European Journal of Cardiovascular Medicine

Transposition of great arteries (TGA) comprises 5–7% of all CHDs1,2. The treatment of choice for d- TGA in neonatal period is arterial switch operation (ASO). Without surgical correction, more than 50% of the infants with transposition will die in the first month of life, 90% die in the first year2. D-TGA with left ventricular outflow tract obstruction (LVOTO) affects only 4% of all patients presenting with TGA, even high-volume centres rarely handle more than five operations per year3. We are reporting a child with D-TGA, LVOTO and ventricular septal defect(D-TGA/VSD/LVOTO) who survived till 6th year of her life without surgery and underwent arterial switch surgery successfully.

A six-year-old female child, known case of D-TGA (diagnosed at birth), presented with cyanosis and easy fatiguability. The patient didn’t undergo surgery after diagnosis due to financial constraint and was eventually lost to follow up. Transthoracic echocardiography demonstrated: D-TGA with a small Ostium Secundum Atrial septal defect (5mm in size) with left to right shunting, a moderate sized subaortic Ventricular Septal defect (7mm in size) with bidirectional shunting and severe sub valvar pulmonary stenosis due to a discrete subpulmonic membrane approximately 5mm below the valve, with a gradient of 80 mm of Hg. The patient had good biventricular function. The Left-ventricular posterior wall thickness was 11mm, interventricular septum thickness was 12 mm, end-diastolic left ventricular diameter was 2.17 cm and left ventricular mass index was 91gm/m2. The measured left ventricle to right ventricular pressure ratio was 0.9. The right and left coronary arteries are arising from 1st coronary sinus. The left circumflex artery was arising from 2nd coronary sinus and was retro pulmonary in its course. The patient had consistently low platelet count (55,000/mm3) for which she was investigated. She was diagnosed with thrombocytopenia due to chronic hypoxia.

Table 1: Threshold echocardiographic criteria for proceeding with arterial switch operation.

On the day of surgery, the patient was premedicated with intravenous Inj Ketamine  and Inj Glycopyrrolate. Pulse oximetry and electrocardiography were placed. Patient was induced with Inj Fentanyl 2microgram/kg and Inj Vecuronium 0 .1mg/kg. Central venous catheter and arterial line were placed. Anaesthesia was maintained with Sevoflurane, Inj Fentanyl and Inj Vecuronium boluses. The patient was heparinised and cardiopulmonary bypass initiated through aortic and bicaval cannulation. Patient was cooled to 28 degrees and Del Nido cardioplegia was used. Arterial switch was performed along with the resection of sub pulmonary ridge. Small patent foramen ovale of size 5mm was left open. The patient came off cardiopulmonary bypass with Inj Milrinone 0.33 microgram/Kg/min and Inj Noradrenaline 0.05 microgram/kg/min. Epicardial echocardiography showed good biventricular function. Both the neo aortic valve ventricle and neo pulmonary valve were competent with neo aortic valve ventricle showing trivial regurgitation. The ventricular septal defect patch was intact. Protamine was administered and haemostasis achieved. Three units of platelet concentrate were transfused. The patient was hemodynamically stable and shifted to ICU.

Fig 1: Surgical decision making in TGA^11,12.(Abbreviations: ASO- Arterial switch operation, TGA- Transposition of great arteries, LVOTO- Left ventricular outflow tract obstruction, IVS-Intact ventricular septum, VSD-Ventricular septal defect, REV-Reparation a l’etage ventruculaire procedure)

The patient was extubated on postoperative day 1. The patient was monitored with daily echocardiographic examinations, electrocardiography, and hemodynamic monitoring. By the 6th postoperative day, the inotropic support had been discontinued completely. Echocardiographic examination on the 6th postoperative day demonstrated normal systolic function with mild regurgitation of the neo-aortic valve and a small left-to-right shunting through the opening left on the atrial septum. The patient was discharged on the 8th postoperative day. 

Figure2: Chest X Ray (PA View) of the patient

Early Arterial Switch Surgery is the treatment of choice for D-TGA in the neonatal period⁴. Although ideal, neonatal ASO demands early diagnosis and immediate access to a cardiac surgical centre. When these are unavailable, one must choose between a late ASO, with or without some form of preparation of the left ventricle, or an atrial switch⁴. Primary ASO may be tried in patients more than 2 months of age with a slight increase in early morbidity and mortality⁴.

Surgical options to correct TGA at a later age are limited because of development of pulmonary vascular obstructive disease ⁵. However, in the rare combination of D-TGA with left ventricular outflow tract obstruction with adequate mixing at the atrial septal level and left ventricle that remains well trained because of LVOTO, anatomical correction with an arterial switch operation can be considered irrespective of the age at presentation⁵. In our case since the left ventricle was well preserved and LVOTO was surgically correctable, the decision to go ahead with arterial switch surgery was taken.  Echocardiography is an important tool in helping us determine the type of surgery suitable for these patients⁶.

There are reports of patients with D-TGA undergoing ASO in adulthood. Bansal et al reported a 25-year-old lady who presented with D-TGA/VSD/LVOTO and underwent a successful single-stage arterial switch operation⁵. Trehan et al reported a case of a 22-year-old man who underwent successful arterial switch operation after having initially undergone pulmonary artery banding for transposition with ventricular septal defect when he was 5 months of age⁷.

 The anesthesiologist attending the ASO must have a good understanding of pathophysiology of D-TGA and its subtypes ⁴. Most patients receive an intravenous induction with a combination of an opiate, muscle relaxant, and inhalational agent.  After induction, arterial and central venous catheters are placed. A left atrial transthoracic line may also be beneficial post repair in children for whom left ventricular dysfunction is anticipated (long bypass time) ¹. Near-infrared spectroscopy (NIRS) monitoring is usually used to monitor cerebral oxygenation throughout the procedure. A pre-bypass TEE exam is done to confirm the preoperative findings and to delineate the cardiac anatomy.

 On cardiopulmonary bypass, it is important to maintain an adequate age-dependent mean arterial pressures, a low central venous pressure, and bilaterally equal and adequate cerebral NIRS values. In many centres, coagulation studies are performed during the later stages of CPB and blood products are ordered accordingly¹. In our patient, since the patient had preoperative thrombocytopenia, 3 units of platelet concentrates were transfused post protamine infusion as recommended by the haematologist.

During rewarming and prior to coming off bypass, inotropic support is started based on the institutional protocol. Poor left ventricular function is the primary issue after separation from CPB in ASO unlike other paediatric cardiac surgical procedures where right ventricular function is the cause of concern¹. TEE, epicardial echocardiography and invasive pressures are used to assess the repair and guide the patient’s hemodynamic management after coming off CPB. It is often difficult to assess coronary blood flow directly with TEE, although the use of wall motion and mitral regurgitation can be used as surrogates of coronary patency. Coronary ischemia is usually due to a problem with the coronary buttons’ anastomoses.

Although an increased need for ECMO support has been reported in patients undergoing late ASO, it is associated with only a slight or nincrease in mortality⁸. Bisoi et al reported 20% of ECMO support and 3.7% mortality in a series of 109 late ASO patients⁹.Kalfa et al reported 11% mortality in patients who underwent ASO for TGA with LVOTO. They concluded that long term outcomes for patients with TGA and anatomic LVOTO are satisfactory¹⁰

In conclusion, late ASO can be performed safely in selected patients with D-TGA/VSD/LVOTO after detailed evaluation, with multidisciplinary involvement and careful perioperative management.

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