[7] Thoracic Aortic Aneurysm Flashcards
What is an aneurysm?
A persistent, abnormal dilation of an artery to 1.5x its normal diameter
What can a thoracic aortic aneurysm involve?
- The ascending aorta or aortic root
- Aortic arch
- Descending aorta
- Thoracoabdominal aorta segments
What % of thoracic aortic aneurysms involve the ascending aorta or aortic root?
60%
What % of thoracic aortic aneurysms are in the aortic arch?
10%
What % of thoracic aortic aneurysms are in the descending aorta?
40%
What % of thoracic aortic aneurysms are in the thoracoabdominal aorta segments?
10%
What is more common, abdominal or thoracic aortic aneurysms?
Abdominal
What has a higher mortality, abdominal or thoracic aortic aneurysms?
Thoracic
Why is the classification of aortic aneurysms important?
Because aneurysms in different locations present with different symptoms, and have different levels of surgical risk
What do thoracic aortic aneurysms develop due to?
Degradation of the tunica media
What is the tunica media?
The layer of the artery which provides tensile strength and elasticity to the wall
What is the result of the degradation of the tunica media in the thoracic aorta?
They artery looses structural integrity and dilates
What happens as the diameter increases in the development of thoracic aortic aneurysms?
The wall tension rises and further increases the diameter in a vicious cycle
What are the main causes of thoracic aneurysms?
- Connective tissue disease
- Bicuspid aortic valve
- Trauma
- Aortic dissection
- Aortic arteritis
- Tertiary syphillis
Give two examples of connective tissue diseases that can cause thoracic aortic aneurysms
- Marfan’s syndrome
- Erlers-Danlos syndrome
Why is there an increased risk of thoracic aortic aneurysm in patients with Turners syndrome?
Due to increased risk of bicuspid aortic valve
Give an example of an aortic arteritis
Takayasu arteritis
What is the mean rate of growth of thoracic aortic aneurysms?
1-2mm/year
When is the rate of growth of thoracic aortic aneurysms higher?
- Marfan’s syndrome
- Descending aneurysms
- Dissected aneurysm
What are the main risk factors for developing thoracic aortic aneurysms?
- Family history
- Hypertension
- Atherosclerosis
- Smoking
- High BMI
- Male gender
- Advancing age
How are thoracic aneurysms typically found?
Incidentally - typically are asymptomatic
What is the most common presenting complaint in those with symptomatic thoracic aortic aneurysms?
Pain
Why is it important to know where the pain is in thoracic aortic aneurysms?
It can potentially localise the aneurysm
Where does an aneurysm in the ascending aorta cause pain?
Anterior chest
Where does an aneurysm in the aortic arch cause pain?
Neck
Where does an aneurysm in the descending aorta cause pain?
Between the scapulae
What are the other symptoms of thoracic aortic aneurysms?
- Back pain
- Hoarse voice
- Distended neck veins
- Symptoms of heart failure
- Dyspnoea or cough
Which thoracic aortic aneurysms can cause back pain?
Descending or thoracoabdominal
What causes back pain in thoracic aortic aneurysms?
Secondary to spinal compression
Which thoracic aortic aneurysm can cause a hoarse voice?
Aortic arch aneurysms
How can thoracic aortic aneurysms cause a hoarse voice?
Damage to the left recurrent laryngeal nerve
How can thoracic aortic aneurysms cause distended neck veins?
From SVC compression
How can thoracic aortic aneurysms cause symptoms of heart failure?
From involvement of the aortic valve
How can thoracic aortic aneurysms cause dyspnoea or cough?
Secondary to tracheal or bronchial compression
What are the clinical signs of thoracic aortic aneurysms on examination?
Clinical signs are not commonly found on examination, however chronic disease may present with the signs of aortic root disease or heart failure
What is the risk with thoracic aortic aneurysms?
They have a risk of rupture or dissection
How will an acute aortic syndrome present?
With sudden onset pain in the back, chest, neck, and/or abdomen
Why are differential diagnoses rarely considered before a diagnosis of a thoracic aortic aneurysm is made?
Because most thoracic aneurysms are found incidentally on imaging
What diagnoses should be considered in a patient presenting with chest or back pain?
- ACS
- PE
- Pneumothorax
- Aortic dissection
How are thoracic aneurysms diagnosed?
Imaging
What should initial inpatient and pre-operative testing involve in patients with thoracic aortic aneurysms?
- Routine bloods, including FBC, U&Es, and clotting
- Group and save
- ECG
- CXR
What imaging can be used in the diagnosis of a thoracic aortic aneurysm?
- CXR
- CT chest scan with contrast
- Transoesophageal echocardiography
What are the signs of thoracic aortic aneurysm on CXR?
- Widened mediastinal silhouette
- Enlarged aortic knob
- Possible tracheal deviation
What is the limitation of a CXR in the diagnosis of a thoracic aortic aneurysm?
A CXR alone is not sensitive enough to make a definitive diagnosis, and further imaging is required
What is the preferred imaging modality for thoracic aortic aneurysms?
CT chest scan with contrast
When is a CT scan with contrast sufficient to definitively diagnose a thoracic aortic aneurysm?
If there is sufficient detail to ascertain the level and size of the aneurysm
What care needs to be taken when measuring the size of a thoracic aortic aneurysm using a CT scan with contrast?
Due to the potentially tortous nature of the thoracic aorta, and the use of axial images in CT scans, care needs to be taken to ensure the actual aortic diameter is being measured, not simply measuring throug the aorta off-axis
How can the issue with measuring the aortic diameter using CT scans be overcome?
Reconstructing axial imaging into 3D images via CT angiography or MR angiography
How are confirmed thoracic aortic aneurysms intially be managed?
Start patients on medical management, alongside any concurrent further investigations and definitive management planned
What medical management should people with thoracic aortic aneurysms be started on?
These patients are at increased cardiovascular risk, and therefore should be initiated on;
- Statins
- Antiplatlet therapy
- Blood pressure management
They should also be encourged to stop smoking
Why should patients with thoracic aortic aneurysms be started on statins and anti-platelet therapy?
To decrease the risk of myocardial infarction
What is the surgical management of thoracic aortic aneurysms dependant on?
The location of the aneurysms
What does the threshold for surgery in thoracic aortic aneurysms depend on?
The health of the patient
Which patients often have a lower threshold for surgical intervention in thoracic aortic aneurysms?
- Patients with Marfan’s syndrome
- Those who have had a previous thoracic dissection
Why do patients with Marfan’s syndrome or a previous thoracic dissection have a lower threshold for surgical intervention?
They are at higher risk of dissection and rupture
What is an ascending aortic aneurysm treated surgically?
When the diameter >5.5cm
How is an ascending aortic dissection treated?
The affected region of the aorta is excised and replaced with a dacron graft
How is an ascending aortic aneurysm treated if the aortic root is involved?
A Bentall procedure is often performed, using a graft that also contains a prosthetic valve
When is an aortic arch aneurysm considered for surgical treatment?
Once the aneurysm is over 5.5cm
How is an aortic arch aneurysm treated surgically?
The affected aorta is replaced with a multi-limbed graft
Why is a multi-limbed graft used in the surgical treatment of aortic arch aneursyms?
It allows for branching of the great vessels
What is there a high risk of aortic arch aneurysm repair?
Cerebral ischaemia from embolisation
When should surgery be considered for the management of a descending aortic aneurysm?
When the diameter exceeds 6.0cm
How can descending thoracic aortic aneurysms be managed surgically?
Can be repaired using open technique or endovascular technique
What is the advantage of endovascular repair over open repair in descending thoracic aortic aneurysms?
It has been shown to produce fewer post-operative complications and have lower mortality
What is the result of the development of a second thoracic aortic aneurysm not being uncommon post-intervention?
Ongoing imaging studies as an outpatient are required following surgery
What imaging studies are used in the follow-up of post-treatment thoracic aortic aneurysms?
CT or MRI
What is the perioperative mortality of thoracic aortic aneurysms?
Between 2-17%
Which kind of thoracic aortic aneurysms have the highest mortality?
Arch aneurysms, 25% mortality
What is the annual risk of rupture or dissection of thoracic aortic aneurysms in patients who are monitored prior to surgery?
- 2% when <5cm
- 3% when 5-5.9cm
- 7% when 6cm or above
