PAEDIATRIC CARDIAC SURGERIES

A ventricular septal defect is an opening in the ventricular septum, or dividing wall between the two lower chambers of the heart known as the right and left ventricles. VSD is a congenital (present at birth) heart defect. As the fetus is growing, something occurs to affect heart development during the first eight weeks of pregnancy, resulting in a VSD.

Normally, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, then is pumped into the lungs where it receives oxygen. Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the left ventricle, and then is pumped out to the body through the aorta.

The ventricles are the two lower chambers of the heart. The wall between them is called the septum. A hole in the septum is called a septal defect. If the hole is located between the upper chambers or atria, it is called an atrial septal defect. Infants may be born with either or both types of defects. These conditions are commonly known as “holes in the heart.”

Normally, unoxygenated blood from the body returns to the right half of the heart, that is the right atrium, then the right ventricle, which pumps the blood to the lungs to absorb oxygen. After leaving the lungs, the oxygenated blood returns to the left half of the heart, that is the left atrium, then the left ventricle, where it is pumped out to provide oxygen to all the tissues of the body. A ventricular septal defect can allow newly oxygenated blood to flow from the left ventricle, where the pressures are higher, to the right ventricle, where the pressures are lower, and mix with unoxygenated blood. The mixed blood in the right ventricle flows back or recirculates into the lungs. This means that the right and left ventricles are working harder, pumping a greater volume of blood than they normally would. Eventually, the left ventricle can work so hard that it starts to fail. It can no longer pump blood as well as it did. Blood returning to the heart from the blood vessels backs up into the lungs, causing pulmonary congestion, and further backup into the body, causing weight gain and fluid retention. Overall, this is called congestive heart failure.

Small holes in the ventricular septum usually produce no symptoms but are often recognized by the child’s health care provider when a loud heart murmur along the left side of the lower breast bone or sternum is heard. Large holes typically produce symptoms 1-6 months after an infant’s birth. Large holes may not have murmurs at all. Instead, the left ventricle begins to fail, producing the following symptoms:

• Fast breathing
• Sweating
• Pallor
• Very fast heartbeats
• Decreased feeding
• Poor weight gain

When a ventricular septal defect is not detected early in life, it can cause more severe problems and more severe symptoms as time goes on. The biggest concern is development of high pressure in the lungs (pulmonary hypertension). If the ventricular septal defect is not surgically closed, irreversible pulmonary hypertension can develop, and the child is no longer operable and has a poor prognosis. The following are typical symptoms of pulmonary hypertension:

• Fainting
• Shortness of breath
• Chest pain
• Bluish discoloration of the skin (cyanosis)

The skin turns faintly bluish when the tissues are not receiving quite enough oxygen. This condition is often termed “hypoxemia” or “hypoxia.”

If a ventricular septal defect is noted before your baby leaves the hospital, several tests may be ordered before discharge.

• An echocardiogram (an ultrasound picture of the heart), a chest X-ray, and blood tests may be taken.
• You will be asked to follow-up with your child’s primary care provider, and you will have to watch closely for signs and symptoms that suggest congestive heart failure or hypoxia.

A ventricular septal defect is detected on physical examination by a systolic murmur audible with a stethoscope along the lower left sternal or breast bone border. It is related to the oxygenated blood “swishing” through the hole or VSD into the right ventricle.

The presence of a hole in the heart can be confirmed by echocardiogram. This painless test uses ultrasound waves to construct a moving picture of the heart. It can quantitate the size of the left-to-right shunt by enlargement of the left ventricle, pressure in the lungs, and actually estimate the degree of shunting by an empirical formula.

Partial anomalous pulmonary venous connection (PAPVC) is a rare congenital cardiac defect. As the name suggests, in PAPVC, the blood flow from a few of the pulmonary veins return to the right atrium instead of the left atrium. Usually, a single pulmonary vein is anomalous. Rarely, all the veins from one lung are anomalous. Thus, some of the pulmonary venous flow enters the systemic venous circulation.

Embryologically, PAPVC is similar to total anomalous pulmonary venous connection (TAPVC); however, TAPVC differs in that all or most pulmonary venous vessels connect to the right side of the heart in TAPVC (see the image below). Knowledge of the variation patterns of normal pulmonary venous drainage is necessary in order to diagnose PAPVC

Partial anomalous pulmonary venous connection presents with variable anatomical patterns resulting in one or more pulmonary veins functionally draining into the right atrium or one of its venous tributaries instead of draining into left atrium.1 PAPVCs may occur as isolated anomalies or may be combined with ASD. The most common variant of PAPVC is the defect located in sinus venosus malformation i.e, superior caval atrial septal defect coexists with PAPVC.2,3 Other variants include right pulmonary vein draining into right atrium,4 connection of right pulmonary vein to IVC (scimitar syndrome) and rarely right pulmonary vein connects to azygos vein or coronary sinus.5,6 Similarly, left pulmonary vein may connect to left brachiocephalic vein through an anomalous vertical vein. Partial but bilateral PAPVC is rare.

Surgical correction of PAPVC varies according to the type of underlying anomaly, however the basic principle remains the segregtion of systemic and pulmonary circulation either by communicating the anomalous pulmonary vein to the left atrium directly or indirectly rerouting through baffle into left atrium.7,8 Our objective was to review the operative results of 55 cases of partial anomalous pulmonary venous connection (PAPVC).

Partially anomalous pulmonary venous return (PAPVR) is similar to total anomalous pulmonary venous connection (or “TAPVC”) in that it’s an abnormality of the connection between the pulmonary veins (which carry oxygenated blood from the lungs to the left side of the heart) and the left atrium (the upper left-hand chamber of the heart that receives oxygen-rich red blood from the lungs and then sends this blood to the left ventricle).

Usually, the pulmonary veins are all connected to the left atrium. When none of them are connected to the left atrium, it’s called “total anomalous pulmonary venous connection.” When some but not all of the pulmonary veins are connected properly, it’s called “partial anomalous pulmonary venous connection” (or “PAPVC”).

Partially anomalous pulmonary venous return (PAPVR) frequently happens in combination with other diagnoses, most often a sinus venosus atrial septal defect (ASD). PAPVC ranges from relatively harmless (as when it’s in association with a superior sinus venosus ASD, to more complicated, such as in a condition called, “Scimitar syndrome.” With Scimitar syndrome, the right pulmonary vein drains to the inferior vena cava (a large vein draining the lower body) rather than into the left atrium. Children with Scimitar syndrome usually have other abnormalities of the right lung, including a small right lung (called “hypoplasia”) and abnormal blood supply to the lung.

PAPVC is usually diagnosed when a caregiver hears a murmur while examining the child, although abnormalities on a routine chest X-ray or other imaging study may also suggest the diagnosis. At the Nemours Cardiac Center, we can confirm the diagnosis with an echocardiogram (or “echo”). An echo is a completely safe and painless test that uses ultrasound (sound waves) to build a series of pictures of the heart.

If the drainage isn’t clear from the echo, then we may need to perform additional tests, including cardiac catheterization, a CT scan or an MRI.

Total anomalous pulmonary venous connection (TAPVC) is a birth defect of the heart in which the veins bringing blood back from the lungs pulmonary veins) don’t connect to the left atrium like usual. Instead they go to the heart by way of an abnormal (anomalous) connection.

Total anomalous pulmonary venous return (TAPVR) is a birth defect of the heart. In a baby with TAPVR, oxygen-rich blood does not return from the lungs to the left atrium. Instead, the oxygen-rich blood returns to the right side of the heart. Here, oxygen-rich blood mixes with oxygen-poor blood. This causes the baby to get less oxygen than is needed to the body. To survive with this defect, babies with TAPVR usually have a hole between the right atrium and the left atrium (an atrial septal defect) that allows the mixed blood to get to the left side of the heart and pumped out to the rest of the body. Some children can have other heart defects along with TAPVR, aside from the atrial septal defect. Because a baby with this defect may need surgery or other procedures soon after birth, TAPVR is considered a critical congenital heart defect. Congenital means present at birth.

The causes of heart defects, such as TAPVR, among most babies are unknown. Some babies have heart defects because of changes in their genes or chromosomes. Heart defects also are thought to be caused by a combination of genes and other risk factors, such as the things the mother or fetus come in contact with in the environment or what the mother eats or drinks or the medicines she uses.

During pregnancy, there are screening tests (also called prenatal tests) to check for birth defects and other conditions. TAPVR might be diagnosed during pregnancy with an ultrasound (which creates pictures of the body). Some findings from the ultrasound may make the health care provider suspect a baby could have TAPVR. If so, the health care provider can request a fetal echocardiogram to confirm the diagnosis. A fetal echocardiogram is an ultrasound specifically of the baby’s heart and major blood vessels that is performed during the pregnancy. This test can show problems with the structure of the heart and how well the heart is working. However, TAPVR defect is not commonly detected during pregnancy. It is hard for doctors to see the pulmonary veins on the prenatal screening tests since not much blood goes to the lungs before the baby is born. It is easier to detect this defect after birth when the blood is flowing to the lungs and returning to the heart.

After a Baby is Born

Symptoms usually occur at birth or very soon afterwards. Infants with TAPVR can have a bluish looking skin color, called cyanosis, because their blood doesn’t carry enough oxygen. Infants with TAPVR or other conditions causing cyanosis can have symptoms such as:

• Problems breathing
• Pounding heart
• Weak pulse
• Ashen or bluish skin color
• Poor feeding
• Extreme sleepiness

Using a stethoscope, a doctor will often hear a heart murmur (an abnormal “whooshing” sound caused by blood flowing through the atrial septal defect). However, it is not uncommon for a heart murmur to be absent right at birth.

If a doctor suspects that there might be a problem, the doctor can request one or more tests to confirm the diagnosis of TAPVR. The most common test is an echocardiogram. This is an ultrasound of the heart that can show problems with the structure of the heart, like holes in the walls between the chambers, and any irregular blood flow. Cardiac catheterization also can confirm the diagnosis by showing that the blood vessels are abnormally attached. An electrocardiogram (EKG), which measures the electrical activity of the heart, chest x-rays, and other medical tests may also be used to make the diagnosis.

Babies with TAPVR will need surgery to repair the defect. The age at which the surgery is done depends on how sick the child is and the specific structure of the abnormal connections between the pulmonary veins and the right atrium. The goal of the surgical repair of TAPVR is to restore normal blood flow through the heart. To repair this defect, doctors usually connect the pulmonary veins to the left atrium, close off any abnormal connections between blood vessels, and close the atrial septal defect.

Infants whose defects are surgically repaired are not cured; they may have lifelong complications. A child or adult with TAPVR will need regular follow-up visits with a cardiologist (a heart doctor) to monitor their progress, avoid complications, and check for other health conditions that might develop as they get older.

Tetralogy of Fallot (TOF): TOF is a serious congenital heart condition causing four structural abnormalities in the heart that lead to a lack of oxygen in the blood. This condition can cause a baby to look blue, though it usually occurs at birth.

Blue baby syndrome, also known as infant methemoglobinemia, is a condition where a baby’s skin turns blue. This occurs due to a decreased amount of hemoglobin in the baby’s blood.

Hemoglobin is a blood protein that is responsible for carrying oxygen around the body and delivering it to the different cells and tissues.

When the blood is unable to carry oxygen around the body, the baby turns blue (cyanotic).

Blue baby syndrome is rare in industrialized countries, but it does occasionally occur in rural areas. Babies born in developing countries with poor water supply continue to be at risk for the condition.

Tetralogy of Fallot (TOF) is a cardiac anomaly that refers to a combination of four related heart defects that commonly occur together. The four defects are:

• Ventricular septal defect (VSD) − a hole between the right and left pumping chambers of the heart
• Overriding aorta − the aortic valve is enlarged and appears to arise from both the left and right ventricles instead of the left ventricle as in normal hearts
• Pulmonary stenosis − narrowing of the pulmonary valve and outflow tract or area below the valve that creates an obstruction (blockage) of blood flow from the right ventricle to the pulmonary artery
• Right ventricular hypertrophy − thickening of the muscular walls of the right ventricle, which occurs because the right ventricle is pumping at high pressure

A small percentage of children with tetralogy of Fallot may also have additional ventricular septal defects, an atrial septal defect (ASD) or abnormalities in the branching pattern of their coronary arteries. Some patients with tetralogy of Fallot have complete obstruction to flow from the right ventricle, or pulmonary atresia. Tetralogy of Fallot may be associated with chromosomal abnormalities, such as 22q11 deletion syndrome.

The pulmonary stenosis and right ventricular outflow tract obstruction seen with tetralogy of Fallot usually limits blood flow to the lungs. When blood flow to the lungs is restricted, the combination of the ventricular septal defect and overriding aorta allows oxygen-poor blood (“blue”) returning to the right atrium and right ventricle to be pumped out the aorta to the body.

This “shunting” of oxygen-poor blood from the right ventricle to the body results in a reduction in the arterial oxygen saturation so that babies appear cyanotic, or blue. The cyanosis occurs because oxygen-poor blood is darker and has a blue color, so that the lips and skin appear blue.

The extent of cyanosis is dependent on the amount of narrowing of the pulmonary valve and right ventricular outflow tract. A narrower outflow tract from the right ventricle is more restrictive to blood flow to the lungs, which in turn lowers the arterial oxygen level since more oxygen-poor blood is shunted from the right ventricle to the aorta.

Symptoms

Tetralogy of Fallot symptoms vary, depending on the extent of obstruction of blood flow out of the right ventricle and into the lungs. Signs and symptoms may include:

• A bluish coloration of the skin caused by blood low in oxygen (cyanosis)
• Shortness of breath and rapid breathing, especially during feeding or exercise
• Loss of consciousness (fainting)
• Clubbing of fingers and toes — an abnormal, rounded shape of the nail bed
• Poor weight gain
• Tiring easily during play or exercise
• Irritability
• Prolonged crying
• A heart murmur

Tet spells

Sometimes, babies who have tetralogy of Fallot will suddenly develop deep blue skin, nails and lips after crying or feeding, or when agitated.

These episodes are called tet spells and are caused by a rapid drop in the amount of oxygen in the blood. Tet spells are most common in young infants, around 2 to 4 months old. Toddlers or older children might instinctively squat when they’re short of breath. Squatting increases blood flow to the lungs.

When to see a doctor

Seek medical help if you notice that your baby has the following symptoms:

• Difficulty breathing
• Bluish discoloration of the skin
• Passing out or seizures
• Weakness

Unusual irritability

Double outlet right ventricle with L-malposition of the great arteries is a rare type of double outlet right ventricle.

Double Outlet Right Ventricle is a congenital heart defect in which both the aorta and the pulmonary artery exit from the right ventricle. In the normal heart, the aorta leaves the left ventricle and the pulmonary artery leaves the right ventricle.

In addition, there is a large ventricular septal defect (VSD), or hole in the muscle wall (septum) that separates the right and left ventricles.  The aorta may be near the VSD or remote from it.  Pulmonary valve stenosis may also be present.