Overview of Endomyocardial Biopsy
There’s a medical procedure called endomyocardial biopsy (EMB) that doctors use to diagnose certain heart diseases. However, not every medical center uses it, and some doctors disagree on when it’s useful. An EMB is used to investigate heart conditions when non-invasive tests, like X-rays or ultrasound, can’t provide a clear diagnosis.
An EMB is not a simple procedure and may lead to some complications. Doctors often prefer to use less invasive methods like a cardiac magnetic resonance imaging (MRI), which uses magnetic fields to create images of the heart, or a positron emission tomography (PET) scan, which uses a special dye to show how your heart is working. These methods can often provide similar insights without needing to take a biopsy.
However, there are situations where an MRI or PET scan can’t give doctors the information they need. In these cases, an EMB can be very helpful in figuring out the problem. Like all diagnostic tools, EMB has its unique pros and cons depending on the specific disease doctors are trying to diagnose. An EMB isn’t just one step, but a whole process that includes deciding whether to do it, taking the biopsy, handling the sample, and interpreting the results.
Besides helping doctors diagnose diseases, EMB also helps medical researchers learn more about heart diseases and how to treat them.
Anatomy and Physiology of Endomyocardial Biopsy
An endomyocardial biopsy (EMB) is a procedure where a small sample of your heart tissue is removed for testing. This can be done in either the right or left side of your heart. However, it’s most often done on the right side, specifically in the right ventricular septum, which is a wall that separates the chambers in your heart.
There are different ways that doctors can reach your heart to perform the EMB. The most common way in the United States is through the right internal jugular vein, which is a large vein in your neck. However, they can also get to your heart through a vein in your leg, either the right or left femoral vein. If they need to access the left side of your heart, they can use an artery in your leg (the right or left femoral artery) or an artery in your arm (the right radial artery).
Knowing the specific structure of your heart and where disease might be located is important for this procedure. This helps your doctor take a sample from the right place and avoid complications. For instance, in a condition called arrhythmogenic right ventricular dysplasia (ARVD), changes are seen in the outer wall of the right ventricle rather than the septum where biopsies are usually taken. Similarly, tumors or growths in the heart, called cardiac masses, may also be found in specific locations depending on where they originated. For example, growths called myxomas are usually found in the left atrium, a chamber in the heart. Secondary growths or tumors often occur in the right side of the heart.
If the disease affects the whole heart, doctors might take more samples to accurately diagnose the condition. Choosing which side of the heart to biopsy might also depend on the results of imaging tests like magnetic resonance imaging (MRI) and electrocardiograms (EKG), which can show the parts of the heart affected by conditions like myocarditis (inflammation of the heart muscle) or cardiac sarcoidosis (an inflammatory disease that affects the heart).
Why do People Need Endomyocardial Biopsy
Endomyocardial biopsy (EMB) is not frequently used as a test in identifying heart disease. However, under some specific circumstances, EMB can be very important for diagnosing certain heart conditions and predicting how they might develop in the future. When considering its usefulness, we often rely on past patient data, experience from many different cases, and expert opinions, since there have been no comprehensive clinical studies on this topic.
In basic terms, we use EMB to identify a variety of heart conditions, such as: unknown cause of heart failure, cardiac sarcoidosis, amyloidosis, inflammatory heart muscle diseases, storage diseases (like hemochromatosis), heart tumors, and side effects from cancer treatment drugs. We can also use it to monitor the health of patients who have had a heart transplant or to differentiate between constrictive pericarditis and restrictive cardiomyopathy or between right ventricular myocarditis and arrhythmogenic right ventricular cardiomyopathy.
EMB is particularly useful in patients who develop severe heart failure (lasting less than 2 weeks). If the usual causes of heart failure are ruled out, conducting an EMB can provide valuable information about the patient’s condition. For example, lymphocytic myocarditis often has an excellent prognosis, whereas giant cell myocarditis and necrotizing eosinophilic myocarditis typically suggest a poorer prognosis. Understanding these conditions can influence treatment decisions.
For patients diagnosed with cardiac sarcoidosis, it’s important not to confuse this with other similar conditions. EMB may not always detect sarcoidosis due to its sporadic involvement in the heart tissue. However, using MRI scans to identify affected areas can increase the accuracy of the biopsy.
People treated with chemotherapeutic drugs (like anthracycline) may need an EMB if the cause of cardiac dysfunction is unknown. Or, in cases of restrictive cardiomyopathy (congested or stiff heart muscle), EMB can provide essential information when other non-invasive tests don’t determine the cause.
EMB can also be used in diagnosing heart tumors (except for myxomas that can break off and clog blood vessels). Although EMB can help identify a variety of tumors, lymphomas are usually the most common ones found.
EMB is also key in patients who have undergone heart transplantation. Routinely conducting an EMB within the first year after the transplant can help detect early signs of transplant rejection, and this information can be used to modify the person’s medication, if necessary.
When a Person Should Avoid Endomyocardial Biopsy
An endomyocardial biopsy (EMB) is a procedure where a tiny piece of your heart muscle is removed so it can be examined. While it’s a powerful diagnostic tool, there are conditions or situations that may make it unsafe to proceed (these are called contraindications). Complete or ‘absolute’ contraindications include certain valve diseases like vegetations (abnormal growths on heart valves) or stenosis (a narrowing of the heart valve), and blood vessel issues like aneurysms (a bulge in a blood vessel) and thrombosis (blood clots). Atrial myxomas (non-cancerous tumors in the heart) can break off and block blood flow, so usually, they should not be biopsied.
Situations that are seen as ‘relative contraindications’ (meaning, they may make the procedure more risky, but not always forbidden) include having coagulopathy (a condition that affects the blood’s ability to clot), taking dual antiplatelet therapy (medications to prevent blood clots), or using therapeutic anticoagulants (blood thinners).
When EMB isn’t an option due to these contraindications, there are alternative methods to look at the heart muscle. These can include tissue doppler echocardiography (a type of ultrasound), scintigraphy (a type of imaging test), and cardiac magnetic resonance imaging (CMRI), which uses magnetic fields and radio waves to create detailed images of the heart.
Equipment used for Endomyocardial Biopsy
A bioptome is a tool that doctors use to take a tiny piece of heart tissue for testing, this is called a cardiac biopsy. This procedure can be done using two different medical imaging techniques, fluoroscopy, which is most commonly used, or echocardiography. The recent versions of bioptomes are built to be more flexible and thinner than the older versions.
For the biopsy, a doctor would need to reach the right or left side of your heart. The doctor can do this by making a small puncture in a vein (usually in the neck or leg area, known as the internal jugular or femoral vein) or an artery (usually in the arm or leg area, known as the radial or femoral artery). This small puncture is where the bioptome is inserted and carefully guided towards the heart.
To get the bioptome to the heart, the doctor uses a technique called the Seldinger technique. This involves placing a small tube, called a sheath, in the puncture and then using it to guide the bioptome to the heart.
Who is needed to perform Endomyocardial Biopsy?
For this heart procedure, it’s essential to have an experienced heart specialist, called an interventional cardiologist, to reduce any risks. This doctor has special training on how to perform EMBs, which is a way to collect samples from the heart. To support the heart specialist, a team of skilled nurses and technologists, who work in a special heart laboratory called a cardiac catheterization lab, will be there to help.
Understanding what the collected heart samples mean requires a lot of knowledge and practice. That is where the cardiac pathologists come in. These are doctors who have received unique training to understand heart disease and problems. They examine samples from heart procedures like EMBs or even from autopsy, which is a way to study the whole body after death. They can accurately understand and explain these samples’ findings.
Preparing for Endomyocardial Biopsy
The bioptome, a tool used to take a small tissue sample from the heart, can be guided using techniques like fluoroscopy in the lab or various types of echocardiography at the patient’s bedside. Echocardiography is as good as fluoroscopy in terms of complications and procedure duration.
In addition to providing an overview of the heart’s structure, doctors can use advanced techniques like voltage mapping and real-time Cardiac Magnetic Resonance (CMR) to target specific areas within the heart with more precision. This helps to decrease errors. However, CMR-guided procedures need special equipment that is compatible with magnetic resonance.
Voltage mapping can be used to identify abnormal heart areas or scars characterized by changes in electric signal conduction. In other words, doctors can find sick parts by watching how electrical current travels in the heart. The use of imaging before the procedure to pinpoint areas of importance can increase the success chances of a heart biopsy. This means using imaging techniques to look inside the heart can help make the biopsy more effective.
How is Endomyocardial Biopsy performed
Before a specific heart procedure called “endomyocardial biopsy”, you must stop any blood thinning medications for 16 hours before and 12 hours after the procedure. A test called INR (international normalized ratio), which measures how long it takes your blood to clot, must also be lower than 1.5 before the procedure. You will be given anesthesia and sedation to put you to sleep and block pain. During the procedure, you will be lying on your back and your heart rate, blood pressure and oxygen levels will be continuously monitored.
During the biopsy procedure, which typically lasts a few minutes, pain medication and sedation will be provided to make you comfortable. Several tissue samples from your heart are taken to ensure accuracy. As soon as these samples are removed, they are prepared for further analysis. They are stored in different types of solutions, such as formaldehyde, glutaraldehyde, and liquid nitrogen, before being studied under a microscope using various techniques.
Samples are stained with different dyes for detailed examination under the microscope to look for changes that indicate different heart conditions. The changes that doctors look for include: inflammation, abnormal heart muscle cell growth and arrangement, cell damage and death, injury to the heart muscle, accumulation of abnormal fibrous tissue, abnormal fatty infiltration, iron accumulation, abnormal protein accumulation (amyloidosis), vascular abnormalities, and other changes that have no significant impact on health.
If inflammation is found, a severity index is calculated based on the number of certain immune cells and their activation status. Some tissue samples are frozen and tested for the presence of viruses that can cause heart disease.
In the case of heart transplants, the tissue samples are examined for signs of inflammation and damage to heart muscle cells. This helps to identify if the body is rejecting the transplanted heart. Sometimes, after a transplant, Quilty lesions can occur, which is a buildup of immune cells in specific parts of the heart.
Your doctor will be mindful of the fact that the procedure itself can potentially cause some changes in the heart tissue samples. These can include certain bands that form in heart muscle cells, gathering of cell components like mitochondria, folding of the cell membrane, cell swelling, and disruption of membrane with changes in components like glycogen and lipids. These are called artifacts. Some artifacts can reveal heart disease, while others may be caused by the way the biopsy was done.
Possible Complications of Endomyocardial Biopsy
Some people might experience problems after certain heart procedures. These issues can be split into two categories: those that happen right away (acute) and those that happen some time later (chronic). Serious problems that can happen right away include a punctured lung (pneumothorax), irregular heartbeats (arrhythmias), tearing of the heart or its vessels (perforation), and fluid accumulating around the heart (pericardial effusion or tamponade). Other early complications can be injury to heart valves, blood clots causing blockage in lungs (pulmonary embolization), nerve damage, internal bleeding (hematoma), unnatural connections between arteries and veins (arteriovenous fistula), and blood clots in deep veins (deep vein thrombosis). Among these, an injury to a heart valve known as the tricuspid valve can especially happen to people who undergo multiple heart biopsies, which is a common procedure for people who had heart transplants. While most people can tolerate a bit of leakage or backflow in the tricuspid valve, it is still important for doctors to be careful not to damage it during heart biopsies.
Delayed problems that can occur later on include bleeding around the area where the biopsy was done, tricuspid valve damage, pericardial tamponade, and deep venous thrombosis. Now, these complications are quite rare, with serious ones happening in less than 1% of procedures, and minor incidents occurring in up to 6% of procedures.
The risk of these complications can depend on the patient’s overall health, the experience of the doctor carrying out the procedure, and whether there are experts in heart pathology available. If you need a heart biopsy, but you are at a medical center where there aren’t any heart biopsy experts, you might have to be transferred to another facility. People with a weak heart or unstable heart rhythms might need specialized care, such as heart pumps or even heart transplants.
What Else Should I Know About Endomyocardial Biopsy?
The effectiveness of endomyocardial biopsy, a procedure that helps identify heart diseases, relies heavily on two things. The first is its ability to help diagnose a disease. The second is what the results could mean for a patient’s treatment plan.
Endomyocardial biopsy is particularly useful when examining different causes of cardiomyopathy, which is a condition that makes it harder for your heart to pump blood to the rest of your body. However, it’s worth mentioning that sometimes, even with this tool, the treatment approach may not change a great deal.
It’s also important to keep in mind that the structural changes detected in a biopsy don’t always correspond to the symptoms a person is experiencing.
Sometimes, light microscopy and staining, the main elements of a biopsy, may not be enough. For instance, in cases of hemochromatosis and similar diseases, where iron and other substances accumulate in the heart, your doctor might need to use other techniques. These could include molecular analysis or tests that identify iron deposits in the heart tissue.
The role of endomyocardial biopsy has changed over time. This is especially true regarding the Dallas criteria, key guidelines for the diagnosis of certain heart conditions. Some people have been diagnosed even though they didn’t meet these criteria. Because of this, some other diseases may require additional tests for accurate diagnosis. For example, the biopsy is about 25% accurate for diagnosing lymphocytic myocarditis and 35% accurate for diagnosing cardiac sarcoidosis.
Given the biopsy has high accuracy but low sensitivity, it is a better diagnostic tool for certain diseases when the symptoms already strongly suggest these diseases. If there’s less initial suspicion of a disease, other tests should be considered first. These can include scans using radioactive substances.
Scientists are also exploring the combination of CMR, a type of MRI scan for the heart, and endomyocardial biopsy, to improve accuracy in diagnosing myocarditis.