Congenital heart disease

5.5 Congenital heart disease



Matthew O’Meara




Essentials



1 Congenital cardiac disease is uncommon in children, but should be considered as a possible diagnosis in an infant or child with respiratory distress, cyanosis or shock.

2 The common congenital cardiac problems have characteristic clinical features that assist with clinical diagnosis and initial management.

3 The radiologic appearance of pulmonary blood flow and electrocardiographic features of axis deviation and ventricular hypertrophy assist the diagnostic evaluation


Introduction



Incidence


Approximately 1% of infants and children in developed countries have congenital cardiac problems. Eight lesions account for 80% of all cases of congenital cardiac abnormalities: ventricular septal defect (VSD); patent ductus arteriosus (PDA); atrial septal defect (ASD); tetralogy of Fallot; pulmonary stenosis; coarctation of the aorta; aortic stenosis (AS); and transposition of the great arteries.



Common heart defects in infancy and childhood


Heart disease in children may present with the presence of an abnormal murmur, the development of symptoms or signs of congestive cardiac failure or central cyanosis. From an Emergency Department perspective, it is more important to identify the degree of cyanosis or cardiac failure, rather than identify the exact anatomic diagnosis. Clinical examination combined with the electrocardiograph and chest radiograph will help the diagnostic process (Figs 5.5.1 and 5.5.2).


image

Fig. 5.5.1 Diagnostic approach to acyanotic congenital heart defects.


AS, aortic stenosis; ASD, atrial septal defect; AVSD Atrioventricular septal defect; CoA, coarctation of the aorta; LVH, left ventricular hypertrophy; PDA, patent ductus arteriosus; PS, pulmonic stenosis; RVH, right ventricular hypertrophy; VSD, ventricular septal defect.


Adapted from Marx: Rosen’s Emergency Medicine, 7th ed. Copyright © 2009 Mosby.


image

Fig. 5.5.2 Diagnostic approach to cyanotic congenital heart defects.


BVH, biventricular hypertrophy; EA, Ebstein’s anomaly; HLHS, hypoplastic left heart syndrome; LVH, left ventricular hypertrophy; PA, pulmonary atresia; PS, pulmonary stenosis; RVH, right ventricular hypertrophy; TAPVR, total anomalous pulmonary venous return; TGA, transposition of the great arteries; TOF, tetralogy of Fallot; TriA, tricuspid atresia; TruncusA, truncus arteriosus.


Adapted from Marx: Rosen’s Emergency Medicine, 7th ed. Copyright © 2009 Mosby.



Clinical features


The age, severity of symptoms, and time of presentation of a child with congenital heart disease (CHD) vary depending on the specific defect, complexity and severity of the defect, and timing of the normal physiologic changes that occur as the fetal circulation transitions to that of a neonate. The more severe or complex CHD lesions may not be clinically apparent immediately after birth. However, as the ductus arteriosus begins to close in the first few weeks of life, cardiac defects with obstructive lesions of the pulmonary or systemic circulations will be unmasked, and these infants will present clinically with acute cyanosis, shock, or both. Even the harsh systolic murmur of a large, isolated ventricular septal defect may not be heard until about the 4th to 6th week of life when the left-to-right shunt across the ventricular septal defect increases due to the decrease in the pulmonary vascular resistance. In general, the more severe the anatomic defect is (i.e., lack of pulmonary blood flow or lack of systemic blood flow), the earlier in life these conditions will manifest with cyanosis and shock.


The possibility of a congenital cardiac problem needs consideration in a child presenting with cyanosis, respiratory distress or shock. There are a number of general principles that may indicate a congenital cardiac problem.


• Is the child centrally cyanosed?
• central cyanosis with normal breathing or only mild respiratory distress suggests a cardiac problem rather than a primary respiratory problem;

• cyanosis that worsens with crying suggests a cardiac cause;

• cyanosis that persists with oxygen suggests a cardiac cause.

• Does the heart sound normal?
• Is there a murmur that cannot be confidently identified as innocent?

• Is the chest radiograph normal?
• Is the heart shape abnormal?

• Is the pulmonary vascularity increased or decreased?

• Is the electrocardiograph abnormal?
• Is the axis abnormal?

• Is there atrial or ventricular hypertrophy?


Acyanotic defects


These make up about 75% of all congenital heart defects. They include those associated with isolated left-to-right shunts such as VSD, ASD, PDA and those without shunting such as AS pulmonary stenosis (PS) and coarctation of the aorta. See Fig. 5.5.1 for an approach to diagnosis based on radiological and electrocardiographic appearance.



Ventricular septal defect


VSDs make up 30% of all cardiac defects. The defect may be small or large and involve the membranous or muscular parts of the septum.


Clinical presentation depends on the amount of left-to-right shunting. A murmur may be noted incidentally on examination or congestive cardiac failure may develop in infants with larger defects and more shunting.


The characteristic clinical features of a VSD are a loud, harsh, high-pitched systolic murmur at the left sternal border, often associated with a thrill. The heart sounds are normal. Larger VSDs may cause a parasternal heave, a displaced apex beat, a softer systolic murmur and a diastolic murmur due to increased flow through the mitral valve. An infant with a large VSD will fail to thrive and become tachypnoeic, sweaty and tired with feeds.


The chest X-ray with small VSDs is normal. With larger defects there may be cardiomegaly and pulmonary plethora. The ECG often has features of biventricular hypertrophy.


Many small VSDs decrease in size or close spontaneously. In untreated cases complications of pulmonary hypertension and aortic valve prolapse may develop. Early surgical closure is indicated in cases where congestive cardiac failure develops in infancy or if pulmonary hypertension is present. Repair at a later age may be required if the defect fails to close or aortic valve prolapse develops.

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Sep 7, 2016 | Posted by in EMERGENCY MEDICINE | Comments Off on Congenital heart disease

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