CONGENITAL HEART DISEASE (CHD)They are typically arise in the 3rd–8th week of gestation.The incidence of significant cardiac abnormalities is 8:1000 live births.In neonates and children with CHD, 15% will have more than one cardiac abnormality and 15% will have another extra-cardiac abnormality.There are approximately nine common congenital heart defects that make up about 90% of all cases of congenital heart disease; the remaining 10% are rare complex cardiac defects.
CONGENITAL HEART DISEASE (CHD) Aetiology :There is often no obvious aetiology; most would appear to be multifactorial with both genetic and environmental influences:Maternal (environmental) factors Infection Rubella Disease DM, Maternal DM ,Drugs/medications Alcohol abuse,Genetic factors Marfan syndrome Trisomy 21 , trisomy 18 (Edwards syndrome) Turner syndrome,
CONGENITAL HEART DISEASE (CHD) Classifications:Congenital heart disease can be broadly classified according to the presence or absence of cyanosis,The presence of central cyanosis, blueness of the trunk and mucous membranes, is due to > 3-5 g/dl of deoxygenated haemoglobin in the arterial circulation.
CONGENITAL HEART DISEASE (CHD) Classifications:I. Cyanotic congenital heart diseases make up 1/3 of cases, and are usually more complex:1. A right to-left shunt resulting in decreased pulmonary blood flow. Many of these lesions consist of a septal defect in con-junction with a right-sided obstructive lesion, producing an obligatory right-to-left shunt. The most common type Tetralogy of Fallot (TOF).
CONGENITAL HEART DISEASE (CHD) Classifications:2. Parallel systemic and pulmonary blood flow rather than in series. This is incompatible with life if there is no mixing, so typically neonates have a patent foramen ovale that allows some mixing of the two circulations at this level. The most common example of this is Transposition of the Great Arteries (TGA).
CONGENITAL HEART DISEASE (CHD) Classifications:3. Defects in the connections to the heart where there is mixing of the systemic and pulmonary flows.An example of such a complex lesion is Total Anomalous Pulmonary Venous Drainage
CONGENITAL HEART DISEASE (CHD) Classifications:II. Acyanotic congenital heart diseases represent : 2/3 of the cases1. Left-to-right shunt with increased pulmonary blood flow:which causes an increase in volume work on the heart e.g. patent ductus arteriosus (PDA), atrial septal defect (ASD) and ventricular septal defect (VSD).
CONGENITAL HEART DISEASE (CHD) Classifications:2. An obstruction of the blood flow across a heart valve on the left heart:such as aortic stenosis or in the aorta itself as occurs with coarctation of the aorta, leading to an increase and work of the heart.
Fallots tetralogyThis is the most common cyanotic congenital heart disease and accounts for about 4-6% of all congenital heart diseases.The four intracardiac lesions originally are: 1. Pulmonary (typically infundibular or subpulmonary) stenosis; 2. Right ventricular hypertrophy 3. VSD; 4. Overriding aorta
Clinical features:The degree of cyanosis depends on the degree of pulmonary stenosis.If there is significant pulmonary stenosis to virtual pulmonary atresia, presentation is in the neonatal period because of duct dependency.As pulmonary stenosis progresses, cyanosis typically develop with in the first year of life.Classically, hypercyanotic spells are thought to be due to infundibular or subpulmonary muscle spasm.Squatting is an adaptation by the child to such hypoxic spells. This increases systemic vascular resistance and the venous return to the head.Physical examination: moderate systolic ejection murmur which may disappear during a spell.Continuous murmurs may be found in patients with aortopulmonary collaterals .Clubbing develops in older children, usually after 6 months of age.
Investigations: ECG : right atrial and right ventricular hypertrophy. Chest x-ray: boot-shaped heart with poorly developed lung vasculature. The Echocar-diography is diagnostic . Cardiac catheterization prior to surgery.
Indications for surgeryThese are based on clinical progression include: Severe cyanosis ( oxygen saturation < 80% on room air), Hypercyanotic spells, Dyspnoea on effort, Syncopal attacks and Polycythaemia.
Surgical options (Curative) When the infant becomes symptomatic, a complete primary repair may be performed as a first procedure, or if asymptomatic, elect for total primary repair early, ideally with in the first 6 months, but usually within the first 3 years. This approach has the advantage of reducing the number of operations, restores normal oxygen saturation earlier in life and so helps development and, by repairing the defect early, leads to less right ventricular hypertro-phy, which may reduce the frequency of late arrhythmias.
Surgical options (Curative)•Reapire of VSDEnlagement ofthe pulmonarytrunk
Surgical options (Palliative) Such palliative procedures divert systemic blood into the pulmonary circulation and may be used to improve oxygenation. Many types of systemic-to-pulmonary artery shunts have been described such as left subclavian to pulmonary artery shunt (Blalock-Taussig) or other modifications. The results of surgery are good with late survival at 5-10 years following correction of tetralogy is 95%, with an operative mortality for a repair of between 5% and 10%, and an incidence of reoperation following tetralogy repair of 5-10%.
Transposition of great arteries (TGA)Is the second most common CHD, making up 2.5-5% of all congenital heart disease, and is the most common cause of cyanosis from a congenital cardiac defect discovered in the new-born period.
Clinical features Severe central cyanosis presenting in the first 48 hours of life, with the cyanosis progressing in the first week. If there is a large atrial septal defect or ventricular septal defect there may be minimal cyanosis initially.Investigations: The chest radiograph: pulmonary plethora, with the heart having an egg on its side appearance, with a small pedicle (aorta in front of pulmonary artery). Cardiac catheterization and echocardiography confirm the diagnosis and delineate the anatomy.
Indications for surgery The outcome for infants with TGA in the first year of life without some form of intervention to increase systemic and pulmonary venous admixture is death in 80-90% of cases. Initial palliation is by percutaneous (Rashkind) balloon atrial septostomy, or alternatively intravenous prostaglandin to keep the ductus open. Definitive repair is usually the Total Arterial Switch procedure, which has replaced the atrial switch or baffle (Mustard or Senning) operation because of reduced long-term complications
I. Patent ductus arteriosusAccounts for 8-12% of congenital heart disease.The ductus arteriosus, a normal fetal communication, facilitates the transfer of oxygenated blood from the pulmonary artery to the aorta shunting blood away from the lungs.Normally, functional closure of the ductus occurs within a few hours of birth; it is abnormal if it persists beyond the neonatal period
Patent ductus arteriosus Clinical features Small shunts usually causing no symptoms, and few signs apart from a continuous machinery murmur in the left sec-ond intercostal space. Larger ducts cause cardiac failure and can uncommonly lead to shunt reversal with cyanosis and clubbing.Investigations : Echocardiography with Doppler colour flow. Cardiac catheterisation is performed only if additional lesions are suspected.Indications for surgery: After 6 months of age, spontaneous closure of PDA is rare. Most should be closed by the preschool age. In the adult, surgical treatment is indicated if there is a persistent left to right shunt, even in the presence pulmonary hypertension.
Patent ductus arteriosusSurgical options In the premature infant, pharmacological closure of the patent ductus arteriosus with indomethacin is generally successful. If medical treatment to close the ductus is unsuccessful, the lesion may be treated by interventional cardiology, using an umbrella or coil duct occlusion device inserted percutaneously. Surgical closure via a left thoracotomy, if the lesion is very large or the patient very small is preferred. This can be accomplished by either ligation or division of the patent ductus arteriosus.
II. Coarctation of the aorta This accounts for 6-7% of congenital heart disease and is defined as a haemodynamically significant narrowing of the aorta, usually in the descending aorta just distal to the left subclavian artery, around the area of the ductus arteriosus
III. Coarctation of the aorta Pathophysiology The upper body is well perfused but the lower body, including the kidneys, is poorly perfused leading to fluid overload, excess renin secretion and acidosis. Children with coarctation are usually male and, if it occurs in females, it is suggestive of Turner syndrome. There are several common associated lesions, including bicuspid aortic valve, ventricular septal defect.
Coarctation of the aorta Clinical features The child may appear well in the first few days of life because the coarctation is bypassed by the ductus arteriosus and oxygenated blood reaches the entire systemic circulation. As the ductus closes, the child becomes progressively more unwell. Hypertension is a common presenting problem in older children, often just upper body hypertension with development of enormous collateral vessels that may cause ribnotching and flow murmurs over the scapula. Other symptoms include prominent pulsation in the neck, tired legs or intermittent claudication on exercise.
III. Coarctation of the aorta Indications for surgery Neonate with severe failure, operation indicated at time of diagnosis If cardiac failure delay 3-6 months Increased incidence of recurrent stenosis if operated at less than 3 months Increased incidence of hypertesion if coarctation is repaired beyond infancy
III. Coarctation of the aortaSurgical options Operative options include resection of the coarctation and end-to-end anastomosis or the use of the left subclavian artery as an onlay flap. In the older patient, th subclavian flap opration is not feasible and resection with end- to-end anastomosis, interposition graft or a jump graft are preferred. Percutaneous balloon dilatation is an alternative procedure in older children and adults and, in particular, for recoarctation.
IV. Atrial Septal Defect (ASD) ASD is a defect in the septum between the left and right atria leading to a left-to-right shunt. It accounts for approximately 6-7% of all congenital heart disease and is more common in females. There are three commonly recognised atrial septal defects.
IV. Atrial Septal Defect (ASD) Symptoms and Signs Most small ASDs are asymptomatic. Larger shunts may cause exercise intolerance, dyspnea during exertion, fatigue, and atrial arrhythmias sometimes with palpitations. Passage of microemboli from the venous circulation across the ASD (paradoxical embolization), often associated with arrhythmias, may lead to cerebral or systemic thromboembolic disorders. Auscultation typically reveals midsystolic (or ejection systolic) murmur and a widely split, fixed S2 at the upper left sternal border in children.
IV. Atrial Septal Defect (ASD) Investigations:Echocardiography will define the anatomy and any other abnormalities including the direction of the shunt.
Indications for surgery For primum & secundum ASD that fail close to spontaneously close treatment is aimed at closing the defect if a left-to- right shunt of 1.5:1 or more is present. Closure is performed during the first decade, most small ostium secundum ASDs (< 3 mm) close spontaneously; about 80% of those between 3 mm and 8 mm close spontaneously by age 18 months. Asymptomatic children with a small shunt require annual echocardiography. Because these children are at risk of paradoxical systemic embolization, some centers recommend a catheter-delivered closure device (eg, Amplatzer Septal Occluder, Cardio-Seal device) even for small ASDs. However, these devices are not suitable for primum or sinus venosus defects because these defects are near important structures.
Surgical options The traditional method of closure involves open-heart surgery with cardiopulmonary bypass (CPB) and closure of the defect either directly with sutures, as with most secundum defects or, if the defect is large, using a pericardial or synthetic patch. Operative mortality for isolated atrial septal defect repairs is < 1%, with excellent prognosis.
V. Ventricular septal defects (VSD) These account for 20-30% of congenital heart disease and affect approximately 2 in 1000 live births. A defect in the interventricular septum that allows a left-to-right shunting of blood. This may occur in isolation or as part of a more complex set of cardiac abnormali-ties (e.g. tetralogy of Fallot, complete atrioventricular canal defect) Four major anatomical types of ventricular septal defect are described, based on the anatomical subsections of the interventricular septum:
Ventricular septal defects Investigations Chest radiography: may show cardiomegaly and pulmonary congestion, ECG showing evidence of biventricular hypertrophy. Echocardiography confirms the diagnosis and can estimate the degree of shunting across the defect. Cardiac catheterisation can quantify the various pressures within the cardiac chambers and so assess degree of pulmonary hypertension.
Ventricular septal defects Clinical featuresSmall defects may close or cause little systemic disturbance.In the first 5 years, up to 30-50% of ventricular septal defects close spontaneously. Clinically, a loud pansystolic murmur can be detected at the left sternal border due to high pressure flow between thé ventricles.Large defects typically present with congestive cardiac failure in the first 2 months of life. There is a preceding history of dyspnoea on exertion, failure to thrive, poor feeding and recurrent chest infections.
Indications for surgery: Approximately one-third of defects close in the first year of life; a further one-third become relatively smaller in relation to the growing heart. In clinically small defects with a good response to medical management, it may be appropriate in the infant to watch and wait, although there is a risk of endocarditis. Generally, surgical closure is indicated for large defects, failure to respond to medical therapy, left-to-right shunts > 2:1, signs of increasing pulmonary vascular résistance and the presence of complications of ventric-ular septal defect.These include (1) aortic regurgitation, which occurs in about 5% of defects; (2) infundibular stenosis, which tends to be progressive and leads to shunt reversal; and (3) infective endocarditis.
Surgical options If the infant is severely symptomatic, the defect should be closed urgently, otherwise elective repair is advised between 1 and 3 years of age in the asymptomatic patient. Most now advocate a primary total correction, usually at the onset of symptoms or by 1 year in the asymptomatic patient. Operative mortality for isolated ventricular septal defect closure is 2- 4%, with long-term prognosis.