Right-to-left circulatory shunt

Alternative names
Right-to-left cardiac shunt; Cyanotic heart disease

Definition

Cyanotic heart disease is a defect or group of defects in the structure or function of the heart or the great vessels, present at birth, consisting of abnormal blood flow from the right to the left part of the circulatory system (either at the level of the atria, the ventricles, or the great vessels).

This abnormal communication (called right-to-left shunt) results in poor oxygenation of the body and therefore cyanosis (bluish coloration of the body).

Causes, incidence, and risk factors

Cyanotic heart diseases are congenital heart defects (heart diseases present at birth) that result in low oxygen levels in the blood and cause the child’s skin to look blue (cyanosis).

This bluish coloration is most often detected on the lips, fingers, and toes or during exercise. Some heart defects cause major problems immediately after birth, and some cause few if any problems until adulthood.

Not all congenital heart diseases are cyanotic. Congenital heart defects that cause cyanosis include the following:

     
  • Tetralogy of Fallot  
  • Transposition of the great vessels  
  • Ebstein’s anomaly  
  • Tricuspid atresia (a deformity of the tricuspid heart valve)  
  • Total anomalous pulmonary venous return  
  • Pulmonic stenosis  
  • Truncus arteriosus  
  • Hypoplastic left heart syndrome

Most congenital heart disease occurs as a birth defect limited only to the heart, but some conditions occur as part of genetic and chromosomal syndromes that affect many organs.

Some syndromes that include congenital heart disease (not all cyanotic) are Down syndrome, trisomy 13, Turner’s syndrome, Marfan syndrome, Noonan syndrome, and Ellis-van Creveld syndrome.

Some congenital heart diseases are caused by drugs, chemical exposure, or infections during pregnancy. Fetal rubella, infection by cytomegallovirus (CMV), maternal alcohol use (fetal alcohol syndrome), lithium carbonate use (for manic-depressive disorder), and retinoic acid use (for acne) are examples of infections and drugs that can cause congenital heart disease.

Symptoms

One symptom is cyanosis, usually seen as a bluish discoloration of the lips, fingers, and toes.

Some children have dyspnea (breathing problems) and adopt a squatting position after physical activity to relieve breathlessness. Others have hypoxic spells, where their bodies are suddenly starved of oxygen. These are characterized by anxiety, hyperventilation, and a sudden increase in cyanosis.

Syncope (fainting) and chest pain may occur.

Other symptoms depend on the specific type of cyanotic heart disease.

Signs and tests

Physical examination confirms cyanosis.

The child may have clubbed fingers, an obvious thickening of the fingertips in response to the poor oxygenation.

Abnormal heart sounds, a heart murmur, and lung crackles may be heard.

Tests will vary depending on the suspected cause, but may be extensive and include a chest X-ray, a complete blood count (CBC), arterial blood gas analysis, ECG (echocardiogram), echo-Doppler, transesophageal echocardiogram (TEE), nuclear imaging tests, cardiac catheterization, and electrophysiologic study (EPS).

Treatment

Some children may need hospitalization to be given oxygen or receive mechanical ventilation.

Medication such as digoxin, diuretics, antiarrhythmics, and prostaglandins may be prescribed.

Several palliative or corrective procedures are currently available that can be performed with a catheter.

The treatment of choice for many congenital heart diseases is surgical repair, sometimes requiring several steps. One commonly used operation is called the Fontan procedure.

Some patients may need a permanent pacemaker.

Expectations (prognosis)
See the specific disorder. Some of these conditions may unfortunately cause sudden death.

Complications

See the specific disorder. Grave complications of cyanotic heart disease include:

     
  • heart failure and hypoxic spells  
  • polycythemia (increased blood count and increased blood thickness and propensity to coagulation)  
  • stroke  
  • infective endocarditis  
  • brain abscess  
  • hemoptysis (bloody sputum)  
  • impaired growth  
  • pulmonary hypertension: increased pressure and resistance in the pulmonary (lung) blood vessels, which ultimately renders the effects of the congenital heart disease irreversible

Calling your health care provider
Call your health care provider if your baby develops cyanosis (bluish skin) or if breathing seems difficult.

Prevention

Avoid the use of alcohol and other drugs during pregnancy. Women who are (or think they might be) pregnant should notify their physicians before receiving prescriptions for medications. Women with manic-depressive disorder should consult their physicians about the risks and benefits of various treatments for this condition during pregnancy.

The immune status for rubella should be evaluated early in the pregnancy. If the mother is not immune she must avoid any possible exposure to rubella and should be immunized immediately following delivery. Genetic counseling may be of help if there is a family history of genetic disorders associated with congenital heart disease.

Johns Hopkins patient information

Last revised: December 5, 2012
by David A. Scott, M.D.

Medical Encyclopedia

  A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 0-9

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.