Presence of cyanosis means deoxygenated blood reaching the systemic circulation bypassing the lungs i.e., right to left shunt. Uniform cyanosis means that right to left shunt is at the level of either atrium or ventricle or ascending aorta. Differential cyanosis means right to left shunt through a patent ductus arteriosus.
CCHD with Decreased Pulmonary Blood Flow ( ~ P B F )The decreased pulmonary blood flow may be due to pulmonary stenosis (PS) or
pulmonary arterial hypertension (PAH).
PS with VSD
This group is also known as Tetralogy of Fallot's physiology. The classic example is Fallot's tetralogy characterized by: (1) Severe PS (Right ventricular outflow tract obstruction) both sub-valvular and valvular, (2) Large unrestrictive VSD, (3) Overriding of Aoi-ta, and (4) Right ventricular hypertrophy.
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| Pulmonary stenosis wit11 VSD |
Pathophysiology
The PS causes concentric hypertrophy of riglit ventricle without enlargement.The right ventricular pressure are equal to or higher than lefl ventricular / aortic systolic pressure to maintain forward blood flow to lungs. Hence an increase in PS results in right to left shunt across large unrestrictive VSD, which is non- turbulent and silent on auscultation. The puln~onary slenosis results in an ejection systolic murmur (ESM), the intensity of which is directly proportional to pulmonary blood flow across the valve. Cyanosis is thus directly proporlional and ESM is inversely proportional to the seveiily of PS. The PS causes a delayed and soft pulmonary coinponent of second sound, which is inaudible in most patients. Hence on bedside examinalion second sound is single since only aortic component is audible. The VSD, by decompressing the right ventricle,limits the severity of right ventricular hypertrophy unlike in pure PS, The left parasternal impulse is, therefore, mild and generally will~out thrill. The hypercyanotic spells (also known as 'Cyanotic spells' or 'tet' spells):
These are peculiar to this group only. It occurs in young infants (usually after two months and rarely after two years), It consists of rapid and deep breathing (Hyperpnoea), worsening of cyanosis, and decrease or disappearance of heart murmur. Any event such as crying, defecation, or increased physical activity that suddenly lowers the systemic venous resistance (SVR) inay initiate the spell by establishing a vicious cycle of hypoxic spells. The sudden onset of tachycardia or hypovolemia can also cause the spells.
Acyanotic /'Pink' TOF.: Depending on seveiity of RVOT obstruction, the magnitude and the direction of the VSD shunt vary. With mild stenosis PS a small to moderate, left to right VSD shunt is present. The systolic pressures are equal in Right Ventricle (RV), Left Ventricle (LV) and Aorta due to large unrestrictive VSD. The PA pressure is slightly elevated and has a moderate pressure gradient between the PA and RV. The heart size and pulmonary 'vascularity is slight to moderately increased.
Differential Diagnosis
1) Fallot's tetrology.
2) Transposition of great arteries with I&D and PS.
3) Tricuspid Atresia with VSD and PS.
4) Single ventricle / Very large VSD, acting as single chamber with PS.
5) Double Outlet Right ventricle (both Aorta and Pulmonary artery wising from right ventricle) with PS .
6) . Corrected Transposition of Great arteries wit11 VSD and PS.
Clinical Features
Symptoms
A heart murmur ,is audible. at birth. Cyanosis is present from early infancy, usually .from neonatal period. Normal birth weight and normal weight gain in easly infancy. Wo Hyper cyanotic spells present. Wo dyspnea on exerlion present. H/o squatting present in older children.
These are peculiar to this group only. It occurs in young infants (usually after two months and rarely after two years), It consists of rapid and deep breathing (Hyperpnoea), worsening of cyanosis, and decrease or disappearance of heart murmur. Any event such as crying, defecation, or increased physical activity that suddenly lowers the systemic venous resistance (SVR) inay initiate the spell by establishing a vicious cycle of hypoxic spells. The sudden onset of tachycardia or hypovolemia can also cause the spells.
Acyanotic /'Pink' TOF.: Depending on seveiity of RVOT obstruction, the magnitude and the direction of the VSD shunt vary. With mild stenosis PS a small to moderate, left to right VSD shunt is present. The systolic pressures are equal in Right Ventricle (RV), Left Ventricle (LV) and Aorta due to large unrestrictive VSD. The PA pressure is slightly elevated and has a moderate pressure gradient between the PA and RV. The heart size and pulmonary 'vascularity is slight to moderately increased.
Differential Diagnosis
1) Fallot's tetrology.
2) Transposition of great arteries with I&D and PS.
3) Tricuspid Atresia with VSD and PS.
4) Single ventricle / Very large VSD, acting as single chamber with PS.
5) Double Outlet Right ventricle (both Aorta and Pulmonary artery wising from right ventricle) with PS .
6) . Corrected Transposition of Great arteries wit11 VSD and PS.
Clinical Features
Symptoms
A heart murmur ,is audible. at birth. Cyanosis is present from early infancy, usually .from neonatal period. Normal birth weight and normal weight gain in easly infancy. Wo Hyper cyanotic spells present. Wo dyspnea on exerlion present. H/o squatting present in older children.
Signs
Cyanosis,, clubbing, polycythemia and normal heart size on palpation. Mild parasternal impulse'usually~without systolic thrill. Single second sound.(widely split and inaudible pulmonary component). Loud Ejection systolic murmur(grade 3-5/6),'heasd best at middle and upper left parasternal border. Diastolic period is very clear, no S3, S4 or diastolic murmur.
PS With Atrial Right To Left shunt (Intact Ivs)
This group of patients has cyanosis due to light to left shunt at atrial level. The diminution in PA pressure and PBF may or may not be due to PS 'per se. There is triad of cyanosis, cardiomegaly, and ischemic lung fields in chest X-ray. There are only two conditions:
1) Severelcritical pure Pulmonary stenosis with failing heart.
2) Ebstein's anomaly of Tricuspid valve with PS.
Clinical Features
Cardiomegaly, Parasternal impulse, Single audible S2; P2 late and soft, S3, S4 present, Pulmonary ESM present. The duration ol' ESM is directly proportional to severity of PS. Ejection click may be audible. Ti-i-icuspid regurgitation murmur present. Post-stenotic dilation of PA on Chest X-ray.
Cyanosis,, clubbing, polycythemia and normal heart size on palpation. Mild parasternal impulse'usually~without systolic thrill. Single second sound.(widely split and inaudible pulmonary component). Loud Ejection systolic murmur(grade 3-5/6),'heasd best at middle and upper left parasternal border. Diastolic period is very clear, no S3, S4 or diastolic murmur.
PS With Atrial Right To Left shunt (Intact Ivs)
This group of patients has cyanosis due to light to left shunt at atrial level. The diminution in PA pressure and PBF may or may not be due to PS 'per se. There is triad of cyanosis, cardiomegaly, and ischemic lung fields in chest X-ray. There are only two conditions:
1) Severelcritical pure Pulmonary stenosis with failing heart.
2) Ebstein's anomaly of Tricuspid valve with PS.
Clinical Features
Cardiomegaly, Parasternal impulse, Single audible S2; P2 late and soft, S3, S4 present, Pulmonary ESM present. The duration ol' ESM is directly proportional to severity of PS. Ejection click may be audible. Ti-i-icuspid regurgitation murmur present. Post-stenotic dilation of PA on Chest X-ray.
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| Ps with aterial RT l o Left septunl |
Pulmonary Atresia With Intact Ventricular Septum
The direct commuilication between RV and PA is absent. The PDA is major source of blood flow to lungs From Aorta. The systemic venous return lo RA must go to LA through ASDI PFO. The RV is i~sually hypoplastic. Syslenlic venous blood mixes with pulmonary venous i.eturn in LA and goes into LV to supply body and lungs. The volume overload is on LA and LV, which is proportional to PBE The infant is usually cyanotic, and S2 is single due to single semilunar valve to close. The hypoplasia of RV and LA and LV overload produces LVH in ECG.
Transposition of the Great Arteries
Abnormal origin of the great artesies from the vent]-icular complex. Pulmoiiary Artery arises from the moipl~ological left ventricle and the Aorta arises from the morphological right ventricle.
Transposition can occur in the presence of appropriate or inappropriate atno-ventricular connections, and are accordingly classified as corr~plete tmrz~po~sition and physiologically corrected tru~zsl~o~sition.Complete transposition of the great arteries (dTGA) : The atria and ventricles are connected appropriately i.e., the right atrium drains into the righl ventricle and left atrium drains into the left ventricle.So, this complex is also termed as 'atrio-ventricular concorclance with ventriculo-arterial discordance'.
Physiologically corrected Pansposition of the great arteries (ZTGA): Atrio-ventricular connections are also inappropriate.So, this complex is described as 'atrio ventricular discordance with ventriculo-arterial discordance'.Complete transposition of great arteries Lethal, relatively frequent malformation. Without treatment, it results in 30 per cent mortality within the first week of life, 50 per cent within the first month, 70 per cent within six month and 90 per cent mortality within the first year of life
Incidence: Complete transposition of the great arteries is the most common cyanotic congenital cardiac lesion - 5 per cent -7 per cent of all congenital cardiac malformations. Total incidence is reported to be between 0.2/1000 to 0.33/1000 live births. It occurs with a strong male predilection (60 per cent -70 per cent ).Association with genetic syndromes is rare; incidence of familial occurrence is low.
Anatomy and Embryology
Transposition of great arteries results from abnormal septation of the Aortopulmonary trunk during embryogenesis so that tlle Pulmonary trunk arises from the left and Aorta arises from the right vetih-icle.
The direct commuilication between RV and PA is absent. The PDA is major source of blood flow to lungs From Aorta. The systemic venous return lo RA must go to LA through ASDI PFO. The RV is i~sually hypoplastic. Syslenlic venous blood mixes with pulmonary venous i.eturn in LA and goes into LV to supply body and lungs. The volume overload is on LA and LV, which is proportional to PBE The infant is usually cyanotic, and S2 is single due to single semilunar valve to close. The hypoplasia of RV and LA and LV overload produces LVH in ECG.
Transposition of the Great Arteries
Abnormal origin of the great artesies from the vent]-icular complex. Pulmoiiary Artery arises from the moipl~ological left ventricle and the Aorta arises from the morphological right ventricle.
Transposition can occur in the presence of appropriate or inappropriate atno-ventricular connections, and are accordingly classified as corr~plete tmrz~po~sition and physiologically corrected tru~zsl~o~sition.Complete transposition of the great arteries (dTGA) : The atria and ventricles are connected appropriately i.e., the right atrium drains into the righl ventricle and left atrium drains into the left ventricle.So, this complex is also termed as 'atrio-ventricular concorclance with ventriculo-arterial discordance'.
Physiologically corrected Pansposition of the great arteries (ZTGA): Atrio-ventricular connections are also inappropriate.So, this complex is described as 'atrio ventricular discordance with ventriculo-arterial discordance'.Complete transposition of great arteries Lethal, relatively frequent malformation. Without treatment, it results in 30 per cent mortality within the first week of life, 50 per cent within the first month, 70 per cent within six month and 90 per cent mortality within the first year of life
Incidence: Complete transposition of the great arteries is the most common cyanotic congenital cardiac lesion - 5 per cent -7 per cent of all congenital cardiac malformations. Total incidence is reported to be between 0.2/1000 to 0.33/1000 live births. It occurs with a strong male predilection (60 per cent -70 per cent ).Association with genetic syndromes is rare; incidence of familial occurrence is low.
Anatomy and Embryology
Transposition of great arteries results from abnormal septation of the Aortopulmonary trunk during embryogenesis so that tlle Pulmonary trunk arises from the left and Aorta arises from the right vetih-icle.
Aortic valve is placed more anteriorly, superiorly and to the right, relative to the Pulmonary valve.
The spatial relationship of the great vessels may be variable.
Physiology and Hemodynatnics
Normally, in the post-natal circulation the pulmonay and aortic circuits are in series so that the deoxygenated blood coming into the right ventricle is oxygenated in the lungs and flows back into the systemic circulation. In transposition of great arteries, the two circuits lun in parallel, with the deoxygenated blood recirculating in the systemic circuit and oxygenated blood recirculating in the pulmonary circuit.
Survival depends on inter-circulatory connections between these two circuits,which may be at the level of the atria (atrial septal defects), ventricles (ventricular septa1 defects) or the great arteries (Patent ductils arteriosis or bronchopulmonary collaterals). The presence and adequacy of these connections determine the degree of mixing of the desaturated systemic blood with the oxygenated pulmonary blood,
which is essential for survival. The other factor which determines the natural history is the limitation to pulmonary blood flow which may occur as a result of obstruction to the left ventricular outflow tract or due to development of pulmonary vascular obstructive disease.Thus, complete transposition of great arteries is further classified as:
1)Transposition of great arteries with intact ventricular septum (or small VSD): There is usually inadequate mixing, which occurs at the level of a patent foramen ovale or a patent ductus arteriosus. (Less commonly, there may be an ahial septal defect of adequate size).Inadequate intercirculatory mixing results in early presentation in the immediate neonatal period with cyanosis, which may initially be mild but rapidly progresses in prominence. As the ductus arteriosus constricts, the intercirculatory mixing further decreases and there is onset of features of severe systemic hypoxemia and acidosis, within the first week of life.
Most of these babies are good-weight babies, otl~erwise well-preserved and apart from the cyanosis physical examination findings may be unrewarding.S l is noilnal and S2 may be single (due to antero-posterior relationship of the great arteiies which pushed the pulmonary artery behind the aorta).There may an ejection systolic murmur usually soft, less than grade216 which lnay represent a functional munnur produced by increased flow across the left ventiicular outflow, or a closing PDA.
Persistence of a large PDA may result in mildel cyanosis and more proininent tachypnea, but classical signs of PDA like continuous murmur and bounding peripheral pulses may be absent in >SO per cent of these patients. Prompt diagnosis and emergent management of transposition of great arteries1 intact ventricular septum is of critical importance as TGAIIVS is a lethal combination of defects.
The spatial relationship of the great vessels may be variable.
Physiology and Hemodynatnics
Normally, in the post-natal circulation the pulmonay and aortic circuits are in series so that the deoxygenated blood coming into the right ventricle is oxygenated in the lungs and flows back into the systemic circulation. In transposition of great arteries, the two circuits lun in parallel, with the deoxygenated blood recirculating in the systemic circuit and oxygenated blood recirculating in the pulmonary circuit.
Survival depends on inter-circulatory connections between these two circuits,which may be at the level of the atria (atrial septal defects), ventricles (ventricular septa1 defects) or the great arteries (Patent ductils arteriosis or bronchopulmonary collaterals). The presence and adequacy of these connections determine the degree of mixing of the desaturated systemic blood with the oxygenated pulmonary blood,
which is essential for survival. The other factor which determines the natural history is the limitation to pulmonary blood flow which may occur as a result of obstruction to the left ventricular outflow tract or due to development of pulmonary vascular obstructive disease.Thus, complete transposition of great arteries is further classified as:
1)Transposition of great arteries with intact ventricular septum (or small VSD): There is usually inadequate mixing, which occurs at the level of a patent foramen ovale or a patent ductus arteriosus. (Less commonly, there may be an ahial septal defect of adequate size).Inadequate intercirculatory mixing results in early presentation in the immediate neonatal period with cyanosis, which may initially be mild but rapidly progresses in prominence. As the ductus arteriosus constricts, the intercirculatory mixing further decreases and there is onset of features of severe systemic hypoxemia and acidosis, within the first week of life.
Most of these babies are good-weight babies, otl~erwise well-preserved and apart from the cyanosis physical examination findings may be unrewarding.S l is noilnal and S2 may be single (due to antero-posterior relationship of the great arteiies which pushed the pulmonary artery behind the aorta).There may an ejection systolic murmur usually soft, less than grade216 which lnay represent a functional munnur produced by increased flow across the left ventiicular outflow, or a closing PDA.
Persistence of a large PDA may result in mildel cyanosis and more proininent tachypnea, but classical signs of PDA like continuous murmur and bounding peripheral pulses may be absent in >SO per cent of these patients. Prompt diagnosis and emergent management of transposition of great arteries1 intact ventricular septum is of critical importance as TGAIIVS is a lethal combination of defects.
2).Transposition of great arteries with large ve~ztricular septal defect: Usually the intercicculatoiy shunt is large resulting in good mixing. As a result the neonate may not initially manifest any signs or symptoms of heart disease.Mild cyanosis may be noted during crying1straining.A~ the pulnloilary vascular resistance falls, the shunting froin light ventricle to left ventricle increases, directing more blood flow into the 1ungs.This in turn results in greater venous retuin into the left atrium and a proportionate increase in the left to right shunt across the inter-atrial communication (PFO or ASD).Reshictive inter-atrial communication results in the child becoming symptomatic by ten to fifteen days of life with congestive cardiac failure and pullnonary venous congestion.Classically, TGA /large VSD presents with CHF between 2-6 weeks of 1ife.Tachypnea and tachycardia become prominent, narrow-split S2 with loud P2 may appear, prominent grade 316-416 pansystolic murmul; S3 and mid-diastolic rumble and gallop rhythm may
become appreciable.
3)Transposition of great arteries with VSD with restricted pulmonary blood flow: Restriction to pulmonary blood flow may occur as a result of dynamic obstruction due to bulging of the interventricular septum into the LV outflow tract. Less commonly, the obstruction may be due to an obstructing sub-valvar fibrous shelf, small Pulmonary Valve annulus or abnormal mitral valve attachment to the outflow tract. These patients present with features of decreased pulmonary blood flow, similar to a neonate with Fallot's Tetralogy,
with extreme cyanosis from birth.
become appreciable.
3)Transposition of great arteries with VSD with restricted pulmonary blood flow: Restriction to pulmonary blood flow may occur as a result of dynamic obstruction due to bulging of the interventricular septum into the LV outflow tract. Less commonly, the obstruction may be due to an obstructing sub-valvar fibrous shelf, small Pulmonary Valve annulus or abnormal mitral valve attachment to the outflow tract. These patients present with features of decreased pulmonary blood flow, similar to a neonate with Fallot's Tetralogy,
with extreme cyanosis from birth.
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