Congenital Heart Disease PDF

The cardiovascular system Congenital Heart Disease Prepared by Dr. shaker Ahmed Alsaggaf  Objectives 1. To outline the epidemiology of C.H.D. 2. To compare antenatal and post natal circulations. 3. To know the etiology and classification of CHD 4. To understand the clinical...

The cardiovascular system Congenital Heart Disease Prepared by Dr. shaker Ahmed Alsaggaf  Objectives 1. To outline the epidemiology of C.H.D. 2. To compare antenatal and post natal circulations. 3. To know the etiology and classification of CHD 4. To understand the clinical features and diagnosis of CHD 5. How to treat patients with CHD.  Epidemiology Heart disease in children is mostly congenital. 8 per 1000 live-born infants have significant cardiac malformations About 10% of stillborn infants have a cardiac anomaly.  Etiology of congenital heart disease Little is known about the etiology C.H.D. A small proportion are related to external teratogens About 8% are associated with major chromosomal abnormalities. Polygenic abnormalities probably explain why a previous child with congenital heart disease doubles the risk for subsequent children and the risk is still higher if either parent has congenital heart disease. 1.Multifactorial inheritance 2-4%. 2. Medications or alcohol or drug abuse during pregnancy (anticonvulsant, warfarin, cocaine,). 3. Maternal viral infection, such as rubella (German measles) in the first trimester of pregnancy. 4. Maternal diseases (diabetes mellitus, SLE) 5. Genetic or chromosomal abnormalities such as Down syndrome, Turner syndrome, Noonan, William, and Marfan syndrome.  Causes of congenital heart disease Causes congenital heart disease Maternal rubella Peripheral pulmonary stenosis infection and PDA Maternal SLE Complete heart block of the baby Maternal diabetes Overall incidence increases specially asymmetrical septal hypertrophy Maternal warfarin pulmonary valve stenosis and therapy PDA Down’s syndrome Atrioventricular septal defect Turner’s syndrome Coarctation of aorta and aortic valve stenosis  Circulatory changes at birth In the fetus, the left atrial pressure is low, as relatively little blood returns from the lungs. The pressure in the right atrium is higher than in the left, as it receives all the systemic venous return including blood from the placenta. The ductus arteriosus shifts the blood from the pulmonary artery to the aorta. The flap valve of the foramen ovale is held open, blood flows across the atrial septum into the left atrium and then into the left ventricle, which in turn pumps it to the upper body.  With the first breaths, resistance to pulmonary blood flow falls and the volume of blood flowing through the lungs increases sixfold. This results in a rise in the left atrial pressure. Meanwhile, the volume of blood returning to the right atrium falls as the placenta is excluded from the circulation. The change in the pressure difference causes the flap valve of the foramen ovale to be closed. The ductus arteriosus will normally close within the first few hours or days.  Presentation Congenital heart disease could present in any way of the followings: 1-Antenatal cardiac ultrasound diagnosis 2-Detection of a heart murmur 3-Cyanosis 4-Heart failure 5-Shock.  Antenatal diagnosis Fetal anomaly scan is performed between 18 and 20 weeks' gestation. If an abnormality is detected, detailed fetal echocardiography is performed by a paediatric cardiologist, who also checks any fetus at increased risk, e.g. where Down's syndrome is suspected, where the parents have had a previous child with heart disease or where the mother has C.H.D. The continuation of pregnancy and delivery then planned.  Classification of CHD Non-cyanotic (Acyanotic): Ventricular septal defect (VSD), Atrial septal defect (ASD), Patent ductus arteriosus (PDA), Aortic stenosis, Pulmonic stenosis, Coarctation of the aorta, Atrioventricular canal (endocardial cushion defect) Cyanotic: Tetralogy of Fallot , Transposition of the great vessels , Tricuspid atresia ,Total anomalous pulmonary venous return ,Truncus arteriosus , Hypoplastic left heart , Hypoplastic right heart , Ebstein's anomaly. Cyanotic heart disease Pulmonary blood flow Pulmonary blood flow  Pulmonary blood flow 1)TOF 2)Pulmonary atresia 3)Tricusped atresia Pulmonary blood flow 1)Transposition of great arteries 2)Truncus arteriosus 3)Single ventricle 4) Hypoplastic Lt heart syndrome The most common anomalies Non-cyanotic (Acyanotic)CHD VENTRICULAR SEPTAL DEFECTVSD  VENTRICULAR SEPTAL DEFECT Definition VSD is a developmental defect of the interventricular septum whereby a communication exists between the cavities of the two ventricles. Classifications of subtypes 1. Perimembranous (infracristal) VSDs: They are the most common types of VSDs and account for 67- 80% of defects 2. Supracristal defects comprise 5-8% of isolated VSDs 3. Muscular VSDs (trabecular) Frequency: VSD is the most common congenital cardiac defect and account for 25- 30 % of all lesions. Sex: VSDs are slightly more common in females; 44% occur in males, and 56% occur in females. VENTRICULAR SEPTAL DEFECT o Pathophysiology:- o The amount of flow crossing a VSD o depends on the size of the defect and the pulmonary vascular resistance. o Even large VSDs are not symptomatic at birth because the pulmonary vascular resistance is normally elevated at this time. o As the pulmonary vascular resistance normally decreases over the first 6to 8 Weeks of life, however, the amount of shunt increases, and symptoms may develop.  When a small communication is present (usually 1.0 cm2), right and left ventricular pressure is equalized. In these defects, the direction of shunting and shunt magnitude are determined by the ratio of pulmonary to systemic vascular resistance  Chronic left-to-right shunt causes gradual ↑pulmonary vascular pressure, ↓gradient between ventricles, and ↓ shunt volume, and finally pulmonary hypertension and right to left shunt, a condition called Eisenmengers’s syndrome  Clinical manifestations Symptoms and physical findings relate to the size of the defect and the magnitude of the left-to-right shunt. o Small VSDs, with little shunt, are often asymptomatic, other than a loud murmur. o Moderate to large VSDs result in pulmonary overcirculation and CHF, presenting as Tachypnea with increased respiratory effort fatigue and diaphoresis with feedings, and poor growth. o a detailed feeding history is important. o Eisenmenger syndrome (VSD with severe pulmonary vascularobstruction): Symptoms include exertional dyspnea, chest pain, syncope, and hemoptysis. o Cyanosis due to right to left shunting. o  The typical physical finding with a VSD is a pansystolic murmur usually heard best at the lower left sternal border. There may be a thrill in the same region.  Investigations Electrocardiography o With a small VSD, the ECG is normal. o With a moderate VSD, left ventricular hypertrophy (LVH) and occasional left atrial hypertrophy (LAH) may be seen. o With a large defect, the ECG shows biventricular hypertrophy (BVH) with or without LAH. o If pulmonary vascular obstructive disease develops, the ECG shows RVH only. X-ray Studies With large VSD cardiomegaly of varying degrees is present and involves the LA, left ventricle (LV), and sometimes RV. Pulmonary vascular markings increase. The degree of cardiomegaly and the increase in pulmonary vascular markings directly relate to the magnitude of the Lt to Rt shunt.  CXR of 6 years old child PA and lateral views showing cardiac enlargement and increased pulmonary markings  Echocardiography. Two-dimensional and Doppler echo studies can identify the number, size, and exact location of the defect; estimate PA pressure; identify other associated defects; and estimate the magnitude of the shunt.  NATURAL HISTORY o Spontaneous closure occurs in 30% to 40% of patients with membranous VSDs and muscular VSDs during the first 6 months of life. It occurs more frequently in small defects.The vast majority of defects that close do so before the age of 4 yr o CHF develops in infants with large VSDs but usually not until 6 to 8 weeks of age. o Pulmonary vascular obstructive disease may begin to develop as early as 6 to 12 months of age in patients with large VSDs, but the resulting right-to-left shunt usually does not develop until the teenage years. o Repeated chest infections and arrhythmias. o Infective endocarditis rarely occurs.  Treatment Children with small VSDs are asymptomatic and have excellent long-term prognoses. Neither medical therapy nor surgical therapy is indicated. Antibiotic prophylaxis against endocarditis should be provided at the time of dental or surgical procedures likely to produce bacteremia. In children with moderate or large VSDs: Furosemide, captopril, and digoxin, is indicated for symptomatic congestive heart failure. Furosemide in a dosage of 1-3 mg/kg/d in 2 or 3 divided doses is used. Captopril in a dosage of 0.1-0.3 mg/kg 3 times daily can be useful to reduce systemic afterload. Digoxin in a dosage of 0.005-0.01 mg/kg/day may be indicated if diuresis and afterload reduction do not relieve symptoms adequately. Indications for surgical repair o Uncontrolled congestive heart failure. o Surgical repair is indicated in older asymptomatic children with normal pulmonary pressure if pulmonary to systemic flow is greater than 2:1. o Supracristal VSD: Early repair may prevent progression of aortic insufficiency. Complications  Most VSDs are closed in surgery, but some VSDs, especially muscular defects, can be closed with devices placed at cardiac catheterization. Complications: Eisenmenger complex. Secondary aortic insufficiency Right ventricular outflow tract obstruction: Subaortic obstruction. Infective endocarditis Prognosis: Children with small VSDs are asymptomatic and have excellent long term prognoses. Closure is earlier and most frequently observed in muscular defects(80%) followed by perimembranous defects (35-40%) in the first fewyears of life. ATRIAL SEPTAL DEFECT  ATRIAL SEPTAL DEFECT Types of atrial septal defects: 1. Ostium secundum defect, the most common type. 2. Ostium Primum defect.. ostium primum defects are virtually always associated with a cleft in the anterior mitralvalve leaflet 3. Sinus venosus 4. Coronary sinus ASD occur in approximately 7% of these children with CHD , The female to male ratio is approximately 2:1. History Infants and young children with ASDs typically are asymptomatic. Most ASDs are diagnosed after a suspicious murmur is detected during a routine health- maintenance examination. Physical A midsystolic pulmonary ejection murmur. Fixed splitting of S2. A large shunt increases flow across the tricuspid valve, and the patient with ASD is likely to have a middiastolic rumble at the left sternal border. Diagnosis Plain radiographic findings in ASD are nonspecific but include right atrial and right ventricular dilatation, pulmonary artery dilatation, and increased pulmonary vascular markings. Echocardiography ECG: right-axis deviation, right ventricular hypertrophy, Left axis deviation suggests an ostium primum-type ASD All types of ASD can result in prolonged PR intervals. This prolongation of internodal conduction may be related to the increased size of the atrium and a long internodal distance. Cardiac catheterization is rarely necessary in the preoperative evaluation of a child with ASD. TREATMENT Medical therapy is of no benefit in children with asymptomatic ASDs. 1. Surgery is ideally performed in children aged 2-4 years, even in asymptomatic patients to prevent adult hood complications like atrial arrhythmias. 2. Closure through cardiac catheterizations. Prognosis The prognosis for a child with ASD is good; the rate of surgical mortality is less than 1%. Approximately 15% of ostium secundum defects close spontaneously. Spontaneous closure does not occur with the other types of ASDs. A few patients with an ostium primum ASD and an abnormal mitral valve may require a second operation for mitral valve dysfunction later in their lives.. PATENT DUCTUS ARTERIOSUS(PDA)  PATENT DUCTUS ARTERIOSUS(PDA) It is a channel that connect the pulmonary artery with the descending aorta (isthmus part). It results from the persistence of patency of the fetal ductus arteriosus after birth. It is the most common lesion in infant of mothers with congenital rubella PDA more common in females (like ASD). The main function of the ductus arteriosus is that during  fetal life it shift the blood from the pulmonary artery to the descending aorta, the patency is maintained by the local secretion of PGE2. Normally, functional closure of the ductus arteriosus occurs by about 15 hours of life in healthy infants born at term. The female-to-male ratio is 2:1, it is more common in premature neonates.  Clinical features: 1. Patients with small PDA usually are “asymptomatic” and on examination there is machinery continuous murmur at the left second intercostal space. 2. medium size : the symptoms appear at 2-5 month of life slow or difficult feeding , repeated chest infections, and failure to thrive O/E: Collapsing pulse with wide pulse pressure On auscultation  classical continuous machinery murmur (systolic & diastolic) at the pulmonary area at the 2nd left intercostal space radiating to the back with a thrill (not always ?).. 3. large size: the symptoms appears since birth which are similar to the moderate type but are more severe, the murmur may be only systolic type , with signs of sever heart failure& pulmonary hypertension along with growth failure Investigations: ECG: In small PDA, it is normal, but large PDA left ventricular hypertrophy (LVH) or biventricular hypertrophy (volume overload). Chest X-ray: Cardiomegaly, plethoric lung, and prominent pulmonary conus. Echo: is diagnostic  Treatment: The premature neonate with a significant PDA usually is treated with intravenous indomethacin.or ibuprofen (intravenous, oral) is frequently effective in closing a PDA if it is administered in the first 10-14 days of life.. “Closure should be done” (6 months – 1 year) whatever the size due to possible complications. Most PDA closures can be done by transcatheter device or coil and some need surgical closure (when catheter closure is not possible or failed). Coil Closure Device Closure Complications  Endocarditis Congestive heart failure Pulmonary vascular obstructive disease Aortic rupture  Prognosis Typically, following PDA closure, patients experience no further symptoms and have no further cardiac sequelae. Premature infants who had a significant PDA are more likely to develop bronchopulmonary dysplasia ENDOCARDIAL CUSHION  DEFECT (ATRIOVENTRICULAR SEPTAL DEFECT ) (AV CANAL DEFECT) 49  Etiology and Epidemiology  The defect occurs as the result of abnormal development of the endocardial cushion tissue, resulting in failure of the septum to fuse with the endo-cardial cushion; this results in abnormal AV valves as well. The complete defect results in a primum ASD, a  posterior or inlet VSD, and clefts in the anterior leaflet of the mitral and septal leaflet of the tricuspid valves. In addition to left-to-right shunting at both levels, there may be atrioventricular valvular insufficiency. The partial defect is presented as ASD primum only  50 51  Clinical manifestation:  The symptoms of CHF usually develop as the pulmonary vascular resistance decreases over the first 6 to 8 weeks of life.  Growth is usually poor.  Many children with Down’s syndrome have complete endocardial cushion defects.  Pulmonary hypertension resulting from increased pulmonary circulation often develops early; this results in a prominent S2. 52 53  Investigation : o An ECG reveals left axis deviation and combined ventricular hypertrophy and may show combined atrial enlargemen o CXR shows cardiomegaly and increased pulmonary vascular markings o Echocaediography is diagnostic and shows the details of the defect.  Treatment o Initial management includes digoxin and diuretics and ACEI for treatment of CHF. o Surgical repair of the entire defect ultimately is required, however. 54 PULMONARY STENOSIS PULMONARY STENOSIS (CONT.): Anatomical classification: 1. Valvular 90% 2. Subvalvular 10% 3. supravalvular Valvular stenosis subvalvular stenosis supravalvular stenosis 56 PULMONARY STENOSIS (CONT.): C/F: Most patients are asymptomatic and discovered accidentally. Symptoms: exertional dypnoea and sometime chest pain. O/E: The asymptomatic patient has normal growth (unless it is a severe case). In symptomatic patients:  S1 is normal.  Non-fixed splitting S2.  Systolic ejection click at pulmonary areas.  Ejection systolic murmur with thrill (i.e. > grade 4), maximally at pulmonary area. 58 PULMONARY STENOSIS (CONT.): CXR: Prominent pulmonary conus caused by post-stenotic pulmonary dilatation. Normal pulmonary vascularity, i.e. there is no oligemia of the lung as expected after pulmonary stenosis because no intracardiac shunt (i.e. all the blood in the heart from the systemic circulation goes to the lung). 60 PULMONARY STENOSIS (CONT.): A B PA view of CXR: A – Normal B – Pulmonary stenosis (PS): Normal vascularity and poststenotic dilation 61 PULMONARY STENOSIS (CONT.): ECG: Rt. Axis deviation and RVH & peaked P-wave (RAH). Echo: 1. For Dx 2. Severity determination 3. Level of stenosis (supra, valvular or sub). Echo: PSAX view with color& Doppler display showing PS 62 PULMONARY STENOSIS (CONT.): Rx: Mild: just reassurance; follow up. Moderate to severe: balloon valvuloplasty; if failed  surgical valvotomy. 63  64 Balloon valvuloplasty COARCTATION OF THE AORTA  Obstructive (stenotic lesions) Coarctation of aorta  It is constrictions of the aorta just below the origin of the left subclavian artery at the origin of the ductus arteriosus.  Etiology and Epidemiology During development of the aortic arch , the area near the insertion of the ductus arteriosus fails to develop correctly,resulting in a narrowing of the aortic lumen. This leasion forms 5-10% of all congenital heart defects. COARCTATION OF THE AORTA (CONT.):  Localized, discrete narrowing of the thoracic aorta occurs in 5-10% of congenital heart disease.  More common in males with M:F = 2:1.  Most common cardiac lesion in Turner syndrome. 67  Coarctation of aorta Clinical Manifestations 1. The more the severe the narrowing the earlier the presentation. 2. Infants present with congestive heart failure: poor feeding, respiratory distress, and shock and may have hypoplastic aortic arch with VSD. 3. Older children are usually asymptomatic or might be only systemic hypertension presenting With leg discomfort with exercise, headache, or epistaxis. 4. On examination A-Decreased or absent lower extremity pulses B- pressure difference between the upper and lower limb by 20 mmHg (diagnostic) C-Upper extremity hypertension. D-Murmur may be present which is systolic and best heard in the left interscapular area of the back. If significant collaterals have developed,  Coarctation of aorta  Investigations 1- In infantile type ECG and CXR show right ventricular hypertrophy with cardiomegaly and pulmonary edema while in older children they show left ventricular hypertrophy and a mildly enlarged heart. RVH LVH  Coarctation of aorta In older children(>8 years) the chest x-ray film may show notching of the ribs due to the development of collaterals.  Coarctation of aorta  Investigations 2-Echocardiography shows the site and degree of coarctation, presence of left ventricular hypertrophy, and aortic valve morphology and function. COARCTATION OF THE AORTA (CONT.): MRI & CT angiography: radiation exposure, costlier, needs GA, not always available  used in difficult cases only. 73  Coarctation of aorta  Treatment 1. In infants management of heart failure and PGE2 infusion to maintain ductus patency then balloon dilatation or surgical repair. 2. In older children balloon dilatation and stenting or surgical repair. Prognosis: The mean age of death for untreated coarctation is about 34 years and the most common cause of death are:  heart failure  infective endocarditis  aortic rupture  intracranial hemorrhage (due to  B.P. or aneurysm) 75 Cyanotic Congenital Heart Disease cyanosis  Cyanosis is a physical sign indicating a bluish purple appearance of the skin or mucous membranes usually caused by an increased concentration of deoxygenated (unsaturated or reduced) hemoglobin (Hgb).  There are many different types of cyanosis, and it is important to differentiate physiologic versus pathologic cyanosis.  While occasionally a benign finding, as in a healthy newborn with acrocyanosis or when observed in the lips and fingers of a child who has been in the cold ocean, acute cyanosis often indicates a significant reduction in oxygen concentration and may signify a life-threatening event. The presence history of cyanosis requires careful evaluation. Peripheral cyanosis:  It is not uncommon in neonate and young infants; it may merely signify that child is feeling cold. Causes:  1. Physiological - cold  2. Reduced cardiac output  3. Peripheral vascular disease e.g.: Polyarteritis nodosa Central cyanosis:  Best seen in the tongue, it may be obvious at rest or only after exertion such as feeding or crying. It is detectable if there is deoxygenated hemoglobin of more than 5 gm/100 ml. Blood, corresponding to an arterial saturation of 75%. The differential diagnosis of central cyanosis includes disorders involving an increase in deoxygenated hemoglobin (respiratory, cardiovascular, neurologic, or other) or hematologic disorders involving abnormal hemoglobin (methemoglobinemia/ sulfhemoglobinemia).  Differential Diagnosis of Central Cyanosis Cardiac: Most of them begin with the letter "T" * Cyanotic congenital heart disease presenting in neonate  - Transposition of the great arteries.  - Tricuspid atresia.  - Total anomalous pulmonary venous drainage.  - Truncus arteriosus.  - Tricuspid regurgitation with Ebstein's anomaly.  - Pulmonary atresia.  - Complex congenital heart disease e.g. single ventricle with critical pulmonary stenosis. Cyanotic congenital heart disease presenting after neonatal period:  - Tetralogy of Fallot  RESPIRATORY DISEASE Airway Choanal atresia/stenosis Pierre Robin syndrome Intrinsic airway obstruction (laryngeal/bronchial/tracheal stenosis) Extrinsic airway obstruction (bronchogenic cyst, duplication cyst, vascular compression) Pulmonary causes:  * Neonatal period:  - Respiratory distress syndrome.  - Aspiration pneumonia (meconium, milk).  - Congenital pneumonia.  Transient tachypnea  - Diaphragmatic hernia  - Lung hypoplasia  * After neonatal period:  - Pneumonia  - Bronchiolitis  - Bronchial asthma  - Cystic fibrosis  - Bronchiectasis  Nervous system and neuromuscular causes:  a. Central nervous system lesions, e.g. birth asphyxia,head trauma Intracranial hypertension, hemorrhage.  b. Central nervous system depression by drugs(direct or through maternal route) , e.g. phenobarbitone.  c. Intercostal muscle weakness, e.g. spinal muscular atrophy.  d. Diaphragmatic weakness, e.g. phrenic nerve palsy. Other causes:  Persistent pulmonary hypertension of the newborn (persistent fetal circulation) the oxygen saturation of the right arm (preductal) is more than the oxygen saturation from the legs (postductal).  Methemoglobinemia (very rare). Pao is normal but the 2 saturation is low.  Polycythemia.  Hypoglycemia  Adrenogenital syndrome  Blood loss  Non cyanotic heart disease with heart failure (cyanosis is mainly due to pulmonary edema) e.g. hypoplastic left heart, Intra pulmonary arteriovenous malformation with right to left shunt. Any sign of respiratory distress is an indication for a physical examination and diagnostic evaluation, including a blood gas or pulse oximetry determination and radiograph of the chest.  Types of cyanosis Some types of cyanosis are not considered pathologic and require no workup; others such as central cyanosis can be associated with a life-threatening disease. Differentiate the type of cyanosis to help guide the workup and treatment. 1. Central cyanosis: bluish skin, including the tongue, mucosal membranes, and lips. This is caused by lack of oxygen in the blood (low PaO2 and low SaO2). While this can occur immediately after birth, persistent central cyanosis is never normal and needs to be evaluated to rule out major cardiac, lung, central nervous system (CNS), metabolic, or hematologic diseases. 2. Peripheral cyanosis: bluish skin with pink lips, mucous membranes, and tongue. Associated with normal PaO2 and normal (or falsely low if sensor wrapped around a cold blue finger or toe) arterial oxygen saturation. It is caused by decreased/sluggish local circulation leading to an increase in deoxygenated blood on the venous side. This is a consequence of increased oxygen extraction by the tissues and may be a physiologic response. Peripheral cyanosis can be a normal finding; can be associated with causes of central cyanosis; or can be caused by vasomotor instability, venous obstruction (venous thrombosis), polycythemia, low cardiac output (cardiomyopathies, hypocalcemia), shock, sepsis, hypothermia, hypoadrenalism, hypoglycemia, vasoconstriction secondary to cold exposure, and elevated venous pressure. Peripheral cyanosis is common in Down syndrome (vasomotor instability). 3. Acrocyanosis (bluish hands and feet only). There is normal oxygen saturation in the blood. A type of peripheral cyanosis, it is cyanosis of the extremities and around the mouth and may be considered a normal finding immediately after birth, within the first 1 to 2 days, or with cold stress. Spasm of smaller arterioles is the cause. In a normothermic older infant, consider hypovolemia as the main cause. 4. Perioral/cirumoral cyanosis (bluish color around the lips and philtrum [nose to upper lip]). There is normal oxygen saturation in the blood. It is common after birth and is due to the close proximity of the blood vessels to the skin. Infants have a prominent superficial perioral venous plexus that can engorge with feeding, and this is not a sign of peripheral or central cyanosis and usually resolves after 48 hours. 5. Traumatic cyanosis. There is normal oxygen saturation in the blood. This is cyanosis of the head and face usually found with petechiae. This is a result of venous congestion during delivery caused by a face presentation or nuchal cord. 6. Pseudo-cyanosis. Bluish color of the skin without hypoxemia, hemoglobin abnormality, or peripheral vasoconstriction. The mucous membranes of the mouth are pink, and with pressure on the skin, the color does not blanch. This can mimic peripheral cyanosis. Most commonly caused by fluorescent lighting in neonatal units, but can also be caused by drug exposure. 7. Cyanosis caused by methemoglobinemia causes a diffuse persistent gray bluish appearance of the infant. Drugs such as lidocaine, benzocaine, and nitrates may result in acquired methemoglobinemia. Lesions Associated with Decreased Pulmonary Blood Flow TETRALOGY OF FALLOT (TOF) Etiology and Epidemiology  TOF is the most common cyanotic congenital heart defect, representing about 10% of all congenital heart defects.There are four structural defects:  ventricular septal defect (VSD)  pulmonary stenosis  Overriding aorta  right ventricular hypertrophy  The VSD is large and the pulmonary stenosis is most subvalvular (infundibular) Clinical features A- Symptoms 1. Most patients are symptomatic with cyanosis at birth or shortly thereafter. Dyspnea on exertion, squatting, or hypoxic spells develop later, even in mildly cyanotic infants. 2. Occasional infants with acyanotic TOF may be asymptomatic or may show signs of CHF from a large left-to-right ventricular shunt. 3.Immediately after birth, severe cyanosis is seen in patients with TOF and pulmonary atresia. 4-Hypoxic ("Tet") spells occur during the 1st 2 yr of life, they are usually progressive. During a spell, the child typically becomes restless and agitated, crying inconsolably, hyperpneic with gradually increasing cyanosis and of the murmur. In severe spells, they develope unconsciousness , convulsions, hemiparesis, or death may occur. Independent of hypoxic spells, patients with tetralogy are at increased risk for cerebral thromboembolism and cerebral abscesses resulting in part from their right-to-left intracardiac shunt.  Treatment of spells (1) Placement of the infant on the abdomen in the knee-chest position while making certain that the infant's clothing is not constrictive. Premature attempts to obtain blood samples may cause further agitation and –ve effect. (2) O2 adminstration (3) S.c morphine not > 0.2mg/kg. (4) B-adrenergic blockers e.g propranolol (0.1-0.2) mg /kg i.v and slowly.  Physical examination 1-Growth and developmental delay in patients with severe untreated tetralogy of Fallot, particularly when oxygen saturation is chronically