Eisenmenger syndrome signs and symptoms include:

• Bluish or grayish skin color (cyanosis)
• Large, rounded fingernails or toenails (clubbing)
• Easily tiring and shortness of breath with activity
• Shortness of breath while at rest
• Chest pain or tightness
• Skipped or racing heartbeats (palpitations)
• Fainting (syncope)
• Coughing up blood (hemoptysis)
• Dizziness
• Numbness or tingling in the fingers or toes
• Headaches
• Abdominal swelling

Eisenmenger syndrome develops most often due to a hole between the chambers of your heart. To understand how Eisenmenger syndrome affects your heart and lungs, it's helpful to know how your heart works.

Heart works

Your heart is divided into four chambers, two on the right and two on the left. In performing its basic job — pumping blood throughout your body — your heart uses its left and right sides for different tasks.

The right side moves blood into vessels that lead to your lungs. In your lungs, oxygen enriches your blood, which circulates to your heart's left side. The left side of your heart pumps blood into a large vessel called the aorta, which circulates blood to the rest of your body.

Valves control the flow of blood into and out of the chambers of your heart. These valves open to allow blood to move to the next chamber or to one of the arteries, and they close to keep blood from flowing backward.

How Eisenmenger syndrome develops

For most people who have Eisenmenger syndrome, the cause of their condition is due to a hole (shunt) between the main blood vessels or chambers of your heart. This shunt is a heart defect you're born with (congenital). Heart defects that can cause Eisenmenger syndrome include:

• Ventricular septal defect. This shunt in the wall of tissue that divides the right and left sides of your heart's main pumping chambers (ventricles) is the most common cause of Eisenmenger syndrome.
• Atrial septal defect. An atrial septal defect is a shunt in the wall of tissue that divides the right and left sides of the upper chambers of your heart (atria).
• Patent ductus arteriosus. This heart defect is an opening between the pulmonary artery that carries oxygen-poor blood to the lungs and the artery that carries oxygen-rich blood to the rest of your body (aorta).
• Atrioventricular canal defect. In this heart defect, there's a large hole in the center of the heart where the walls between the upper chambers (atria) and lower chambers (ventricles) meet. Some of the valves in your heart also may not function properly.

For each of these defects, the increased pressure of blood flowing through the shunt increases the pressure in your pulmonary artery. Over time, this increased pressure damages the smaller blood vessels in your lungs.

Eisenmenger syndrome occurs when blood flows backward through the shunt, causing oxygen-rich and oxygen-poor blood to mix. This lowers the oxygen level in your blood (cyanosis), and your red blood cell count increases to try to make up for the lack of oxygen.

Eisenmenger syndrome occurs when a congenital heart defect is not treated or detected early enough to be closed before damage to the lung arteries occurs. If you or your child receives a diagnosis of a heart defect, it's important to start treatment promptly, including having surgeries or procedures to help correct the defect.

A family history of heart defects also increases the risk of a baby being born with a congenital heart defect, including the possibility of developing Eisenmenger syndrome. Talk to your doctor about screening other family members for heart defects if you've been diagnosed with a heart defect or Eisenmenger syndrome.

Regular medical treatment and monitoring is important to manage complications of Eisenmenger syndrome, including:

• Low oxygen levels in your blood (cyanosis). The reversed blood flow through your heart lowers the amount of oxygen your body's tissues and organs receive. This causes you to have a lower tolerance for physical activity and your skin to have a bluish or a grayish color.
• High red blood cell count (erythrocytosis). Because you aren't getting enough oxygen-rich blood circulating throughout your body, your kidneys release a hormone that increases your number of red blood cells, the cells that carry oxygen throughout your body.

Having too many red blood cells can reduce the blood flow to other organs and increase your risk of developing blood clots.

• Arrhythmias. Enlargement and thickening of the walls in the heart, along with low oxygen levels, may cause an irregular heart rhythm (arrhythmia).

Some types of arrhythmias can cause blood to pool in your heart's chambers, where it can clot. If the clot travels out of your heart and blocks an artery, you can have a stroke, heart attack or clot in the lungs (pulmonary embolism).

• Sudden cardiac arrest. If you develop an arrhythmia as a complication of Eisenmenger syndrome, it's possible the arrhythmia could suddenly stop your heartbeat.

Cardiac arrest is the sudden, unexpected loss of heart function, breathing and consciousness. Without immediate medical attention, you can die of sudden cardiac arrest in minutes.

You can also go into cardiac arrest during or after surgical procedures, usually related to changes in blood pressure caused by anesthesia.

• Heart failure. The increased pressure in your heart can cause your heart muscles to weaken, decreasing your heart's pumping effectiveness. Eventually, this can lead to heart failure.
• Coughing up blood (hemoptysis). Increased pressure in the lungs and problems with your blood caused by Eisenmenger syndrome can cause life-threatening bleeding into your lungs and airways, causing you to cough up blood and further lowering your blood oxygen level. Bleeding can also occur in other parts of the body.
• Stroke. Stroke can occur when a blood clot travels from your heart to your brain. This blood clot may then block a blood vessel in the brain, leading to a stroke.

The high levels of red blood cells in Eisenmenger syndrome also increase your risk of blood clots and stroke.

• Kidney problems. Low oxygen levels in your blood may lead to problems with your kidneys. This can also increase your risk of developing gout.
• Pregnancy risks. Due to the demands pregnancy puts on a mother's heart and lungs, women who have Eisenmenger syndrome shouldn't become pregnant. If you have Eisenmenger syndrome, pregnancy poses a high risk of death for both you and your baby.

Eisenmenger syndrome is a life-threatening condition. The prognosis for people diagnosed with Eisenmenger syndrome depends on the type of congenital heart defect and other medical conditions. People who are diagnosed with Eisenmenger syndrome can survive as long as age 60 and sometimes longer.