Exam: VS T 37, P164, RR 64, oxygen saturation 83% on oxygen by nasal prongs. Weight 50th percentile. He is alert and active in mild respiratory distress, with visible cyanosis. HEENT exam is negative. His heart rhythm is tachycardic. He has a mild right precordial heave with a grade 3/6 ejection murmur at ULSB and a diminished 2nd heart sound. His lungs are clear. Liver and spleen are not enlarged. He has normal peripheral pulses with cyanotic nail beds and mucous membranes.
An echocardiogram is obtained which identifies cyanotic congenital heart disease. This is confirmed at cardiac catheterization. He subsequently undergoes palliative surgery with improved oxygenation and appearance of a continuous murmur. He is discharged in stable condition to be followed on an outpatient basis and to undergo further corrective surgery at a later date.
Cyanosis is a bluish discoloration of skin and mucous membranes. It results from reduced hemoglobin in blood of at least 3-5 gm/dL (1). Cyanosis can be secondary to cardiac, respiratory, hematologic and metabolic causes. Methemoglobinemia, decreased alveolar hypoventilation secondary to depressed respiratory center or obstruction of the respiratory passages, polycythemia, and hypoglycemia, shock, and sepsis may also cause cyanosis, or at least something that resembles cyanosis. It can be central or peripheral. Peripheral cyanosis is secondary to low cardiac output, in which acrocyanosis usually occurs with cool extremities and small pulse volume with bluish discoloration at the tip of the nose and fingers, and less in the mucous membranes. It is often difficult to differentiate pulmonary from cardiac causes of cyanosis in the newborn. A hyperoxy test may be helpful, whereby an arterial pO2 is measured in room air, which is then compared to a arterial pO2 measured in an FiO2 of about 90%-100% for about 10-15 minutes. Respiratory problems with alveolar hypoventilation usually improve with paO2 measurements well above 100-150 mmHg, whereas in right-to-left shunt cardiac lesions, the improvement in arterial pO2 is very minimal. Echocardiogram and chest x-ray are useful in differentiating these causes.
The above mentioned case represents a diagnostic and management problem. Classifying cyanotic congenital heart defects into those with increased vascularity with an accentuated second heart sound and those with decreased blood flow with a diminished second heart sound, can simplify the differential diagnosis to an extent. Chest x-ray findings and attention to the second heart sound may help. Lesions with increased or normal blood flow with accentuated second heart sounds include transposition of the great vessels, truncus arteriosis, total anomalous pulmonary venous return, single ventricle, single atrium, and hypoplastic left heart. Eisenmenger syndrome also falls into this category, but this is an acquired condition in which a patient with a left-to-right shunt and chronic CHF develops pulmonary hypertension and a subsequent right-to-left shunt. Those lesions with decreased blood flow and diminished second heart sound include tetralogy of Fallot or tetralogy of Fallot-like lesions, pulmonary atresia, tricuspid atresia, and Ebstein's malformation.
Transposition of the great vessels is the most common cyanotic congenital heart disease in the newborn infant (tetralogy of Fallot is more common overall, but many tetralogy of Fallot cases present after the newborn period). Transposition represents 4%-5% of all congenital heart defects (2). The aorta arises from the right ventricle and pulmonary artery from the left ventricle, with the aorta positioned anterior and to the right of the pulmonary artery. It is incompatible with life unless a communication exists between systemic and pulmonary circulation, as the two circulations are in parallel (and independent). During the newborn period, the PDA and patent foramen ovale (PFO) maintain this communication. As the PDA starts to close and the PFO by itself is inadequate in size, the patient develops intense cyanosis, and the patient becomes tachypneic. On auscultation, the second heart sound is greater in intensity, as the aortic valve is anterior. A heart murmur may not be present unless other associated lesions are present. An electrocardiogram may show right ventricular hypertrophy, but this is non-specific since RVH is present in normal newborns. Chest x-ray shows increased pulmonary vascular markings and a narrow mediastinal shadow secondary to a small thymus, sometimes giving the appearance of "egg on side" or "apple on a string" appearance. Echocardiography confirms the diagnosis and delineates the other associated lesions. Inadequate mixing between systemic and pulmonary circuits represents a medical emergency and a prostaglandin E1 infusion which maintains ductus arteriosus patency (to preserve mixing) may be lifesaving, followed by balloon atrial septostomy (Rashkind procedure). Surgical management consists of an arterial switch procedure (aorta and pulmonary artery are anastomosed to the correct ventricle), which is the operation of choice. The atrial switch (atrial baffling) such as Senning or Mustard procedures are no longer done because of the development of later complications. Survival without surgery is unlikely. The arterial switch procedure offers the best prognosis with a mortality of about 5%.
Tetralogy of Fallot constitutes 4%-9% of congenital heart disease and is the most common cyanotic congenital heart disease when considering all age groups together. Tetralogy of Fallot and pulmonary atresia with ventricular septal defect consist of: a) ventricular septal defect, b) pulmonary stenosis, c) overriding of the aorta, and d) right ventricular hypertrophy. Approximately 25% have a right-sided aortic arch, and about 4% have a coronary artery anomaly. The degree of cyanosis depends on the degree of pulmonic outflow obstruction. This is quite variable, from a slight obstruction, to severe obstruction with pulmonary atresia. Pulmonary atresia constitutes about 18% of the children with tetralogy of Fallot (3). The major right ventricular outflow obstruction in tetralogy of Fallot is infundibular stenosis. With mild stenosis, there may be congestive heart failure in infancy, also known as "pink tetralogy of Fallot." As infundibular stenosis increases, progressive cyanosis develops (due to less pulmonary blood flow), and infants and children may develop cyanotic or hypoxic spells, which consist of sudden onset of increased cyanosis, excessive crying, hypoxemia, acidosis, dyspnea, fainting, rarely seizures, and occasionally death if untreated. During these episodes (called "Tet" spells), there is increased right-to-left shunting (with less pulmonary flow), and decreased systemic vascular resistance. Older infants and children may assume a squatting position during playtime or long walks which increases systemic vascular resistance and decreases right to left shunting, increasing their oxygenation.
Clinical examination shows a loud systolic ejection murmur from the right ventricular outflow obstruction at the left sternal border conducted to the upper sternal border towards the suprasternal notch. The second pulmonary sound may be diminished, but the aortic component may be loud, as the aorta is anterior.
The electrocardiogram shows the non-specific right ventricular hypertrophy. Chest x-ray shows decreased pulmonary vascular markings (reduced pulmonary perfusion) and right ventricular hypertrophy with a leftward apex. There is an absence or decreased main pulmonary artery segment, which may give the appearance of a "boot shaped heart." Echocardiography demonstrates a ventricular septal defect with an overriding of the aorta, pulmonic stenosis, right ventricular hypertrophy, and in about 25% of cases, a right aortic arch (i.e., the aorta goes over the right mainstem bronchus instead of the left) is also present. Cardiac catheterization is done in cases in which the anatomy of the defect is not clear on echocardiogram.
Management during the newborn period consists of administration of prostaglandin E1 when the infant is markedly cyanotic and pulmonary blood flow is ductus dependent. This is followed by a systemic artery to pulmonary artery shunt (Blalock-Taussig shunt). Treatment of hypercyanotic spells is directed towards improving pulmonary blood flow. These include oxygen, knee/chest position, morphine, intravenous fluids, sodium bicarbonate, propranolol (beta-blocker), or increasing systemic vascular resistance by administration of drugs, such as phenylephrine. Total surgical correction of the defect is performed under cardiopulmonary bypass, and it can now be performed in young infants from 3-6 months of age or earlier (4). Prognosis is good with total correction. However, the majority of them still have residual defects and some of them may need reoperation and life long medical follow up.
Truncus arteriosus consists of a single arterial vessel arising from the heart, positioned over a ventricular septal defect, supplying systemic, coronary and pulmonary circulations. It accounts for about 1%-4% of the congenital heart defects. Associated anomalies are common, such as DiGeorge syndrome. Symptomatology depends upon the amount of pulmonary blood flow. With increased blood flow, symptoms of congestive heart failure such as tachypnea, cyanosis, retractions, etc., develop. There may be a systolic murmur at the left sternal border or an apical aortic ejection click. A diastolic murmur of truncal insufficiency may be heard along the left sternal border. The electrocardiogram may show right or left or combined ventricular hypertrophy. Chest x-ray shows an enlarged heart and increased pulmonary vasculature. There may be a right aortic arch (25%). The echocardiogram shows a truncal root overriding VSD, and pulmonary arteries arising from the trunk. Cardiac catheterization may be indicated when the anatomic features are not clear on echocardiography. Management consists of treatment of congestive heart failure followed by surgery. Surgical correction consists of closure of the VSD, separation of the pulmonary arteries from the trunk and anastomosing them through a conduit from the right ventricle (Rastelli procedure). The prognosis is poor in untreated cases. After surgery, they will need long term follow up as they will eventually need to have the conduit graft replaced.
Total anomalous pulmonary venous return (TAPVR) occurs in about 1%-2% of patients with congential heart disease. There are four types of TAPVR causing left-to-right shunt: Supracardiac, cardiac, infracardiac, and mixed. In the supracardiac type, pulmonary veins join to form a common vein which drains into the SVC. In the cardiac type, the common pulmonary veins drain into the right atrium directly or via the coronary sinus. In the infracardiac type, the common pulmonary vein courses downward through the diaphragm into the portal vein, which then drains via hepatic veins into the inferior vena cava.
Anomalous pulmonary venous return could be total or partial. An atrial septal defect is necessary for survival, since the oxygenated blood (from the pulmonary veins) must somehow reach the left side of the heart. Symptomatology depends on the amount of mixing and whether or not the pulmonary veins are obstructed. Cyanosis and signs and symptoms of congestive heart failure develop and progress rapidly. There may be a grade 2/6 systolic ejection flow murmur heard along the left sternal border, or it may be absent. The electrocardiogram shows right ventricular hypertrophy and right atrial hypertrophy. Chest x-ray shows increased pulmonary vascular markings or even edema, and the heart may be normal in size or minimally enlarged. The echocardiogram may show right ventricular volume overload, and a color-flow Doppler study may help in locating the common pulmonary venous channel and its drainage. If the resolution is poor, cardiac catheterization and angiocardiography may help in delineating the anomaly further. Treatment consists of correction of the defect by surgery. If surgery is delayed and there is inadequate mixing, palliative balloon septostomy may be performed. Prognosis is good after surgery. Prognosis is poor in neonates with obstructive TAPVR. Long term follow up is needed to assess restenosis and late arrhythmias.
Tricuspid atresia consists of an absence or atretic tricuspid valve and a hypoplastic right ventricle. Blood from the right atrium enters the left atrium through an atrial septal defect or foramen ovale. They may have associated lesions such as TGA, VSD, PDA, right aortic arch, pulmonic stenosis or atresia. Communication between right and left circulation is essential to sustain life. Symptomatology depends on the amount of pulmonary blood flow. In the absence of a VSD, as the PDA closes, patients may develop intense cyanosis, tachypnea and tachycardia. The electrocardiogram usually shows left axis deviation (very unlike the RVH seen in normal newborns) and right atrial hypertrophy and left-ventricular hypertrophy. Chest x-ray may show increased or decreased pulmonary blood flow depending on the shunt and a normal or mildly increased heart size. Echocardiography usually delineates these abnormalities and very rarely a cardiac catheterization may be needed. Prostaglandin E1 may be life saving in infants with low oxygen saturation with duct dependent pulmonary blood flow. This is followed by a modified Blalock Taussig anastomosis. If the interatrial communication is narrow (small PFO/ASD) then a balloon or blade atrial septostomy is performed (5). Surgical correction initially consists of a bilateral Glenn procedure (superior vena cava to right pulmonary artery shunt) followed by an inferior vena cava anastomosis to the right pulmonary artery through an intra or extra cardiac baffle (modified Fontan procedure). Prognosis is good after surgery but patients will need multiple surgeries with associated morbidity such as pleural effusion, ascites, arrhythmia and mortality.
Ebstein anomaly is characterized by downward displacement of the septal and posterior leaflets of the tricuspid valve which are attached to the right ventricular septum. The anterior leaflet is elongated and is displaced downward within the right ventricular cavity causing "atrialization of the right ventricle" (i.e., the right ventricle is small). There is usually a PFO or an ASD or PS (pulmonic stenosis). Cyanosis depends up on the right to left shunt. Auscultation may reveal a triple or quadruple gallop rhythm and a split second heart sound. A pansystolic murmur of tricuspid insufficiency or an ejection murmur of PS may be heard. The electrocardiogram shows a right bundle branch block pattern, giant P waves and sometimes first degree AV block or WPW syndrome (delta wave). Chest x-ray shows a huge right atrium and gross cardiomegaly. Echocardiography reveals the lesions of Ebstein anomaly and only rarely is cardiac catheterization needed. Treatment is mainly palliative and there are no good surgical options. In older patients, tricuspid annuloplasty and rarely tricuspid valve replacement may be performed. Prognosis depends on the severity of the lesion. Prognosis is good with mild lesions and poor with severe lesions with other associated anomalies/malformations.
Hypoplastic left heart syndrome consists of a combination of mitral stenosis or atresia, severe aortic stenosis or atresia, and a small left ventricle. Systemic circulation depends on the patency of the ductus. These infants may appear reasonably well at birth until either the pulmonary vascular resistance drops or the PDA closes. They then present with shock, variable cyanosis, poor pulses, poor perfusion and CHF. A systolic murmur may or may not be present. Chest x-ray shows increase vascularity and EKG may show RV hypertrophy. Echocardiography is diagnostic. Early management consists of administration of PGE1 and treatment of CHF. Surgery consists the Norwood surgical procedure and a few centers perform cardiac transplantation for this lesion. Prognosis is guarded.
Questions
1. A two day old cyanotic infant with a grade 3/6 ejection systolic murmur is noted to have decreased pulmonary vascular markings on chest x-ray and left axis deviation on EKG. The most likely diagnosis is:
. . . . . a. Tetralogy of Fallot
. . . . . b. Transposition of Great Vessels
. . . . . c. Truncus Arteriosus
. . . . . d. Tricuspid Atresia
2. A 2 year old infant is noted to have mild cyanosis who assumes a squatting position during long walking. He is noted to have increasing fussiness followed by increasing cyanosis, limpness and unresponsiveness. The most likely underlying lesion is:
. . . . . a. Hypoplastic left heart
. . . . . b. Transposition of the Great Vessels
. . . . . c. Anomalous Pulmonary Venous Return
. . . . . d. Tetralogy of Fallot
. . . . . e. Aspiration with obstruction to air passages
3. An infant with a marked cyanotic congenital heart defect with decreased pulmonary vascularity should be treated with:
. . . . . a. Digoxin
. . . . . b. Indomethacin
. . . . . c. Prostaglandin E1
. . . . . d. Epinephrine
4. Cyanosis is produced by the presence of deoxygenated hemoglobin of at least:
. . . . . a. 1-2 gm/dL
. . . . . b. 3-5 gm/dL
. . . . . c. 6-8 gm/dL
. . . . . d. 9-10 gm/dL
5. A "tet spell" or "blue" spell of tetralogy of Fallot is treated with all of the following except:
. . . . . a. oxygen
. . . . . b. knee chest position
. . . . . c. morphine
. . . . . d. digoxin
. . . . . e. propranolol
. . . . . f. phenylephrine
. . . . . g. sodium bicarbonate
6. Pulmonary vascularity is increased in all of the following except:
. . . . . a. TAPVR
. . . . . b. Tricuspid atresia
. . . . . c. TGV
. . . . . d. Hypoplastic left heart
7. Pulmonary vascularity is decreased in all of the following except:
. . . . . a. Tetralogy of Fallot
. . . . . b. Pulmonary atresia
. . . . . c. TAPVR
. . . . . d. Tricuspid atresia
References
1. Green M. Chapter 48. Cyanosis. In: Green M (ed). Pediatric Diagnosis. 1998, Philadelphia: W.B. Saunders, pp. 389-395.
2. Hoffman JIE, Christianson R. Congenital heart disease in a cohort of 19,502 births with long-term follow-up. Ann J Cardiol 1978;42:461.
3. Flyer DC. Chapter 30. Tetralogy of Fallot. In: Flyer DC (ed). Nadas' Pediatric Cardiology. 1992, Hanley & Belfus, Inc., pp. 471-491.
4. Reddy VM, Liddicoat JR, Hanley FL. Midline one-stage complete unifocalization and repair of pulmonary atresia with ventricular septal defect and major pulmonary collateral. J Thoracic Cardiovasc Surg 1995;109:832.
5. Rao SP. Chapter 50-Tricuspid atresia. In: Moller JH, Hoffman JIE (eds). Pediatric Cardiovascular Medicine, 2000. New York: Churchill & Livingston, pp. 421-441.
6. Waldman JF, Wernly JA. Cyanotic congenital heart-disease with decreased pulmonary blood flow in children (cardiology). In: Berger S (ed). Pediatr Clin North Am 1999;46(2):385-404.
Answers to questions
1.d, 2.d, 3.c, 4.b, 5.d, 6.b, 7.c