Congenital heart disease may result in seizures through neurovascular events caused by cyanotic right-to-left shunts. Transposition of the great arteries and tetralogy of Fallot account for 90% of such neurologic complications, which result from:

  • hypoxia
  • polycythemia
  • clotting factor deficiencies
  • thrombocytopenia

Children under 4 years of age are at higher risk of anemic and thromboembolic complications of cyanotic heart disease. Autopsy series have documented cerebrovascular events in up to 19%.17

A series of patients with suspected congenital heart disease underwent EEG and neurologic examination prior to cardiac catheterization. Even in those with normal neurologic examinations, a high proportion of EEG abnormalities were found, suggesting subclinical neurologic involvement in both cyanotic and acyanotic congenital heart disease.18

Seizures occurred in 15% of infants following hypothermic cardiopulmonary bypass surgery, making them the second-most-common neurologic complication. Seventy percent of these were focal seizures.19

Seizures are also frequent following repair of cyanotic disease. In a study from Boston Children’s Hospital, the incidence of electrographic seizures after correction of transposition of the great arteries was 20%, but only 6% had clinically apparent seizures. Seizures were associated with longer duration of deep hypothermic circulatory arrest and diagnosis of ventricular septal defects.20

Congenital heart disease with left-to-right shunts may also cause neurologic injuries associated with seizures. Silent atrial septal defects, including patent foramen ovale, may go unrecognized until adulthood, when they are often detected by investigating the cause of stroke in young adults. Routine transthoracic echocardiography fails to identify up to 75% of patent foramen ovale defects, resulting in an underestimate of this congenital defect in series not using more sensitive echocardiographic procedures, such as transesophageal echocardiography with contrast.21

Brain abscesses can occur when hypoxic blood bypasses the lungs via a right-to-left shunt, especially with abnormal cardiac structure allowing embolization. Rare under 2 years of age, brain abscesses occur in 2% of cyanotic congenital heart disease patients, with a peak incidence between 4 and 7 years of age.22

Congenital heart disease also occurs in syndromes of multiple congenital abnormalities, further predisposing these patients to seizures. Congenital heart diseases in autopsy series are associated with a 68% incidence of cerebral malformations.26Multisystem genetic conditions include:

  • Down syndrome 23
  • Kallman syndrome 24
  • tuberous sclerosis 25

Infants with severe cardiac and neurologic anomalies may not survive childhood, and those who have successful surgical repair commonly experience serious arrhythmias and may require antiarrhythmics and anticoagulants. These arrhythmias can precipitate convulsive syncope and occasionally recurrent seizures if permanent structural damage to the brain results, such as through a stroke.

Coarctation of the aorta may be associated with intracranial aneurysms, although subarachnoid hemorrhage due to aneurysmal rupture is rare in pediatric patients. Early repair minimizes the risk of cerebrovascular complications.27

Adapted from: Boggs J. Cardiac disorders. In: Ettinger AB and Devinsky O, eds. . Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;39-47. 
With permission from Elsevier (www.elsevier.com).

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