What is Brachiocephalic (Innominate) Artery Compression Syndrome ?
Innominate artery compression syndrome (IACS) is a rare disease caused by an abnormal formation in the aorta (the main blood vessel in the body) called a vascular ring. This condition causes pressure on the windpipe and food pipe, affecting breathing and swallowing. Some vascular rings fully encircle the organs in your chest (complete rings), while others do not (incomplete rings). In IACS, specifically, the innominate artery doesn’t fully encircle the organs but puts pressure on the windpipe from the front, forming an incomplete ring.
The symptoms of IACS are different for different people, but it typically shows up in children. Some may experience mild breathing problems, like shortness of breath, wheezing, or persistent cough. Others might have repeated lung infections which are often misdiagnosed. In some severe cases, patients might have problems breathing, and using imaging tests or a bronchoscope (a device to look into the airways) can help doctors identify the issue quickly.
If a patient regularly shows symptoms, surgery might be considered to reduce the pressure on the windpipe. But those with less severe symptoms can often manage their condition with treatments focused on keeping their airways clear and controlling lung infections. Sometimes, extra oxygen may be provided if needed.
The first successful operation to treat a vascular ring was done by Dr. Robert Gross at Boston Children’s Hospital. He initially discovered a vascular ring during an autopsy (the examination of a body after death), prompting him to suggest that splitting the ring during a person’s lifetime could relieve the constricted windpipe and food pipe. Dr. Gross then applied these findings in real life: he successfully operated on a 1-year-old child with a double aortic arch, who had been persistently wheezing and frequently hospitalized due to severe lung infections. In 1953, Dr. Gross summarized his experience with surgery for aortic arch anomalies and, even after over 70 years, his recommendations are still considered relevant.
What Causes Brachiocephalic (Innominate) Artery Compression Syndrome ?
IACS, or Innominate Artery Compression Syndrome, falls under a group of conditions referred to as vascular rings. Vascular rings are abnormalities in the structure of the aorta and its branches that can cause the esophagus and trachea (the tube leading to the lungs) to be squeezed. This abnormality often arises during the early stages of fetal development as the aorta and its branches are forming.
The formation of the aorta starts with the aortic sac, which initially appears bloated above another structure called the truncus arteriosus. This sac eventually grows two extensions, leading to important parts of the aorta: the right side forms the brachiocephalic artery (supplying blood to the right arm and the head), and the left combines with the stem of the sac, forming an early part of the aortic arch – the primary artery carrying oxygenated blood from the heart.
Alongside the aortic sac, primitive aortic arches develop and play a role in forming significant arteries. For instance, the first arch contributes to the formation of the maxillary artery (which supplies blood to the face), the second helps form the hyoid and stapedial arteries, while the third forms the carotid arteries (supplying blood to the brain). Additionally, the fourth arch gives rise to the part of the subclavian artery that supplies blood to the right arm, whereas the left part of the same arch forms a part of the main aortic arch.
However, not all initial aortic arches persist or contribute to the final aortic system. For example, the fifth arch either never forms or regresses (shrinks and disappears), while the sixth arch separates into two parts, each contributing to the formation of the pulmonary arteries (carrying deoxygenated blood to the lungs).
If there’s any abnormality during the formation of these arches, like an unusual amount of growth or shrinkage, it can lead to vascular rings. This can result in varying degrees of compression on the trachea and esophagus, leading to a range of symptoms. For example, a right-sided aortic arch can form if the fourth arch on the right side persists while the left one shrinks. This can cause compression on nearby structures.
The most common types of vascular rings are classed as either “complete” (like right aortic arch with an aberrant left subclavian artery, or double aortic arch) or “incomplete” (like Innominate Artery Compression Syndrome or a condition called Pulmonary Artery Sling).
Complete vascular rings involve a ring of vessels surrounding and squeezing the trachea and esophagus, while incomplete rings don’t entirely encircle these structures. IACS is defined as an incomplete ring, where the innominate artery squeezes the trachea from the front by at least 75% to 80%.
There’s still some debate about the true anatomy of the innominate artery and whether IACS is a form of aortic arch malformation. Initially, it was thought that the compression occurs when the innominate artery, which runs from the left chest to the right arm, crosses the midline of the chest. Some recent studies looking at the anatomy of the aortic arch in infants and children found that the innominate artery originates from the front or left side of the trachea in most cases. However, only a small fraction of these showed symptoms significant enough to need surgery.
Furthermore, some evidence suggests that the origin of the innominate artery shifts to the right as a person grows into adulthood, which is why IACS is rarely diagnosed beyond infancy. Some researchers think IACS could be due to crowding in the space at the front of the chest (anterior mediastinum) or associated with softening of the trachea (tracheomalacia). However, it’s likely that the cause isn’t solely due to an unusual origin of the innominate artery from the aortic arch, but a combination of various factors.
Risk Factors and Frequency for Brachiocephalic (Innominate) Artery Compression Syndrome
Innominate artery compression syndrome is the top cause of airway restriction due to a blood vessel. While the frequency of this syndrome isn’t confirmed, it’s usually rare, and affects roughly 3% of people. Interestingly, abnormalities in chest X-Rays, indicating front side throat compression, can be seen in up to 30% of the general public and as many as 71% of patients with birth defects in the heart. Yet, only a small number require surgery.
Certain groups of people have a higher chance of suffering from this syndrome. These include individuals who have had a history of esophageal atresia or tracheoesophageal fistula repair (both serious conditions of the esophagus and trachea), and those diagnosed with Morquio A syndrome, a rare genetic disorder.
It has also been noticed in patients with a birth defect known as a congenital diaphragmatic hernia. This is believed to be due to the repositioning of the mediastinum (the central part of the chest) towards the underdeveloped left lung after hernia repair.
Signs and Symptoms of Brachiocephalic (Innominate) Artery Compression Syndrome
Accurately diagnosing IACS, or Innominate Artery Compression Syndrome, requires a detailed health history and physical examination. The symptoms mimic many other throat conditions, leading to frequent misdiagnoses. Individuals with IACS often report several respiratory complaints, the most troubling of which is reflex apnea, a temporary halt in breathing. This may happen when food passing near the compressed area of the trachea, or a buildup of secretions, triggers this reflex. Typically, the person will briefly stop breathing and may turn blue (cyanosis) but usually recovers in a few minutes.
Most patients experience more than one respiratory symptom, with 60 to 70% reporting over three. Generally, these symptoms start to appear in the first year of life. The fragile and easily collapsible trachea in infants is likely the cause. In some cases, symptoms may not emerge until teenage years. Younger patients often exhibit more severe symptoms such as reflex apnea and stridor (noisy breathing). IACS may also occasionally present with opisthotonos, a painful spasm causing the head, neck, and spine to arch backward.
- Difficulty breathing
- Wheezing
- Noisy breathing (stridor)
- Cough
- Recurring respiratory infections
- Respiratory distress
- Reflex apnea
An aberrant right subclavian artery is a different form of a primary blood vessel found in nearly 1% of the population. Approximately 60% of these cases involve a Kommerell’s diverticulum, a bulging at the origin of the aberrant artery— left or right—in a left-sided or right-sided aortic arch, respectively. Though most persons with this variant silent, they may sometimes complain of difficulty swallowing, or dysphagia, shortness of breath, or chest pain. The symptoms frequently depend on the size of the swell and where it compresses, which could be behind the esophagus, between the esophagus and trachea, or in front of the trachea.
Testing for Brachiocephalic (Innominate) Artery Compression Syndrome
If your doctor suspects that you might have Innominate Artery Compression Syndrome (IACS) they will have to run a wide array of tests to confirm the diagnosis. IACS is a rare condition and it is often confused with other more common conditions because they show similar symptoms. Some of the tests that may be performed include chest X-rays, bronchoscopy (a procedure that looks into the airways in your lungs), esophagoscopy (an examination of the inside of the esophagus using a thin tube with a light and camera attached), angiography (imaging test that uses x-rays to view your body’s blood vessels), CT scan, MRI, and lung function tests.
The doctor might first look for signs of IACS in a chest x-ray, which may show a dent at the front of the windpipe. However, this test is not always accurate as some patients who respond positively to bronchoscopy might not show abnormalities initially on their x-ray.
The most credible technique to identify IACS is bronchoscopy. This is done by inserting a flexible tube into your windpipe while you are under mild anesthesia. In a patient with IACS, this technique will reveal a compressed windpipe leaning towards the right, and a tiny hole-like structure in the left part of it, mostly at the lower parts of the windpipe. It is important to note that these findings can vary greatly depending on how deeply the patient is anesthetized and the way the bronchoscopy is performed.
Along with bronchoscopy, a tracheobronchoscopy might be performed. In this procedure, the patient is initially asked to breathe normally while the surgeon inspects the windpipe and bronchial tubes for any deformities or swelling. Following this, the anesthesia is scaled back to make the patient cough, revealing the characteristic collapse of the airway. The final phase involves pumping air into the windpipe to detect any permanent compressions, abnormal branching, or fistulas (an abnormal connection between an organ and another structure).
Sometimes, an esophagoscopy or a barium swallow (an examination to assess the functioning of the esophagus) is performed to rule out any other causes for the symptoms. If your esophagus shows abnormal pressure from outside, it may point towards a different type of vascular ring disorder as IACS doesn’t create pressure on the esophagus.
In the past, doctors used angiograms, which are specific imaging tests that take detailed pictures of your blood vessels, to evaluate the structure of the arteries around the aorta (main artery supplying blood to the body). Nowadays, however, CT scan and MRI are typically used instead of angiograms. They offer detailed information about the relationship between the branches of the aortic arch, the windpipe and the structures surrounding it. It is necessary to mention though that CT scans and MRIs may sometimes underestimate the level of windpipe compression.
Pulmonary function tests are used to confirm if the airway obstruction is due to IACS and to evaluate the severity of the condition. This test may be taken before and after exercise in older children and adults. Special lung function tests have also been developed for infants recently.
If you are being tested for IACS, an echocardiogram (an ultrasound of the heart) should also be performed, as about 12% of patients with vascular rings also have some form of congenital heart disease.
Treatment Options for Brachiocephalic (Innominate) Artery Compression Syndrome
When it comes to Innominate Artery Compression Syndrome (IACS), the type of treatment patients receive depends heavily on how severe their symptoms are. If the symptoms aren’t too severe, patients might be able to manage them without surgery, by keeping their airways clear and treating any respiratory infections they might have. They could also use additional oxygen if needed. However, in more serious cases where patients experience severe breathing issues or if their treatment isn’t working well enough, surgery might be necessary.
An Italian surgical team has created a roadmap to help determine whether surgery or non-surgical treatment is the best choice. They suggest non-surgical treatment for children who only experience mild symptoms, few bacterial complications, long symptom-free periods, and improvements over time. On the other hand, surgical therapy is recommended for patients with severe symptoms, frequent complications, short symptom-free periods, and worsening symptoms.
The most common surgical procedure for IACS is called aortopexy. It involves moving the aorta, innominate artery, or both away from the trachea by suspending them from the sternum. This procedure is usually performed using either a right or left thoracotomy (an incision made into the chest), or other methods such as a median sternotomy (an incision down the center of the chest), or an upper midline hemisternotomy (an incision made into the top part of the sternum). The specific approach used would depend on which vessels are being moved.
Some studies have suggested alternative methods. For example, reimplanting the innominate artery. This involves moving the artery and requires the patient to be on blood thinning medication during the surgery. However, this method is somewhat controversial due to the risks involved.
Another surgical technique known as hemisternotomy has shown promise in treating IACS, with symptom relief in 78% of patients at one center. This procedure allows for a complete removal of the thymus, which provides an increased view of the nerves and reduces the risk of nerve damage. It also allows for greater movement of the innominate artery, thereby reducing pressure on the trachea. In addition, if needed, the procedure can be easily converted to a full sternotomy, allowing for a complete exploration of the trachea.
Occasionally, some patients will have other issues with their airways in addition to the vascular compression caused by IACS. These patients might require another procedure called tracheobronchoplasty, alongside surgery to relieve pressure from the vasculature.
It’s worth noting that patients with thoracic cage abnormalities rarely suffer from IACS because of their pre-existing condition. However, when it does happen, these patients usually require a more complex reconstruction to address the vascular compression of the airway.
What else can Brachiocephalic (Innominate) Artery Compression Syndrome be?
When a doctor is trying to diagnose IACS (Intermittent Asthma and Chronic Symptoms), they have to rule out many other diseases that can affect the airway, heart, and upper digestive tract. These diseases can appear similar to IACS, so they need to be considered. The following are some potential conditions that might be confused with IACS:
- Airway
- Laryngomalacia (softening of the voice box)
- Tracheomalacia (softening of the windpipe)
- Tracheal stenosis (narrowing of the windpipe)
- Vocal cord paralysis (loss of function in the vocal cords)
- Reactive airway disease (a condition where the airways overreact to certain triggers)
- Sleep apnea (a sleep disorder where breathing stops and starts)
- Cardiovascular
- Vascular rings (an abnormal formation of the blood vessels that encircle the windpipe and esophagus)
- Cardiomegaly (an enlarged heart)
- Gastrointestinal
- Gastroesophageal reflux (a digestive disorder that affects the lower esophageal sphincter)
- Laryngopharyngeal reflux (a condition where stomach acid and other stomach contents flow backward into the throat)
It’s important for the doctor to carefully consider these conditions and conduct appropriate tests to make an accurate diagnosis.
What to expect with Brachiocephalic (Innominate) Artery Compression Syndrome
Many people report feeling much better after having surgery for IACS, or innominate artery compression syndrome. Research shows that up to 90% of patients see a relief of symptoms after undergoing either the aortopexy or the reimplantation methods, which are two different types of surgery for this condition.
However, it’s important to note that in some instances people may continue to experience symptoms. This is often due to other existing conditions such as subglottic stenosis (narrowing of the airway), laryngomalacia (a voice box condition), and tracheoesophageal fistula (an abnormal connection between the windpipe and the tube that food travels down).
In a study done by Gardella and colleagues, they found that out of 16 patients who had the aortopexy procedure for IACS, only one person experienced symptoms that affected their lifestyle. Everyone else was either completely free of symptoms or only had them occasionally.
Possible Complications When Diagnosed with Brachiocephalic (Innominate) Artery Compression Syndrome
The procedures to repair IACS often have a low complication rate. The most common issue faced after the surgery is the need for additional surgeries, which can be as high as 5% for both aortopexy and innominate artery reimplantation methods. Other surgical complications can range between 0% to 25%, although recent research suggests the rate is closer to 2%. Problems that patients might face include wound infection, a longer than usual period of being attached to a breathing machine, fluid around the heart, and a condition known as post-cardiotomy syndrome.
Potential Complications:
- Need for additional surgeries
- Wound infection
- Extended use of breathing machines
- Fluid around the heart
- Post-cardiotomy syndrome
Preventing Brachiocephalic (Innominate) Artery Compression Syndrome
Innominate artery compression syndrome (IACS) is a rare medical condition characterized by a vascular ring, which is an abnormal formation of the blood vessels around the windpipe and food pipe. If you experience any breathing issues that may suggest IACS, it’s crucial to undergo a comprehensive evaluation.
If IACS is diagnosed and you need surgery, both you and your family should understand the risks and benefits of the operation. Plus, you should know that the procedure has a promising outlook and good long-term results, but keep in mind that some symptoms might persist even after surgery.
If, on the other hand, the doctors found the innominate artery compressing the airway, but surgery isn’t necessary, you should learn about the signs and symptoms that might suggest a worsening condition and when you should seek medical help.
Lastly, it’s good news that children and infants diagnosed with IACS but who don’t require surgery usually outgrow the symptoms. They can expect to live a normal lifespan.
