Congenital Flashcards
What is the most common form of ASD; accounting for two-thirds of cases?
Ostium Secundum ASDs
Ostium Secundum ASDs involve what region of the IAS?
The region of the fossa ovalis (the most central part of the IAS).
How can ASDs be acquired?
As a result of 1. Balloon mitral valvuloplasty, 2. EP procedures or 3. Due to puncture during right heart catheterisation or pacing procedures.
What is often required to detect and fully assess an ASD?
‘Agitated’ saline contrast studies or a TOE.
Which is the best window to view/assess an ASD in?
The subcostal window.
True or false; right heart size may be dilated as a consequence of a left-to-right shunt in the presence of an ASD?
True.
With an ASD, what may be present (indicating right heart volume overload)?
Paradoxical septal motion.
In what part of the cardiac cycle does flow across an ASD usually occur?
Diastole.
Atrial septal aneurysms are associated with ASDs; how are aneurysms defined?
As a bulge protruding at least 10mm into the right or left atrium (or, if mobile, swinging by at least 10mm from side to side) and with a diameter across their base of at least 15mm.
How can an ASD be closed?
Percutaneously or surgically.
When is percutaneous close of a secundum ASD appropriate?
If there is an adequate rim of tissue around the defect to allow deployment of a septal occluder device.
Surgical closure of an ASD requires thoracotomy to open one of the atria and suture a patch over the defect, what is the patch made of?
Dacron or the patient’s own pericardium.
What is the most common type of VSD?
Perimembranous VSD.
Where are perimembranous VSDs located?
In the membraneous part of the septum (adjacent to the aortic and tricuspid valves).
How can perimembranous VSDs be classified?
As either a perimembranous outlet defect, or a perimembranous inlet defect.
Where are muscular VSDs located?
In the muscular part of the septum.
How can muscular VSDs be classified?
As anterior, mid-muscular, posterior (or inlet) and apical.
Multiple muscular VSDs are referred to as what?
A “Swiss cheese” septum.
What kind of murmur to VSDs produce?
A pan-systolic murmur.
True or false; the smaller the defect, the quieter the murmur.
False; the smaller the defect, the louder the murmur.
Describe the flow relationship with the cardiac cycle in a VSD?
Doppler will usually show high velocity flow (from left-to-right) during systole, with lower-velocity flow during diastole.
True or false; small VSDs are restrictive.
True.
Why do restrictive VSDs result in high-velocity flow?
Because minimal equalisation of pressures occurs, leading to a high pressure gradient between the LV and RV, causing a high-velocity Doppler signal.
True or false; RV dilatation occurs in the presence of a VSD.
False.
Why doesn’t RV dilatation occur with a VSD?
Because blood moves in systole from the LV to the RV to the PA without pooling in the RV.
In the presence of a VSD, left heart dilation can occur, why?
Because increased pulmonary blood flow (and therefore increased pulmonary venous return to the LA) can cause LA and LV dilatation due to volume overload.
A left-to-right VSD shunt can cause pHTN which may result in what?
Reversal of the shunt (Eisenmenger syndrome) - whereby deoxygenated blood will enter the systemic circulation (bypassing the lungs).
Eisenmenger syndrome reduces the overall oxygen content in the arterial circulation, patients will clinically present how?
With cyanosis (a blue discolouration of the skin and tongue), together with breathlessness and a fall in exercise capacity.
True or false; many VSDs will spontaneously close.
True.
VSDs that close spontaneously may leave what?
A small ventricular septal aneurysm as a remnant.
AVSDs can be subdivided into what two categories?
Complete or partial.
How are complete AVSDs characterised?
By a primum ASD that is contagious with an inlet VSD and the presence of a common AV valve.
What is a common AV valve?
A single atrioventricular connection that has a left component (the mitral valve in a normal heart), and a right component (tricuspid valve in the normal heart) that typically has five leaflets.
What are the five leaflets of a common AV valve?
Anterior and posterior bridging leaflets, an anterior leaflet and right and left lateral leaflets.
How are partial AVSDs characterised from complete AVSDs?
By the absence of an inlet VSD.
What are the anatomical hallmarks of a partial AVSD?
A primum ASD and a cleft in the aMVL (there are distinct mitral and tricuspid valves with a complete and separate annulus).
What is Qp/Qs?
A ratio between the stroke volume of the right and left heart and is a measure of the severity of shunting.
What is the ductus arteriosus?
A normal foetal cardiac structure that connects the superior junction of the main PA and left PA to the descending Ao.
What is the purpose of the ductus arteriosus?
It allows the majority of blood to reach the systemic circulation directly (thus bypassing the lungs) which do not serve any ventilatory function.
Usually the ductus arteriosus closes within the first day of life, leaving behind a chord like remnant known as what?
The ligamentum arteriosum.
What are the main clinical features of a PDA?
Difficulty in breathing/failure to thrive (in neonates), tachycardia, a wide pulse pressure/bounding pulse, machinery or Gibson’s murmur (a continuous systolic-diastolic murmur) and clubbing/cyanosis.
Will a PDA result in dilatation of the right or left heart?
Left heart.
Why does a PDA result in left heart dilatation?
Because left-to-right shunting will result in pulmonary over-circulation and left heart volume overload.
Why will no right heart dilatation occur with left-to-right shunting of a PDA?
Because shunting occurs at the level of the pulmonary artery.
True or false; with long-standing left-to-right PDA shunting, exposure of the pulmonary artery system to high pressure and increased flow results in a pulmonary HTN. If pulmonary vascular resistance exceeds systemic vascular resistance, ductal shunting will reverse (and become right-to-left).
True.
What may be present with a PDA that is also seen in aortic regurgitation?
Diastolic flow reversal in the descending Ao.
What medications can be used to close a PDA?
Prostaglandin inhibitors.
When might Prostaglandins be used to maintain patency of the ductus arteriosus?
In the presence of transposition of the great arteries.
Invasive techniques to close a PDA include what?
Percutaneous closure devices or surgical ligation.
What is the difference between a bicuspid and pseudo bicuspid AOV?
A bicuspid AOV has two functioning cusps (usually of equal size), with a single line of coaptation. Pseudobicuspid valves have three cusps, but with fusion of two of the cusps (by a raphe) so that the valve is functionally bicuspid.