common Congenitial Cardiac Pathology in ct

Take note of abnormalities below and think as to how this may affect contrast enhancement and timings while performing chest angiograms.

vascular ring

A vascular ring occurs when the aorta or its branches form a complete ring around the trachea and the oesophagus.

This can occur from:

Double aortic arch (image across)
Right aortic arch with left ligamentum arteriosum

https://www.chop.edu/conditions-diseases/vascular-ring

RCH CASE EXAMPLE

Report:

1. Vascular ring secondary to double aortic arch variant (right arch dominant, with the left common carotid arising from the right arch).

2. Mild narrowing of the trachea at the level of the vascular ring and further mild focal narrowing at the origin of the right main bronchus

RCH CASE EXAMPLE

Right sided aortic arch with aberrant left subclavian vein causing posterior compression of the oesophagus as well as narrowing of the trachea. Mild narrowing and effacement of the proximal right main bronchus is noted in between the right pulmonary artery and descending aorta.

ventricular septal defect (VSD)

What is it?

The most common heart defect; it is a hole in the ventricular septum of any size that causes blood to flow from the RV to the LV.

Why could this be important to know in CT?

In cases of big VSD's, the contrast will enhance the LV and Aorta very quickly. If monitoring contrast in Angiograms this is useful to know as you may need to drop the delay to monitoring time to ensure you don't miss the peak enhancement.

https://www.rch.org.au/cardiology/heart_defects/Ventricular_Septal_Defect_VSD/

aortic stenosis (AS)

What is it?

Thickened and narrowed aortic valve that may lead to hypertrophy in the left ventricle.

Why could this be important to know in CT?

Gating these scans could lead to better visualisation of the aortic valve.

https://www.rch.org.au/cardiology/heart_defects/Aortic_Stenosis_AS/

aortic coarctation

What is it?

Stricture of the aortic arch

Why could this be important to know in CT?

The aorta will be very narrow in certain points. If possible try not to monitor/test bolus over this area as it would be hard to see enhancement in the aorta.

https://www.rch.org.au/cardiology/heart_defects/Coarctation_of_the_Aorta_HD/

RCH CASE EXAMPLE OF AORTIC COARCTATION

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double inlet left ventricle (DILV)

What is it?

In this abnormality both atria are connected to the left ventricle. Usually there is a small (hypoplastic) right ventricle (RV), which may be on the opposite side of the heart to the usual. The PA's and aorta are supplied from the pumping of the left ventricle.

Often associated with other cardiac abnormalities (PA stenosis, aortic coarctation)

Why could this be important to know in CT?

Everything will enhance at a similar time eg, PA's and aorta will enhance together.

https://www.rch.org.au/cardiology/heart_defects/Double_Inlet_Left_Ventricle_DILV/

double outlet right ventricle (DORV)

What is it?

In this abnormality, the two great arteries (Aorta and Pulmonary Artery) both originate from the right ventricle. Blood backflows from the left ventricle into the RV via the VSD to supply the great arteries.

Why could this be important to know in CT?

Everything will enhance at a similar time eg. PA's and Aorta will enhance together. There may be two peaks of contrast enhancement (one from the RV and one from the LV/VSD).

https://www.rch.org.au/cardiology/heart_defects/Double_Outlet_Right_Ventricle/

tetralogy of fallot (TOF)

What is it?

Consists of 4 abnormalities:

Pulmonary valve stenosis
Hypertrophied right ventricle
VSD
Shifting of the aorta towards the right so it sits above the VSD

This results in limited flow to the PA's and deoxygenated blood being circulated around the body.

Why could this be important to know in CT?

Important to know if this has been temporarily repaired with a shunt from the aorta to the PAs. Shunting may affect the timing of the scan as blood to the PA's would be supplied from the aorta rather than from the RV.

See image across (middle image)

<------------

Complete repair (below image)

<----------------

https://www.rch.org.au/cardiology/heart_defects/Fallots_Tetralogy/

hypoplastic left heart syndrome (hlhs)

What is it?

The left side of the heart is very poorly formed and cannot support the main circulation (around the body). The left ventricle and aorta are abnormally small (hypoplastic).

This is amongst the most severe forms of heart defect. Most babies are very ill in the early days of life and need urgent surgery to survive. Surgical intervention can include the following steps:

The first stage of surgery is called a 'Norwood' operation and can include a Sano shunt. This stage redirects blood flow to the PA's and improves the size and connection between the RV and aorta.

The next stage can include a BCPC shunt.

The final stage is called a Fontan operation.

sano shunt

Right ventricle to Pulmonary Arteries

bcpc shunt

Superior Vena Cava to Pulmonary Arteries

fontan

Inferior Vena Cava and Superior Vena Cava to Pulmonary Arteries

imaging a bcpc shunt

The PA's are only receiving blood from upper limb veins.

Why could this be important to know in CT?

The contrast will be very dense in the PAs if we use an upper limb PIVC. A lower limb PIVC is preferable in these patients as contrast will be less dense after circulating through the heart, body and back into the venous system to reach the PA's. This means a longer delay will be required prior to scanning.

Lower limb PIVC used

Left: 29 sec post contrast scan delay. Aorta higher density and BCPC shunt low contrast opacification. Contrast has not been given enough time to reach IVC--> Heart --> Aorta --> Upper limb and head --> SVC --> PA

Right: 59 sec post contrast delay. Contrast has recirculated round the body. Equal contrast opacaifacion of the aorta and BCPC shunt

imaging a fontan

The PA's and shunt now obtain their blood from the systemic venous system directly (not going through the heart prior to reaching PA's).

Why could this be important to know in CT?

The contrast will be very dense in the PAs initially.

Therefore we perform a long slow injection of contrast and scan at 90 seconds to ensure there is systemic circulation of contrast through the shunt.

If this is not captured then we can perform a second image at 150 seconds

Link to Fontan CTA Protocol: Force CT-CP-717 Fontan Gated CTA Chest.docx

patent ductus arteriosus

What is it?

Connection between aorta and PA's remains open after birth

Why could this be important to know in CT?

PA's may have two peaks of contrast enhancement (one from RV, one from Aorta)

https://www.rch.org.au/cardiology/heart_defects/Patent_Ductus_Arteriosus_PDA/

interrupted aortic arch

What is it?

Part of the aorta is absent. The PDA supplies the blood to the descending aorta. It is therefore crucial that the PDA stays open.

Why could this be important to know in CT?

Ascending Aorta will be enhanced off the LV, Descending aorta will be enhanced off PA's.

https://www.rch.org.au/cardiology/heart_defects/Interrupted_Aortic_Arch/

pulmonary stenosis (PS)

What is it?

Narrowing and thickened pulmonary valve. Causes reduced flow to PA's.

https://www.rch.org.au/cardiology/heart_defects/Pulmonary_Stenosis/

total Anomalous Pulmonary Venous Drainage (TAPVD)

What is it?

Pulmonary veins connect to systemic vein rather than the LA.

Can be connected to subclavian veins (above image) or connect inferior to the heart to the IVC (below image).

An ASD supplies the left heart.

https://www.rch.org.au/cardiology/heart_defects/Total_Anomalous_Pulmonary_Venous_Drainage/

transposition of the great arteries

What is it?

The aorta and PA's are on the wrong side. The PDA and foramen ovale must remain open to send oxygenated blood to the body. This is crucial for the survival of these patients prior to the correction surgery.

https://www.rch.org.au/cardiology/heart_defects/Transposition_of_the_Great_Arteries/

tricuspid atresia

What is it?

Absence of any connection between the right atrium and the right ventricle leading to blood being diverted from the right atrium to the left atrium.

These conditions are corrected by a BCPC shunt or Fontan Shunt (see above)

https://www.rch.org.au/cardiology/heart_defects/Tricuspid_Atresia/

major aortopulmonary collateral arteries (mapca's)

What is it?

MAPCAs are persistent tortuous fetal arteries that arise from the descending aorta and supply blood to pulmonary arteries in the lungs usually at the posterior aspect of the hilum.

Why could this be important to know in CT?

Enhancement of MAPCAs arise from aortic enhancement.

https://radiopaedia.org/articles/major-aortopulmonary-collateral-arteries

truncus arteriosus

What is it?

Common origin aorta and PA's. Patients have VSDs as well.

Will have conduit repair between RV and PAs (see image below)

Why could this be important to know in CT?

The Aorta and PA's will enhance at the same time if not corrected.

https://www.rch.org.au/cardiology/heart_defects/Truncus_Arteriosus/

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