tests:
- Complete blood count: May show Howell-Jolly bodies (indicating asplenia)
- Liver function tests
- Genetic testing: For mutations in associated genes
Differential Diagnosis:
- Other heterotaxy syndromes (e.g., left atrial isomerism)
- Isolated complex congenital heart defects
- VACTERL association
- Isolated asplenia or polysplenia
Management
Management of Ivemark syndrome is complex and requires a multidisciplinary approach:
Cardiovascular Management:
- Surgical intervention for complex heart defects:
- Staged palliative procedures (e.g., Blalock-Taussig shunt, Glenn procedure)
- Definitive repair when possible
- Medical management of heart failure
- Arrhythmia management
Infection Prevention and Management:
- Antibiotic prophylaxis (due to asplenia)
- Vaccinations:
- Pneumococcal vaccine
- Haemophilus influenzae type b vaccine
- Meningococcal vaccine
- Annual influenza vaccine
- Patient and family education on early signs of infection
Gastrointestinal Management:
- Surgical intervention for intestinal malrotation if symptomatic
- Nutritional support
Developmental Support:
- Early intervention programs
- Physical and occupational therapy as needed
- Special education services when appropriate
Genetic Counseling:
- For family planning and recurrence risk assessment
Prognosis
The prognosis for Ivemark syndrome is generally poor, but has improved with advances in cardiac surgery and medical management:
- Mortality:
- Historically, most patients did not survive beyond infancy
- With modern management, some patients now survive into adulthood
- Factors affecting prognosis:
- Severity of cardiac defects
- Timing of diagnosis and intervention
- Complications related to asplenia (e.g., overwhelming sepsis)
- Long-term complications:
- Recurrent infections
- Chronic heart failure
- Pulmonary hypertension
- Developmental delays
Regular follow-up with a multidisciplinary team is essential for optimal management and to address complications as they arise.
