Eisenmenger syndrome or Eisenmenger's syndrome is defined as the process in which a long-standing left-to-right cardiac shunt caused by a congenital heart defect (typically by a ventricular septal defect, atrial septal defect, or less commonly, patent ductus arteriosus) causes pulmonary hypertension and eventual reversal of the shunt into a cyanotic right-to-left shunt. Because of the advent of fetal screening with echocardiography early in life, the incidence of heart defects progressing to Eisenmenger syndrome has decreased. Eisenmenger syndrome in a pregnant mother can cause serious complications, though successful delivery has been reported. Maternal mortality ranges from 30% to 60%, and may be attributed to fainting spells, blood clots forming in the veins and traveling to distant sites, hypovolemia, coughing up blood or preeclampsia. Most deaths occur either during or within the first weeks after delivery. Pregnant women with Eisenmenger syndrome should be hospitalized after the 20th week of pregnancy, or earlier if clinical deterioration occurs. Signs and symptoms Signs and symptoms of Eisenmenger syndrome include the following: Cyanosis (a blue tinge to the skin resulting from lack of oxygen) High red blood cell count Swollen or clubbed fingertips (clubbing) Fainting (also known as syncope) Heart failure Abnormal heart rhythms Bleeding disorders Coughing up blood Iron deficiency Infections (endocarditis and pneumonia) Kidney problems Stroke Gout (rarely) due to increased uric acid resorption and production with impaired excretion Gallstones One of the most severe and common complications of Eisenmenger syndrome is cardiac arrhythmia, especially supraventricular arrhythmias. Approximately 40% of patients diagnosed with Eisenmenger syndrome were also found to have these arrhythmias during routine ECG screenings. These arrhythmias have worse prognosis in patients with Eisenmenger syndrome, compared to the general population, and can be a source of sudden cardiac death. Causes A number of congenital heart defects can cause Eisenmenger syndrome, including atrial septal defects, ventricular septal defects, patent ductus arteriosus, and more complex types of acyanotic heart disease. Pathogenesis The reason Eisenmenger syndrome often presents later in life can be explained by alterations of the normal physiology of the heart and the maladaptive responses that occur over time. The larger and more muscular left side of the heart must generate the high pressure required to supply blood to the extensive, high-resistance systemic circulation. In contrast, the smaller, right side of the heart must generate a much lower pressure in order to pass blood through the low-resistance, high compliance circulation of the lungs. The