Overview of Cardiac Surgery
Cardiac surgery, which is mainly concerned with treating heart conditions and issues with the thoracic aorta, is a medical practice that has seen a lot of progress over the years. This kind of surgery is typical for many heart issues, with the middle of the sternum being cut open in what’s known as a median sternotomy approach.
Ever since the 1800s, significant advancements, including methods like cardiopulmonary bypass (or CPB, which is a technique that temporarily takes over the function of the heart and lungs during surgery), coronary artery bypass grafting (or CABG, a type of heart surgery that improves blood flow to the heart), valve repairs and minimally invasive techniques, have made cardiac surgery more effective and safer. Although newer methods have emerged, traditional methods are still critical, particularly for complicated cases.
Cardiac surgery doesn’t treat just one condition; it addresses a broad range. Everything from inborn heart defects to advanced coronary artery disease can be treated with cardiac surgery. To get the best results, it’s essential to choose the right treatment for the patient carefully.
The evolution of cardiac surgery has seen many milestone treatments. For example, Ludwig Rehn performed the first successful treatment of a heart injury in 1896. Over time, the high death rates of early heart operations led to the development of cardiopulmonary bypass, a technique that temporarily takes over the function of the heart and lungs during surgery. Nowadays, treatment options for ischemic heart disease caused by atherosclerosis include surgical revascularization and bypass grafting, complemented by medication therapy.
Valve diseases were first treated with a procedure that involved passing through the narrow orifice of the mitral stenosis to dilate or cut it. This technique was first performed by Cutler, back in 1923. The first artificial heart valve was introduced in 1952, marking a significant development. Over the years, surgical methods have advanced from single-valve procedures to the 4-valve replacement introduced in 1992.
In 1944, the first operation for a congenital heart defect, responsible for a condition called tetralogy of Fallot, was performed. Cardiac arrhythmias, a group of conditions in which the heartbeat is irregular, too slow, or too fast, can be treated with a procedure known as the Cox-Maze procedure. Pacemakers, which help control abnormal heart rhythms, also underwent significant development.
The first heart transplants were performed in 1967, marking another crucial advance in cardiac surgery. Heart transplants now include immunosuppressive treatment, to prevent the body from rejecting the new heart. Devices that provide mechanical circulatory support were first used extracorporeally or outside the body, in 1982. Modern devices now offer potential long-lasting solutions to diverse rhythm problems.
However, cardiac surgery comes with high risks, both during and after the operation. Advanced equipment and well-trained staff are required. Complications can arise during the perioperative period – the timeframe surrounding an individual’s surgical procedure. These can include inflammation following cardiopulmonary bypass, decreased heart pumping function, irregular heart rhythm, need for significant amounts of blood transfusion, and issues with multiple organs such as kidney injury or stroke.
With upcoming medical advancements like minimally invasive techniques, the field of cardiac surgery is changing and adapting. These advancements attempt to make heart surgery safer and more accessible. Other improvements in this field include the establishment of cardiac arrest centers, the broader use of extracorporeal membrane oxygenation (or ECMO, where blood is oxygenated outside the body), improved process systems, and consideration for an aging patient population.
Anatomy and Physiology of Cardiac Surgery
The rib cage is like a protective case for the organs in your chest. This protection makes it a bit harder for surgeons to reach deep inside. The rib cage includes the ribs on the sides, the sternum or breastbone at the front, and moves to the back to meet the upper part of the spine. Inside this space, you have two sections on each side for the lungs, and the middle part houses important structures like the food pipe (esophagus), windpipe (trachea), major veins and arteries, nerves, and a bag-like structure containing the heart. Sometimes, if there’s a collection of blood, it can press on the heart, affecting the blood flow.
As we think about how blood moves in the body, it passes through four main areas in the heart. It enters the upper right area of the heart, moves to the lower right area, then goes to the lung to get fresh oxygen. This right side of the heart doesn’t need much pressure. The left side, which then gets the oxygen-rich blood from the lungs and sends it to the rest of the body, needs to work a bit harder, so it has more muscle. The blood then moves to the upper left area of the heart, goes to the lower left area, and then is pumped to the rest of the body.
The unique design of the heart valves, which control the blood flow, can make it tricky for doctors to replace them with artificial ones without any leaks. The two valves on the left side of the heart each have their own shape, which requires different design and techniques for replacement. Furthermore, the segments and structures that support these valves are also crucial to keep in mind for successful treatments.
The heart also has its own electrical system that controls your heartbeat. The beat can speed up or slow down based on signals from your nervous system. Problems can happen when this system has irregularities, resulting in conditions like a fast, irregular heartbeat (atrial fibrillation), which is something that often needs to be fixed after heart surgery. There are procedures like the Maze procedure that can help to correct this by regulating the electrical activity in the heart.
When it comes to surgery that helps improve blood flow to the heart (commonly known as bypass surgery), the type of vessels used to do this is really important. Arteries usually last longer than veins. There are some frequently used vessels for this kind of surgery like the internal mammary arteries found in your chest and the saphenous veins from your legs. The choice of the vessel often depends on the location of the area of the heart they are trying to reach.
Why do People Need Cardiac Surgery
Cardiac surgery is recommended based on guidelines put together by doctors who specialise in treating heart conditions. These decisions are often made by a group of doctors, including heart specialists and surgeons. Before deciding the best way forward, they often need to look at images of your heart, which could be obtained from scans such as an echocardiogram, CT scan, or an MRI.
One reason you might need heart surgery is if you have a heart valve problem. Your heart valves can become stiff (stenosis) or they can leak (regurgitation). Doctors usually categorise these conditions as mild, moderate, or severe. If your condition is severe, you may need surgery to repair or replace the affected valve.
A common valve condition is severe aortic stenosis. This is when the opening of the aortic valve is too small (less than 1 cm²). A new treatment, called Transcatheter Aortic Valve Replacement (TAVR), introduced by Cribier in 2002, has been particularly beneficial for patients who are too sick for traditional surgery. Doctors will consider various factors such as the patient’s overall health, previous surgeries, and physical frailty, to decide whether the patient should go for TAVR or traditional surgery.
In treating aortic regurgitation, another type of valve disease, doctors need to consider the patient’s symptoms and certain measures of the heart’s function. For instance, if the left part of your heart isn’t pumping well, or if it has grown too large, you may need surgery. Those with severe aortic stenosis could also be identified and treated based on certain scan measurements.
Mitral stenosis, which is mostly caused by rheumatic heart disease, and mitral regurgitation, are other conditions that require treatment depending on the cause. Repairs are usually carried out on the mitral valve, especially if there is damage to the valve itself. Severe conditions can be identified and treated based on certain scan measurements.
Heart surgery may also be recommended for complex cases like multivalvular disease, which involves issues with more than one heart valve. When combined with other heart diseases, the decision can get complex due to a limited number of studies.
Cardiac surgery can be beneficial in correcting heart rhythm problems by implanting devices like pacemakers or defibrillators. It’s also often used to treat congenital heart diseases. These conditions are birth defects that happen when the heart, or blood vessels near the heart, don’t develop correctly before birth. Special surgeries have been designed for treating particular genetic conditions.
Surgery might also be needed for non-heart conditions that impact the heart like tumors or severe pulmonary embolism. Tumors can be either benign (noncancerous) and malignant (cancerous), and depending on their impact may need removal. If you have aneurysm or break in your thoracic aorta, you may need surgery to repair it or replace it with a graft.
If you suffer from coronary artery disease, which is narrowing of the blood vessels due to a build-up of fatty material, heart bypass surgery might be a good option, as decided by your medical team. Surgery might also be helpful if you have severe heart failure and medicines are not improving your condition. For this, you might need a heart transplant or resynchronization therapy, which is a treatment to help the electrical system of your heart to work better.
When a Person Should Avoid Cardiac Surgery
Before having heart surgery, doctors must consider many factors, including the patient’s overall health and any potential obstacles. This type of surgery is usually performed in cases of severe heart disease and is considered only when the benefits outweigh the possible risks.
Doctors often use specific tools like the EuroScore, Parsonnet score, and STS score to calculate the risk of the surgery and determine if the patient can safely undergo it. These tools help doctors to make the best decision for the patient’s health.
There are instances when the surgery may need to be delayed. For example, if a patient’s health condition is unstable, it might be safer to wait. Deciding the best time to perform a heart bypass operation, also known as CABG, after a heart attack can be a tough decision for doctors. In cases of a severe heart infection that requires valve replacement (endocarditis), doctors may sometimes need to operate even when the patient is seriously ill (septic) to get the infection under control.
Equipment used for Cardiac Surgery
Heart surgery requires advanced tools and dependable monitoring devices. Some of the diagnostic equipment used include certain types of catheters and ultrasounds which helps doctors understand how the heart is performing and if there’s any disease. Doctors have to look out for and manage certain things like blood flow from the heart, how well the body responds to increases in blood volume, and how much oxygen is reaching the body’s tissues.
Treatment tools include devices that maintain or assist heart rhythm such as pacemakers, assist devices, ECMO (a device that provides heart and lung support), and CPB (a machine which temporarily takes over the function of the heart and lungs during surgery, also called a heart-lung machine). The use of CPB started back in the 1930s, and it has been improved and refined over the decades. Today, it is alive and well, helping to save many lives in heart surgeries by allowing the heart to be still during the operation.
However, CPB can have some side effects including an inflammation response in the body that is similar to what happens during an infection. Surgeons have found ways to lessen these side effects, including changes to how the surgery is carried out, reducing the duration and size of CPB, and altering the tubing surface. There are also methods to reduce the inflammation caused by CPB, such as using certain medications and applying special coatings to the CPB circuits. The inflammation usually peaks on the first day after surgery and gradually reduces over time. Many different methods are proposed to help lessen these effects.
The use of heart-lung machines and other support devices often means doctors need to frequently check how well the blood clots to prevent bleeding problems. In some cases, more detailed tests may be needed, such as tests for specific clotting factors.
One type of ECMO (a machine that supports the heart and lungs) focuses on adding oxygen to the blood and removing carbon dioxide. Another type, known as Veno-arterial ECMO, not only adds oxygen and removes carbon dioxide, but also helps to partially replace the heart’s pumping action. These ECMOs can be used as a form of temporary support until the heart recovers, as a short-term solution before another treatment, or until a transplant operation can be performed. Another device, the intra-aortic balloon pump, is less commonly used now as it doesn’t appear to affect the chances of survival.
Choosing the right artificial heart valve when a replacement is necessary is very important. There are two main types: mechanical valves, which last longer but require lifelong blood-thinning medications, and are generally recommended for younger patients, and bioprosthetic valves, which are made from animal tissue, don’t require lifelong blood thinners but tend to degrade over time and may require another replacement surgery. Bioprosthetic heart valves are often recommended for women planning to have children and older patients. There is another procedure for replacing the aortic valve, known as the Ross procedure, which involves using the patient’s own pulmonic valve.
Who is needed to perform Cardiac Surgery?
Once a student finishes medical school, they can choose to train as a heart (cardiac) surgeon. This type of training differs in how long it takes and what it involves. For those who already have general surgery experience, they need an extra 2 years of specialized education. Alternatively, there are also 6-year programs that give additional training for more specific areas like minimally invasive surgery, heart surgery for both adults and children, blood vessel surgery, endovascular interventions (treatments where medical tools are passed through a blood vessel), general chest (thoracic) surgery, and heart failure surgery.
Studying to become a heart surgeon is tough and competitive because the field is always changing and evolving. Plus, with growing numbers of elderly people and people with multiple health conditions, restrictions on work hours, and the development of new surgical techniques, the demand is high. Some experts even predict that we may experience a shortage of health care professionals in various countries in the coming years.
The team involved in heart surgery includes heart surgeons and extracorporeal technologists (people who handle the heart-lung machine during surgery), anesthesiologists (doctors who give you medicine to make you sleep during surgery), heart ICU doctors, surgery nurses, heart doctors (cardiologists), and radiologists (doctors who read medical images like X-rays). Each of these professionals receives specialized training to make sure they can do their jobs well.
Preparing for Cardiac Surgery
Before a heart surgery, several tests are performed to understand how well the patient’s body is functioning and to plan for the surgery. These tests include:
* Blood tests to check the health of organs like the kidneys and liver, to see how well the blood clots, to count the number of blood cells and to measure the balance of body salts.
* An ECG, or an electrocardiogram, which is a simple test that checks the heart’s rhythm and electrical activity.
* Echocardiography and cardiac catheterization to spot any disease in the arteries that supply blood to the heart and any issues with the heart valves.
* Chest x-ray or chest CT scans to look at the lungs and the structure of the chest. This helps plan the surgical technique.
* Neck ultrasound to assess the risk of stroke.
* Ultrasound of the veins in the lower body to check if they can be used for grafts.
* CT scans to evaluate blood vessels and bones.
In patients with certain heart conditions, a history of stroke, heavy smoking, or who are above the age of 65, an ultrasound of the neck, called a Carotid Doppler, may be done. This tries to find any narrowing of the large neck vessels that carry blood to the brain. If such narrowing is found, more tests might be needed and a particular operation might be considered.
CT scans are particularly helpful in planning a heart bypass surgery (CABG). They give a detailed picture of the area to be operated, helping decide the best approach to use. Each approach, like primary sternotomy (cutting the breastbone), redo sternotomy (repeating a previous breastbone cut), and minimally invasive thoracotomy (cutting the chest wall) has their own risks. CT scans, along with CT angiography (which uses a dye to see blood vessels), provide a non-invasive way to check blood vessels and bones for operation planning.
Management of blood thinning medications before, during, and after the surgery also needs great care. These medications may have to be stopped a few days before the surgery depending upon their type. For instance, a drug named clopidogrel should be halted 5 days before surgery, while others such as ASA and heparin can be continued until surgery. Ensuring good blood flow through the heart is balanced against the risk of excessive bleeding due to these medicines. There are strategies to manage this, which include different surgery techniques, careful monitoring and management of clotting, giving certain clotting factors and platelets, and using medicines that prevent breakdown of blood clots.
How is Cardiac Surgery performed
Open heart surgery is a common medical procedure around the world. Traditionally, this type of surgery is performed by cutting into your upper chest area (called a sternotomy or upper hemisternotomy) to access your heart. This procedure is used to treat several heart conditions, one of the most common being coronary artery bypass grafting (CABG).
During the open-heart surgery, the sac that encloses your heart (known as the pericardial sac) is opened through a T-shaped cut, while being careful to avoid damaging the two phrenic nerves that run along each side of the heart. Once the heart is exposed, the surgeon will use special tools to temporarily bypass the heart and stop it from beating (a process called cardioplegia). This allows the surgeon to safely move the heart to get a better view of the target arteries.
An ultrasound tool is used during surgery to check the ascending aorta (the main artery coming from the heart) for any hardening or blockages. Once the bypass grafts (the blood vessels that will be used to bypass any arterial blockages) have been prepared, they are connected to the blocked arteries and the aorta. After making these connections (also called anastomoses), the surgeon will check to make sure that blood is flowing through the grafts properly.
Once the procedures involving the heart are completed, the chest cavity is closed up and the sternum (or breastbone) is secured with wires. Tubes are left inside your chest to drain any fluid, and special electrodes are placed on the heart to help manage any rhythm problems. These electrodes are connected to a pacemaker and they will be removed before you leave the hospital.
A different type of bypass surgery called off-pump coronary artery bypass (OPCAB) can be particularly helpful for patients who have a higher risk of complications or a lot of hardening in the ascending aorta. This method is less likely to cause a stroke because it avoids using the clamping process (which can potentially dislodge harmful plaque). It also involves less manipulation of the aorta, which can lower the risk of creating any blood clots.
Minimally invasive surgery and endoscopic coronary artery bypass grafting (CABG) involve making smaller incisions and using special instruments and video guidance. These techniques can lead to less trauma and faster recovery after surgery, but they require additional training and are only available at certain facilities. With advances in technology, robotic systems are now also being used to perform these types of surgeries.
During heart surgery, techniques like cooling the body and using the special solution (called cardioplegia) can also help protect your heart tissue. There are even procedures for repairing heart valves, including techniques for the tricuspid and mitral valves. For example, depending on the specific surgical needs, aneurysms (weak and bulging spots) and dissections (tears) in the ascending aorta can be repaired using the David, Yacoub, or Bentall techniques.
Possible Complications of Cardiac Surgery
The death rate during heart surgery is generally around 2% to 3%. Afterwards, patients might experience some serious complications such as excessive bleeding, stroke, kidney failure, poor blood flow to the intestines, irregular heartbeats, heart failure, and breathing problems. It’s worth noting that heart surgeries are a significant consumer of national blood supply, due to complications such as excessive bleeding and blood clotting issues.
Around 18% of heart surgery patients might face acute kidney issues, and about 2% might need dialysis. These complications can influence both healthcare costs and patients’ treatment decisions.
Heart surgeries have seen an increase in post-surgery stroke complications, which might be linked to an overall increase in patient health risks. It’s found that strokes occurred in 1.8% of patients undergoing Coronary Artery Bypass Grafting (CABG, a type of heart surgery), with the incidence increasing over time. Strokes were particularly common in older patients and women, and they were associated with a three times higher risk of death during hospital stay, longer hospital stays, and higher hospitalization costs.
Another issue after heart surgeries is heart attacks. They can be difficult to diagnose due to heart damage caused during surgery. For diagnosis, doctors often rely on methods like Electrocardiography (ECG), echocardiography (a type of ultrasound for heart), coronary angiography (an imaging technique), etc. Depending on the cause, treatment may vary but often includes conservative medical treatment, Percutaneous Coronary Intervention (procedure to open narrowed coronary arteries), and in some cases, redoing the CABG.
After replacing the mitral valve in the heart, some patients might face issues wherein the blood flow from the heart to the body can be obstructed due to abnormal movement of the valve leaflets. Depending on the severity, treatment may necessitate medication or surgery. Certain factors can increase the risk of this complication, like a thick muscle wall separating the heart’s chambers and a small left ventricle.
Pain management after heart surgery is vital due to the intense discomfort. Medicines to manage pain are typically given in high doses soon after surgery, with doses decreasing over time. Effective pain management is crucial for recovery and aids in survival.
For recovery after surgery, patients are advised to move about early, as it has shown to improve the healing process. This might include preserving muscle strength, reducing lung complications, shortening hospital stay, improving life quality, and decreasing death rates. Early movement might also help reduce confusion associated with intensive care stays.
Patients operated for separation of the breastbone (sternotomy) are usually advised certain activity restrictions, avoiding lifting heavy objects, driving, or using hands to sit or stand. A new movement protocol suggests patients recovering from sternotomy to limit arm extension to reduce strain on the healing sternum.
It can sometimes be challenging for doctors to tell between normal post-surgery swelling and infection because both often present with similar signs such as fever, swelling, and high inflammation markers. However, if these symptoms appear after the second or third day post surgery, the doctor might check for an infection.
Lastly, antibiotics are administered before and after surgery for 24 to 48 hours to reduce the risk of infection after the procedure.
What Else Should I Know About Cardiac Surgery?
Heart surgery is extremely important for maintaining heart health, especially given the increasing rates of heart diseases that are often caused by issues like hardening of the arteries, high blood pressure, and certain lifestyle choices. In the United States, about 1%-2% of all money spent on healthcare is used for heart surgeries, with the average hospital stay costing around $40,000, totalling about $20 billion. This increasing need for heart surgery highlights the importance of having enough specially trained heart doctors and surgeons.
