Congenital Heart Defects Flashcards by Lauren Horsburgh

What are the two shunts present in the foetal circulation which allow mixing of the oxygenated and deoxygenated blood?

Ductus arteriosus

Foramen ovale

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Describe the foetal circulation

The foetus receives oxygenated blood from the mother’s placenta. Because the lungs are not fully formed, the vascular resistance within the pulmonary arteries is high therefore the blood from the IVC takes the path fo elastic’s resistance and passes through the foramen ovale directly into the left atrium. A minority of blood will pass into the right ventricle and through the pulmonary vein but nearly all of this passes through the ductus arterioles into the aorta.

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The chambers of the heart are identified by their characteristic and not by their position. T/F?

True

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What is the difference in morphology between the appendages of the right and. left atria?

Right- broad appendage

Left - narrow, sausage-shaped appendage

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What is the difference in morphology between the right and. left ventricles?

Right - heavy trabeculations, muscular band called the moderator band, chordae tendinae insert into the septum
Left - smooth endocardium, 2 papillary muscles, ellipsoid cavity

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The atrioventricular valve always follows the atrium. T/F?

False - it follows the ventricle

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The aortic and pulmonary valves always stay with their relevant artery and so can be connected to the wrong ventricle. T/F?

True

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Give examples of acyanotic congenital heart defects

Ventricular septal defects
Persistent ductus arteriosus
Atrial septal defects
Pulmonary stenosis
Aortic stenosis
Coarctation of the aorta

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Give examples of cyanotic congenital heart defects

Tetralogy of fallot
Transposition of the great arteries
Atrioventricular septal defects

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What is the most common type of atrial septal defect?

Secundum

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Where in the atria does the hole occur in a secundum atrial septal defect?

Centre of the atria

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Where in the atria does the hole occur in a primum atrial septal defect?

Close to the atrioventricular valve which can distort the valve leading to it becoming leaky or regurgitant

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How can a secundum atrial septal defect lead to right ventricular failure?

Causes a left to right shunt as blood moves from a higher to lower pressure. The extra blood being received into the right ventricle causes right ventricle dilation which inhibits the ability of the ventricle to pump efficiently and will eventually cause right ventricular failure

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It is not unusual for ASDs to be first diagnosed in adulthood. T/F?

True

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What are the possible presentations of an atrial septal defect?

Murmur
Arrhythmia and palpitations due to stretching of right atrium
Shortness of breath
Embolic stroke

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How are atrial septal defects treated?

Surgically with a sternotomy

Through the groin vessels with a transcatheter device

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At what point in the aorta is a coarctation commonly seen?

Insertion point of the ductus arteriosus.

After the left subclavian artery

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How can a coarctation of the aorta lead to left ventricular failure?

The narrowing of the aorta means that the left ventricle has to generate a higher pressure to push the blood through so the patient will develop left ventricular hypertrophy which can progress to left ventricular failure

What are the possible presentations of severe coarctation of the aorta?

Poor lower limb perfusion (cold feet, claudification of the legs, abdominal angina)
Headache and nosebleeds due to increased systemic pressure proximal to the coarctation

Hypertension may be the result of coarctation of the aorta. T/F?

True

What discrepancies in blood pressure may you find in a patient with coarctation of the aorta?

Upper limb pressure is greater than the lower. limb pressure

There may be radio-femoral defat in coarctation of the aorta. T/F?

True

What other congenital defects is aortic coarctation associated with?

Bicuspid aortic valve

Berry aneurysms

How can coarctation of the aorta be treated?

Surgery - narrowed aorta is cut out or reconstructed using the subclavian artery
Transcatheter - balloon passed through and inflated to stretch the narrowed artery

Describe the congenital defect which occurs in transposition of the great arteries?

The aorta and the pulmonary artery switch places so that the aorta is attached to the right ventricle and the pulmonary artery is connected to the left ventricle

Transposition of the great vessels affects males more than females. T/F?

True - in a 4:1 ratio

How can the embryonic shunts be kept open in a baby with transposition of the great arteries to keep the infant alive until surgery can be performed?

Prostaglandins

Describe the atrial switch procedure which used to be performed on patients with transposition of the great arteries?

A channel is created for venous blood to pass into the pulmonary artery via the left ventricle and the atrial septum is cut away to allow oxygenated blood to pass through the right atrium and into the aorta via the left ventricle. This is how venous blood is redirected to the appropriate side of the heart

What is the major issue with the atrial switch procedure used to treat patients with transposition of the great arteries?

The right ventricle is expected to pump blood through the systemic circulation which is not designed to do and so systemic ventricular failure will develop over time

In the arterial switch procedure to treat transposition of the great arteries, the aorta and pulmonary artery are disconnected and switched into their appropriate positions. What is the major difficulty in this procedure?

Care needs to be taken with the coronary arteries which have to be reconnected to the aorta If not carefully stitched back on, these can occlude and cause an Mi or sudden-death post-operatively.

What are the four components to tetralogy of fallot?

Ventricular septal defect Right ventricular outflow obstruction Overriding aorta Right ventricular hypertrophy

What is an overriding aorta?

Aortic valve is enlarged and appears to arise from both the left and right ventricles

What is involved in the corrective surgery for tetralogy of fallot?

Closing VSD with a patch Resection of the right ventricular outflow obstruction Enlargement of the pulmonary artery with a patch.

What are some of the long term issues with repaired tetralogy of fallot?

Progressive regurgitation of the pulmonary valve leading to right ventricle overload, dilatation and eventually failure Increase in right ventricular pressure can cause a rise in right atrial pressure which then dilates and can trigger arrythmia Patients with BT shunts may develop pulmonary artery stenosis

What is a univentricular heart?

A congenital heart condition which results in only one effective pumping ventricle.

What are some of the anomalies which can be described as single ventricle defects?

Tricuspid atresia Hypoplastic left heart syndrome Doublet inlet of left ventricle

Surgery in patients with univentricular hearts aims to create two functioning ventricles but this is not possible in all patients. In this case, what type of circulation will be created for the patient?

Fontan circulation

Describe fontan circulation

A single ventricle supports the systemic circulation by disconnected it form the pulmonary valve and artery The IVC and SVC are redirected and plumbed straight into the pulmonary arteries ultimately bypassing the heart altogether. Deoxygenated blood flows directly from the IVC/SVC to the pulmonary arteries, is oxygenated in the lungs and returns to the left atrium, passes through the mitral valve into the single ventricle and is then passed through the aortic valve into the aorta and systemic circulation

Describe the timeline of surgeries required to create a Fontan circulation

BT shunt - first few days after birth Norwood procedure - first week of life Bi-driectional glen - 3-6 months Fontan completion - 2-3 years

Describe the Norwood operation

The right ventricle becomes the systemic ventricle A new aorta is made from part of the pulmonary artery and the original artery is reconstructed to provide blood flow to the body A small tube graft is placed either from an artery to the lung vessels or from the right ventricle to the lung vessels

Describe the BT shunt procedure

The carotid or subclavian artery is connected directly to the pulmonary artery

Describe the bi-drectional glen procedure

The SVC is taken off the heart and sewn directly onto the pulmonary artery

Why are patients with a Fontan circulation so haemodynamically vulnerable?

Without a right ventricle to actively pump blood into the pulmonary circulation, a sufficiently high systemic venous pressure is require to drive the deoxygenated blood directly into the pulmonary arteries Pulmonary vascular resistance needs to be low for optimal flow into the lungs