Congenital Heart Disease

N C Joshi
Congenital Heart Disease - Treatment
During the last 50 years, advances in technology, drug therapy and surgical skill offers hope to children with the simplest to the most complex heart defects. The management includes
- Pre and Post operative medical treatment
- Surgical intervention
- Non operative, interventional procedures
For reasons of simplicity, principles of management are discussed assuming minute details are not within the scope of this contribution.

Every normal looking newborn baby should have a careful physical examination including auscultation of the precordial region, palpation of brachial and femoral arteries and evaluation of blood pressure in the superior and inferior extremities. A neonate with a murmur or an abnormal pulse or persistent tachypnea which does not have a clear extracardiac origin; cyanosis which is not clearly due to brain damage or pulmonary and hematological disorder should have specialized pediatric cardiology evaluation. Also a careful cardiac evaluation is necessary in children with frequent respiratory infections, increased perspiration, feeding difficulties and failure to thrive.

Congestive heart failure
Congestive heart failure in children is related to various mechanical problems - diastolic and systolic overload, valvular regurgitation and myocardial abnormalities. General aspects of medical treatment of CHF are based upon judicious use of digitalis, diuretics and vasodilators agents with correction of precipitating factors like fever, hypoxia, anemia, infection. Appropriate correction of electrolyte imbalance, hypocalcemia is of paramount importance especially in infants. Low cardiac output sometimes dominates the clinical picture of heart failure where correction of metabolic acidosis is very important. Babies should remain in the hospital till stabilized and maintenance treatment should be followed at intervals.

Management of hypercyanotic spells
A baby with history of cyanotic spells should be ideally hospitalized and operated soon. But impending cyanotic spell can be managed by simple methods such as pacifying the child, holding in a knee-chest position and avoiding invasive procedures. If a spell does not respond, a more aggressive treatment, which includes Oxygen, sedation i.e. IV Morphine and beta blockers (IV Propranolol or metoprolol) can be used to relieve the infundibular spasm. In severe cases resistant to these measures, general anesthesia with assisted ventilation is advisable. If these measures too fail, emergency systemic arterial pulmonary shunt may be life saving.

To avoid relapses, prophylactic beta-blockers, iron supplement (if hematocrit <45%) and repeated phlebotomies may be required.

Treatment of intercurrent infections
Repeated respiratory infections in conditions with left to right shunt and cerebral abscess in cyanotics need to be searched diligently and treated with specific antimicrobial therapy.

Treatment of infective endocarditis
This is an uncommon complication below 2 years of age. It is commonly seen in conditions where a high pressure source (left ventricle or aorta) drives blood at high velocity through a narrow orifice ( coarctation of aorta, small VSD, small ductus or regurgitant aortic or mitral valves) into low pressure sink (atrium, pulmonary trunk, right ventricle) producing a venturi effect and damage to endocardium.

The classical tetrad of the clinical features of endocarditis are infection, heart diseases, embolism and immunological disease.

The selection of the antibiotic given is guided by blood cultures and sensitivity. Treatment should start at clinical suspicion while awaiting results of specific investigations. Initial antibiotic regimen should be broad spectrum e.g. a combination of penicillin and Gentamicin or cephalosporin and aminoglycoside. The final choice will be according to culture and sensitivity. The therapy should be continued from 4 to 6 weeks. Surgical interventions may be necessary for progressive worsening of congestive heart failure, repeated embolic episodes and non-response to antibiotic treatment.

Medical manipulation of ductus in pre-operative period
To maintain ductal patency in ductus dependent circulation in cyanotic congenital heart diseases and left sided obstructive lesions, prostaglandin infusion has revolutionised the management of congenital heart disease in neonatal period.

On the other hand, non-surgical closure of ductus has been successfully achieved by oral or intravenous Indomethacin in preterm babies.

Surgical interventions are of two types:

Palliative operations that mitigate symptoms or extend life without addressing the basic pathophysiology of congenital cardiac lesions. Examples include the creation of systemic to pulmonary artery shunt and the placement of pulmonary artery band.

Corrective surgery is intended to completely or near completely
- Separate the pulmonary and systemic circulations
- Restore adequate quantities of appropriately oxygenated blood to each capillary bed
- Reduce volume and pressure overloads towards normal levels.

Cardiac catheterization has added a new dimension in the management of congenital heart disease in some conditions provide an effective alternative option to circumvent the surgical management. Interventional catheterization can be grouped into four general types:
- Atrial septostomy
- Balloon valve dilations
- Vessel Dilations and vascular stents
- Occlusion procedures

These procedures are performed in catheterization laboratories by a trained pediatric interventional cardiologist and require a large inventory of catheters and devices.

Atrial Septostomy Procedures
Atrial Septostomy procedure is indicated for palliation for congenital heart lesions in neonates and young infants in whom all systemic, pulmonary or mixed venous blood must travel a restrictive interatrial communication in order to return to the systemic circulation. This includes complex defects associated with hypoplastic left ventricles and infants with total anomalous pulmonary venous drainage. The procedure involves passing an inflated balloon catheter rapidly across the atrial septum so as to create a non-restrictive atrial septal defect. In infants older than 1 month, a blade septostomy catheter is recommended due to the thick septum to achieve the final result. These procedures are emergent in nature and can be performed in catheterization laboratory under fluoroscopy control or in intensive care unit under echocardiographic guidance.

Balloon Valve Dilation
Stenotic valves can be opened by the use of balloon catheters. The pressure created by the balloon wall as it expands across a stenosed valve leads to opening of the valve by splitting of the commissures and dilation of the valve annulus. The balloon is rapidly inflated to a recommended pressure, till the waist in the balloon disappears. Pressure gradients are recorded before and after the dilation of the valve. This procedure has been successfully used for aortic and pulmonary stenosis. Dilation of the right ventricular outflow tract in patients with Tetralogy of Fallot with a view to palliation is an emerging indication. Availability of low profile balloons has significantly reduced the vascular access complications. Avoidance of thoracotomy and cardiopulmonary bypass with their inherent risks and morbidity are definite advantages of these procedures.

Vessel Dilatations and Vascular Stents
This procedure utilizes a catheter with a small, cylindrical, fixed-maximal-diameter balloon mounted on it. The balloon catheter is passed over a guidewire, positioned across the area of stenosis and inflated with relatively high pressure. This stretches the area of stenosis to the predetermined diameter of the balloon. Current indications for vessel dilation include postoperative coarctation of the aorta and native coarctation. Branch pulmonary artery dilation can be done successfully using high pressure balloons. Systemic and pulmonary vein dilation have also been performed. Intravascular stents provide the necessary scaffolding to prevent recoil and restenosis following balloon dilation. These are being particularly used in branch pulmonary arteries, aorta and pulmonary veins.

Occlusion procedures
These procedures have been used to occlude abnormal or persistent intracardiac (e.g., atrial and ventricular septal defects) and extracardiac (e.g., PDA and arteriovenous fistulas) shunts. The occlusion devices are delivered selectively through specially designed catheters to occlude the shunts. Porstmann plug, Rashkind double umbrella device, PDA coils and Duct-occlud pfm are amongst the various devices available for closure of ductus arteriosus. Limited success has been achieved in closure of small atrial and ventricular septal defects using clamshell double umbrella device. Newer devices with different geometries aimed at achieving procedural ease, complete occlusion of the shunts and reducing device embolization rates are being continuously developed.

Congenital Heart Disease Congenital Heart Disease 01/16/2001
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