Congenital Heart Disease

Associated Anomalies with Congenital Heart Disease

Musculoskeletal - 8.8%

Specific Syndromes - 8.5%

Central Nervous - 6.9%

Urinary - 5.3%

Gastrointestinal - 4.2%

Respiratory - 3.8%

Endocrine - 1.3%

Immunologic-Hematologic - <1.0%

Reproductive - <1.0%

Other 2.9%

Recurrence Risks Given One Sibling Who Had a Cardiovascular Anomaly

VSD - 3%

PDA - 3%

ASD - 2.5%

TF - 2.5%

PS - 2%

CoA - 2%

AS - 2%

D-TGA - 2%

AV Canal- 2%

EFE - 4%

TA - 1%

Ebstein's Anomaly - 1%

Truncus Arteriosus - 1%

PA - 1%

HLHS - 2%

Congenital Heart Disease - Definition

Congenital heart disease is defined as the structural, functional or positional defect of the heart in isolation or in combination, present from birth, but may manifest at any time after birth or may not manifest at all.

Congenital heart disease remains a problem of major importance particularly for the family physician, who is first in the line of medical professionals, to diagnose and counsel the patients and the family. It is the most common single group of congenital abnormalities accounting for about 30 percent of the total.

Congenital Heart Disease - Incidence

The general reported incidence varies from 8-10 per 1000 live newborn population. There are eight common lesions, which account for 85 percent of all cases. They are:

• ventricular septal defect (VSD)

• patent ductus arteriosus (PDA)

• atrial septal defect (ASD)

• pulmonary valve stenosis

• aortic valve stenosis

• coarctation of the aorta

• Tetralogy of Fallot

• Transposition of great arteries

The remaining 15 percent accounts for a variety of more rare and complex lesions. Congenital heart disease as a whole occurs with an equal frequency in males and females but some lesions such as aortic stenosis, coarctation of the aorta are more common in males, while patent ductus arteriosus and atrial septal defects are more common in females. About 13 percent of patients with one heart defect, will have an additional cardiac defect. About 10 to 15 percent of patients with heart defects will have another non-cardiac deformity. The risk of siblings being affected by congenital heart disease is between 2 and 4 percent. So, parents who have had one child with congenital heart disease should, if they wish, be advised by a genetic counselor.

Congenital Heart Disease - Etiology

No specific causes are found in most cases of congenital malformations of the heart. In minority cases, clear-cut single causes, either environmental or genetic, are responsible. No good evidence is available implicating the interaction of specific genetic and exogenous factors in the causation of cardiac malformation in man, though experiments on animals suggest such an interaction.

Inheritance

A few families are reported in which defect follows dominant pattern of inheritance, e.g. atrial septal defect, supravalvular aortic stenosis, cardiomyopathy. Recessive autosomal inheritance confined to the heart is exceptional.

Chromosomal Abnormalities

About 5 percent of patients with congenital heart disease are associated with some chromosomal abnormalities (Table 1).

Table 1: Incidence of Congenital Heart Disease with chromosomal abnormalities

Environmental Factors

Increased incidence of congenital heart defect has been noted with intrauterine viral infections, maternal drug consumption during the first trimester of pregnancy, and pregnancy-induced systemic maternal diseases. (Table 2)

Table 2: Incidence of Congenital Heart Disease with environmental factors.

Maternal Infections:

• Rubella: PDA, pulmonary stenosis, VSD, ASD

• Mumps: Endocardial Fibroelastosis

  Maternal Drugs

• Phenytoin: Variable

• Vitamin D: Supravalvular aortic stenosis

  Maternal Disease

• Diabetes: Transposition of great arteries

• Systemic Lupus Erythematosus: Congenital Heart Block

Multifactorial Causation

The most accepted theory for the genetic basis of congenital heart disease is a multifactorial hypothesis. It suggests that the abnormalities of genes may not be enough to cause cardiac malformations, but may manifest in the presence of above mentioned adverse environmental hazards.

Congenital Heart Disease - Classification

Congenital heart diseases are basically divided into the following groups:

• Structural heart defects

• Functional heart defects, e.g. congenital cardiac arrhythmias

• Positional heart defects, e.g. dextrocardia

Structural heart defects are divided into two main groups:

• Acyanotic defects

• Cyanotic defects

Each group is subdivided according to:

• pulmonary blood flow: increased, decreased or normal

• dominant ventricle - left or right

• pulmonary hypertension - present or absent

The clinical diagnosis of a congenital heart is complex when first considered but with sound anatomy and physiologic principles and proper understanding of clinical manifestations, it may become simple. If information is handled with the framework of the following figures, the clinical diagnosis becomes simple.

Murmurs

• Incidence: 2/3 to 3/4 of all children

• Types of murmurs: systolic, diastolic and continuous

• Groups of murmurs:

• Functional murmur - secondary to anemia, fever etc.
• Innocent murmur - Still's murmur, venous, hum, etc
• Organic murmur - secondary to cardiovascular defect function

Cyanosis

Causes of cyanosis with excessive pulmonary blood flow:

• Transposition of great arteries

• Total anomalous pulmonary venous return

• Hypoplastic left heart syndrome

• Truncus arteriosus

Causes of Cyanosis with Inadequate Pulmonary Blood flow

• Pulmonary atresia or severe stenosis with

• Ventricular septal defect

• Intact ventricular septum

• Tricuspid atresia or stenosis

• Tricuspid insufficiency

Congestive Heart Failure

Causes of CCF in 1st week of life:

Cardiac causes:

• Hypoplastic left heart syndrome

• Coarctation of aorta

• D-transposition of great arteries

• Myocarditis

  Extracardiac causes:

• A-V malformation

• Anemia

• Polycythemia

• Infant of diabetic mother

Causes of CCF after 1st week of life

In a 2 month old:

• D-transposition of great arteries

  Between 2 months to 6 months of age:

• Ventricular septal defect

• Patent ductus arteriosus

• Endocardial cushion defect

• Endocardial fibroelastosis

• Anomalous left coronary artery

• Left ventricle obstruction

  Between 6 months to 1 year of age:

• Endocardial fibroelastosis

• Ventricular septal defect

  Between 1 year to 15 years of age:

• Myocarditis

• Rheumatic fever

• Subacute bacterial endocarditis

• Acute glomerulonephritis

Congenital Heart Disease - Clinical Presentation

Despite a large number of cardiac defects that exist, there are only a limited number of physiological disturbances that can be produced. Congenital heart disease usually presents in infancy as cyanosis or heart failure or a combination of both, heart murmur, circulatory shock, stridor, hypercyanotic spells, different respiratory tract infections, and growth failure.

Cyanosis

Cyanosis is blue discoloration of the skin, mucus membranes, and nails due to the presence of desaturated hemoglobin more than 5 gm/dl percent in arterial blood. Those cardiac anomalies in which systemic venous return reaches systemic circulation without passage through the lungs, presents with central cyanosis and clubbing of fingers.

Cyanosis occurs under following circumstances:

• Reduced pulmonary blood flow in defects with right ventricular outflow tract obstruction

• Right to left shunts as in Tetralogy of Fallot

• Discordant ventriculoarterial connections as in transposition of great arteries, and

• Mixing of venous and arterial blood as in truncus arteriosus or single ventricle.

Heart Failure

When the heart cannot supply the blood flow demanded by tissues, a clinical syndrome of symptoms and signs manifest from elevated atrial pressure. It manifests with rapid and labored breathing due to pulmonary edema, pallor with peripheral cyanosis due to poor cardiac output, tachycardia, and excessive sweating due to increased sympathetic activity and feeding difficulties.

Heart failure occurs in following situations:

• Volume overload in all defects with left to right shunt like ventricular septal defect, atrial septal defect, patent ductus arteriosus,

• Pressure overload in pulmonary and aortic valve stenosis

• Intrinsic myocardial diseases as in cardiomyopathies, and

• Decreased or increased diastolic fillings as in tachyarrhythmias and bradyarrhythmias.

Heart Murmurs

In older children and in infants, congenital heart disease presents as a heart murmur detected on routine examination. The murmurs are produced due to abnormal pressure gradient across laminar or nonlaminar pathways. The murmur is continuous in patent ductus arteriosus, pansystolic in ventricular septal defect and pulmonary stenosis, and diastolic in atrioventricular valve stenosis.

Shock

Cardiac malformations resulting in a hypoplastic ascending aorta, aortic atresia result in low cardiac output. The child appears extremely ill with cold extremities, diminished pulses, low blood pressure, peripheral cyanosis, and is semicomatose.

Hypercyanotic Spells

In cardiac malformations with pulmonary infundibular stenosis, the obstruction is of dynamic variety. Whenever the muscular outflow tract contracts, blood flow to the pulmonary circuit diminishes and the patient gets intense cyanosis. It occurs in Fallot's tetralogy and defects with Fallot's physiology.

Stridor

Malformations leading to compression of trachea and bronchi causing obstruction of the airways, present with stridor, as seen in vascular rings and in a dilated pulmonary artery due to increased pulmonary blood flow.

Chest Pain

Malformations like the anomalous origin of the left coronary artery, severe aortic stenosis lead to myocardial ischemia and the patient presents with episodes of screaming, pallor, and chest pain.

Recurrent Respiratory Tract Infections

In cardiac defects with a left to right shunt, as seen with a ventricular septal defect and patent ductus arteriosus, there is a decreased lung compliance which leads to frequent respiratory tract infections.

Growth Failure

Growth failure is a very common manifestation of heart defects due to poor oxygen saturation in the growing tissues, persistent heart failure, and frequent respiratory infections with undernutrition.