What signs and symptoms of cardiovascular dysfunction can be seen on inspection of the child?

Consider the following 2 cases and discuss the questions below before reading the tutorial.

Case A

A 3 month old baby presents with poor feeding and failure to thrive. She was born at term after a normal pregnancy. Mum describes that the baby always breathes very fast, that she takes a long time to feed and gets very sweaty. On examination the baby is pink, malnourished and breathless. She has a respiratory rate of 50 and has marked intercostal and sub-costal recession. She has a loud pan-systolic murmur and her liver is palpable at 2cm. A CXR shows increased pulmonary vascular markings and a large heart [>60% of the thoracic diameter].

Case B

A 9 year old girl presents with fever and chest pain. Her mother informs you that she had a sore throat a few weeks ago for which she did not receive any treatment. On examination you notice that her right knee and left elbow are swollen and painful. On auscultation of her heart you hear a loud pansystolic murmur.

Questions:

1. What is meant by “cyanotic” or “acyanotic” cardiac lesions? List example of each.
2. What is Eisenmengers syndrome?
3. What is meant by duct dependence?
4. How can you recognise cardiac disease in children?
5. What is the likely diagnosis for case A and where does it fit into your classification?
6. List as many different cardiac lesions as you can think of and describe the type, and location of the murmur associated with it eg aortic stenosis, ejection systolic murmur, upper right sternal edge.
7. Describe how you would systematically look at a paediatric CXR and some of the features you may be looking for in cardiac disease.
8. What investigations, if available, could help you to identify cardiac disease?
9. What is the diagnosis for case B and what is the likely cause of the heart murmur? How many children worldwide do you think are affected with this condition?
10. What are the features of an ‘innocent’ heart murmur?

Tutorial:

Heart disease in children may be congenital or acquired. This tutorial will consider the different types of heart disease in children and the recognition and investigation of children with heart disease.

1. Congenital heart disease

i. Structural heart defects

The incidence of congenital heart disease [CHD] varies between 5 and 8/1000 live births. The cause of most congenital heart disease is unknown, but is likely to be related to genetic defects, teratogens [such as maternal alcohol or drugs, including anti-epileptics or warfarin], or maternal disease [rubella, diabetes].

The incidence of different types of structural heart disease varies between populations, but ventricular septal defect [VSD] is the most common lesion in all populations. The incidence of different types of CHD is shown in table 1 below.

Table 1. The incidence of types of CHD in the UK

ii. Genetic defects

Recognisable chromosomal abnormalities are present in 25% of children with CHD. The diagnosis of a chromosomal abnormality should lead to active assessment for CHD. The most common chromosomal abnormality is Down’s syndrome [trisomy 21] – 40% of children with Down’s syndrome have CHD, most commonly atrioventricular septal defect [AVSD] or VSD. Genetic defects associated with cardiac lesions are shown in table 2 below:

Table 2. Genetic defects associated with cardiac lesions

iii. Classification of structural defects

It is useful to classify congenital heart disease according to the pathophysiology of the major heart lesion, in particular, whether the lesion is associated with cyanosis [‘blue’] or is acyanotic [‘pink’], also whether the lesion is associated with abnormal flow between the cardiac chambers [abnormal ‘shunt’], obstruction to flow, abnormal connections of the major vessels or abnormal mixing.

Table 3. Classification of common congenital heart lesions

iv. Duct dependent circulation

In utero, the placenta is the main site for gas exchange for the developing foetus and the blood flow to the foetal lung is minimal. Blood from the right ventricle bypasses the lungs and passes directly from the pulmonary artery to the aorta via a foetal vessel called the arterial duct. After birth, a number of changes occur in transition from the foetal to the newborn circulation including expansion of the lungs [which reduces pulmonary vascular resistance] and closure of the arterial duct, so that blood now perfuses the lungs. There are certain severe congenital cardiac lesions that are only compatible with life if the arterial duct remains open – the circulation is said to be ‘duct dependent’. These babies typically present with acute collapse as the duct closes within the first 5 days of life [the differential diagnosis is septic shock].

Examples of duct dependent circulations include critical coarctation of the aorta [duct dependent systemic circulation] or pulmonary atresia [duct dependent pulmonary circulation]. In critical coarctation there is extreme narrowing of the aorta just where the arterial duct joins the aorta, and blood supply to the lower half of the body is only possible if it passes from the pulmonary artery to the descending aorta via the duct. In pulmonary atresia, the only blood supply to the lungs is that which passes from the aorta to the pulmonary artery via the duct. Continued survival of these babies requires infusion of prostglandin E1 [prostin] to keep the duct open until urgent cardiac surgery is possible. NB prostin also causes pyrexia and apnoeas and these babies may require ventilation while on prostin infusions.

v. Eisenmenger’s syndrome

Lesions associated with left to right shunt, such as AVSD, cause high pulmonary blood flow and congestive cardiac failure. The normal physiological response to high pulmonary blood flow is for the pulmonary vascular resistance to increase. With time, the pulmonary vascular resistance will exceed the systemic vascular resistance, and the flow across the shunt will reverse [Eisenmenger’s syndrome]. Clinically, this is associated with an initial improvement in symptoms of cardiac failure as pulmonary blood flow reduces, followed by increasing cyanosis as the shunt reverses to become right to left. Surgical closure of the shunt is not possible at this stage as the resistance to flow through the pulmonary circulation is too high and right ventricular failure will occur. Individuals with Eisenmenger’s syndrome are deeply cyanosed, may develop haemoptysis, endocarditis or cerebral abscess, and will eventually die from cardiac failure.

Eisenmenger’s syndrome occurs before the age of 1 year in children with very high pulmonary blood flow, such as unrepaired AVSD, but may occur at the age of 40-50 years in adults with unrepaired ASD who have had moderately increased pulmonary blood flow over many years. Corrective cardiac surgery to avoid Eisenmenger’s must be undertaken before the onset of pulmonary vascular disease, the ideal age dependent on the severity of the underlying lesion.

vi. Further details and diagrams of the normal heart and common congenital heart lesions.

See the following web links for further details of congenital heart lesions:

• //www.med.yale.edu/intmed/cardio/chd/
• //www.nlm.nih.gov/medlineplus/ency/article/001114.htm

vii. Arrhythmias in children

Another form of congenital heart disease in children may be the presence of abnormal conduction pathways that lead to the development of cardiac arrhythmias, particularly supraventricular tachycardia.

Supraventricular tachycardia may be caused by abnormal conduction pathways such as the Wolf-Parkinson-White syndrome, characterised on the ECG by a short P- R interval and an abnormal delta wave on the upstroke of the QRS complex. The child may develop sudden episodes of tachycardia associated with heart rates of >240beats/min, up to 300beats/min. These appear on ECG as narrow complex rhythms. The child may feel faint and uncomfortable during an arrhythmia. The arrhythmia may terminate spontaneously or be terminated by vagal manoeuvres such as brief immersion of the face in ice cold water, carotid sinus massage [massage to the carotid artery in the neck], or in older children, a Valsalva manoeuvre. Specific treatment is with rapid bolus of intravenous adenosine, or if this fails, synchronised cardioversion. Beta blockers may be used to prevent further episodes of tachyarrhythmia – many children will grow out of these episodes with time. Transcatheter radiofrequency ablation of the accessory pathway is undertaken in specialist centres for older children whose symptoms are not controlled by drugs.

Supraventricular tachycardia must be differentiated from ventricular tachycardia [VT]. In VT the rate is often slower [ 5 years.

Percussion

• may be useful to estimate liver size and the presence of ascites [rarely due to cardiac failure in children]

Auscultation

• Cardiac murmurs. Cardiac murmurs associated with a left to right shunt such as a VSD may not be very obvious in the newborn period when the pulmonary vascular resistance is high. The pulmonary vascular resistance falls in the first few days of life – the loud systolic murmur due to a VSD will become apparent and the child may develop increasing heart failure as the flow increases across the shunt. The loudness of cardiac murmurs may be graded.

Table 5. Cardiac murmurs in children

Innocent cardiac murmurs.

The commonest murmur heard in children is the functional, innocent or physiological heart murmur, which is heard in 10% of normal children. The classical innocent murmur in children is the known as the ‘Still’s’ murmur. Innocent murmurs may also be due to flow murmurs associated with increased cardiac output, heard in children with a fever or anaemia. The heart is structurally normal in all children with an innocent murmur. A murmur in a child may be classified as innocent if the child has no other signs or symptoms of cardiac disease, and the murmur has certain characteristic features:

• Soft [no thrill]
• Systolic and short [never pansystolic]
• Asymptomatic
• Best heard at the left sternal edge, no radiation
• Changes with posture – softer when standing

iii. Investigations

Special investigations include the CXR, ECG, echocardiography and cardiac catheterisation.

Chest X-Ray. In looking at the CXR in a child, always consider the age of the patient and if the film was taken in the sitting or lying position. The CXR should be evaluated systematically:

A – Adequacy and alignment

The film should be sufficiently penetrated to just visualise the disc spaces of the lower thoracic vertebrae through the heart shadow. At least 5 anterior rib ends should be seen above the diaphragm on the right hand side. Alignment can be assessed by ensuring that the medial ends of both clavicles are equally spaced about the spinous processes of the upper thoracic vertebrae.

B – Bones

Check the ribs, clavicles and vertebrae. [Rib notching is sometimes seen in severe coarctation of the aorta]

C – Cartilage and Soft Tissues

Lungs: Compare side to side and upper, middle and lower third of the chest. Look for pleural effusions, pneumothorax, vascular markings that are increased or decreased [plethoric or oligaemic], fluid in the fissures, white lung areas which could be consolidation or haemorrhage.

Heart: Look at the size of the heart, is it enlarged? Is the shape unusual? [see below]. In normal infants the heart is up to 60% of the thoracic diameter, 50% thereafter. Remember that a normal cardiac shadow does not rule out cardiac disease.

The upper mediastinum: In children under the age of 18 months, the normal thymus may simulate superior mediastinal widening [above the level of the carina].

D – Diaphragms

The boarder between the heart and the diaphragm and the diaphragm and the ribs [cardiophrenic and costophrenic angles] should be clear on both sides. Loss of definition of the left diaphragm behind the heart suggests left lower lobe collapse, an abnormal hump suggests diaphragmatic rupture, a hazy diaphragm suggests effusion or collapse in the bordering lung segment, and an elevated diaphragm suggests phrenic nerve palsy.

There are some classical appearances of the CXR in children:

• ‘Egg-on-side’ = Transposition of great arteries in a neonate.
• Boot shaped heart = Tetralogy of Fallot [right ventricular hypertrophy and reduced pulmonary markings
• ‘Snowman in a snow storm’ = Obstructed total anomalous pulmonary venous connection in a neonate.
• Globular heart. Usually associated with pericardial effusions, may be secondary to pericarditis or dilated cardiomyopathy.
• Situs. In the normal situation [situs solitus] the heart is on the left with the gastric bubble on the left and the liver on the right. In situs inversus these relations are reversed.
• Oligaemic lung fields are seen in conditions associated with reduced pulmonary blood flow such as TOF and pulmonary atresia.
• Plethoric lung fields are seen in children with left to right shunts, especially VSD and AVSD.

The electrocardiogram [ECG]

The ECG may be useful to investigate rhythm and conduction abnormalities, as well as assessing chamber hypertrophy and strain. Interpretation of the paediatric ECG is complex and must take the child’s age into account, with comparison to tables of normal values.

Echocardiography

Echocardiography is a form of cardiac imaging that uses reflection of ultrasound pulses from interfaces between tissue planes. It can be used to generate detailed real time images of the cardiac anatomy. Doppler ultrasound may be used to estimate pressure gradients across valves and VSDs. Echocardiography has become the standard investigation for all patients with valvular heart disease, congenital heart disease, myocardial and pericardial disease, and in assessing myocardial function.

Cardiac Catheterisation

Cardiac catheterisation is used to answer specific diagnostic questions in children with congenital heart disease. A catheter can be passed into the heart chambers under X-ray control to measure intracardiac pressures and oxygen saturations, or for radiological imaging by injection of contrast media. Interventional cardiology is a growing speciality that provides definitive treatment for a growing number of conditions, for instance closure of ASD or PDA by insertion of occlusion devices, balloon dilatation of pulmonary stenosis, or diathermy ablation of abnormal conduction pathways.

Further reading

Paediatric cardiology: an introduction. Archer N, Burch M. Chapman Hall Medical. Philadelphia 1998

Answers to Questions.

Most answers are covered in the tutorial text.

1. A lesion is “cyanotic” if it allows deoxygenated blood to bypass the lungs and mix with oxygenated blood in the systemic circulation. This makes the patient cyanosed with low saturations. A lesion where there is either no mixing of oxygenated and deoxygenated blood, or the lesion allows oxygenated blood to pass from the left side of the heart to the right is termed “acyanotic”. The patients’ saturations are normal.
2. See text.
3. See text.
4. See text.
5. The diagnosis in Case A could be any of the acyanotic lesions. She has a history starting at birth so it is unlikely to be due to an acquired infective illness.
6. See table 5.
7. See text.
8. See text.
9. Case B: Rheumatic heart disease with mitral regurgitation. About 8 million children are affected worldwide.
10. See text.