What is Isolated Coronary Artery Anomalies?
Coronary artery anomalies (CAAs) are a diverse set of disorders, present from birth, that affect the origin, path, and structure of the coronary arteries that supply blood to the heart. Anomalies are rare features or patterns seen in less than 1% of people. Today, with the advancements in heart imaging and angiography – a technique which uses X-rays to view the heart’s blood vessels, more and more such disorders are being identified and different types are being described.
It’s becoming increasingly important to understand the normal and variation in the anatomy of coronary arteries. These changes are often seen in people with heart disorders that are present from birth. However, recent research has also reviewed the development of both normal and abnormal coronary arteries.
This part focuses on anomalies of the coronary arteries that occur independently and are not associated with other heart disorders that a person has had since birth (i.e. isolated coronary artery anomalies).
What Causes Isolated Coronary Artery Anomalies?
The exact reasons why abnormalities in the heart’s coronary arteries (known as Coronary Artery Anomalies, or CAAs) develop aren’t completely clear. However, a great deal of study on how hearts grow in the womb has given us some insights. The creation of coronary arteries is a complex process that relies on several factors.
These include the formation of coronary sinuses on a specific part of an embryonic heart (called the bulbus cordis) that eventually turns into the aorta, the formation of certain small blood vessels in the heart known as cardiac sinusoids, the development of coronary arteries in specific grooves in the heart that ultimately connect with the coronary buds, and ensuring that the coronary arteries match up with their origin sinuses. If anything goes wrong in any of these steps, it can result in abnormalities in the coronary circulation.
Risk Factors and Frequency for Isolated Coronary Artery Anomalies
Thanks to major improvements in heart imaging technology like CT and magnetic resonance angiography, we’re seeing an increase in detected cases of coronary artery anomalies. In fact, it’s estimated that around 1.3 million people in the U.S. have these significant artery anomalies, which are a leading cause of sudden cardiac death. Previous data suggested that about 1% of the population had these anomalies, but a recent study of 1950 cases suggested the true number is closer to 5.6%. While this may not reflect the entire population, it does point towards a higher incidence than previously thought. Currently, there’s no known link to race or gender. Autopsies revealed that 12% to 33% of young athletes who experienced sudden cardiac death had this specific type of artery anomaly.
Signs and Symptoms of Isolated Coronary Artery Anomalies
Coronary artery anomalies (CAAs) are uncommon, and most adults with these conditions don’t show any symptoms. The first sign of a problem can sometimes be sudden heart failure. Other times, patients might experience symptoms like chest pain at a young age, fainting during exercise, shortness of breath, heart palpitations, and tiredness. However, these symptoms are usually not clearly linked to the coronary artery anomalies, and they don’t often raise suspicion about the condition.
- Sudden heart failure as the first symptom
- Chest pain at a young age
- Fainting during exercise
- Shortness of breath
- Heart palpitations
- Tiredness
Testing for Isolated Coronary Artery Anomalies
Most people with coronary artery anomalies (abbreviated as CAAs), which are unusual features or problems with the heart’s arteries, either pass away suddenly or don’t experience any specific symptoms for a large part of their lives. Often, they only get checked when they feel chest pain that’s different from common heart-related chest pain. It’s during these checks, which involve a procedure called coronary angiography that generates images of the heart’s blood vessels, that CAAs are usually detected.
It’s tricky to set a typical screening method because of these reasons. If a doctor suspects a CAA, they use a gradual approach to diagnose it, starting with the least invasive tests and increasing it if necessary. An echocardiogram, which uses sound waves to make a picture of the heart, can be used as an initial step to identify the structure of the heart’s arteries. However, it may not provide a complete assessment of the heart’s function.
Echocardiography, though a beneficial tool, might not always be the best way to diagnose the condition. A study has shown that the prevalence of a specific type of CAA was less when evaluated via routine echocardiograms compared to when identified by coronary angiography.
Other non-invasive tests include coronary computed tomographic angiography (coronary CT angiography) and cardiac magnetic resonance angiography (CMRA). These tests have shown great promise in diagnosing CAAs, especially since they can now provide a three-dimensional view of the heart’s structure. Currently, the best way to diagnose CAAs is through coronary CT angiography. Recent research has indicated that this test often detects more CAAs than coronary angiography, suggesting that the latter could underestimate the number of CAAs.
However, both these tests use contrast agents, which are substances used to make body structures more visible in the imaging tests. These agents can lead to significant side effects, especially in patients with kidney disease. CT angiography also exposes patients to a relatively high level of radiation. In contrast, CMRA doesn’t involve radiation exposure, making it a preferred imaging method for younger patients if the echocardiogram doesn’t provide a definitive diagnosis.
For patients with diagnosed CAAs, a nuclear stress test can be done to evaluate for stress-induced reduced blood flow to the heart’s muscles and scars. This test helps provide a baseline for future monitoring in case further treatment becomes necessary. If symptoms are present in a patient with known CAAs, a more invasive procedure like coronary angiography along with the use of intravascular ultrasound might be needed to determine the course of treatment.
Treatment Options for Isolated Coronary Artery Anomalies
Managing coronary artery anomalies (CAAs), a group of different conditions relating to abnormal coronary arteries, remains a challenging task. At present, there isn’t enough data on the natural progression of each type of CAA, which makes it difficult to decide the best course of treatment. Therefore, when making decisions about treatment, doctors consider the specific symptoms and type of anomaly present in each patient.
For high-risk anomalies, where the arteries originate from an abnormal location in the heart, patients are generally advised to avoid intense and unnecessary physical exertion. For an in-depth evaluation of these anomalies, physicians might perform a nuclear stress test. This test involves imaging the heart to identify areas of low blood flow and areas that aren’t receiving enough blood when the heart is under stress, like during exercise. Coronary angiography with Intravascular Ultrasound (IVUS) might also be advised to determine the severity of the narrowed artery, the myocardial territory (part of the heart muscle) it supplies, and the risk of sudden cardiac death.
Once the evaluation is complete, patients have three treatment options. The first is conservative management – monitoring the condition and using medications to manage symptoms. The second option is coronary angioplasty, a procedure that uses a balloon and a stent (a small, metal mesh tube) to widen the narrowed artery. The third option is surgical correction, where surgeons repair or replace the abnormal coronary artery.
For younger patients, surgical correction is often preferred over the use of a stent due to a lack of data about the long-term success of stenting in this age group. For older adults who have CAAs, coronary angioplasty with stenting might be considered as part of their treatment plan.
What else can Isolated Coronary Artery Anomalies be?
When someone has symptoms that could be due to anomalies or abnormalities in their coronary arteries (the blood vessels supplying the heart), doctors need to consider that several other conditions could cause similar problems. These conditions include:
- Narrowing of the coronary arteries due to the build-up of fatty substances (atherosclerosis)
- A condition where the heart becomes enlarged and can’t pump blood effectively (dilated cardiomyopathy)
- A condition where the heart muscle becomes thickened (hypertrophic cardiomyopathy)
- When the heart muscle doesn’t get enough blood supply (myocardial ischemia)
- Blockages in the lungs’ main artery or one of its branches (pulmonary embolism)
- Problems with the valves in the heart (valvular dysfunctions)
- Abnormal heart rhythms originating from the two lower chambers of the heart (ventricular arrhythmias)
These are all issues that doctors need to rule out when a patient shows up with symptoms that may look like coronary artery anomalies, in order to make a correct diagnosis.
What to expect with Isolated Coronary Artery Anomalies
The outlook for patients largely depends on the specific type of heart abnormality they have. Most of these abnormalities don’t affect a patient’s long-term health and are considered non-threatening. However, some can lead to serious health problems such as sudden cardiac death, myocardial ischemia (inadequate blood flow to the heart), early endocarditis (an infection of the heart’s inner lining), and congestive heart failure (a condition that weakens the heart’s pumping capacity).
The abnormalities most commonly associated with sudden cardiac death are unusual origins for the main arteries supplying blood to the heart. These include the origin of the left main coronary artery from the right sinus of Valsalva and the origin of the right coronary artery from the left sinus of Valsalva.
Possible Complications When Diagnosed with Isolated Coronary Artery Anomalies
Coronary artery anomalies (CAAs) – which are unusual structures of the heart’s main blood vessels – have been linked with sudden heart-related death and diseases like endocarditis (an infection of the heart’s lining) or conditions causing poor blood flow to the heart muscle (myocardial ischemia) and congestive heart failure. In addition to these health issues, CAAs can also complicate different heart-related procedures, including ones where doctors visualize heart functions (coronary angiography), open up blocked arteries (percutaneous coronary intervention), or perform heart surgery.
Among athletes and military recruits, CAAs are the second top reason for sudden heart-related deaths. Certain types of CAAs, where the left or sometimes the right coronary artery starts in the wrong place (either from a lung artery or the right ventricle), can result in myocardial ischemia.
Some CAAs may cause arteriovenous fistulas – abnormal passageways between an artery and a vein – which can change normal blood flow patterns. Large arteriovenous fistulas can cause shunting, where the blood bypasses certain parts of the body. This can lead to volume overload, or too much blood for the heart to efficiently pump, possibly resulting in congestive heart failure. The location of the coronary artery fistulas can also augment the risk for endocarditis – an infection that can damage the heart valves.
Common Complications of Coronary Artery Anomalies:
- Sudden heart-related death
- Myocardial ischemia
- Endocarditis
- Congestive heart failure
- Difficulty in coronary angiography, percutaneous coronary intervention, and cardiac surgery
- Formation of abnormal passageways between an artery and a vein
- Volume overload
- Potential for heart valve damage
Preventing Isolated Coronary Artery Anomalies
If young athletic individuals begin to experience symptoms such as shortness of breath (dyspnea), chest pain (angina), fainting (syncope), or abnormal heartbeats (palpitations), they should seek medical help straight away. It’s crucial to get timely medical evaluation to protect from serious issues, which could even include sudden death. If they have conditions related to abnormal heart arteries (coronary artery anomalies), these individuals should see a team of specialists. This team might include experts who specialize in minimally invasive heart treatments (interventional cardiology), heart surgery, and birth-heart-defect specialists (congenital heart specialists). They can discuss what the best choices are for testing and treatment. Until the heart issue is fixed, it’s also crucial that these individuals avoid heavy physical activity.
