**6.1.4 Cardiac catheterization and angiography**

Oxygen saturation data reveal systemic venous and arterial desaturation, usually proportional to the degree of right ventricular outflow obstruction. Usually no left-to-right shunts are demonstrated. Pulmonary venous and left atrial saturations are usually normal. The left ventricular and aortic saturations are diminished because of right-to-left shunt across the VSD. Aortic saturation is a better (than left ventricular) indicator of the degree of desaturation because of better mixing distally. The peak systolic pressures in both ventricles are equal because of a large VSD. The top of the right ventricular pressure curve is flat when compared to that of patients with PS with intact ventricular septum in which it is triangular. The pulmonary arterial pressures are low to normal with demonstrable peak systolic gradients across the pulmonary valve and infundibulum. However, multiple gradients may not be demonstrable in all patients either because of technical (multiple holes in the catheter or rapid withdrawal) or physiologic reasons. Angiographic data should be used to supplement pressure information for assessment of degree and level of right ventricular outflow obstruction. The left ventricular and aortic pressures are normal without any gradient across the aortic valve.

Angiographic evaluation of anatomy of TOF is generally recommended prior to total surgical correction, although at some centers detailed echocardiographic data may be considered adequate. Selective left ventricular angiography in a left axial oblique view to demonstrate the size and function of the left ventricle and the size and location of the VSD, particularly to exclude muscular VSD is important. Similarly selective right ventricular angiography to study its architecture, size and function and to evaluate right ventricular outflow obstruction is recommended. Pulmonary arteriogram in a sitting up view to visualize the size of the main and branch pulmonary arteries and to exclude branch pulmonary artery stenosis should be obtained. Aortic root angiography is also necessary to visualize coronary artery anatomy, especially to exclude coronary arteries crossing the right ventricular infundibulum. Origin of the left anterior descending coronary artery from the right coronary artery occurs in a significant number of cases of TOF and should be excluded, if necessary, by selective coronary angiography.

#### **Management**

30 Congenital Heart Disease – Selected Aspects

The ECG shows signs of right ventricular hypertrophy. Right atrial enlargement is less

Hemoglobin and hematocrit along with red blood cell indices should be monitored periodically in all children with cyanotic congenital heart defects including TOF. The degree and duration of hypoxemia determine the level of hemoglobin. In the absence of adequate iron intake, relative anemia with hypochromia and microcytosis may develop. Because this is a risk factor for developing cerebrovascular accidents, the relative anemia should be

The echo is very helpful in confirming the diagnosis and in evaluating several of the issues related to TOF. Enlargement of the right ventricle, large VSD, aortic over-ride and right ventricular outflow tract obstruction can be imaged. Shunting across the VSD and increased Doppler flow velocity across the right ventricular outflow tract can be demonstrated. Size of the main and proximal branch pulmonary arteries can be evaluated although the distal

Oxygen saturation data reveal systemic venous and arterial desaturation, usually proportional to the degree of right ventricular outflow obstruction. Usually no left-to-right shunts are demonstrated. Pulmonary venous and left atrial saturations are usually normal. The left ventricular and aortic saturations are diminished because of right-to-left shunt across the VSD. Aortic saturation is a better (than left ventricular) indicator of the degree of desaturation because of better mixing distally. The peak systolic pressures in both ventricles are equal because of a large VSD. The top of the right ventricular pressure curve is flat when compared to that of patients with PS with intact ventricular septum in which it is triangular. The pulmonary arterial pressures are low to normal with demonstrable peak systolic gradients across the pulmonary valve and infundibulum. However, multiple gradients may not be demonstrable in all patients either because of technical (multiple holes in the catheter or rapid withdrawal) or physiologic reasons. Angiographic data should be used to supplement pressure information for assessment of degree and level of right ventricular outflow obstruction. The left ventricular and aortic pressures are normal without any

Angiographic evaluation of anatomy of TOF is generally recommended prior to total surgical correction, although at some centers detailed echocardiographic data may be considered adequate. Selective left ventricular angiography in a left axial oblique view to demonstrate the size and function of the left ventricle and the size and location of the VSD, particularly to exclude muscular VSD is important. Similarly selective right ventricular angiography to study its architecture, size and function and to evaluate right ventricular outflow obstruction is recommended. Pulmonary arteriogram in a sitting up view to visualize the size of the main and branch pulmonary arteries and to exclude branch pulmonary artery stenosis should be obtained. Aortic root angiography is also necessary to visualize coronary artery anatomy, especially to exclude coronary arteries crossing the right ventricular infundibulum. Origin of the left anterior descending coronary artery from the

**6.1.3.2 Electrocardiogram** 

treated with oral supplemental iron.

gradient across the aortic valve.

pulmonary arteries cannot easily be seen by echocardiogram.

**6.1.4 Cardiac catheterization and angiography** 

**6.1.3.4 Echocardiogram** 

commonly seen. **6.1.3.3 Blood work** 

The goal of management of TOF patients is to allow total surgical correction with minimal mortality and morbidity and to prevent or treat complications inherent to cyanotic heart defects in general and TOF in particular. Protection against subacute bacterial endocarditis, prevention and/or prompt treatment of dehydration, and periodic monitoring for relative anemia secondary to iron deficiency and prompt treatment when found should be undertaken. Palliative or corrective surgical procedures should be performed prior to development of significant polycythemia. Exercise, as tolerated should be permitted unless symptoms develop with activity.

Treatment of an infant with cyanotic spell may be summarized (Rao 1989a) as follows:


Congenital Heart Defects – A Review 33

arising from the right ventricle and the pulmonary artery from the ventricle). The systemic venous blood from the vena cavae enters the right atrium and right ventricle and from there into the aorta while the pulmonary venous blood enters the left atrium and left ventricle and from there into the pulmonary artery. Thus, the circulation is parallel instead of normal inseries circulation. Because of this reason, the systemic venous blood does not get oxygenated and the pulmonary venous blood does not get delivered to the body. The infant will not survive unless there are intercirculatory shunts such as atrial or ventricular septal defect or

Clinical features depend upon the anatomic type, namely Group I, TGA with intact ventricular septum; Group II, TGA with VSD, and Group III, TGA with VSD and PS (Rao

In group I with intact septum, the infants usually present with cyanosis within the first week of life. They may otherwise be asymptomatic. However, they will soon become tachypnoeic and develop respiratory distress. If they are not appropriately treated, they become acidotic and go on to become lethargic without lack of spontaneous movement, and

Group II TGA patients with VSD present with symptoms of congestive heart failure (tachypnea, tachycardia, sweating, and poor feeding) between 4 to 8 weeks of life, but the

Group III patients (TGA with VSD and PS) have variable presentation, depending upon the severity of PS. If there is poor mixing, they may present early in life and mimic TGA with intact septum. If the PS is severe, the presentation is essentially similar to that described in the TOF section. With moderate PS the presentation is late with longer survival. With mild

The group I patients with intact septum are usually severely cyanotic but are without distress until severe hypoxemia and acidosis develop. Clubbing is not present in the newborn period and may not develop until 3 to 6 months. The right ventricular impulse is increased and the second heart sound is single. Either no murmur or a grade I-II/Vl nonspecific ejection systolic murmur may be auscultated. In group II patients, tachypnea, tachycardia, minimal cyanosis, hepatomegaly, increased right and left ventricular impulses, single second sound, a grade III-IV/VI holosystolic murmur at the left lower sternal border and a mid-diastolic flow rumble (murmur) at the apex may be present. In group III patients, the findings are similar to TGA with intact septum, TGA with VSD, or TOF depending upon

Chest x-ray in the intact septum group is benign with normal to minimal cardiomegaly and normal to slightly increased pulmonary vascular marking. The thymic shadow may rapidly involute and a narrow pedicle (superior mediastinum) may be seen. A combination of the above signs may sometimes assume "egg-shaped" appearance on a postero-anterior chest

PS, congestive heart failure signs may be present, similar to group II patients.

patent ductus arteriosus.

**6.2.1 Symptoms** 

eventually die.

cyanosis is minimal.

**6.2.2 Physical examination** 

the degree of mixing and severity of PS.

**6.2.3 Noninvasive evaluation 6.2.3.1 Chest roentgenogram** 

2010).

used. The recommended loading dose of Esmolol is 500 mcg/kg followed by 50-100 mcg/kg/min.


If the infant improves with the management outlined above, total surgical correction of the cardiac defects, if anatomically feasible, or a systemic-to-pulmonary artery shunt to improve pulmonary blood flow on an elective basis within the next day or so may be performed. More recently, we have used balloon pulmonary valvuloplasty as an alternative to Blalock-Taussig shunt, especially if valvar obstruction is a significant component of right ventricular outflow obstruction (Rao et al 1992). Another alternative to surgery is oral propranolol (dosage as above) which may help postpone surgery by several months to years.

Total surgical correction to include closure of VSD in such a manner as to direct left ventricular output into the aorta and resection of the infundibulum and/or relief of pulmonary valvar obstruction can be performed almost at any age. Enlargement of the right ventricular outflow tract with a pericardial patch (or other prosthetic material) may be necessary in some cases. Sometimes total corrective procedures are not feasible with "respectable" mortality either because of pulmonary arterial (and/or annular) hypoplasia, "smallish" left ventricle, and/or anomalous course of a major coronary artery in the right ventricular infundibulum. Size and age of the patients also enter into such decision making. If it is deemed that a given patient is not suitable for total surgical correction, palliative surgery may be utilized to augment pulmonary blood flow and to allow the patients to grow into an age, size and anatomy that are more likely suitable for complete correction. Classic or modified Blalock-Taussig shunt is clearly a preferred surgical method for this purpose. We have used balloon pulmonary valvuloplasty in TOF patients to augment pulmonary blood flow and to allow for growth and development of the pulmonary arterial system and left ventricle so that a total surgical corrective procedure could be performed at a later time with a greater chance for success (Rao et al 1992).

Discussion of the management of TOF with pulmonary atresia, TOF with MAPCAs (multiple aorto-pulmonary collateral arteries) and TOF with syndrome of absent pulmonary valve is beyond the scope of this chapter and the reader is referred elsewhere (Alapati and Rao 2011) or to the standard textbooks.

#### **6.2 Transposition of the great arteries**

Transposition of the great arteries (TGA) is the most common cyanotic congenital heart defect presenting in the newborn period. It constitutes 5% of all CHD and 10% of all cyanotic CHD. There are multiple definitions used to describe TGA. Perhaps, the most accurate description is "a condition in which the aorta arises from the morphologic right ventricle and the pulmonary artery from the morphologic left ventricle". In the most common form, usually referred to as complete transposition, the atria are normal in position (situs solitus of the atria), there is atrioventricular concordance (right atrium connected to the right ventricle and the left atrium to the left ventricle), d loop of the ventricles (right ventricle on the right and left ventricle on the left), and ventriculo-arterial discordance (aorta arising from the right ventricle and the pulmonary artery from the ventricle). The systemic venous blood from the vena cavae enters the right atrium and right ventricle and from there into the aorta while the pulmonary venous blood enters the left atrium and left ventricle and from there into the pulmonary artery. Thus, the circulation is parallel instead of normal inseries circulation. Because of this reason, the systemic venous blood does not get oxygenated and the pulmonary venous blood does not get delivered to the body. The infant will not survive unless there are intercirculatory shunts such as atrial or ventricular septal defect or patent ductus arteriosus.

#### **6.2.1 Symptoms**

32 Congenital Heart Disease – Selected Aspects

9. If the infant does not improve with any of the aforementioned measures, an emergency systemic-to-pulmonary artery shunt (the author prefers modified Blalock-Taussig anastomosis) should be performed. Occasionally, total correction, if the anatomy is adequate, may he performed on an emergency basis. The important principle is that the

If the infant improves with the management outlined above, total surgical correction of the cardiac defects, if anatomically feasible, or a systemic-to-pulmonary artery shunt to improve pulmonary blood flow on an elective basis within the next day or so may be performed. More recently, we have used balloon pulmonary valvuloplasty as an alternative to Blalock-Taussig shunt, especially if valvar obstruction is a significant component of right ventricular outflow obstruction (Rao et al 1992). Another alternative to surgery is oral propranolol

Total surgical correction to include closure of VSD in such a manner as to direct left ventricular output into the aorta and resection of the infundibulum and/or relief of pulmonary valvar obstruction can be performed almost at any age. Enlargement of the right ventricular outflow tract with a pericardial patch (or other prosthetic material) may be necessary in some cases. Sometimes total corrective procedures are not feasible with "respectable" mortality either because of pulmonary arterial (and/or annular) hypoplasia, "smallish" left ventricle, and/or anomalous course of a major coronary artery in the right ventricular infundibulum. Size and age of the patients also enter into such decision making. If it is deemed that a given patient is not suitable for total surgical correction, palliative surgery may be utilized to augment pulmonary blood flow and to allow the patients to grow into an age, size and anatomy that are more likely suitable for complete correction. Classic or modified Blalock-Taussig shunt is clearly a preferred surgical method for this purpose. We have used balloon pulmonary valvuloplasty in TOF patients to augment pulmonary blood flow and to allow for growth and development of the pulmonary arterial system and left ventricle so that a total surgical corrective procedure could be performed at

Discussion of the management of TOF with pulmonary atresia, TOF with MAPCAs (multiple aorto-pulmonary collateral arteries) and TOF with syndrome of absent pulmonary valve is beyond the scope of this chapter and the reader is referred elsewhere (Alapati and

Transposition of the great arteries (TGA) is the most common cyanotic congenital heart defect presenting in the newborn period. It constitutes 5% of all CHD and 10% of all cyanotic CHD. There are multiple definitions used to describe TGA. Perhaps, the most accurate description is "a condition in which the aorta arises from the morphologic right ventricle and the pulmonary artery from the morphologic left ventricle". In the most common form, usually referred to as complete transposition, the atria are normal in position (situs solitus of the atria), there is atrioventricular concordance (right atrium connected to the right ventricle and the left atrium to the left ventricle), d loop of the ventricles (right ventricle on the right and left ventricle on the left), and ventriculo-arterial discordance (aorta

(dosage as above) which may help postpone surgery by several months to years.

8. Infrequently, general anesthesia may be necessary to break the spell.

infant requires more pulmonary blood flow.

a later time with a greater chance for success (Rao et al 1992).

Rao 2011) or to the standard textbooks.

**6.2 Transposition of the great arteries** 

mcg/kg/min.

used. The recommended loading dose of Esmolol is 500 mcg/kg followed by 50-100

Clinical features depend upon the anatomic type, namely Group I, TGA with intact ventricular septum; Group II, TGA with VSD, and Group III, TGA with VSD and PS (Rao 2010).

In group I with intact septum, the infants usually present with cyanosis within the first week of life. They may otherwise be asymptomatic. However, they will soon become tachypnoeic and develop respiratory distress. If they are not appropriately treated, they become acidotic and go on to become lethargic without lack of spontaneous movement, and eventually die.

Group II TGA patients with VSD present with symptoms of congestive heart failure (tachypnea, tachycardia, sweating, and poor feeding) between 4 to 8 weeks of life, but the cyanosis is minimal.

Group III patients (TGA with VSD and PS) have variable presentation, depending upon the severity of PS. If there is poor mixing, they may present early in life and mimic TGA with intact septum. If the PS is severe, the presentation is essentially similar to that described in the TOF section. With moderate PS the presentation is late with longer survival. With mild PS, congestive heart failure signs may be present, similar to group II patients.

### **6.2.2 Physical examination**

The group I patients with intact septum are usually severely cyanotic but are without distress until severe hypoxemia and acidosis develop. Clubbing is not present in the newborn period and may not develop until 3 to 6 months. The right ventricular impulse is increased and the second heart sound is single. Either no murmur or a grade I-II/Vl nonspecific ejection systolic murmur may be auscultated. In group II patients, tachypnea, tachycardia, minimal cyanosis, hepatomegaly, increased right and left ventricular impulses, single second sound, a grade III-IV/VI holosystolic murmur at the left lower sternal border and a mid-diastolic flow rumble (murmur) at the apex may be present. In group III patients, the findings are similar to TGA with intact septum, TGA with VSD, or TOF depending upon the degree of mixing and severity of PS.

#### **6.2.3 Noninvasive evaluation**

#### **6.2.3.1 Chest roentgenogram**

Chest x-ray in the intact septum group is benign with normal to minimal cardiomegaly and normal to slightly increased pulmonary vascular marking. The thymic shadow may rapidly involute and a narrow pedicle (superior mediastinum) may be seen. A combination of the above signs may sometimes assume "egg-shaped" appearance on a postero-anterior chest

Congenital Heart Defects – A Review 35

pulmonary artery pressure is usually increased with associated VSD while with PS it may be

Selective right ventricular angiography reveals a morphologically right ventricle with opacification of an anteriorly and superiorly displaced aorta. The aortic valve is located to the right of the pulmonary valve (d-TGA). The aorta ascends in a normal fashion and usually descends on the left side of the spine. The size and function of the right ventricle and presence of tricuspid insufficiency should be evaluated. If a VSD is present, it may be visualized. A laid-back view of the aortic root angiography along with a lateral view may be useful in demonstrating coronary artery anatomy. Aortography may, in addition, be useful in demonstrating PDA and CoA. Left ventricular cineangiogram reveals a morphologic left ventricle with prompt opacification of the pulmonary artery. The pulmonary valve is located posterior, inferior and to the left of the aortic valve. Left ventricular angiography should be scrutinized for subvalvar and valvar PS. A VSD may be visualized, if present.

Untreated, TGA with intact septum carries a poor prognosis. The initial management of this and other cyanotic neonates is similar. Monitoring the infant's temperature and maintenance of neutral thermal environment is extremely important. In hypoxemic infants, ambient oxygen should be administered. In cyanotic CHD patients, no more than 0.4 FIO2 is necessary. Metabolic acidosis (pH < 7.25), if any, should be corrected with sodium bicarbonate (usually 1-2 mEq/kg diluted half and half with 5% or 10% dextrose solution) immediately. Respiratory acidosis should be cared for by appropriate suctioning, intubation and assisted ventilation. Hypoglycemia may be a significant problem; therefore, the infant's serum glucose should be monitored and the neonates should routinely receive 10% dextrose in water intravenously. If hypoglycemia (<30 mg/100ml) occurs, 15% to 20% dextrose solution should be administered. Similarly hypocalcemia should be monitored for and treated, if found. If an infant is getting progressively hypoxemic, it is likely that the intercirculatory pathways (patent foramen ovale and patent ductus arteriosus) are closing. Prostaglandin El (PGEI) (0.05 to 0.1 mcg/kg/min) intravenously may help open the ductus, thus improve oxygenation. Balloon atrial septostomy may be necessary to improve hypoxemia even after PGE1. Total surgical correction by arterial switch procedure (Jatene) is

the treatment of choice in these neonates and will be discussed here-under.

TGA patients with VSD usually present with heart failure and aggressive anticongestive measures are indeed needed. Balloon atrial septostomy may help relieve pulmonary venous congestion and improve oxygenation. These patients will require Jatene procedure with

TGA patients with VSD and PS may have varying presentation. If the reason for hypoxemia is poor mixing, balloon atrial septostomy is the treatment of choice. If the hypoxemia is secondary to decreased pulmonary flow, a Blalock-Taussig type of shunt may be needed. Sometimes both balloon septostomy and balloon dilatation of pulmonary valve may be performed via catheters in some of these children. Eventually these patients require a

Mustard procedure, which was originally described in 1964 was the most commonly used operation for TGA in the past. In this operation, hemodynamic correction of the defect is achieved by re-directing the systemic and pulmonary venous returns by means of an intraatrial baffle. Better understanding of the conduction system and its blood supply coupled

low to normal.

**6.2.5 Management** 

closure of VSD.

Rastelli type of repair.

roentgenogram. In group II patients with VSD, moderate to severe cardiomegaly and increased pulmonary vascular markings are usually seen. In group III patient, mild to at worst moderate cardiomegaly may be observed. The pulmonary vascular marking may be increased, normal or decreased, dependent upon the severity of PS.

#### **6.2.3.2 Electrocardiogram**

The ECG in a neonate with TGA and intact septum (Group I) may be normal with the usual right ventricular preponderance seen during this age. In older infants clear-cut right ventricular hypertrophy is seen and in addition right atrial enlargement may be observed. In group II patients, biventricular hypertrophy and left atrial enlargement are usual. In group III, right ventricular or biventricular enlargement is seen.

#### **6.2.3.3 Echocardiogram**

The echo is usually helpful in the diagnosis and assessment. Demonstration of transposition of the great arteries is somewhat difficult in view of the fact that atrial and ventricular anatomy is normal and the aortic and pulmonary valves look similar on echocardiographic study. If one can follow the great vessel arising from the left ventricle and demonstrate its bifurcation, identifying it as a pulmonary artery, the diagnosis is easy. One of the helpful indirect signs is somewhat a posterior course the great vessel off of the left ventricle in a precordial long axis view, indicating pulmonary artery in contradistinction to anteriorly coursing ascending aorta. On-end visualization of the aorta and pulmonary artery on a precordial short axis view of the heart is also helpful in suggesting TGA. The presence of an inter-atrial communication and patent ductus arteriosus and shunt across them by color and pulsed Doppler can also be evaluated. In addition to these, demonstration of VSD and PS will place the patients into the respective groups.

#### **6.2.3.4 Other laboratory data**

Blood gas values are useful in demonstrating the degree of hypoxemia and ventilatory status. Hemoglobin and hematocrit are particularly useful in the follow-up of older children.
