Congenital Heart Disease
- Congenital heart disease refers to a defect in the heart or great vessels, or
persistence of a fetal structure after birth.
Many congenital heart defects result from a combined or interactive effect of genetic and
environmental factors, such as the following
- Fetal exposure to drugs such as phenytoin, lithium, warfarin, and valproic acid
- Fetal exposure to alcohol—tetralogy of Fallot, atrial septal de-fect, ventriculoseptal
- Fetal exposure to secondary tobacco smoke—septal and right-sided defects
- Maternal systemic viral infections such as rubella (patent ductus arteriosus, pulmonic
stenosis, coarctation of aorta) or cox-sackie B5 (endocardial fibroelastosis) Increased
maternal age—ventriculoseptal defect, tetralogy of Fallot
- Maternal metabolic disorders such as phenylketonuria (coarc-tation of aorta and patent
ductus arteriosus), diabetes mellitus (ventricular septal defects, cardiomegaly,
transposition of great arteries), and hypercalcemia (aortic stenosis, pulmonic steno-
sis, aortic hyperplasia)
- High altitude—patent ductus arteriosus, atrial septal defect
- Maternal complications of pregnancy such as increased age and antepartal bleeding
- Genetic factors—family recurrence patterns
- Prematurity—patent ductus arteriosus, ventricular septal defect
Congenital heart defects are generally categorized by the patho-physiology and
hemodynamics, rather than by whether a defect causes cyanosis. The categories of defects
include the following:
■Increased pulmonary blood flow
■Decreased pulmonary blood flow
■Obstructed systemic blood flow
Heart Defects by Pathophysiology
Clinical Manifestations Types of Defects Etiology
Tachypnea, tachycardia, Patent ductus arteriosus, atrial Increased pulmonary blood
murmur, congestive heart septal defect, ventricular flow
failure, poor weight gain, septal defect, atrioventricular
diaphoresis, periorbital canal defect (endocardial edema, frequent respiratory cushion defect)
Cyanosis, hypercyanotic Pulmonic stenosis, tetralogy of Decreased pulmonary blood
episodes, poor weight gain, Fallot, pulmonary atresia, flow
polycythemia tricuspid atresia
Diminished pulses, poor color, Coarctation of aorta, aortic Obstructed systemic blood
delayed capillary refill time, stenosis, hypoplastic left heart flow
decreased urine output, syndrome, mitral stenosis,
congestive heart failure with interrupted aortic arch
Cyanosis, poor weight gain, Transposition of great arteries, Mixed defects—all are within
pulmonary congestion, total anomalous pulmonary one of the above categories,
congestive heart failure may venous connection, truncus but the difference is that
occur with increased shunting arteriosus, double outlet right postnatal survival is dependent
ventricle upon mixing of systemic and
pulmonary blood flow
The presence of a heart murmur is often the first indication of a congenital heart defect. A loud
murmur indicates blood is flowing with higher pressure than normal to get through a
narrowed valve or vessel, or through a shunt (movement of blood between the systemic and
pulmonary circulation through an abnormal anatomic opening, such as between the ventricles).
CONGENITAL HEART DEFECTS THAT INCREASE PULMONARY BLOOD FLOW
Etiology and Pathophysiology
- The pressures on the left side of the heart are higher than on the right side.
- When a connection occurs between the left and right side of the heart, blood will
shunt from the left side to the right side and increase the amount of blood that is pumped
to the lungs. The size of the connection and how much blood passes through it determine
if or how quickly the child will develop signs associated with congestive heart.
- The increased pulmonary blood flow causes increased pulmonary vascular resistance
(constriction of the pulmonary vascular bed) in an effort to reduce the blood flow,
and pulmonary artery hypertension.
- Right ventricular hypertrophy develops to counteract the increasing pulmonary vascular resistance and deliver the increased volume of blood to the lungs.
- The infant’s heart rate, respiratory rate, and metabolic rate are increased due to the
high pulmonary blood flow.
- Sucking breast milk or formula takes energy, and diaphoresis may be noted with feeding.
Often the infant is unable to obtain enough calories to support the metabolic rate and
growth, so poor weight gain may be noted.
- Congestive heart failure may develop if the pulmonary system is overloaded with
blood, leading to dyspnea, tachypnea, intercostal retractions, and periorbital edema.
- Frequent respiratory infections occur because the wet environment in the lungs
supports bacterial growth. The symptoms of congestive heart failure appear earlier when
the heart defect is more severe and complex.
1. Patent Ductus Arteriosus (PDA)
- Common congenital defect caused by persistent fetal circulation that occurs in 5–10% of
all infants with congenital heart disease. When pulmonary circulation is established and
systemic vascular resistance increases at birth, pressures in the aorta become greater than