**6. Clinical presentation**

Infants with TGA are generally born at term and are normally developed [7, 8, 13]. They may be asymptomatic initially and develop variable cyanosis and respiratory distress shortly after birth. Most patients present with mild shallow tachypnea, which may not be associated with significant retractions. The neonates appear comfortable compared to the degree of cyanosis. Cyanosis is "fixed" and does not respond to oxygen supplementation, resulting in a failed hyperoxia test. If DTGA is uncomplicated, there may not be any murmur. The cases complicated with VSD, PS, and LVOO present with murmurs specific to the lesions. On auscultation, S1 may be loud and single with no audible P2 sound.

The cyanosis in DTGA varies from mild to severe. The degree of mixing between the deoxygenated and oxygenated blood and the presence of other cardiac anomalies determine the severity of cyanosis [7, 8, 13]. If associated with restrictive PFO or ASD, intact ventricular septum or very small VSD severe cyanosis during the newborn period may be noted, which is initially modified by the presence of a patent DA. If a VSD is present, the mixing is better, and the oxygen desaturation not significant; hence the lesion may be detected by a failed pulse oximetry screening at birth. Infants with large VSDs may have no cyanosis or mild cyanosis only when crying or straining. These infants develop CCF over the first month of life. If DA is open and pulmonary vascular pressure low, cyanosis is less intense as the shunting across DA is from left to right. If associated with both VSD and LVOO cyanosis at

**157**

*Transposition of Great Arteries*

differential cyanosis.

year of life.

**7. Diagnosis**

hypoxia [13].

*DOI: http://dx.doi.org/10.5772/intechopen.99205*

birth is extreme, the severity depending upon the degree of diminution of pulmonary blood flow due to left ventricular outflow tract obstruction. DTGA associated with VSD and progressively advancing pulmonary vascular obstructive disease is an uncommon variety and presents with progressive cyanosis despite early palliative procedure and absence of CCF. If DTGA is associated with an intact ventricular septum and PDA along with one of the following: pulmonary hypertension, coarctation of the aorta, or interrupted aortic arch, the infant may have higher postductal oxygen saturations than the preductal, as the better-saturated blood flows into the descending aorta via right-to-left ductal shunting. This sometimes presents as

About 80% of infants born with TGA are asymptomatic for the first 24–48 hours

Antenatal diagnosis of TGA by fetal echocardiography has improved since the visualization of outflow tracts to evaluate the major arteries' relationship is regularly performed. Postnatally, any baby failing the CCHD test or presenting with tachypnea and cyanosis that does not improve with 100% oxygen supplementation should raise the suspicion of a shunting cardiac lesion. A Hyperoxia test confirms the fixed shunting and differentiates between cardiac and pulmonary etiology of

Echocardiography with Doppler Study is confirmatory. The procedure should include evaluating atrioventricular and ventricular arterial connections and the presence of other anatomical cardiac anomalies, including those of coronary arteries. In D-TGA, two-dimensional echocardiography in the subcostal view demonstrates a great artery arising from the posteriorly situated left ventricle and bifurcating into left and right pulmonary arteries, while in the short-axis or parasagittal view, the aorta is visualized coming out anteriorly from the right ventricle [7, 8, 13, 14]. The atrial evaluation is important to confirm the presence of FO or ASD and the degree of interatrial flow, which determines the critical intercirculatory mixing. The presence of a VSD assures mixing but suggests the possibility of aortic arch anomalies. Complex TGA with VSD and coarctation have worse surgical outcomes and mortality. The presence of patent DA and the degree and direction of shunting blood are important information to obtain. Coronary artery anatomy and its variations must be ascertained via echocardiography, angiography or cardiac magnetic resonance imaging (MRI) prior to surgery. Atrioventricular valvular anomalies and chordae tendineae's relationship with interventricular septum and

Electrocardiography in TGA is generally normal with right-axis deviation and right ventricular hypertrophy. Biventricular hypertrophy may be noted if DTGA is complicated with large VSD, PDA, PS, or LVOO. Chest radiography may show normal or slightly increased heart size or the typical "egg on a string" appearance with

ventricles are other important features to evaluate before surgery.

of life since the DA is open [13]. After discharge, as the DA closes, such babies return with acute cardiorespiratory decompensation with hypoxemia and severe metabolic acidosis due to tissue hypoperfusion. The universal application of the pre-discharge Congenital Cyanotic heart disease pulse oximetry screening test, recommended by the AAP has significantly improved the chances of a timely diagnosis of TGA in neonates, and such situations are now minimized. In some cases, the presentation may be delayed by days or even weeks, but most are revealed within the neonatal period. If untreated, about 30 percent of TGA cases will die in the first week, 50 percent in the first month, and almost 90 percent within the first

#### *Transposition of Great Arteries DOI: http://dx.doi.org/10.5772/intechopen.99205*

*Congenital Anomalies in Newborn Infants - Clinical and Etiopathological Perspectives*

Infants with TGA are generally born at term and are normally developed [7, 8, 13]. They may be asymptomatic initially and develop variable cyanosis and respiratory distress shortly after birth. Most patients present with mild shallow tachypnea, which may not be associated with significant retractions. The neonates appear comfortable compared to the degree of cyanosis. Cyanosis is "fixed" and does not respond to oxygen supplementation, resulting in a failed hyperoxia test. If DTGA is uncomplicated, there may not be any murmur. The cases complicated with VSD, PS, and LVOO present with murmurs specific to the lesions. On auscultation, S1 may be

The cyanosis in DTGA varies from mild to severe. The degree of mixing between the deoxygenated and oxygenated blood and the presence of other cardiac anomalies determine the severity of cyanosis [7, 8, 13]. If associated with restrictive PFO or ASD, intact ventricular septum or very small VSD severe cyanosis during the newborn period may be noted, which is initially modified by the presence of a patent DA. If a VSD is present, the mixing is better, and the oxygen desaturation not significant; hence the lesion may be detected by a failed pulse oximetry screening at birth. Infants with large VSDs may have no cyanosis or mild cyanosis only when crying or straining. These infants develop CCF over the first month of life. If DA is open and pulmonary vascular pressure low, cyanosis is less intense as the shunting across DA is from left to right. If associated with both VSD and LVOO cyanosis at

**156**

**6. Clinical presentation**

*Hemodynamics in DTGA (curtsey MSD manual).*

**Figure 4.**

loud and single with no audible P2 sound.

birth is extreme, the severity depending upon the degree of diminution of pulmonary blood flow due to left ventricular outflow tract obstruction. DTGA associated with VSD and progressively advancing pulmonary vascular obstructive disease is an uncommon variety and presents with progressive cyanosis despite early palliative procedure and absence of CCF. If DTGA is associated with an intact ventricular septum and PDA along with one of the following: pulmonary hypertension, coarctation of the aorta, or interrupted aortic arch, the infant may have higher postductal oxygen saturations than the preductal, as the better-saturated blood flows into the descending aorta via right-to-left ductal shunting. This sometimes presents as differential cyanosis.

About 80% of infants born with TGA are asymptomatic for the first 24–48 hours of life since the DA is open [13]. After discharge, as the DA closes, such babies return with acute cardiorespiratory decompensation with hypoxemia and severe metabolic acidosis due to tissue hypoperfusion. The universal application of the pre-discharge Congenital Cyanotic heart disease pulse oximetry screening test, recommended by the AAP has significantly improved the chances of a timely diagnosis of TGA in neonates, and such situations are now minimized. In some cases, the presentation may be delayed by days or even weeks, but most are revealed within the neonatal period. If untreated, about 30 percent of TGA cases will die in the first week, 50 percent in the first month, and almost 90 percent within the first year of life.
