Atrioventricular septal defect Flashcards
What is an atrioventricular septal defect?
Spectrum of congenital heart malformations that share a defect in the atrioventricular septum and abnormalities in the AV valves (mitral and tricuspid)
How can AVSDs be classified?
Complete
Partial
What percentage of all congenital heart defects do AVSDs account for?
5%
Which syndrome is strongly associated with AVSDs?
Downs syndrome (trisomy 21)
When does the AV septum form?
4-5 weeks
What do AVSD defects arise from?
Failure of superior and inferior endocardial cushions to fuse correctly leading to displacement of AV valves and causing the inlet portion of ventricular septum to be scooped out
Describe the pathophysiology in complete AVSD
Increased shunting of blood from left to right occurring at both atrial and ventricular levels
Pulmonary vascular resistance decreases normally over first 6 weeks of life and patient develops a large left to right shunt through both atrial and ventricular defects
Causes excessive pulmonary blood flow leading to heart failure and elevated pulmonary vascular resistance AV valves are usually abnormal and incompetent resulting in regurgitation
Describe the pathophysiology of partial AVSD
Left to right shunting at the level of atrial septal defect
Causes volume overload of both right atrium and right ventricle and pulmonary over circulation but pulmonary pressures are usually normal to mildly elevated therefore symptoms may be minimal until adulthood or may present in late childhood
Give some clinical features of AVSD
Tachypnoea Tachycardia Poor feeding Sweating Failure to thrive
What does the severity of clinical symptoms of AVSD depend on?
The degree of pulmonary overload and heart failure
When do virtually all AVSD patients have symptoms?
By 1 year of age
Give some examination findings of AVSD
Undernourished child - shows characteristics of downs syndrome, signs of congestive heart failure, hepatomegaly, gallop rhythm, generalised oedema and crackles may be present
Hyperactive precordium
Prominent systolic heave along the left sternal border
Palpable apical thrill
Auscultation -ejection systolic murmur or mid diastolic murmur. Wide and fixed splitting of S2
What investigations would you do for AVSD
Bloods - karyotopying for trisomy 21
ECG
CXR
Echo
What ECG changes occur with AVSD?
Superior QRS axis
Prolonged PR interval
P wave morphology
Right ventricular hypertrophy
What is shown on CXR in AVSD?
Cardiomegaly
Prominent pulmonary artery
Pulmonary vascular markings
