CONGENITAL HEART DISEASE (CHD)

Transcription

1 CONGENITAL HEART DISEASE (CHD) DEFINITION It is the result of a structural or functional abnormality of the cardiovascular system at birth GENERAL FEATURES OF CHD Structural defects due to specific disturbance of normal embryological development Haemodynamic consequences vary depending upon location & nature of anomaly Relatively common cause of heart failure in children Multiple anomalies occur eg. Fallot s tetralogy Can be treated or palliated surgically AETIOLOGY Environmental factors maternal viral infections (especially Rubella) Chronic maternal alcohol abuse Drugs such as thalidomide Genetic * Other than the heart, there are also CHD-associated with extracardiac abnormalities. 4 th & 9 th weeks after constipation, Common atrial & ventricular chambers are divided by septa Cardiac valves develop Primitive truncus arteriosus divides into the aorta & pulmonary artery TERMS Shunt: an abnormal communication between chambers or blood vessels Malformation: left to right shunt, right to left shunt, obstruction PHYSIOLOGIC CONSIDERATIONS Pressure - normal post-partum left > right Vascular resistance - magnitude of flow is determined by resistance - systemic resistance is more than pulmonary resistance

2 RIGHT TO LEFT SHUNT LEFT TO RIGHT SHUNT Diminished pulmonary blood flow Poorly oxygenated blood enters systemic circulation Dusky blueness of skin & mucous membrane (cyanosis) Cyanotic congenital heart disease Increased pulmonary blood flow Pulmonary hypertension (not associated with cyanosis) Acyanotic congenital heart disease CATEGORIES Cyanotic CHD: Tetralogy of Fallot, Tricuspid atresia Acyanotic CHD: Atrial septal defect (ASD), Ventricular septal defect (VSD), Patent ductus arteriosus (PDA) CLINICOPATHOLOGICAL FEATURES Poor feeding, failure to thrive & impaired growth Respiratory disease or tachypnoea Cyanosis Clubbing Cardiac failure Pulmonary hypertension Infective endocarditis LEFT TO RIGHT SHUNTS 1 ATRIAL SEPTAL DEFECT (ASD) Most common congenital anomaly An abnormal opening in the atrial septum Left to right shunt because pulmonary vascular resistance is less than systemic vascular resistance Most ASDs are well tolerated Right heart failure occurs > 30 years Diastolic rumbling murmur due to increased flow across tricuspid valve Pulmonary hypertension Right ventricular hypertrophy

3 2 VENTRICULAR SEPTAL DEFECT (VSD) Account for about 25% of all cases of congenital heart disease in infancy Signs and symptoms depend on their size and position these defects can be estimated by echocardiography Small defects close spontaneously as the heart grows Surgical closure is indicated for larger muscular defects Left ventricular pressure is more on the right side of the heart shunting of the blood through the defect The size and site of the ventricular defect determine the extent of this shunt Prominent physical sign: loud pansystolic murmur Most important complication: cardiac failure Basic pathology in VSD Incomplete closure of ventricular septum Flow of blood from left ventricle to right ventricle during systole Pansystolic murmur Increased pulmonary artery blood flow Pulmonary hypertension, right ventricular hypertrophy (present at birth) VSD pathophysiology Left to right shunt Small defect High pressure difference loud murmur Little functional disturbance Large defect No pressure difference Flow determined by resistance of vascular beds Eisenmenger complex may develop

4 3 PATENT DUCTUS ARTERIOSUS (PDA) Normal circulation in fetal life PDA in utero allows arterial blood to bypass the unexpanded lungs In fetal life, i. pulmonary vascular resistance is high ii. right heart pressure is more than the left side Blood flow from right to left atrium through foramen ovale And from pulmonary artery to aorta via ductus arteriosus Normally ductus arteriosus closes within first few days of life In person having patent ductus arteriosus, The ductus arteriosus remains patent There will be a left to right shunt Blood flows from aorta to pulmonary artery results in pulmonary hypertension PDA results when the ductus arteriosus remains open after birth About 90% of PDAs occur as an isolated anomaly Some are associated with ventricular septal defect, coarctation of the aorta, or pulmonary or aortic stenosis The length and diameter of the ductus vary widely EISENMENGER S SYNDROME It occurs in response to substantial left-to-right shunting Morphologic alterations occur in the small pulmonary arteries & arterioles Leading to pulmonary hypertension Reversal of the intracardiac shunt Occurs in association with a VSA (ASD & PDA)

5 COARCTATION OF AORTA Definition: A congenital localized constriction in the diameter of the aorta is known as a coarctation Accounts for 5% of all forms of congenital cardiovascular disease More common in males Associated with aortic valve abnormalities congenitally bicuspid valve Progression degree of constriction: Severe symptoms develop soon after birth If the coarctation is undetected or untreated, collateral circulation develops (to increase blood flow to the lower part of the body) Involves branches of the intercostal srteries (become dilated and tortuous) Enlarge vessels may erode portions of the rib notching on chest X-ray Hypertension in the upper limbs, with a much lower pressure in vessels distal to the coarctation The intensity of the femoral pulse is often much reduced The abnormal blood flow through the coarcted segment may produce a systolic murmur, best heard in the posterior chest There are two types, where two classic forms have been described: 1. Infantile form 2. Adult form Criteria Infantile form Adult form General features Clinical features with tubular hypoplasia of the aortic arch proximal to a PDA symptomatic in early childhood cyanosis of lower extremities life-threatening discrete ridge-like infolding of the aorta just opposite the closed ductus arteriosus (ligamentum arteriosum) distal to the arch vessels hypertension of upper extremities poor perfusion of lower extremities and kidneys rib notching

6 RIGHT TO LEFT SHUNTS Complex congenital heart disease Rare disorders, present soon after birth Individual cardiac chambers are imperfectly developed or incorrectly connected Commonest: Fallot s tetralogy, first described in Marseilles in the 14 th century Example of right to left shunts: Fallot s tetralogy, transposition of great vessels 1 FALLOT S TETRALOGY Ventricular septal defect An enlarged aorta which overrides the defect & receives blood from both the right and left ventricles Stenosis of the pulmonary valve Associated right ventricular hypertrophy Most common congenital cyanotic heart defect after infancy Associated with other anomalies: - Right aortic arch (25%) - Atrial septal defect (10%) known as pentalogy of Fallot - Coronary artery anomalies Clinical features Aorta receives both oxygenated blood from the left ventricle and deoxygenated blood from the right, cyanosis develops Pulmonary stenosis restricts blood flow from the right ventricle into the lungs Systolic murmurs VSD/pulmonary stenosis (restriction of blood flow to the lungs) Right heart failure, bacterial endocarditis can ensue Dyspnoeic children with Fallot s are characterized by knee-chest position - Attempt to increase venous return from the lower limb - To reduce peripheral arterial perfusion, thereby increasing the flow across the ductus arteriosus or ventricular septal defect to the right side of the circulation 2 TRANSPOSITION OF GREAT ARTERIES The aorta arises from the right ventricle and the pulmonary artery emanates from the left ventricle The AV connections are normal right atrium joins right ventricle and left atrium emptying into left ventricle The anomaly results in two separate circulations Post-natal survival requires a shunt VSD/PDA Morphology: Right ventricular hypertrophy right ventricle functions as the systemic ventricle Left ventricular atrophy left ventricle supports the low resistance pulmonary circulation Treatment: A complete surgical correction is often possible, usually by switching the pulmonary artery and aorta at their origin from the heart