COACH Columbus Ohio Adult Congenital Heart Disease Program The Heart Center at Nationwide Children’s Hospital & The Ohio State University Single Ventricle Defects Normal Heart Structure The heart normally has four chambers. Two upper chambers (atria) receive blood from the veins, and the two lower chambers (ventricles) pump blood out of the heart. The right ventricle pumps blue blood (oxygen- PV poor) to the lungs to receive more oxygen. The left MV ventricle pumps red blood (oxygen-rich) to the body. AV Sometimes one of the ventricles fails to develop properly. Single ventricle is an abnormality that is present at birth TV (congenital), and is marked by the presence of only one functional pumping chamber (ventricle). RA = Right Atrium Valves RV = Right Ventricle TV = Tricuspid PA = Pulmonary Artery PV = Pulmonary LA = Left Atrium MV = Mitral LV = Left Ventricle AV = Aortic Congenital Heart Defects causing Single Ventricle Single ventricle usually occurs from one of the following congenital heart defects. In all single ventricle heart defects, other heart defects, such as Atrial Septal Defect (ASD), Ventricular Septal Defect (VSD), or Patent Ductus Arteriosus (PDA) allow the child to survive initially. These defects allow “blue blood” (low oxygen) to mix with “red blood” (high oxygen). Mixing of the blood causes “blueness”: in medical terms this is called cyanosis. Cyanosis means the body doesn’t get as much oxygen as it wants. 1 Hypoplastic Left Heart Syndrome Hypoplastic left heart syndrome is the most common single ventricle defect. It occurs in 1 or 2 of every 10,000 babies born. In hypoplastic left heart syndrome, the left ventricle, mitral valve, aortic valve and the RA = Right Atrium aorta are under-developed. RV = Right Ventricle PA = Pulmonary Artery LA = Left Atrium LV = Left Ventricle Ao = Aorta Tricuspid Atresia The tricuspid valve is a doorway that allows blood to flow from the right atrium into the right ventricle. Tricuspid atresia means the valve develops abnormally or not at all. Therefore, the right ventricle isn’t used and doesn’t grow properly. Tricuspid atresia occurs in less than one of every 10,000 babies born. RA = Right Atrium RV = Right Ventricle PA = Pulmonary Artery LA = Left Atrium LV = Left Ventricle Ao = Aorta Double Inlet Left Ventricle Double inlet left ventricle occurs when both atria connect to the left ventricle. The right ventricle then fails to develop adequately. Double inlet left ventricle occurs in less than one of every 10,000 babies born. RA = Right Atrium PA = Pulmonary Artery LA = Left Atrium Ao = Aorta 2 Double Outlet Right Ventricle Normally, the right ventricle pumps blood out the pulmonary artery to the lungs and the left ventricle pumps blood through the aorta to the body. In double outlet right ventricle, both the pulmonary artery and the aorta connect to the right ventricle. The left ventricle then fails to develop properly. Double outlet right ventricle RA = Right Atrium occurs in less than one of every RV = Right Ventricle 10,000 babies born. PA = Pulmonary Artery LA = Left Atrium LV = Left Ventricle Ao = Aorta Treatment of Single Ventricle Defects Single ventricle heart defects are usually diagnosed near birth and sometimes even before birth. In order for a child to reach adulthood, they will typically have undergone several heart surgeries. The first operations help deliver more blood to the lungs so the body can receive more oxygen. Most people with single ventricle will ultimately have a Fontan operation. The Fontan operation separates the circulation so that no mixing of blood occurs. It allows for a nearly normal oxygen supply to the body and decreases the workload on the single ventricle. Operations leading to the Fontan Stage 1: Shunts Waterston A connection between the ascending aorta (Ao) and the right pulmonary artery (PA) 3 S C Blalock-Taussig A A connection between the subclavian artery and the pulmonary artery, classically performed on the right side, it can be created on either side. Ao = Aorta PA = Pulmonary Artery SCA = Subclavian Artery Stage 2: Bidirectional Glenn This connects the superior vena cava (SVC) to the right pulmonary artery (PA) and divides the main pulmonary artery, partially separating the blue blood from the red blood. RA = Right Atrium LA = Left Atrium Ao = Aorta PA = Pulmonary Artery LV = Left Ventricle SVC = Superior Vena Cava Stage 3: Fontan operation There are 3 major forms of the Fontan operation: the Classic, the Lateral Tunnel, and the Extracardiac Fontan. Each of these forms completely separates the blue and red blood so there is no cyanosis. 4 Classic Fontan Lateral Tunnel Fontan Extracardiac Fontan Adults with Single Ventricle: Long-term complications Arrhythmias Normal healing after surgeries involves some scarring. Since scar tissues do not behave as normal healthy tissue in the heart, there can be long term complications related to the scar formation. People with single ventricle and Fontan repair may develop arrhythmias (abnormal heartbeats, either too fast or too slow). Slow heart rhythms can occur because the heart’s natural pacemaker (sinus node) fails to send out a signal as often as it should. This occurs in one of every 6 or 7 people with single ventricle and is treated with a pacemaker. A pacemaker monitors the natural heartbeat signal and sends a signal to stimulate the heartbeat if the natural heartbeat is too slow. Pacemaker Pacemaker leads 5 Abnormal, fast arrhythmias can arise from either the atria or the ventricle. About half of all people with single ventricle and Fontan will develop atrial arrhythmias. These can be effectively treated with a procedure called ablation (ah blay’ shun). Ablation can be done by catheter or during surgery. Ablation destroys the electrical pathways that cause arrhythmias. The occurrence of arrhythmias may indicate other complications with the Fontan repair such as heart enlargement due to poor blood flow or leaky heart valves. Sometimes, an abnormal fast arrhythmia is treated with an implantable defibrillator (ICD), similar to a pacemaker but for fast arrhythmias. Ablation device Ablation lines during surgery Cyanosis (Low oxygen) Even after the Fontan repair, people with single ventricle can develop cyanosis. The severity of the cyanosis depends on many factors that influence the amount of mixing of red and blue blood. The most common reasons a person with a Fontan becomes cyanotic are: * The small hole often left in the Fontan (fenestration) is allowing too much mixing, * Abnormal connections between arteries and veins in the lungs (AVM’s) * Growth of collateral (extra) blood vessels, * A leak at the suture line separating the blue blood from the red blood in the heart (Baffle). Although the person is cyanotic, they may not appear blue. The earliest evidence of cyanosis is the blood oxygen level measured in the office or during exercise. This is one reason why regular clinic visits are so important. The earlier your doctor finds an abnormality, the more likely he can correct it before it causes long-term problems. A heart catheterization can both evaluate and treat the causes of cyanosis. 6 Baffle Leak closed by Baffle Leak: note the Amplatzer device (disk puff of dye outside the next to the vessel) vessel. Liver abnormalities After the Fontan repair, the blood flow from the body back to the heart can be slower than normal. This may cause blood to “back up” in the liver. Liver congestion alters the normal liver function and may result in abnormal production of proteins, clotting factors and other enzymes. Abnormal liver function indicates a need for a detailed evaluation of the heart’s function and the Fontan repair. Protein-Losing Enteropathy Protein-losing enteropathy (PLE) is a condition in which the body spills protein out through the gut. This leads to diarrhea and swelling (edema) as well as fluid collection around the abdomen, lungs or heart. Other consequences of PLE include abdominal pain and blood clotting. PLE may progress to wasting and death in its most severe form. PLE occurs in less than 10% of people with single ventricle and Fontan. There is a limited understanding of why PLE occurs or how to treat it. Heart Failure Over time, fibrosis (scarring) may weaken the heart muscle. Weakened, the ventricle fails to pump blood effectively to meet the needs of the body. This is called heart failure. Heart failure is treated with medications but may indicate a need for revision of the Fontan repair. As the heart weakens, it stretches and may prevent the valves from closing completely. Incomplete closure of the valves causes leaking of blood across the valve and may result in further strain on the heart. It may be necessary to replace the leaky heart valve with an operation. 7 Blood Clots People who have cyanosis or who have had a Fontan operation may be at risk of developing blood clots. Clots form because of abnormal clotting proteins in the blood or because of sluggish blood flow through the veins and the Fontan pathway. If a small hole remains in the heart, a clot can pass through the hole and cause a stroke. The hole also allows blue blood to cross over and mix with red blood, causing cyanosis. To minimize the risk of forming blood clots, people with single ventricle may be treated with blood thinners (anticoagulants) such as warfarin or aspirin. How to keep your heart healthy Ongoing medical care for the adolescent and adult with single ventricle is extremely important. It must be conducted by a team with specialized knowledge of complex congenital heart disease. Routine evaluation will include ECG, oximetry (measurement of blood oxygen level), and echocardiogram (ultrasound). Additional diagnostic tests: A Holter monitor is a continuous, 24-hour recording of the ECG that may be used to look for arrhythmias.