Abstract
Background: The thoracic aorta is made up of the ascending, descending, aortic arch, and aortic root. An aneurysm in the aorta is a ballooned part in the artery that exceeds the artery’s usual diameter by fifty percent. It develops due to weakening and thinning of the arterial wall.1 Thoracic aneurysms are far less common than abdominal aortic aneurysms and data supports that 10 out of every 100,000 elderly adults may get affected by it.2 Patients with thoracic aortic aneurysms (TAA) rarely experience symptoms, and 95% of TAA patients are asymptomatic.
Case history: A 47-year-old male patient came with a medical history of hypertension, dyslipidemia, and but no smoking. During the first visit, the patient presented with two months of dull back pain. The patient’s blood pressure was 180/110 mm of Hg. The initial assessment involved performing an X-ray of the chest and an echocardiography (ECHO). The images and data from the ECHO and X-ray revealed a thoracic aneurysm on the descending part. After a confirmatory CT scan, the diagnosis of TAA was made.
Conclusion: In our case report, conservative method was successful in the management of a mild symptomatic descending thoracic aortic aneurysm. However, the size, growth pace of an aneurysm, underlying cause of an aortic aneurysm, and severity of symptoms are the deciding factors for doctors to recommend either conservative or surgical intervention to repair it.3 If an aneurysm ruptures or dissects, immediate surgery may be required.
In general, surgical indications of abdominal aortic aneurysms (AAA) are based on size and growth rate of aneurysm, and the existence of symptoms. American College of Cardiology, American Heart Association and European Society of Cardiology guidelines6,7 have recommended the surgical repair for all symptomatic AAAs (ruptured, associated with dissection, causing pain) regardless of aneurysm size. For asymptomatic patients, these guidelines have recommended the surgical repair in the existence of degenerative thoracic aneurysm, chronic aortic dissection, intramural hematoma, penetrating atherosclerotic ulcer, mycotic aneurysm or pseudoaneurysm, and for patients whom the ascending aorta or aortic sinus diameter is 5.5 cm or greater.
Keywords: Thoracic aortic aneurysm, asymptomatic, Thoracic endovascular aortic repair
Introduction
The thoracic aorta is made up of the ascending part, aortic arch, descending part, and aortic root.4 An aneurysm forms when the artery’s usual diameter increases by fifty percent.5
When the aneurysm’s diameter, whether it is in thoracic or in abdominal part of the aorta, is greater than 10 cm, it is considered as giant (thoracic/abdominal) aortic aneurysm.2,3
Thoracic aortic aneurysms (TAAs) are less common than abdominal aortic aneurysms and it affects 10 out of every 100,000 elderly adults.2
It occurs due to the intrinsic fragility of the aortic wall. Patients with TAAs rarely experience symptoms, and 95% of TAA patients are asymptomatic.6, 7 The reason these aneurysms are referred to as “silent killers” is that they can result in severe consequences like aortic dissection or rupture.8 Twenty-two percent of patients who have an aneurysm complication die before reaching the hospital.9 Most TAAs affect the ascending or root of aorta, which is followed by the descending and occasionally the arch of aorta.9
There are multiple possible etiologies for TAAs. Patients who develop symptoms or experience aneurysm-related problems (such as acute aortic regurgitation, dissection, or aortic rupture) should have their TAA repaired. However, the majority of these patients do not show any symptoms.[10] Reducing aortic stress and preventing additional aortic enlargement are the goals of conservative therapy of asymptomatic TAA.10 Patients with no symptoms who don’t fit the repair criteria also need to have their aneurysms monitored continuously. Endovascular repair has been increasingly utilized as a first-line treatment.11 The endovascular technique has several advantages such as avoiding the need for an incision during a thoracotomy or sternotomy, preventing aortic cross-clamping, reducing blood loss, and lessening end-organ ischemia.12 In this study, we are reporting a case of a mild symptomatic descending thoracic aneurysm.
Case History
A 47-year-old male patient came with a medical history of hypertension and dyslipidemia. He had never smoked. During the first visit, the patient presented with a complaint of back and chest pain for two months. On examination the patient’s blood pressure was 180/110 mm of Hg. Our initial assessment involved taking a chest X-ray and an ECHO. The data from his ECHO and the image from the X-ray [Fig.1] revealed him to be having a thoracic aneurysm. After a confirmatory CT scan, the diagnosis of TAA was established.
In the CT aortogram report, there was evidence of a left-sided aortic arch with the aorta emerging from the left ventricle. Aneurysmal dilatation of the descending thoracic aorta was seen where the length of the aneurysm was calculated to be about 23 cm with fusiform dilatation and eccentric circumferential thrombus inside (maximum diameter 9.2 x 8.5 cm, contrast filed lumen measures about (6.8 x 6.2) cm. [Fig.2]
Other than back and chest pain, the patient did not exhibit any mass-effect symptoms such as dyspnea or cough. He got a full cardiac evaluation at that time, showing no abnormalities in heart function and 0.9 mg/dl of blood creatinine. Consequently, we advised the patient to undergo the surgical procedure. However, the patient was noncompliant and strongly preferred TAA’s conservative management. Based on our assessment, we decided to start the patient on conservative treatment and monitor him for a year.
At a follow-up after four months, the CT angiography showed no problems. The patient was doing well and we got no complaints from the patient regarding his health at the 12-month follow-up.
Fig-1: A) Chest x-ray, B) Echocardiography of the patient
Fig- 2: A) & B) CT angiogram of the patient
Discussion
TAAs are thought to be under-reported in frequency since they often show no symptoms. Six to ten cases are estimated to occur for every 100,000 patients in a year.13 Patients with TAA greater than 6.0 cm had an estimated 15.6% likelihood of rupture, dissection, or mortality from all causes before surgical intervention. The same study found that only 54% of patients with large TAAs survived for five years without surgery.14
The pathophysiology of TAA involves a process known as cystic medial necrosis where the muscle, collagen, and elastin tissue within the tunica media of the aorta wall are damaged due to degeneration.2,15 As a consequence of the high pressure of intraluminal blood flow, the aortic wall weakens and dilates. This definition distinguishes an aneurysm from a false aneurysm, where the latter is a perivascular pulsatile hematoma resulting from a vessel injury that is frequently observed during endovascular operations.2
Mycotic aneurysm is another kind that arises from infection and can be confirmed with the presence of two or more of the following characteristics—sepsis, positive blood culture, positive culture from the aneurysmal wall, or a distinctive radiological appearance.2,16 Another kind of aneurysm develops after an acute episode of aortic dissection.2
Since hypertension is a contributing factor in 50–60% of deaths from TAAs (aortic dissection and rupture), the patient in this case was diagnosed with the illness before receiving treatment. 15% of patients with aneurysms greater than 10 cm survive for five years.2 A triple abnormality may be manifested by diastolic murmurs and, less frequently, by the signs and symptoms of congestive heart failure. However, massive TAAs can also result in a local mass effect, such as compression of the trachea or mainstem bronchus, which can induce dyspnea, coughing, fatigue, wheezing, chest pain, or recurrent pneumonitis.2,17,18 Another common symptom of an aortic rupture is sudden, severe pain in the neck, back, chest, and/or abdomen.2
Primary or secondary aortoesophageal fistulae (AEsF) are categorized as complications in large TAAs. It is well recognized that the majority of TAA patients have no symptoms, and the diagnosis is often obtained by accident when doing imaging examinations for other purposes.2,17,18 As the gold standard for diagnosis, contrast-enhanced CT scans and MR angiography are the recommended imaging techniques to evaluate aneurysms.2,17,18
Unless they exhibit symptoms or comorbidities, patients with aneurysms smaller than 6 cm are typically not candidates for surgery and may instead get medicinal treatment. For individuals with proven aneurysm growth of more than 1 cm annually, repair is also advised. Elective surgery can be performed at a size of 5.5 cm for ascending and 6.5 cm for descending aortic aneurysms. Comparing propranolol to non-blocker therapy, studies have demonstrated a noticeably slower rate of aortic dilatation, fewer aortic events, and decreased mortality.2,17,18
Conclusion and Recommendations
In our case report, conservative method was successful in the management of a mild symptomatic descending thoracic aorta aneurysm (DTAA). We found our patient was experiencing no problem at his last follow-up. However, the size, growth pace, and underlying cause of an aortic aneurysm are the key parameters for clinicians to recommend surgical repair or conservative management. If an aneurysm ruptures or dissects, immediate surgery may be required. Open surgical repair and thoracic endovascular aortic repair (TEVAR) are the most common types of surgeries performed.19 Intervention may not be beneficial for survival in DTAA <55 mm. To defend surgery in the small aneurysm group, operative outcomes need to be remarkable. It is necessary to obtain additional data from case series and case-control studies to elucidate the late complications and re-intervention rate after a 5-year follow-up.20
Review of the Case Report with Guidelines
Professor Abul Hassan Muhammad Bashar, MBBS, BCS (Health), PhD (Japan), FACS (USA) have the following observations regarding the case report.
- Traditionally the management of descending thoracic aortic aneurysm (DTAA) is dictated by size, symptoms, growth rate and complications. The cut-off diameter for surgical intervention is >5.5 cm as revised by American Heart Association (AHA) and American College of Cardiology (ACC) in 2022. Interventions are recommended for even smaller aneurysms in some specific conditions like Marfan’s syndrome, heritable thoracic aortic aneurysms etc.
- Relative aortic aneurysm size in relation to body surface area is considered a more important parameter than absolute aortic size in predicting complications. Using the aortic size index (ASI) of aortic diameter (cm) divided by body surface area (m2), patients can be stratified into the following three groups; ASI < 2.75 cm/m 2 – Low risk for rupture (4%/year); ASI 2.75-4.25 cm/m 2 – Moderate risk (8%/year); ASI >4.25 cm/m 2 – High risk (20-25%/year). Sharing the ASI for this patient can give a more objective perspective for predicting complications.
- Aneurysm growth of ≥0.5 cm/y is also a risk factor for rupture (AHA/ACC-2022). Follow-up CT angiography may be included to compare aneurysm growth.
- From the size consideration, the patient described in the present report was perhaps a candidate for intervention. Given the extent of the aneurysm (Crawford Type I), it would be an extremely challenging undertaking with the existing facilities in the country. However, pros and cons of surgery and endovascular management vis a vis conservative treatment should be discussed, even if it is a theoretical exercise.
- It is apparent in the one year follow up that the patient did not complain of new symptoms. For a wider reach in the cardiac management society the clinician may share the conservative treatment that was prescribed to the patient including the modification of risk factors. In particular, optimization of BP control and agents used should be discussed.
- Surgical/endovascular treatment for DTAA is now feasible in Bangladesh. Introduction of Thoracic Endovascular Aortic Repair (TEVAR) has opened a whole new avenue for these patients and early outcome is highly satisfactory with very low rates of complications. Device cost remains an obstacle which is expected to ease out in the years to come.
Case Report by:
Dr. Golam Mahfuz Rabbani, MBBS, BCS (Health ), MD (Cardiology), Interventional Cardiologist, Department of cardiology, Jashore Medical College Hospital, Jashore, Bangladesh.
Reviewed by:
Prof. Dr Abul Hasan Muhammad Bashar, MBBS, BCS (Health), PhD (Japan), FACS(USA), Professor, Dept. of Vascular Surgery, NICVD, Dhaka
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