Cardiac Disorders - Epidemiology Flashcards
Cardiac Disorders
Epidemiology
- *The most common congenital heart lesions**
- *Left-to-right shunts (breathless)**
- Ventricular septal defect 30%
- Persistent arterial duct 12%
- Atrial septal defects
Right-to-left shunts (blue)
- Tetralogy of Fallot 5%
- Transposition of the great arteries 5%
Common mixing (breathless and blue)
- Atrioventricular septal defect (complete) 2%
Outflow obstruction in a well child (asymptomatic with a murmur)
- Pulmonary stenosis 7%
- Aortic stenosis 5%
Outflow obstruction in a sick neonate (collapsed with shock)
- Coarctation of the aorta 5%.
Cardiac Disorder
Aetiology
Maternal Disorders:
Rubella infection (peripheral pulmonary stenosis PDA - 30-50%
Systemic lupus erythematosus Complete heart block (anti-Ro and anti-La antibody)
Diabetes melitus Incidence increased
Maternal drugs
Warfarin therapy Pulmonary valve stenoisis, PDA
Fetal alcohol syndrome ASD, VSD, tetrology of fallot
Chromosome abnormality
Downs syndrome (trisomy 21) Atrioventricular septal defect, VSD
Edwards syndrome (trisomy 18) Complex
Patau syndrome (trisomy 13) Complex
Turners Syndrome (45XO) Aortic valve stenosis, coarctation of the aorta
Chromosome 22q11.2 deletion Aortic arch anomalies, tetrology of fallot, common arterial trunk
William syndrome (7q11.23) Supravalvular aortic stenosis, peripheral pulmonary artery stenosis
microdeletion
Noonan syndrome (PTPN11 mutation) Hypertrophic cardiomyopathy, artrial septal defect pulmonary septal defect
Circulatory changes at birth
- In fetus, the left atrial pressure is low, as relatively little blood returns from the lungs. The pressure in the right atrium is higher than in the left, as it receives all the systemic venous return including blood from the placenta.
- blood returns from the lungs. The pressure in the right atrium is higher than in the left, as it receives all the systemic venous return including blood from the placenta.
- The flap valve of the foramen ovale is held open, blood flows across the atrial septum into the left atrium and then into the left ventricle, which in turn pumps it to the upper body
- With the first breaths, resistance to pulmonary blood flow falls and the volume of blood flowing through the lungs increases six-fold
- results in a rise in the left atrial pressure. Meanwhile, the volume of blood returning to the right atrium falls
- Meanwhile, the volume of blood returning to the right atrium falls as the placenta is excluded from the circulation
- The change in the pressure difference causes the flap valve of the foramen ovale to be closed.
- The ductus arteriosus, which connects the pulmonary artery to the aorta in fetal life, will normally close within the first few hours or days
Cardiac Disorder
Heart Murmurs
- Most common presentation of congenital heart disease is with a heart murmur
- Majority of children with murmurs have a normal heart. They have an ‘innocent murmur’, which can be heard at some time in almost 30% of children
It is obviously important to be able to distinguish an innocent murmur from a pathological one.
Hallmarks of an innocent ejection murmur are (all have an ‘S’, ‘innoSent’):
- aSymptomatic patient
- Soft blowing murmur
- Systolic murmur only, not diastolic
- left Sternal edge.
Also:
- Normal heart sounds with no added sounds
- No parasternal thrill
- No radiation.
Cardiac disorders
Heart failure
Symptoms:
- Breathlessness (particularly on feeding or exertion)
- Sweating
- Poor feeding
- Recurrent chest infections.
Signs:
- Poor weight gain or ‘faltering growth’
- Tachypnoea
- Tachycardia
- Heart murmur, gallop rhythm
- Enlarged heart
- Hepatomegaly
- Cool peripheries.
Cardiac disorders
Causes of heart failure
Neonates – obstructed (duct-dependent) systemic circulation
- Hypoplastic left heart syndrome
- Critical aortic valve stenosis
- Severe coarctation of the aorta
- Interruption of the aortic arch
Infants (high pulmonary blood flow)
- Ventricular septal defect
- Atrioventricular septal defect
- Large persistent ductus arteriosus
Older children and adolescents (right or left heart failure)
- Eisenmenger syndrome (right heart failure only)
- Rheumatic heart disease
- Cardiomyopathy.
Cardiac disorders
Cyanosis
- Peripheral cyanosis (blueness of the hands and feet) may occur when a child is cold or unwell from any cause or with polycythaemia
- Central cyanosis, seen on the tongue as a slate blue colour, is associated with a fall in arterial blood oxygen tension. It can only be recognised clinically if the concentration of reduced haemoglobin in the blood exceeds 5 g/dl, so it is less pronounced if the child is anaemic
- Check with a pulse oximeter that an infant’s oxygen saturation is normal (≥94%). Persistent cyanosis in an otherwise well infant is nearly always a sign of structural heart disease.
Cyanosis in a newborn infant with respiratory distress (respiratory rate >60 breaths/min) may be due to:
- Cardiac disorders – cyanotic congenital heart disease
- Respiratory disorders, e.g. surfactant deficiency, meconium aspiration, pulmonary hypoplasia, etc.
- Persistent pulmonary hypertension of the newborn (PPHN) – failure of the pulmonary vascular resistance to fall after birth
- Infection – septicaemia from group B streptococcus and other organisms
- Metabolic disease – metabolic acidosis and shock.
Cardiac disorders
Types of presentation with congenital heart disease
Congenital heart disease presents with:
- Antenatal cardiac ultrasound diagnosis
- Detection of a heart murmur
- Heart failure
- Shock.
- Cyanosis.
Cardiac disorders
Diagnosis
ECGs in children
https://www.slideshare.net/mandarhaval/pediatric-ecg
Important features
- Arrhythmias
- Superior QRS axis (negative deflection in AVF)
- Right ventricular hypertrophy (upright T wave in V1, over 1 month of age)
- Left ventricular strain (inverted T wave in V6)
Pitfalls:
- P-wave morphology is rarely helpful in children
- Partial right bundle branch block – most are normal children, although it is common in ASD
- Sinus arrhythmia is a normal finding.
Cardiac disorders
Left-to-right shunts
These are:
- Atrial septal defects
- Ventricular septal defects
- Persistent ductus arteriosus.
Atrial septal defect:
Cardiac disorders
Left-to-right shunts
Partial atrioventricular septal defect (primum ASD, pAVSD)
Partial AVSD is a defect of the atrioventricular septum and is characterised by:
- An inter-atrial communication between the bottom end of the atrial septum and the atrioventricular valves (primum ASD)
- Abnormal atrioventricular valves, with a left atrioventricular valve which has three leaflets and tends to leak (regurgitant valve).
Cardiac disorders
Left-to-right shunts
Physical signs
Symptoms:
- None (commonly)
- Recurrent chest infections/wheeze
- Arrhythmias (fourth decade onwards)
Physical signs:
- An ejection systolic murmur best heard at the upper left sternal edge
- A fixed and widely split second heart sound (often difficult to hear) – due to the right ventricular stroke volume being equal in both inspiration and expiration
- With a partial AVSD, an apical pansystolic murmur from atrioventricular valve regurgitation
Cardiac Disorders
Persistent ductus arteriosus (PDA, persistent arterial duct)
- ductus arteriosus connects the pulmonary artery to the descending aorta
- normally closes shortly after birth.
- In persistent ductus arteriosus it has failed to close by 1 month after the expected date of delivery due to a defect in the constrictor mechanism of the duct
Clinical features:
- a continuous murmur beneath the left clavicle
- murmur continues into diastole because the pressure in the pulmonary artery is lower than that in the aorta throughout the cardiac cycle
- pulse pressure is increased, causing a collapsing or bounding pulse.
- when the duct is large there will be increased pulmonary blood flow with heart failure and pulmonary hypertension
