Introduction:
The human heart is four-chambered with two atria and two ventricles. The right and left side of the heart is separated by a wall called the septum. A small hole is present in the septal wall of the fetus called the foramen ovale. In the intrauterine period, the lungs have not started functioning. The oxygen-rich blood from the mother’s placenta reaches the fetus. The blood reaches the right side of the fetal heart and moves to the left through the foramen ovale, from where it reaches the whole body.
After birth, the lungs start functioning, and the foramen ovale closes soon after birth. In the case of babies with congenital defects like cyanotic heart defects, the foramen ovale acts as a passageway for mixing oxygenated and non-oxygenated blood and keeps the baby alive until surgery. But soon after birth, the foramen ovale closes, and if surgery is not carried out, then cyanosis worsens, and the baby may die.
Septostomy is a life-saving procedure that keeps the foramen ovale patent, thus creating a right-to-left intracardiac shunt that allows the mixing of oxygen-rich and oxygen-poor blood. The opening is maintained until definitive surgery is done. The procedure was invented by the pediatric cardiologist William Rashkind and is also called Rashkind septostomy.
What Are the Indications for Septostomy?
The indications for septostomy include the following:
1. Cyanotic Heart Defect: Septostomy is indicated in the case of cyanotic heart defects. A cyanotic heart defect is when non-oxygenated blood does not reach the baby’s lungs. Due to this, the body tissues are devoid of sufficient oxygen supply. As a result, bluish skin discoloration or cyanosis occurs. Severe cyanosis is dangerous and requires immediate medical attention. Performing septostomy in such cases keeps the baby alive until surgery. Septostomy is commonly performed in case of dextro-transposition of the great arteries (d-TGA). This condition occurs due to trans positioning or switching of two major blood vessels, the aorta, and pulmonary artery. As a result, oxygenated blood moves back to the lungs, and deoxygenated blood circulates to different body parts. Another condition where septostomy is performed is tricuspid atresia due to defective tricuspid valve formation. As a result, blood flow from the atrium to the ventricle is blocked.
2. Pulmonary Hypertension: In patients with pulmonary hypertension who do not respond to medical therapy, a septostomy is performed before lung transplantation. Pulmonary arterial hypertension is a rare condition but has a high mortality rate. Septostomy in such patients creates an intracardiac shunt that decompresses the right ventricle, which is overloaded. In cases where the condition does not respond to medical care, palliative management is required until lung transplantation, achieved with septostomy.
3. Hypoplastic Left Heart Syndrome: Hypoplastic left heart syndrome is a congenital disability in which the left side of the heart is underdeveloped. Hence blood flow is insufficient for the rest of the body. Septostomy is done in patients with hypoplastic left heart syndrome to decompress the pulmonary venous chamber.
4. Post-Operative Right Ventricular Failure: Septostomy is done in case of postoperative right ventricular failure for decompressing the right ventricle.
How Is the Procedure Septostomy Performed?
Septostomy is usually performed to provide temporary and short-term palliation before a surgical procedure. Interatrial septal stenting has a long-term effect but possesses a risk of thromboembolism. There are different modifications of the septostomy procedure, which include the following types:
- Balloon Atrial Septostomy:
It is most effective in neonates less than 6 weeks of age. In patients with d-TGA, if the atrial septal defect (ASD) is less than 4 mm it is considered restrictive. If septostomy is performed in such cases and ASD is made nonrestrictive, it results in interatrial mixing and increases systemic arterial oxygen saturation. As a result, the neonates are stabilized until the surgical procedure.
A transthoracic echocardiography is used to monitor balloon atrial septostomy as it accurately identifies the balloon position and prevents misplacement of the catheter and injury to other structures. It also helps in the immediate identification of complications like perforation, balloon rupture, and valvular laceration.
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Blade Atrial Septostomy:
Blade atrial septostomy is also called Park septostomy. It is indicated in infants above 6 weeks with a thick interatrial septum. A park blade catheter makes multiple cuts in the septum by changing the catheter angle. The procedure is completed with a static balloon to produce the defect. But there is a risk of injury to cardiac structures and neurological complications, so it is rarely used.
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Static Balloon Atrial Dilatation:
Static balloon atrial dilatation is indicated in patients with a thick atrial septum. A septal tear is produced by overstretching the balloon in a fixed position.
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Cutting Balloon Atrial Septostomy:
Cutting balloon atrial septostomy is indicated in patients with a thick interatrial septum and small left atrium. The septum is perforated by a radiofrequency wire, after which a cutting balloon is used. Static balloon dilatation completes the procedure.
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Interatrial Septal Stenting:
Interatrial septal stenting is used for long-term palliation in patients with a thick interatrial septum. A smaller balloon diameter is used to achieve interatrial communication. Echocardiography is used in stent positioning. Though it provides long-term palliation, mechanical complications and the risk of thromboembolism are associated with the procedure.
What Are the Risks Associated With Septostomy?
Septostomy involves risks associated with a surgical procedure like:
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Allergic reaction.
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Infection.
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Anesthesia complications.
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Blood loss.
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Arrhythmia (abnormal heart rhythm).
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Injury to cardiac structures.
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Neurological complications.
Septostomy is associated with a high direct mortality rate. It is associated with around 7 % mortality within one day following the procedure and approximately 14 % after one month.
Conclusion:
Septostomy is an invasive procedure that keeps the foramen ovale patent for short-term palliation or long-term (in the case of interatrial septal stenting) until definitive surgery is performed. It keeps the infant alive until definitive surgical correction and is usually performed as a bedside procedure in the neonatal intensive care unit. The procedure is guided by echocardiography and fluoroscopic imaging. It involves risks associated with any surgical procedure and has a high direct mortality rate. Nevertheless, a life-saving procedure in infants with cyanotic heart defects keeps the infant alive until definitive surgery.
