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Aortobronchial Fistula - Causes, Symptoms, Diagnosis, and Treatment

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Aortobronchial fistula is a communication between the aorta and the tracheobronchial tree. Read the article to know more.

Written byDr. Sowmiya D

Medically reviewed byDr. Sapkal Ganeshrao Patilba

Published At January 29, 2022
Reviewed AtOctober 12, 2024

Introduction:

Aortobronchial fistula is a rare yet fatal condition that, if left untreated, has a high mortality rate. Some studies reveal that the incidence is underestimated because more than 30 % of cases are diagnosed only while performing an autopsy. The mortality rate is high because of low suspicion and the nature of the disease, wherein there is sudden massive hemoptysis that could be life-threatening.

What Is Aortobronchial Fistula (ABF)?

Fistulas are abnormal communication between any organ, blood vessel or any other structure. When it happens between an aorta and a tracheobronchial tree, it is called an aortobronchial fistula. Most of the time, the communication is between the aneurysm and the bronchus wall. The left bronchial tree is most commonly involved, as the distance between the descending aorta and the left bronchial tree is less than the distance between the ascending and right.

What Are the Causes?

Earlier in the 1960s, mycotic aneurysms, which are caused by tuberculosis and syphilis, were the leading cause of ABF. It was also due to degenerative aneurysms and postoperative pseudoaneurysms. Now, it is due to previous surgical graft treatment for aortic coarctation or a chronic aortic aneurysm. Primary aortobronchial fistula occurs very rarely in a patient who has not undergone cardiac surgery. In recent times, atherosclerosis and iatrogenic conditions have become the most common cause of ABF. It may also be due to pseudoaneurysms, traumatic thoracic aorta injuries, and penetrating aortic ulcers.

What Are the Symptoms of Aortobronchial Fistula?

Hemoptysis is the most typical symptom of aortobronchial fistula. But it is common in many other medical conditions also. A hemoptysis episode in a patient who has had a thoracic aortic aneurysm or undergone an aortic surgery should be intensely suspicious of aortobronchial fistula. Sometimes, even the first episode can end up fatal for the patient. Patients who develop ABFs often present with mild and intermittent hemoptysis, for which the etiology is diverse. It is further complicated to arrive at a proper diagnosis because of the lack of a diagnostic test that can clearly demonstrate an aortobronchial fistula. Other symptoms include back pain, chest pain, a mass near the aorta, or shock.

How to Diagnose Aortobronchial Fistula?

Diagnosis could be challenging even with radiography, CT (computed tomography) scan, bronchoscopy, and echocardiography. Diagnostic tests should be undertaken as soon as the airway is stabilized and hemodynamic status is assessed after an episode of hemoptysis. The chest radiographs demonstrated an aneurysm in 46.5 % of the cases, but the most reliable test is a thoracic aortogram. A fistulous tract was rarely identified preoperatively by angiography and bronchoscopy, and it is potentially hazardous as it can dislodge a sealing clot. Findings on CT include pseudoaneurysm, aortic anatomy abnormalities, lung parenchyma consolidation, and compression of the bronchial tree. CT is more efficient in determining the cause of hemoptysis than a bronchoscopy. Mostly, the diagnosis is based on the clinical signs rather than the imaging findings. After the diagnosis, multidisciplinary involvement should be made, considering patient risk factors and clinical stability.

What Are the Treatment Options?

When a patient has massive hemoptysis, the initial management will aim at protecting the airways and ensuring a stable hemodynamic volume. If the bleeding site is known, the patient is placed in a lateral decubitus position, with the bleeding side down. This prevents aspiration into the unaffected lung. The patient is then shifted to an intensive care unit, where careful monitoring and effective management are provided. Suppose the respiratory or hemodynamic status of the patient is compromised, and an emergency rigid bronchoscopy is attempted to clear the airways and safely isolate the non-affected lung, thus preserving ventilation. Once the hemodynamic and respiratory conditions are stabilized, then surgical management should be considered.

Traditionally, the surgery involved closure of the aortic side of the fistula by patch closure or prosthetic graft placement and repair of the bronchial side of the fistula by either resection or simple closure by direct suturing. The currently available treatment options include conservative therapy, open-heart surgery, and THEVAR (thoracic endovascular aortic repair). Thoracic endovascular stenting is a simpler and less invasive approach than traditional open-heart surgeries. However, they also have a risk of endoleak, migration, left arm ischemia, and infection due to direct communication with the contaminated airway. The treatment method to be used in each patient will depend upon the individual anatomy of the infected area, but careful steps must be taken to maintain distal perfusion. All the infected material or the prosthetic material must be removed, and a viable autologous biological barrier must be placed to avoid the future recurrence of fistulas. It can be taken from the pleura, diaphragm, vascularized intercostal or internal artery pedicle, or non-infected residual aneurysm sac.

What Are the Complications?

Studies show that complications occur many years after the intervention. As a consequence of infection or inflammation, there is always a chance for graft infection and erosion, leading to the recurrence of fistula. Other complications include stroke, paralysis, respiratory failure, acute renal insufficiency, ischemic cardiac events, acute hemorrhage, and secondary graft infection.

Some genetic or congenital conditions can enhance the risk of arteriovenous fistula. Some risk factors are

  • Old age.

  • Female gender.

  • Cardiac catheterization is done when the procedure includes blood vessels in the groin.

  • Some medications include blood thinners such as anticoagulants, and some medications are taken to control bleeding.

  • Enhanced blood pressure.

  • High BMI (body mass index).

When to See the Doctor?

If the person has signs and symptoms of this condition, they have to consult with the doctor immediately. Earlier, this condition was diagnosed, and it will be easier to treat. Earlier diagnosis can also help to prevent complications like blood clots and heart failure.

Conclusion:

Aortobronchial fistula is often a rare complication of thoracic aortic operations. If diagnosed, the survival rate is greater than 80 %. If not, the condition is fatal. Hence, an early diagnosis and prompt treatment are essential for the survival of the patient. Thoracic endovascular aortic repair of aortobronchial fistulas is an emerging treatment modality for this rare but highly lethal condition. In addition, the ABF may recur after an initially successful THEVAR procedure. The feasibility and long-term durability of this intervention are mainly unknown. Hence, continued clinical and radiographic surveillance is necessary.

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Frequently Asked Questions

ABF is the abbreviation for aortobronchial fistula. It is the connection between the thoracic aorta (the largest artery carrying blood from the heart to the body parts) and the adjacent tracheobronchial tree (the branch-like structure that supplies air to the lungs).
Generally, fistulas are difficult to treat without surgery. Nowadays, however, various treatment options are available other than surgery, depending on the type and severity of the fistula. For example, a bioprosthetic plug is used for anal fistulas.
If left untreated, fistulas can cause a lot of discomfort. Some fistulas, on being treated, can cause a bacterial infection, which in turn can lead to fistula drainage, abscess (pus-filled cavity), sepsis (a life-threatening complication of an infection), and risk of developing cancer. It can also turn a simple fistula into a complex one that is difficult to safely treat.
Fistula, if diagnosed and treated properly, may not be life-threatening as they are treatable easily. But if left untreated, they can be fatal as they can result in complications such as sepsis, a serious condition that can cause low blood pressure, organ damage, and even death.
The medications prescribed by the doctors depend on the type of fistula. Some of the medications given include vasodilators, antibiotics, calcium channel blockers, neuromuscular blockers, and benzodiazepines.
Fistula tracts do not heal on their own. Hence, they must be treated. Some fistulas are simple to treat, while some are complex tracts. But it should be noted that if one is experiencing symptoms of a fistula, they should get it checked immediately and the correct treatment as if left untreated for a long time, it can be dangerous for them.
Fistula requires immediate medical attention and can be treated if diagnosed early. However, fistula surgery can be an emergency if the fistula develops complications like an abscess, sepsis, and cancer.
Like any other surgery, fistula surgery also has some risks involved. Some of them are infection and chances of recurrence. Most fistula surgeries are performed through minimally invasive laparoscopic procedures, which involve fewer postoperative risks.
Fistula can rarely become cancerous. However, if left untreated for a long period of time, the risk of developing cancer increases. Some studies suggest that the presence of a fistula for more than ten years can sometimes result in cancer development.
Having curd and skimmed milk is beneficial for people suffering from anal fistula. Consuming curd can be helpful if one is suffering from an irritable bowel as curd has probiotics or good bacteria that can put healthy bacteria back into the digestive tract.
People suffering from fistula should avoid strenuous exercise, fatty and fried foods, smoking, alcohol, caffeine, and high sugar content. People with fistula should take every precaution as told by the doctor, as the aim is to get better and not worse.
Following the surgery, the person can experience mild to moderate pain or discomfort in the operated region. The surgery is performed under anesthesia, so the person will not feel pain during the surgery but may have postoperative pain.
Ayurveda does have a cure for fistula, but that depends on the location of the fistula and its severity. Ayurvedic treatments such as increasing digestive power using ayurvedic medicines are helpful in an anal fistula.
Fistula surgery can take about 30 minutes to one hour, depending on the type of fistula, but a person will have to spend some time in the hospital before and after the surgery. Most people can go back to their normal routine and work after one to two weeks of the surgery.
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Dr. Sapkal Ganeshrao Patilba from iCliniq
Dr. Sapkal Ganeshrao Patilba

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