Overview of Right Heart Cardiac Catheterization
In 1929, a medical trainee from Germany named Werner Forssmann did the first right heart catheterization on himself. Catheterization is a procedure that doctors use to diagnose and treat some heart conditions. What he did was he inserted a long, thin tube called a catheter into his left arm vein and pushed it further until it reached the right side of his heart. He then injected drugs directly into his heart through the catheter.
In the past, similar procedures had only been done on animals. For instance, an English Vicar named Stephen Hale and a physiologist named Claude Bernard used to insert tubes into the veins and arteries of horses to measure their heart temperatures.
The first successful human catheterization laid the groundwork for the development of a broad range of catheterization procedures. These procedures use catheters, often guided by X-ray imaging, to diagnose and treat various medical conditions without the need for invasive surgeries. After Werner Forssmann, medical practitioners continued to improve catheterization techniques.
Because of their significant contributions to this field, Andre’ Frederic Cournand and Dickinson W. Richards from New York, alongside Forssmann, received the Nobel prize in Medicine in 1956.
The right heart catheter was then widely used to explore and understand the workings of the heart and the lungs in patients with chronic lung disease and congenital heart disease. This catheter, known as the pulmonary artery catheter, was instrumental for measuring blood flow from the heart.
In an effort to enhance the pulmonary catheter, Dr. Swan added a balloon to the catheter’s end. This addition made it easier for doctors to place the catheter at the patient’s bedside, and it allowed them to continuously monitor the pressure in the heart and lungs. Furthermore, Dr. Ganz introduced a feature at the tip of the catheter that could directly measure the heart’s output using a method called thermodilution. Because of the widespread use of this improved catheter, it became commonly known as the “Swan-Ganz” catheter.
Anatomy and Physiology of Right Heart Cardiac Catheterization
Right heart catheterization is a procedure often carried out through the common femoral vein in the leg, the internal jugular vein in the neck, or the antecubital veins in the arm. In simpler terms, this is a process where a small tube is inserted into a vein, either in your leg, neck, or arm, so your doctor can examine your heart.
When done through the leg, the femoral vein goes to the external iliac vein and then drains into the inferior vena cava, which eventually leads to the right side of the heart. Basically, this means that the blood from your leg travels up into your heart.
When this procedure is executed through the arm, the cephalic vein (the main vein in your arm) drains into the subclavian vein, a major vein beneath the collarbone, which then leads to the right side of the heart.
In the neck, the internal jugular vein links with the subclavian vein to form the brachiocephalic vein. Veins from both sides of the neck flow into the superior vena cava, another large vein, which leads to the right side of the heart.
The procedure involving the antecubital veins in your arm is linked with a shorter procedure time and a lower chance of significant swelling caused by bleeding underneath the skin (hematomas). In other words, using the veins in the arm can result in a quicker procedure and less risk of bruising or swelling afterwards.
Why do People Need Right Heart Cardiac Catheterization
When doctors suspect a condition called cardiogenic shock, which happens when your heart can’t pump enough blood to your body, they might perform certain examinations. In simplest terms, cardiogenic shock is a serious condition that can be life-threatening if not treated immediately.
The same examinations are also done when a patient is short of breath, and doctors need to find out if the patient has certain heart conditions. Some of these conditions include pulmonary hypertension (high blood pressure in the arteries of your lungs), constrictive pericardial disease (a condition where the outer layer of your heart becomes stiff, and your heart can’t fill properly with blood), restrictive cardiomyopathy (a condition that stiffens the walls of your heart’s lower chambers), or heart failure with a preserved ejection fraction (a heart condition where your heart doesn’t relax between beats as it should).
These examinations can also be used to see how well a patient is responding to medicine used to treat pulmonary hypertension.
They might also be performed for conditions like cardiac tamponade, which is a medical emergency where fluid accumulates in the sack around the heart, putting pressure on it and preventing it from working well. They could be used to quantify an intracardiac left-to-right shunt (an abnormal connection that lets blood flow from the left to the right side of the heart).
After heart surgery or a complicated heart attack, or in the case of heart failure or shock, these examinations can be used to guide how much fluid a patient should be given and for monitoring the patient’s heart and blood flow.
For adults born with heart defects, patients being evaluated for a heart transplant, or patients who have had a heart transplant, these examinations can come in handy too. Especially, when there are new or worsening symptoms suggestive of graft rejection after a heart transplant, these examinations can be helpful.
Before implanting a left ventricular assist device (a mechanical pump implanted inside a person’s chest to help a weakened heart pump blood), these examinations are crucial. After the device has been implanted, doctors use these examinations to make sure that the device is working correctly.
In situations of valve disease and when there are discrepancies between what a patient is experiencing and what non-invasive diagnostic tests are showing, these examinations can provide additional valuable information.
When a Person Should Avoid Right Heart Cardiac Catheterization
Certain conditions can completely prevent a specific medical procedure. These include having an infection or a tumor on the right side of the heart, or having a blood clot. Other conditions might make the procedure risky, but not impossible. These conditions include complications like severe coagulopathy, a condition that affects the blood’s ability to clot, or bleeding diathesis, when someone is prone to excessive bleeding. Furthermore, doctors need to be careful when the patient has irregular heartbeats or suffers from left bundle branch block, a condition that slows down the electrical impulses that control the heartbeat, to avoid causing further irregularities in the heart rhythm.
Equipment used for Right Heart Cardiac Catheterization
Various kinds of heart lung blood vessel (pulmonary artery) tubes (catheters) are available in the market. Some of these can not only measure pressure, but also assess how much blood your heart pumps (thermodilution assessment of cardiac output). Certain catheters have a special device attached (thermistor) that allows doctors to measure the cardiac output using the thermodilution technique. Catheters to be placed in the pulmonary artery are typically 110 cm long, and their width, known as the French size, can vary from 5F to 8F, based on the manufacturer. All these catheters have a yellow end (distal port) and a blue end (proximal port) for various functions. The presence of a thermistor adds a third port or opening to the tube.
Who is needed to perform Right Heart Cardiac Catheterization?
When your heart treatment happens in a place called the cardiac catheterization lab, three main people help you out. These are the doctor doing the procedure, the nurse who gives you medications, and a technologist who tracks your heart’s activity during the treatment. The doctor typically gets some help from another person called a cardiovascular technologist. They work together to make sure your treatment goes smoothly and safely.
Preparing for Right Heart Cardiac Catheterization
Once the patient has given their permission for the procedure, they are escorted to the cardiac lab where the procedure will take place. The patient lies flat on their back on the table. The area of the body where the doctors will be working is cleaned and a sterile drape is applied to help prevent infections. Chlorhexidine, a strong disinfectant, is used for this cleaning. Both the main doctor and their assistant need to wear clean hospital gowns, gloves, and caps, as well as face shields for additional protection.
The doctors then prepare all the necessary tools (needles, sheaths – which are tubes used to guide the catheter, and the catheters themselves – which are thin flexible tubes), making sure to flush them (run a sterile solution through them) to avoid any air bubbles from entering the patient’s bloodstream when they are used.
How is Right Heart Cardiac Catheterization performed
Doctors use a local anesthetic to numb the area where they will be working, so you don’t feel any pain. They’re going to access your vein, usually in your femoral (thigh), jugular (neck), or antecubital (elbow) area. They might use an ultrasound to help guide them, and they use a special, sterile sleeve to keep everything clean.
They put a small tube (called a sheath) into your vein and then thread a pulmonary artery catheter through that sheath. The catheter has a little balloon on the end, which they inflate after it’s in your vein. This balloon helps guide the catheter further inside your body.
If you’re wondering how they know how far to go, they use certain measurements and watch the catheter on a special x-ray, called fluoroscopy. For instance, from the neck vein, they put the catheter roughly 20 cm in. From the thigh vein, they go about 45 cm in. These measurements help them make sure the catheter gets all the way to your heart’s right atrium, which is one of its chambers.
Once they get to the right atrium, they start to monitor and record your heart’s pressure. It’s important for the doctor to position the equipment just right; otherwise, they might get incorrect pressure readings. They want to be sure that their measurements are accurate.
The catheter is then moved to the right ventricle, another chamber in your heart, and the pressure is recorded again. It’s then moved into a position to measure the pressure in the tiny blood vessels in your lungs. After that’s done, the balloon is deflated and the catheter is pulled back a bit into the pulmonary artery (a big blood vessel in the lungs) to record the pressure there. It’s crucial to mention that during all this process, the best moment to take these pressure measurements is at the end of a breath out.
The doctor may also take a blood sample from the artery to measure the amount of oxygen there. They can then calculate your cardiac output, which is a measure of how much blood your heart pumps. Cardiac output helps doctors understand how well your heart is working. They may use a method called thermodilution, where they inject a cold saline solution into the catheter to further measure your heart’s functionality. This is generally done a minimum of three times to get a more precise average cardiac output.
Lastly, the catheter can be manipulated into different locations such as the superior or inferior vena cava (large veins that carry blood into your heart) or the right ventricle or right atrium of your heart to get more blood samples or further estimate oxygen levels.
Possible Complications of Right Heart Cardiac Catheterization
Some potential issues that can come up after the placement of a catheter into the heart include irregular heart rhythms or temporary blockage of electrical signals in the heart. These can usually be fixed when the catheter is adjusted or removed. In rare cases, if there is a previous blockage on the left side of the heart, a complete block can occur which might require a temporary pacemaker to be placed.
Another rare complication is an air embolism, which can happen if there’s air inside the catheters or the devices used to measure blood pressure. The signs of this can include sudden chest pain, difficulty breathing, low blood pressure, and quick heartbeat. If this happens, the patient should be laid down with their feet raised and oxygen must be delivered. This helps decrease the amount of nitrogen in the blood and allows for faster reabsorption of the air. In some cases, treatment involving high-pressure oxygen may be needed.
The rate of accidental punctures in the lung artery is about 0.03%. This can happen during a measurement procedure using a catheter, especially in patients who already have high blood pressure in the lungs or are on blood thinners. If it does happen, the patient might suddenly have difficulty breathing and experience symptoms of low blood flow from the heart. Pictures taken with X-rays can confirm if the catheter tip is placed too far within the lung arteries. If such a puncture does happen, the catheter should be left in place, and the patient might need intermittent positive pressure ventilation. The patient should be rapidly intubated (a tube placed into the airways) using a double-lumen endotracheal tube and placed on the side in order to protect the unaffected lung from any ongoing bleeding. An expedition surgery or blocking off the blood vessels should be considered.
For catheters placed directly into the lung arteries for a longer time, additional risks include infection near the access site, damage to the lung tissue, irregular heart rhythms, clot formation, and perforation of the pulmonary artery or right side of the heart.
What Else Should I Know About Right Heart Cardiac Catheterization?
A right heart catheterization is a procedure that doctors use to understand how well your heart is working. They insert a thin tube into a blood vessel that leads to your heart, enabling them to measure various aspects of its function.
The values that doctors usually look at include the pressure in different parts of the heart. For instance, the average pressure in the right atrium of a healthy heart is between 1 to 5 millimeters of mercury (mm Hg). The right ventricle, another part of the heart, has systolic (active) and diastolic (resting) pressures ranging from 15 to 30 mm Hg and 1 to 7 mm Hg respectively. Other measurements include the pressures in your pulmonary artery and your pulmonary capillary wedge, both of which have their own normal ranges.
These pressure measurements can help doctors calculate other important health markers. These include your heart’s output, how hard it’s working, and how well your blood vessels are functioning.
Something that is often assessed during this procedure is the way the pressure changes in your right atrium or pulmonary capillary wedge. These can show up as patterns of highs (upstrokes) and lows (descents) that let doctors identify irregularities in the heart’s function.
Different kinds of irregularities can show up in these pressure waveforms. For example, if you have atrial fibrillation (an abnormal heart rhythm), you would lose one of the upstrokes from the waveform. Other abnormalities could be caused by issues like heart blockages, fast heart rates, or heart valve problems. Each of these problems can cause unique changes in the waveform.
If your doctor sees high systolic pressures in your right ventricle and pulmonary artery, this could suggest conditions like pulmonary embolism or hypertension. Some conditions could cause a rise and a balance in end-diastolic pressures and pulmonary capillary wedge pressures, such as constrictive pericarditis, restrictive cardiomyopathy, and cardiac tamponade.
The catheterization can also help calculate your heart’s output, or how much blood it’s pumping. They might do this using principles developed by Adolf Fick in 1870 or by directly measuring temperature changes (the thermodilution technique) when injecting saline into your blood. Both methods have their pros and cons and are more or less accurate depending on certain circumstances.
However, all these methods provide valuable insights into how well your heart is working, helping doctors detect and manage any issues promptly.