Author: Jason M Kendall, Robert Tulloh / Editor: Steve Fordham / Codes: PAP13 / Published: 17/06/2013 / Review Date: 17/06/2016
Introduction
Context
Congenital heart disease (CHD) accounts for 10% of all congenital anomalies. It is still the commonest cause of death in the first year of life. Children with CHD may present at any time from birth to adult life. They may require intervention immediately or not at all. About one-third of children will have severe defects and become symptomatic in infancy.
Children or adults with undiagnosed CHD will often present to the emergency department (ED) with complications of their underlying disease. Even those who have undergone correction often have residual deficits making them prone to acute illness.
Definition
CHD is defined as structural heart disease present at birth. It is common and affects around 1% of all newborns (actual incidence of 8 per 1000 live births).
Potential outcome
The outcome for an infant with CHD depends on the type and severity of the defect as well as the presence of extra-cardiac malformations which are more common in this group of children. The more complex, cyanotic defects carry a poorer prognosis. Many of these are associated with death in infancy without surgical treatment. Those who have successfully undergone surgery usually remain well through childhood but the prognosis for adult life remains unclear.
The role of the clinician
Non-specialist clinicians are often nervous about potential misdiagnosis and treating such diseases incorrectly. The consequence of such errors can be the rapid demise of the patient. This article will help the emergency physician feel more confident about identifying problems related to CHD and how to treat them.
Pathophysiology
(i) Circulatory changes at birth:
Fetal circulation differs from postnatal circulation in two important ways:
- Oxygenated blood enters the circulation from placental transfer
- Pulmonary blood flow accounts for less than 20% of total cardiac output due to high pulmonary vascular resistance
Starting at birth and continuing over the first few days of life the cardiovascular system undergoes several physiological changes:
- The lungs inflate causing a decrease in pulmonary vascular resistance allowing greater pulmonary blood flow and an increase in oxygen tension
- The ductus arteriosus (see Fig 1) closes soon after birth as the smooth muscle surrounding the ductus constricts in response to increased oxygen tension and fall in prostaglandins. Functional closure is complete within 60 hours in the vast majority of term newborns
- The increased pulmonary blood flow and increased pulmonary venous return leads to an increase in left atrial pressure, causing the foramen ovale (see figure 1) to close therefore separating the right and left atria
- The ductus venosus closes as the flow dwindles in the umbilical vein after the umbilical cord has been clamped
Physiological closure of these structures in certain types of CHD may lead to deterioration in the infants clinical condition, classically seen in duct-dependent circulations. Clinical problems are also seen when these structures remain patent beyond the immediate postnatal period, for example patent ductus arteriosus.
Fig 1: Structure of newborn heart
(ii) Classification:
CHD is broadly classified as cyanotic or acyanotic.
Acyanotic lesions account for approximately 75% of CHD and acyanotic CHD is associated with increased or normal pulmonary blood flow (Fig 1).
Cyanotic lesions account for approximately 25% of CHD and cyanotic CHD is associated with right to left shunt i.e. reduced pulmonary blood flow (Fig 2).
(iii) Aetiology:
There are many genetic and environmental factors that make CHD more likely and these should be sought when taking the history. Specific gene defects are known in almost all the conditions (Table 1). Maternal factors are also associated with certain forms of CHD (Table 2).
Table 1: Specific gene defects:
Table 2: Maternal factors:
Clinical Presentation
Common types of CHD
Table 1 provides a summary of the more common types of CHD and their presentations.
The following sections detail the various presentations of CHD in the ED and outline the defects, clinical features, investigations and management of the examples mentioned in Table 1.
Left to Right Shunts
(1) Atrial Septal Defect
There are two main types of ASD:
- Secundum ASD (80% of ASDs)
- Partial atrioventricular septal defect (primum ASD, pAVSD)
Both present with similar symptoms and signs, but their anatomy is quite different. The secundum ASD is a defect in the centre of the atrial septum involving the foramen ovale (Fig 1). Partial AVSD is a defect of the atrioventricular septum.
Fig 1: Secundum ASD
Clinical presentation
| Symptoms |
|
| Physical Signs |
|
Investigations
| Chest radiograph |
|
| ECG |
|
| Echocardiography |
|
Management
Children with significant ASD will require treatment. For secundum ASDs this is by cardiac catheterisation with insertion of an occlusion device but for partial AVSD surgical correction is required. Treatment is usually undertaken at about 3-5 years of age in order to prevent right heart failure and arrhythmias in later life.
(2) Ventricular Septal Defect
VSDs are common, accounting for 30% of all cases of congenital heart disease. There is a defect anywhere in the ventricular septum (Fig 2), perimembranous (adjacent to the tricuspid valve) or muscular (completely surrounded by muscle).
They can most conveniently be considered according to the size of the lesion. Small VSDs are smaller than the aortic valve in diameter, perhaps up to 3 mm. Large VSDs and complete AVSDs are the same size or bigger than the aortic valve.
Fig 2: VSD
(i) Small VSD
Clinical presentation
| Symptoms |
|
| Physical Signs |
|
Investigations
| Chest radiograph |
|
| ECG |
|
| Echocardiography |
|
Management
These lesions will close spontaneously. This is ascertained by the disappearance of the murmur with a normal ECG on follow-up by a paediatrician or paediatric cardiologist and by a normal echocardiogram. Whilst the VSD is present, prevention of bacterial endocarditis is attempted by maintaining good dental hygiene.
(ii) Large VSD
Clinical presentation
| Symptoms |
|
| Physical Signs |
|
Investigations
| Chest radiograph |
|
| ECG |
|
| Echocardiography |
|
Management
Drug therapy for heart failure is with diuretics often combined with captopril. Additional calorie input is required. There is always pulmonary hypertension in children with large VSD or complete AVSD and left-to-right shunt. This damages the lungs as increased pulmonary blood flow and pulmonary hypertension will ultimately lead to irreversible damage of the pulmonary capillary vascular bed. (Eisenmenger Syndrome, see later).
To prevent this, surgery is usually performed at three to six months of age in order to manage heart failure and failure to thrive and to prevent permanent lung damage from pulmonary hypertension and high blood flow.
(3) Patent Ductus Arteriosus
The ductus arteriosus connects the pulmonary artery to the descending aorta. In term infants, it normally closes shortly after birth. In PDA, it has failed to close by one month due to a defect in the constrictor mechanism of the duct. The flow of blood across a PDA is then from the aorta to the pulmonary artery (i.e. left to right Fig 3), following the fall in pulmonary vascular resistance after birth. In the preterm infant, the presence of a PDA is not from congenital heart disease but due to prematurity.
Fig 3: Patent ductus arteriosus
Clinical presentation
| Symptoms |
|
| Physical signs |
|
Investigations
| Chest radiograph |
|
| ECG |
|
| Echocardiography |
|
Management
Closure is recommended to abolish the lifelong risk of bacterial endocarditis and of pulmonary vascular disease. Closure is with a coil or occlusion device introduced via a cardiac catheter at about 1 year of age. Occasionally, surgical ligation is required.
Summary of left-to-right shunts
Right to Left Shunts
(1) Tetralogy of Fallot
In Tetralogy of Fallot, as implied by the name, there are four cardinal anatomical features (see Fig 1):
- A large VSD
- Overriding of the aorta with respect to the ventricular septum
- Subpulmonary stenosis causing right ventricular outflow tract obstruction
- Right ventricular hypertrophy as a result
Tetralogy of Fallot is the most common cause of cyanotic CHD and these children often present with cyanosis (oxygen saturations 94%) or collapse, usually in the first week of life.
Fig 1: Tetralogy of Fallot
Clinical presentation
| Symptoms |
|
| The classical description of severe cyanosis, hypercyanotic spells and squatting on exercise, developing in late infancy, is now rare in developed countries, but still common in the developing world.It is important to recognise hypercyanotic spells, as they may lead to myocardial infarction, cerebrovascular accidents and even death if left untreated. They are characterised by a rapid increase in cyanosis, usually associated with irritability or inconsolable crying because of severe hypoxia, and breathlessness and pallor because of tissue acidosis. | |
| Physical Signs |
|
Investigations
| Chest radiograph |
|
| ECG |
|
| Echocardiography |
|
Management
Initial management is medical, with definitive surgery at around 6 months of age. It involves closing the VSD and relieving right ventricular outflow tract obstruction, sometimes with an artificial patch, which extends across the pulmonary valve.
Infants who are very cyanosed in the neonatal period require a surgically placed shunt to increase pulmonary blood flow.
Hypercyanotic spells
Hypercyanotic spells are usually self-limiting and followed by a period of sleep. If prolonged (beyond about 15 minutes), they require prompt treatment with:
- Fluid: 20 ml/kg bolus
- Oxygen: high-flow
- blocker intravenous propranolol: 20 mcg/kg slowly
- Antibiotics: assume infection was the precipitating factor
- Morphine can be used sparingly, avoid respiratory depression, (50 100 mcg/kg sc/im/iv)
- agonist: this can be life saving if other measures have not worked quickly. Use phenylephrine (0.1 mg in a 10 ml syringe, dilute to 10 ml with saline, and give very small aliquots until pulse and cardiac output return). The patients hands and feet will go white temporarily
Hypercyanotic spells are an indication for early surgery. Do not send a child home from the emergency department (ED) without informing cardiology.
(2) Transposition of the Great Arteries
The aorta is connected to the right ventricle, and the pulmonary artery is connected to the left ventricle. Deoxygenated blood is therefore returned to the body and oxygenated blood is returned to the lungs. There are two parallel circulations. Unless there is mixing of blood between them, this condition is incompatible with life.
Fortunately, there are a number of naturally occurring associated anomalies, e.g. VSD, ASD and PDA, as well as therapeutic interventions which can achieve this mixing in the short-term.
Fig 2: Transposition of the Great Arteries
Clinical presentation
| Symptoms |
|
| Physical signs |
|
Investigations
| Chest radiograph |
|
| ECG |
|
| Echocardiography |
|
Management
- In the sick cyanosed neonate, the key is to improve mixing
- Maintaining the patency of the ductus arteriosus with a prostaglandin infusion is mandatory
- A balloon atrial septostomy may be a life-saving procedure which may need to be performed in 20% of those with transposition of the great arteries
- All patients with transposition of the great arteries will require surgery, which is usually the arterial switch procedure in the neonatal period
Other Causes of Common Mixing presenting with cyanosis:
Pulmonary atresia with intact ventricular septum or with VSD
Pulmonary atresia is a complete blockage between the right ventricle and the pulmonary artery. The circulation is dependent on mixing of blood via an ASD, VSD or PDA.
Truncus arteriosus
If the aorta and pulmonary artery do not divide, the child is born with a persistent truncus arteriosus or common arterial trunk. This one big artery has one large valve instead of there being pulmonary and aortic valves. Mixed oxygenated and deoxygenated blood are carried both into the pulmonary and systemic circulation.
Ebsteins anomoly
The right atrium is unusually large and the right ventricle small with a low riding tricuspid valve and an ASD; the result is reduced pulmonary blood flow and mixing through the ASD.
Summary of right-to-left shunts
Outflow obstruction in the well child
(1) Aortic Stenosis
The aortic valve leaflets are partly fused together, giving a restrictive exit from the left ventricle. There may be one to three aortic leaflets. Aortic stenosis may not be an isolated lesion.
Clinical presentation
| Symptoms |
|
| Physical signs |
|
Investigations
| Chest radiograph |
|
| ECG |
|
Management
In children, regular clinical and echocardiographic assessment is required in order to assess when to intervene. Children with symptoms on exercise or who have a high resting pressure gradient (more than 64 mmHg) across the aortic valve will undergo balloon valvotomy. Balloon dilatation in older children is generally safe and uncomplicated, but in neonates this is much more difficult and dangerous.
Most neonates and children with significant aortic valve stenosis requiring treatment in the first few years of life will eventually require aortic valve replacement. Early treatment is therefore palliative and directed towards delaying this for as long as possible.
(2) Pulmonary Stenosis
The pulmonary valve leaflets are partly fused together, giving a restrictive exit from the right ventricle (see figure).
Clinical presentation
| Symptoms |
|
| Physical Signs |
|
Investigations
| Chest radiograph |
|
| ECG |
|
Management
This uncommon lesion is not duct dependent. It gradually becomes more severe over many years.
(3) Adult type Coarctation of the Aorta
Coarctation of the aorta is a narrowing of the aorta.
Clinical presentation
| Symptoms |
|
| Physical signs |
|
Investigations
| Chest radiograph |
|
| ECG |
|
Management
When the condition becomes severe, as assessed by echocardiography, a stent may be inserted at cardiac catheter. Sometimes surgical repair is required.
Summary of Outflow obstruction in the well child
Outflow obstruction in the sick infant
Coarctation of the aorta presenting in infancy
CoA is due to arterial duct tissue encircling the aorta just at the point of insertion of the duct. When the duct closes, the aorta also constricts causing severe obstruction to the left ventricular outflow. These children usually present sick with heart failure and shock in the neonatal period.
Clinical presentation
| Symptoms |
|
| Physical signs |
|
Investigations
| Chest radiograph |
|
| ECG |
|
Management
- Management is to resuscitate first (ABC)
- Prostaglandin should be commenced at the earliest opportunity
- Referral is made to a cardiac centre for early surgical intervention
Adolescent and Young Adult Presentation of CHD
An acute medical emergency related to CHD in the adolescent and young adult population is rarely due to a new presentation of structural CHD.
Presentation of CHD in adolescence and young adults includes:
- Postoperative complications (e.g. pericardial effusion, infective endocarditis, pulmonary hypertension)
- Arrhythmias
- Pulmonary Hypertension (i.e. Eisenmenger Syndrome)
- Left ventricular outflow obstruction
- HOCM (hypertrophic obstructive cardiomyopathy)
- Aortic stenosis
- This may the first presentation of congenital heart disease, perhaps with an atrial arrhythmia
Eisenmenger Syndrome
As a consequence of a large left-to-right shunt for many years, the pulmonary vascular resistance will slowly rise. Eventually, the shunt will reverse and the patient will become cyanosed, typically at about 15-20 years of age (Eisenmenger Syndrome).
At this point they are usually stable for many years, with typical survival into the 4th or 5th decade of life. However, they may then present with some of the complications of a right-to-left shunt and of pulmonary hypertension.
Patients with Eisenmenger Syndrome can present with:
(i) Syncope
- This may be the first presenting feature in a child or young adult with pulmonary hypertension. It must be differentiated from teenagers who present with neurocardiogenic syncope or vasovagal syncope.
- Taking a good history is important, and then clinical examination will detect cyanosis, a loud P2 and right ventricular heave.
- ECG will show right ventricular hypertrophy.
(ii) Exercise intolerance and asthma or COPD or breathlessness on exertion
- This is often the next insidious symptom of pulmonary hypertension, often due to Eisenmenger syndrome. Non-wheezing asthma is the cardinal feature. Again full history, clinical examination and ECG will assist in the detection of such patients. Generally, the first presentation of severe asthma should be accompanied by an ECG after early management.
(iii) Haemoptysis
- This is often a preterminal event in Pulmonary Hypertension or Eisenmenger Syndrome. It may occur with a chest infection or when there is severe right heart failure.
(iv) During Pregnancy
- Those with pulmonary hypertension due to any cause are usually advised not to become pregnant. If this does occur, it is lethal in 50% of cases and management must be undertaken in a specialised unit.
General approach to management in the ED
There are three main ways CHD may present to the ED:
- Collapse and shock e.g. coarctation of the aorta presenting in the neonate
- Heart failure e.g. large VSD in a 3 month old baby
- Cyanosis e.g. Fallots tetralogy
In addition, CHD may also present with an asymptomatic heart murmur, but this is not usually to the ED.
Infants may present to the ED non-specifically unwell with features of cardiovascular collapse and it is important to remember other causes of cardiorespiratory compromise in addition to CHD. In particular, it is often difficult to differentiate CHD from pulmonary disease or sepsis in the newborn.
Learning Bite
Always include CHD in the differential diagnosis of any critically ill newborn.
(1) Collapse and shock
A patient with CHD may present with collapse and shock, which is defined as an acute state where the circulation is inadequate to meet the metabolic demands of tissues.
However, other cardiac conditions (e.g. cardiomyopathies, arrhythmias, pericardial effusion, etc.) may also present in a shocked state. There are also many non-cardiac causes of shock (e.g. sepsis, anaphylaxis, inborn errors of metabolism) which must be considered in the differential diagnosis of shock and metabolic acidosis.
Collapse and/or shock due to structural heart disease is usually associated with left-sided obstructive lesions that result in inadequate systemic blood flow (eg aortic stenosis, coarctation).
Specific features of shock include:
- Reduced spontaneous movements
- Mottled skin
- Prolonged capillary refill time
- Decreased pulses or Narrow pulse pressure
- Hypothermia and Widening of toe-core temperature difference
- Tachycardia
- Tachypnoea and Respiratory distress
- Hypotension
- Oliguria/ anuria
- Lactic acidosis
Management
General principles
General principles of resuscitation are crucial, airway, breathing then circulation. Maintain adequate inspired oxygenation, regardless of the cause.
There is often a concern that giving oxygen may be dangerous, (e.g. might close a life-sustaining ductus). In general resuscitation, this is highly unlikely and standard resuscitation interventions should be used first. Once the cause of collapse is known, then this can be modified.
Management of the neonate
- Strongly consider commencing a prostaglandin infusion even before a diagnosis has been made.
- Starting dose of PGE2 is typically 5 nanogm/kg/min
- Watch for apnoeas
- Consider volume expansion, but only repeat if there is an improvement
Volume expansion
- Only give fluid if there is good evidence of Hypovolaemia
- Follow local policy on whether to use colloid or crystalloid but consider:
- Plasma expander (e.g. 4.5% Human Albumin Solution) 5 ml/kg
- Normal Saline 10 ml/kg
- Packed Red Cells 5 ml/kg if there is evidence of recent blood loss or PCV <0.35
- Give fluid volume cautiously in increments over 30 minutes
- Larger boluses may be required for rapid intravascular expansion
Discuss with a cardiologist early
- Consider Invasive BP monitoring (always be aware of possibility of Coarctation)
- Consider CVP monitoring
- Correct metabolic acidosis
Consider inotropes if there is:
- Large heart on chest radiograph
- No improvement with fluid bolus
- Catecholamines (adrenaline, noradrenaline, dopamine, dobutamine)
- Phosphodiesterase inhibitors (milrinone, enoximone) rarely used in the emergency situation
Use markers of tissue perfusion to decide threshold for intervention
Assess effects of intervention using HR, BP, acid base status and perfusion
Non-cardiac causes of collapse and shock in the infant:
The table below outlines the management you should always consider when a sick collapsed baby presents to the ED.
Learning Bite
Do not forget non-cardiac causes of shock in a patient with CHD, especially sepsis.
(2) Heart failure
Tachypnoea is the major feature of heart failure in children.
The diseases implicated are very different in the first week of life to those after this time:
- Up to 7 days, most infants with heart failure have an obstructed left heart, especially with duct dependent lesions (most likely to be coarctation of the aorta)
- After 7 days, this is most likely to be due to left to right shunt (most likely to be VSD)
Specific features of heart failure
- Poor feeding
- Excessive weight gain
- Tachypnoea, breathlessness
- Head bobbing
- Respiratory distress
- Fine crepitations on auscultation
- Poor peripheral perfusion
- Sweating
- Mottled, clammy, cool skin
- Poor femoral pulses
- Tachycardia
- Hyperdynamic precordium
- Gallop rhythm
- Hepatomegaly
- Cardiomegaly and increased pulmonary vascularity on chest X-ray
- Specific signs due to underlying cause
Children will not present in heart failure with left to right shunt due to CHD after 1 year, since they will be developing pulmonary vascular disease by this time. The thickening of the pulmonary artery walls in response to the left-to-right shunt, will limit the pulmonary blood flow and the signs of heart failure.
Management
The principles of managing heart failure in the first week of life are to give prostaglandin with or without inotropes
The principles of managing heart failure after the first week of life are to reduce preload with diuretics and reduce afterload with ACE inhibitors whilst maintaining optimal nutritional intake.
During the first year of life, the pulmonary vascular resistance has continued to rise, such that the features of cardiac failure gradually resolve. Patients will be developing pulmonary hypertension and pulmonary vascular disease.
Specific features of managing heart failure include the following:
- Resuscitate as appropriate, but be careful: do not give too much fluid
- Check that the infant is improving with each bolus of fluid
- If not, then consider that an inotrope or other infusion may be needed
- Consider commencing a prostaglandin infusion even before an exact diagnosis has been made if there is suspicion of a duct-dependent lesion
- Discuss with a cardiologist early if cause unknown
- Correct anaemia if present
- Consider inotropes if there is evidence of myocardial dysfunction
- Give furosemide IV 1 mg/kg 6 to 12 hourly, if there are good femoral pulses
Learning Bite
Prostaglandin is likely to be beneficial for infants with heart failure in the first week of life; pre-load and after-load reduction with diuretics and ACE Inhibitors are used for heart failure presenting beyond 1 week, once outflow tract obstruction is excluded.
(3) Cyanosis
Cyanosis is the clinical description of the bluish discolouration of the skin and mucous membranes that corresponds to greater than 5 g/dl of deoxygenated haemoglobin in the blood. Mild degrees may not be observed and a saturation monitor should be used to confirm normality. Look for central cyanosis in the tongue and mucous membranes.
Cyanosis (oxygen saturation less than 94%) may be due to cardiac disease, respiratory disease, metabolic disease or sepsis.
Pitfall
Be mindful of where the saturation probe is positioned. It should be in the right hand to pick up cyanotic heart disease (Pre-ductal saturation). If only the feet are blue (post-ductal saturation), then it could be due to right to left shunt at the duct in coarctation of the aorta.
Assessing cyanosis
When assessing whether cyanosis may be present, remember the following points:
- Peripheral cyanosis is normal in the first few days of life and cyanosis only whilst crying is rarely significant
- Polycythaemia or methaemoglobinaemia may cause a baby to appear blue but are not associated with structural cardiac defects
- Anaemia and dark skin tones make it more difficult to detect cyanosis
- Some babies with cyanotic heart disease may appear fairly pink due to the high affinity for oxygen of fetal haemoglobin
Learning Bite
Cyanosis with little or no respiratory distress and lack of radiographic evidence of lung disease suggests underlying congenital heart disease.
Management
In a neonate (under 4 weeks), it is always worth considering the use of a prostaglandin infusion. Oxygen is not helpful in the treatment of cyanotic CHD, indeed, one of the ways to make the diagnosis is to show that there is little improvement in saturations when oxygen is given. Then an echocardiogram performed by an expert in this field can be undertaken. Operation is performed appropriate to the condition.
MedicoLegal and other considerations
Key Learning Points
- It is important to assess the whole patient with known CHD when they present to the ED because CHD is often part of a syndrome with physiological disturbances beyond the heart
- Heart failure in the first week of life is due to an obstructed left ventricle. It is potentially life threatening and is likely to require a prostaglandin infusion
- Heart failure in the infant beyond the first week of life is due to a left to right shunt, usually a VSD
- A sick collapsed neonate can reasonably be treated for respiratory disease, sepsis and cardiac disease together until a definitive diagnosis is made
- Many patients with CHD present with non-specific symptoms and signs, such as breathlessness and failure to thrive. They are often misdiagnosed as respiratory disease
- Left to right shunts will not present with heart failure after the first year of life
- Cyanotic congenital heart disease will not respond to oxygen therapy
- Adults with CHD may present to ED as a complication of known CHD, or as a new presentation with complications
- Pulmonary Hypertension has many causes, any of which will be improved with oxygen therapy
- Paediatric Heart Disease: a Clinical Guide. Piers Daubeney, Michael Rigby, Michael Gatzoulis, Koichiro Niwa. BMJ Books 2012.
- Congenital Diseases of the Heart: Clinical-Physiological Considerations. Abraham Rudoplh. Wiley-Blackwell Publications. 2009.