The term transposition describes an abnormal or discordant ventriculoarterial connection in which the aorta arises from the morphologically right ventricle and the pulmonary artery arises from the morphological left ventricle. Cyanosis in the first day of life suggests the possibility of transposition and if the ventricular septum is intact, patients become severely cyanotic within hours of birth. When the transposition is associated with a large ventricular septal defect (VSD), cyanosis is less and may not be noticed in the first few months. Diagnosis should be done rapidly from hyperoxia test, chest x-ray, ECG and echocardiography. Prostaglandin infusion should be started immediately and balloon atrial septostomy (BAS) should be performed to allow mixing between pulmonary and systemic circulation. Then, ideally, anatomical correction or arterial switch operation should be performed within one month of age.
A newborn term in baby weighing 4 Kg had been admitted to the neonatal intensive care unit (ICU) immediately after cesarean section with the diagnosis of perinatal asphyxia and aspiration pneumonia. He had a history of delayed cry after delivery and his APGAR score was six at first and fifth minutes of life. He was tachypneic and cyanosed on admission, his chest x-ray showed no evidence of lungs pathology. Hyperoxia test was positive in favor of cyanotic congenital heart disease. He had been suspected clinically as a case of TGA and confirmed later by color Doppler echocardiography. Echocardiography also showed a small perimembranous VSD of 2 mm size and a tiny PDA. In the initial three days, he was stable in spite of desaturation and tachypnoea but from the fourth day he had started showing signs of hemodynamic instability with desaturation and severe respiratory distress. His condition was discussed with the parents and decision was taken for urgent balloon atrial septostomy as a life-saving measure. A central femoral venous line was established and dopamine infusion started. He was taken to the cath laboratory on the fifth day of his life and balloon atrial septostomy was done with the aim to create a hole in the atrial septum.
Equipment used: 7 Fr catheter introducer sheath, 20G leader catheter, Haemostatic bleed back valve, 5Fr
NIH catheter, Miller septostomy balloon, pressure tubing red line (line I) and blue line (line, II), 20G x 11/2″
needle and .021 x 100 cm guidewire. Drugs used: Ini. Ketamine (1.5 mg/Kg) and Inj. Midazolam (0.1 mg/Kg I.V.)
Procedure: The patient was sedated initially with Inj. Ketamine and Midazolam and secured to the table.
He was then connected to the ECG monitoring and pulse oximetry and baseline readings are taken. Cleaning and draping was done leaving both femoral areas exposed. The groins were anesthetized with 1% lignocaine. The left femoral vein was entered percutaneously and a 7Fr sheath was placed. A 5Fr NIH catheter was attached to line II and flushed whilst advancing the catheter through the sheath to inferior vena cava (IVC). A saturation and pressure run was performed in all chambers of the right side of the heart i.e. superior vena cava (SVC), innominate vein, right atrium, right ventricle (RV) etc. Also, 1 ml of dye was injected into the innominate vein to rule out the presence or absence of left SVC. Cine angiogram was performed in the right ventricle which showed aorta arising from the RV. Then NIH catheter was taken out. Miller septostomy balloon was checked properly and introduced through IVC to the right atrium and then to the left atrium through foramen ovate. The balloon was inflated initially with 2 ml contrast taking care about the safety of the pulmonary veins and mitral valve. Balloon was then withdrawn gradually until it pressed against the atrial septum. Inflated and locked balloon was then pulled down with sudden jerk across the septum. Care was taken to prevent complication like avulsion of the IVC. The balloon was deflated immediately to avoid occlusion of the IVC. This procedure was repeated four times with increasing amount of contrast inside the balloon (up to 4 ml). The balloon was then removed on negative pressure. Again NIH catheter was used to run saturation and pressure on the right as well as left side of the heart. A cine angiogram was obtained from left ventricle this time. On completion of the procedure, the femoral venous line was preserved for giving medication. The whole procedure was performed under anesthesia
Immediately after the procedure patient’s saturation went up and left atrial pressure dropped down. Clinically, patient resumed pink color with Spo2 of 95%. The respiratory rate went down to normal and body perfusion became better. Echocardiography showed 8 mm defect in the atrial septum. The patient was shifted to a neonatal intensive care unit (ICU) with dopamine infusion at the rate of 10 microgram Kg/min with an aim to wean off in 24 hours. But the patient developed severe sepsis within 48 hours of the procedure and injections ceftazidime, cloxacillin and dobutamine were added. His condition improved gradually and he was discharged from the CMH on the 14th day of the procedure with an advice for arterial switch operation within six weeks.
Transposition of the great arteries is the second commonest cyanotic lesion. It describes the reversal of the anatomical relation of the great arteries. Normally, the aorta is posteromedial and the pulmonary artery is anterior and leftward. In a transposition, each vessel assumes the position of the other. The physiological effect of this is to produce effectively two separate circulations rather than the normal figure of eight circulations. Mixing of two circulations is possible through patent ductus arteriosus and foramen ovale initially. As soon as ductus closes, severe cyanosis becomes apparent1,2,3. In simple transposition, without other complex association, the baby looks apparently well at birth but becomes persistently cyanosed within the first days of life. If prompt action is not taken the baby becomes increasingly blue and develops a progressive metabolic acidosis. This happened in this case who was more or less stable for the first three days when a tiny PDA was seen in echocardiography. But when his PDA closed on day three he became severely cyanosed and acidotic. Cardiac catheterization is not usually necessary for diagnostic purpose but if the child needs to be treated by balloon septostomy. it should be performed and confirmation of the diagnosis is usually carried out at the same time by giving contrast injection into both ventricles. The pressure and saturation in all the cardiac chambers and great arteries can be measured. Other associated lesions like ASD, VSD, PDA, left ventricular outflow obstruction, and coronary artery can also be evaluated.
Echocardiography can help not only in anatomical diagnosis but also in treatment modalities. In some very sick neonates who are severely acidotic and hypoxic, immediate balloon atrial septostomy can be performed in the ICU with echo guidance.
Successful management of infants with DTGA requires the close coordination of the referring hospital, transport service and the receiving centre. If managed suboptimally, brain injury if not death, may be the result. For these babies, urgent transfer to paediatric cardiology unit is mandatory. If the baby is severely cyanotic and acidotic the metabolic acidosis should be corrected with intravenous sodium bicarbonate and prostaglandin infusion should be started to keep the ductus patent. This in turn will increase the left artial pressure, thus help in opening the foramen ovale and allow mixing at the atrial level. The problem with prostaglandin infusion is that it may induce apnoea, so prophylactic intubation and ventilation is sometimes recommended. The subsequent management of ncomplicated transposition is uniform in most centres and consist of balloon atrial septostomy to provide adequate mixing of saturated and unsaturated blood.
For balloon atrial septostomy, the catheter is advanced under radiographic control untill the balloon at the tip is in the left atrium, taking care that it does not enter into the pulmonary veins or left ventricle. The balloon is then inflated with contrast media and pulled by sharp tug back into the right atrium and mouth of inferior venacava. The size of the hole produced can be estimated by seeing what volume in the ballloon can easily be withdrawn without resistance. The left atrial pressure and systemic saturation will show dramatic improvement immediately. All this management are life saving and to stabilize the patient for surgery. So, corrective surgery should be performed as per protocol of the respective cardiac centre. Now a days, arterial switch operation is the treatment of choice for patients with transposition of the great arteries. This should be- performed before one month of age of the babies to avoid complications from left ventricular (LV) pressure fall. As LV supports pulmonary circulation, its pressure starts dropping after birth, so it will not be possible for low pressure LV to support systemic circulation after arterial switch operation if it is performed after one monthl. There are other types of surgeries available for simple and complex TGA cases, for example, atrial switch (Musturd, Senning) or two stage switch operation etc. But balloon arterial septostomy (BAS) is the first and life saving step for this patients, specially in those places where facility for arterial switch operation is not available.