BT SHUNT : The Blalock–Taussig shunt (also referred to as a Blalock-Thomas-Taussig shunt) is a surgical procedure to give palliation to cyanotic heart defects which are common causes of blue baby syndrome. In modern surgery, this procedure is temporarily used to direct blood flow to the lungs and relieve cyanosis while the infant is waiting for corrective or palliative surgery.
One branch of the subclavian artery or carotid artery is separated and connected with the pulmonary artery. The lung receives more blood with low oxygenation from the body. The first area of application was tetralogy of Fallot.
The Blalock–Taussig shunt may be used as the first step in the Fontan procedure.
What does a BT shunt do?
The Blalock–Thomas–Taussig shunt (commonly called the Blalock–Taussig shunt) is a surgical procedure used to increase pulmonary blood flow for palliation in duct dependent cyanotic heart defects like pulmonary atresia, which are common causes of blue baby syndrome.
The procedure is no longer in use in its original form. Now a length of artificial tubing, 3 to 4 millimeters in diameter, is sewn between either the subclavian or the carotid artery and the corresponding side branch of the pulmonary artery, thus obviating the need to cut off blood supply and making it easier to regulate the blood flow to the lungs. Some centers now use a shunt directly from the right ventricle to the pulmonary artery, a Sano shunt. This is done to avoid the reduced diastolic blood flow in the coronary circulation associated with the Blalock–Taussig shunt.
Pulmonary artery banding (PAB): is a technique of palliative surgical therapy used by congenital heart surgeons as a staged approach to operative correction of congenital heart defects. This technique was widely used in the past as an initial surgical intervention for infants born with cardiac defects characterized by left-to-right shunting and pulmonary overcirculation. Within the last two decades, early definitive intracardiac repair has largely replaced palliation with pulmonary artery banding. This trend has evolved because many centers have demonstrated improved outcomes with primary corrective surgery as an initial intervention in the neonate with congenital heart disease. Although the use of pulmonary artery banding has recently significantly decreased, it continues to maintain a therapeutic role in certain subsets of patients with congenital heart disease.
The primary objective of performing pulmonary artery banding is to reduce excessive pulmonary blood flow and protect the pulmonary vasculature from hypertrophy and irreversible (fixed) pulmonary hypertension. More recently, pulmonary artery banding has played a role in the preparation and “training” of the left ventricle (LV) in patients with D-transposition of the great arteries (d-TGA) who are evaluated for a delayed arterial switch procedure. It has found a similar role in training the LV in patients with L-transposition of the great arteries (L-TGA) who may also be candidates for an arterial switch procedure.
Coarctation of the Aorta :is a congenital heart defect that happens when there is a narrowing of the aorta as it makes the turn to supply the lower part of the body. The coarctation (narrowing) is usually located, just after the takeoff of the left subclavian artery (the branch to the left arm).
The left heart pump (Left Ventricle), then has to pump harder to force the blood to get through the narrowed area, so that the abdomen and legs can receive enough blood, with time the left ventricle muscle becomes thicker (hypertrophied).
The blood pressure gets higher, so as to push the blood across the narrowed area. As the blood squeezes through the obstructed area, it scatters under high pressure into strong jets; most of which move the blood forward but others hit hard against the walls of the aorta. Since so much moving energy is wasted in trying to force the blood through, the pressure beyond the narrowed area itself will be low.
In your child, this leads to high pressure in the arms and low pressure in the legs. High pressure in the arms would also be transmitted to high pressure to the arteries going to the brain. If this pressure goes untreated it may affect the arteries in the brain and cause stroke.
Because of high blood pressure in the in the upper part of the body, your child may complain of headaches, nose bleeds, or blurred vision. And since the lower body is receiving blood at low pressure, the growth of the lower body be compromised, the lower body will look small compared with the upper body. The legs may be shorter than usual, cold, and when your child tries to play or run he may complain of pain in his calves (intermittent claudication). This is like muscle cramps but they are caused by a lack of blood supply to exercising muscles.
If the doctor finds that your child has high blood pressure it is very important to check that he does not have coarctation of the Aorta. If he complains of his calves hurting when he plays that also the pulses in his legs are normal and he does not have decreased pulses. It is very important to recognize and treat this condition very early, because if the blood pressure stays high for a long time, after correcting the defect the blood pressure may not return back to normal and your child may need medication for his entire life.
The bidirectional Glenn procedure :is the surgery used to prepare the heart for a Fontan procedure. It is a surgery in which a detour (shunt) is created from the aorta to the pulmonary artery. The surgery is performed on infants and young children who are born with a congenital heart defect that reduces the amount of oxygen-rich blood circulating throughout the body. These infants often show signs such as a bluish tint (cyanosis) to the skin, lips, fingernails and other parts of the body. Although a successful procedure will improve immediate signs and symptoms of the underlying heart defect, the procedure does not correct the heart defect. Other surgeries are usually necessary in the future to repair the defect itself.
The surgery involves an incision in the chest, but it is not an open-heart surgery. Parents can expect their infant to remain in the hospital for about three to six days after the surgery. Parents are also encouraged to discuss with a pediatric cardiologist and heart surgeon all benefits and risks associated with this procedure. In most cases, the benefits greatly outweigh the risks.
Although not exactly a Fontan operation, a bidirectional Glenn (BDG) shunt is similar to it – and is called a type of “Partial Fontan” operation. It is also called Bidirectional Cavo-Pulmonary Shunt (BCPS).
The bidirectional shunt is performed by connecting the superior vena cava (SVC) to the right branch of the pulmonary artery using fine sutures, and dividing or tying up the pulmonary artery. Now, venous blood from the head and upper limbs will pass directly to the lungs, bypassing the right ventricle. The venous blood from the lower half of the body however will continue to enter the heart.
At a second operation, the lower body venous blood will also be diverted to the lungs, thus creating the “complete” Fontan circulation.
The bidirectional Glenn shunt is preferred in very small babies – below 2 years of age – in whom the lung vessel resistance is still quite high, and in borderline cases with abnormal pulmonary arteries. While avoiding the risk of failure of a complete Fontan operation, it also partly relieves symptoms. If all is well after the Glenn shunt, and the lung vessel resistance is low, a change to complete Fontan is possible. Otherwise, nothing further is done.
It decreases volume load on the single ventricle while improving oxygen saturation as compared to the pre-operative state. In addition, by being a low-pressure shunt, it does not carry the risk of causing lung blood vessel thickening and hardening.