Saline contrast echocardiography complements cardiac interventions in neonates with transposition of great arteries and abnormal ductus venosus anatomy

Abstract

We present a rare case of premature low birthweight neonate with right diaphragmatic hernia and transposition of great vessels requiring balloon atrial septostomy. Congenital diaphragmatic hernia poses a unique challenge to umbilical venous catheterisation. Based on the radiographic position of umbilical vein catheter, umbilical venous cannulation was attempted; however, the catheter could not be navigated to the right atrium. Saline contrast echocardiography was used to delineate the abnormal umbilical and ductus venosus drainage. Eventually, the procedure was successfully completed via the femoral venous approach. We emphasise the importance of defining ductus venosus anatomy and umbilical venous drainage using a simple tool like saline contrast echocardiography before performing catheterisation using the umbilical venous access in such cases.

Background

Altered anatomy of thoracic and abdominal organs in congenital diaphragmatic hernia (CDH) leads to a change in the course of umbilical venous drainage.^1–3 This variation in umbilical venous drainage and ductus venosus anatomy adds to the risk of cardiac catheterisation. Very few case reports have discussed complications in the management of D- transposition of great arteries (D-TGA) and CDH mostly with normal birth weight.⁴ Both low birth weight (LBW) and prematurity present significant challenges in the management of congenital heart disease. Cardiac interventional procedures can be successfully performed in LBW neonates, although with increased risk.^{5 6} Here, we highlight the challenges involved in using the umbilical venous approach while performing emergency cardiac interventional procedure in an unstable LBW premature neonate with TGA and right CDH (RCDH).

Case presentation

A female neonate with a birth weight of 1640 g and APGAR score of 3 and 8 was delivered at 36+2 weeks of gestation by lower segment caesarean section with an antenatal diagnosis of D-TGA with intact ventricular septum (IVS). RCDH was detected at 34+2 weeks of gestation; however, prenatal hepatic herniation was not identified. Postnatally, after initial resuscitation and intubation, umbilical venous catheter (UVC) was inserted, and arterial duct patency was maintained with prostaglandin E1 infusion. An echocardiogram confirmed the diagnosis of D-TGA-IVS with a large patent ductus arteriosus and a restrictive foramen ovale. Due to inadequate mixing at the atrial level, the neonate had metabolic acidosis, hypotension and desaturation. This was further aggravated by pulmonary hypertension due to RCDH. To stabilise the neonate before arterial switch operation, she was started on high-frequency oscillatory ventilation and inhaled nitric oxide, and she underwent bedside balloon atrial septostomy (BAS) under echocardiographic guidance at 4 hours of life.

Prior to the procedure, left femoral vein access was secured as backup and arterial pressure monitoring was done via a left radial arterial line. The position of UVC was confirmed by chest radiograph (figure 1), and thereafter BAS was attempted under sterile conditions. However, the balloon catheter could not be negotiated to the right atrium (RA) and was visualised to be posterior to the cardiac structures on echocardiography (figure 2A, B; videos 1 and 2).

Figure 1.

Anteroposterior chest radiograph showing the tip of umbilical venous catheter (black arrow) to the right of T9–T10 vertebral bodies.

Figure 2.

Echocardiographic images of umbilical venous catheter. (A) Subcostal echocardiographic image showing umbilical venous catheter and the RA. (B) Subcostal echocardiographic image showing RA, LA, guide wire in RA (white arrow) and umbilical venous catheter (black arrow) posterior to the LA. LA, left atrium; RA, right atrium.

Video 1.

bcr-2021-244023supp001.mp4 ^{(668.9KB, mp4)}

DOI: 10.1136/bcr-2021-244023.video01

Video 2.

bcr-2021-244023supp002.mp4 ^{(668.9KB, mp4)}

DOI: 10.1136/bcr-2021-244023.video02

Saline contrast injected via the UVC showed microbubbles appearing in the hepatic veins and not through the inferior vena cava (IVC) (figure 3A, B; video 3). Hence, the umbilical vein approach was abandoned, and the BAS was subsequently completed successfully using the femoral venous access. Following BAS, non-restrictive atrial septal defect with bidirectional flow was achieved and clinical parameters consequently improved.

Figure 3.

Saline contrast study. (A) Subcostal echocardiographic image showing hepatic vein (arrow) joining the IVC, which then enters the RA. (B) Subcostal echocardiographic image after saline contrast injection showing microbubbles in hepatic vein (arrow) and not in the IVC. IVC, inferior vena cava; RA, right atrium.

Video 3.

bcr-2021-244023supp003.mp4 ^{(668.9KB, mp4)}

DOI: 10.1136/bcr-2021-244023.video03

An abdominal ultrasound performed subsequently revealed a part of the liver and bowel within the right hemithorax, along with collapse of the right lung, which was consistent with RCDH and hepatic herniation. This was confirmed during surgery when the neonate underwent repair of CDH on the seventh day of life. The neonate was gradually weaned off inotropes, prostaglandin E1, high-frequency oscillatory ventilation and inhaled nitric oxide. At the time of writing this case report, the neonate weighed 1960 g, maintained oxygen saturation of 85% and underwent arterial switch operation.

Discussion

D-TGA with inadequate circulatory mixing between systemic and pulmonary circulation presents with desaturation, poor perfusion and metabolic acidosis soon after birth. Arterial switch surgery is the surgery of choice for infants with D-TGA. It is essential to stabilise the infant and provide adequate mixing at atrial level through BAS while awaiting arterial switch surgery.⁷

BAS was done under echocardiographic guidance at the bedside to prevent transportation risks and radiation exposure.⁸ Assuming that ductus venosus is still patent in premature infants within the first few hours of life and to prevent venous complications such as catheter-related thrombosis and iliofemoral vein occlusion, umbilical venous route was preferred.^{5 9} Normal position of the UVC on radiograph is determined when the venous catheter navigates to the right side of thoracolumbar vertebral bodies without angulation or with gentle rightward angulation as illustrated in figure 4A. Furthermore, the tip of the catheter should be projecting above the right hemidiaphragm corresponding to its preferred anatomical location in ductus venosus or at RA/IVC junction. Variation in the radiographic appearance of UVC occurs depending on the herniation of liver in CDH. In left CDH with left liver lobe herniation, on radiograph, the UVC can be deviated to the left or right of spine depending on its tip position within the portal venous system.^{1 3} This corresponds to the alteration in the anatomy of umbilical vein, portal veins and hepatic vein with liver herniation. In RCDH, rightward and cephalad deviation of the UVC is expected on radiograph, corresponding to herniation of the right lobe of liver. The radiograph of our patient showed a normal position of UVC tip, which is to the right of T9–T10 vertebral body (figure 1).

Figure 4.

Illustration of umbilical venous drainage in normal neonate and altered anatomy of ductus venosus in right congenital diaphragmatic hernia. (A) Schematic illustration for normal drainage of umbilical vein. Umbilical venous catheter passes from the umbilical vein to the ductus venosus to enter the right atrium. (B) Schematic illustration showing the course of umbilical venous catheter into the right portal vein in case of right diaphragmatic hernia with liver herniation. Note the horizontal course of ductus venosus into the inferior vena cava.

Sagel et al diagnosed hepatic herniation in RCDH by opacifying portal vein with contrast injected in umbilical vein.¹⁰ However, there is paucity of literature describing ductus venosus anatomy in RCDH using saline contrast and its impact on cardiac interventions which require umbilical venous catheterisation. Defining the course of ductus venosus, umbilical vein and portal vein anatomy would identify the extent of intrathoracic hepatic herniation, which would help during the surgical repair of CDH.¹⁰ When not using fluoroscopy, performing saline contrast echocardiography is important, particularly in RCDH, prior to establishing routine neonatal umbilical vascular access or bedside cardiac interventions.¹¹

In this case, as depicted in figure 4B, the herniation of the right lobe of the liver causes UVC to follow a straight course into the right portal vein rather than ductus venosus. This explains the normal position of the tip of UVC on radiograph. The herniation of the right lobe of liver results in ductus venosus joining the IVC at an acute angle. There is preferential flow of umbilical venous blood to the portal venous system, which may result in premature closure of the ductus venosus. Hence, we believe that there may be a structural and/or functional change in the ductus venosus due to hepatic herniation in RCDH, which was delineated through saline contrast injection.

Prenatal diagnosis of CDH provides significant advantage in the planning of emergency neonatal cardiac interventions requiring umbilical vein access. It is known that the herniation of liver in CDH has influence on the outcome of the patient. RCDH is less common compared with left CDH; however, most cases of RCDH are associated with liver herniation. Liver herniation in RCDH would be difficult to diagnose by ultrasound due to the identical echogenicity of lung and liver tissue. Fetal MRI is done at many centres for CDH to detect liver herniation. Some authors have proposed using colour Doppler studies to predict hepatic herniation in left diaphragmatic hernia.¹ However, feasibility of similar evaluations in RDCH has not been proven.

Learning points.

• When using umbilical vein for vascular access for cardiac interventions or otherwise, it is essential to identify inappropriate umbilical venous catheter (UVC) placement to prevent life-threatening complications. Relying merely on radiographic definition of UVC position, especially in congenital diaphragmatic hernia (CDH), may not be enough. We hypothesise that the ductus venosus may undergo premature closure or may be hypoplastic due to a horizontal course in patients with diaphragmatic herniation of liver.

• Saline contrast echocardiography is a useful bedside alternative to fluoroscopy to define the drainage and anatomy of umbilical vein and ductus venosus to inferior vena cava before any cardiac intervention via umbilical venous access.

• Pre-empting the procedure with alternate access may be important for the success of cardiac interventions such as balloon atrial septostomy.

• Antenatal estimation of the fetal weight and diagnosis of abnormalities that may influence the catheter course provide significant advantage in the planning of emergency neonatal cardiac interventions requiring umbilical vein access.

Ethics statements

Patient consent for publication

Parental/guardian consent obtained.