Overview of Coronary Artery Surgery
Treating heart disease, known as coronary artery disease, has been a focus for doctors since the early 1800s. The initial surgical treatments didn’t really work and weren’t used widely. They included a variety of procedures: surgically modifying the sympathetic nervous system to reduce symptoms of chest pain, removing the thyroid to decrease hormonal stimulation to the heart, tying the internal mammary artery to increase the flow of blood through other vessels, scraping the sac around the heart to stimulate new blood vessel growth, and tying off the outflow vein of the heart to alleviate symptoms.
However, three early heart surgery procedures were relatively successful and notable. The first surgery, named after Dr. Claude Beck, involved a two-stage connection between the major artery and the vein of the heart. The second surgery, named after Dr. Arthur Vinberg, involved placing the internal mammary artery into the muscle of the heart’s left ventricle. The third surgery involved the direct removal of the fatty plaque from the coronary artery.
Coronary artery surgery progressed thanks to the groundbreaking work of Alexis Carrel on arterial connections and collaborations on the development of a heart-lung machine in the 1930s. Surgeons’ ability to perform operations on a still and empty heart through bypassing the heart’s circulatory system helped pave the way for the advancement of coronary artery bypass grafting. Renowned surgeons like Robert Goetz, Rene Favoloro, Vasilii Kolesov, Michael Debakey, and David Sabiston were all major contributors to its development.
Today, the main procedure under the banner of coronary artery surgery is coronary artery bypass grafting, although there’s renewed interest in coronary endarterectomy, a surgery that removes plaques from the coronary arteries. This discussion focuses more on consensus recommendations and outcomes related to bypass grafting.
The term “coronary artery surgery” doesn’t typically include procedures done with a catheter, a tiny tube threaded through your blood vessels. The term may also cover rare cases of trauma to the coronary vessels, whether caused by medical procedures, blunt force, or penetrating injuries. Treatment for these conditions can range from simple observation to catheter-based therapy, sewing the hole shut, or a bypass. The best treatment depends on the patient’s stability and anatomy along with the location and severity of the lesion.
Anatomy and Physiology of Coronary Artery Surgery
The design and functioning of the coronary arteries, which include the left main (LM), left anterior descending (LAD), circumflex artery (Cx), and right coronary artery (RCA) is discussed in other sections. These arteries are important pieces of the heart’s blood supply system.
Why do People Need Coronary Artery Surgery
Heart surgery was first invented back in the 1970s; however, with advances in technology, a type of major heart operation done through a small incision is now available. This method is known as a less invasive cardiac procedure. Back in 2011, the American College of Cardiology (ACC) and the American Heart Association (AHA) publicly shared a set of guidance on the types of heart patients who could benefit the most from traditional heart surgery versus a less invasive catheter-based intervention.
These recommendations outline situations where heart surgery – such as Coronary Artery Bypass Grafting (CABG) – is suggested (known as Class I indications), as opposed to scenarios where the procedure could be beneficial but alternatives might also work (Class II indications). Here’s an easy-to-understand rundown of these various situations:
Class I indications for CABG
- If there’s a severe narrowing (stenosis) by more than half in the left main artery of the heart, and if there isn’t an alternate escape route for the blood (known as a patent bypass graft).
- Severe narrowing of three arteries by more than 70% each.
- Severe narrowing of two arteries by more than 70%, if one of the two is the artery near the upper part of the heart’s front wall (proximal LAD).
- CABG or a less invasive cardiac procedure can be used for single artery narrowing by more than 70%, if the patient still experiences chest pain despite the best medical treatment available.
- CABG or catheter-based interventions might be used if a good amount of heart muscle is at risk due to a vessel narrowing by more than 70% leading to rapid irregular heartbeats that can cause cardiac arrest.
- CABG may be required in emergency cases after a heart attack for complications such as tear or hole in the heart’s wall, acute improper functioning of the mitral valve, or a spontaneous tear in the heart wall.
Class II indications for CABG
- Heart surgery may be better than a less invasive catheter-based procedure for patients with complex narrowing of three arteries and a special score more than 22, according to the Syntax scoring system (a method based on how coronary vessels look in an X-ray angiogram).
- Patients with more than 70% narrowing of multiple arteries and have a somewhat impaired pumping function of the heart (an ejection fraction between 35 to 50%)
- Disease involving two arteries, neither of which is the upper part of the heart’s front wall, but there’s a significant lack of blood supply to the heart tissue (>20% perfusion defect)
- A single vessel narrowing more than 70% involving the upper part of the heart’s front wall (proximal LAD) with a significant lack of blood supply to the heart.
- CABG is usually preferred over a less invasive procedure for patients with diabetes and complex narrowing in multiple arteries if the surgeon uses a specific type of graft from the chest (left internal mammary graft).
Keep in mind that a group of heart doctors and specialists will review your options for treatment, especially in more complicated cases. Getting a heart team’s input is key to making the best decision for your heart health.
When a Person Should Avoid Coronary Artery Surgery
The ACC/AHA 2011 guide for heart doctors also points out when Coronary Artery Bypass Graft (CABG), otherwise known as heart bypass surgery, should not be done due to its potential risks:
– One should not have emergency bypass surgery if they’re stable, have ongoing chest pain but only a small part of their heart muscle is viable or healthy.
– If someone has undergone Percutaneous coronary intervention (PCI – a non-surgical method to treat the blocked coronary arteries), that restored blood flow to the outer layer of the heart but not the small vessels inside (a condition known as no reflow), emergency bypass surgery should not be performed.
– Emergency bypass should also not follow a failed PCI procedure if there is no current heart muscle damage or serious arteries blockage.
– Patients with a type of heart rhythm disorder known as ventricular tachycardia, and a scar on their heart muscle, but don’t show signs of active heart muscle damage, should not have the operation.
– A person with stable blockages in the heart should not have the surgery if the narrowings are less than 70% in arteries other than the left main coronary artery, and the disease only affects the right coronary artery or the circumflex artery, or if the blood flow is adequate (>0.80).
– They also advise against grafting the right coronary artery with an artery graft unless the narrowing is over 90%.
People suffering from end-stage kidney disease and non-heart related conditions that limit their life expectancy are also advised against heart bypass surgery.
Also, if a person has had a specific type of heart attack, known as a transmural myocardial infarction, going for bypass surgery within three days or within six hours for a non-transmural heart attack, both can result in death during hospital stay, so doctors should avoid such quick decisions. It also seems sensible to wait at least four weeks after a stroke before performing bypass surgery.
Other severe conditions like liver failure, end-stage lung disease, severe mental health issues, and advanced cancer should be evaluated on an individual basis when considering bypass surgery.
Equipment used for Coronary Artery Surgery
To carry out a Coronary Artery Bypass Graft (CABG) surgery, which is a common type of heart surgery that helps to improve blood flow to the heart, several pieces of equipment are necessary:
* A surgical operating room: This is a sterile place where surgeries are performed.
* Sterile drapes, gowns, gloves: These are worn to maintain a sterile environment and reduce the risk of infection.
* Cardioplegia: It’s a solution used to stop the heart during surgery. This creates a more stable environment for the surgeon to work in.
* Cardiopulmonary bypass machine: This device temporarily takes over the function of the heart and lungs during surgery, maintaining the circulation of blood and oxygen in the body.
* Endoscopic vein harvest scope: This is a tool used to safely remove veins from the leg or chest, which will be used to bypass the blocked coronary arteries.
* Echocardiography ultrasound: An ultrasound machine that provides real-time images of the heart to help guide the surgeon.
* Swan-Ganz catheter: A thin tube that is inserted into the heart through a vein in the neck or groin, used to monitor the heart’s performance and response to treatment during the surgery.
* Sternotomy saw: A specialized saw used to safely open the chest and gain access to the heart.
* Operative instruments and all supplies (sutures, pledgets): Various tools used in the surgery, sutures (stitches) are used to sew the chest back together and pledgets are small pieces of material used to support sutures and prevent leaks of blood or other fluids.
Who is needed to perform Coronary Artery Surgery?
Before the operation
There’ll be a team of medical professionals involved to ensure everything goes smoothly before your operation. This team consists of the following:
– Internal medicine physician: This is a doctor specialized in the diagnosis and non-surgical treatment of various illnesses.
– Cardiologist: This is a heart specialist who checks your heart condition to make sure it is safe for you to undergo the operation.
– Interventional cardiologist: Another type of heart doctor, who may perform certain procedures to help prepare you for surgery.
– Cardiothoracic surgeons: These doctors specialize in surgeries of the heart and chest area. They’ll perform your operation.
– Echo tech: This is a technician who uses an echocardiogram (a device that uses sound waves to make a picture of your heart) to check how well your heart is working.
– Nursing: The nurses will take care of you, administer medications if needed, and answer any questions you have.
During the operation
During surgery, these professionals work together to ensure everything goes as planned:
– Cardiac anesthesia team: These are the doctors who will put you to sleep so you don’t feel any pain during the operation.
– Perfusionist team: They operate the heart-lung machine, which takes over the work of your heart and lungs during surgery.
– First assistant: This is another surgeon who helps the main surgeon during the operation.
– Operating room (OR) nursing staff and scrub techs: These are the nurses and technicians who make sure that all the tools and devices used during the surgery are clean and properly prepared.
– Cardiac intensivist: This is a doctor who specializes in the intensive care of patients with heart conditions.
– Echo tech: This technician performs echocardiograms during the surgery to monitor your heart’s performance.
After the operation
Once the operation is completed, these professionals help with your recovery:
– Cardiac ICU nurse: A nurse specialized in caring for patients with heart conditions in the Intensive Care Unit (ICU), ensuring you get the care and monitoring needed after surgery.
– Physical therapist: This person will help you regain strength and mobility after your operation.
– Cardiac rehab specialist: This professional will guide you through exercises and lifestyle changes to help get your heart back in shape and prevent future problems.
Preparing for Coronary Artery Surgery
Before you have coronary artery bypass graft surgery (CABG), doctors usually conduct several tests, such as an angiogram, electrocardiogram, and echocardiogram, to understand your heart’s health. They might also take a detailed medical history and conduct a physical examination. The purpose of these tests is to identify any conditions that might affect your surgery and recovery.
For example, they’ll check for any heart-related issues, like heart failure, valve disease, pulmonary hypertension, and heart rhythm problems. They’ll also look for other health conditions, such as diabetes, obesity, lung disease, or a history of smoking, as these could affect your procedure and recovery. Your doctor may take into account if you’ve had chest surgery or radiation in the past, any issues with your blood vessels, and other health conditions.
Most patients will already be on a regime of medications which may need adjustment around the time of surgery based on established medical guidelines. For instance, if your heart’s ejection fraction (a measure of how well your heart pumps blood) is more than 30%, you may need to take beta-blockers at least 24 hours before your CABG operation. The reason for this is to reduce the risk of death and irregular heartbeats. If you can’t take beta-blockers, amiodarone might be an alternative to help prevent irregular heartbeats.
Maintaining healthy cholesterol levels is very important. Your doctor might recommend taking statins to reduce your LDL (bad) cholesterol to less than 100mg/dL or by 30% from your previous levels. Keeping your blood sugar under control is equally crucial, particularly before and after your surgery, to prevent complications such as heart-related deaths and wound infections.
If you’re a woman who’s gone through menopause and is on estrogen/progesterone therapy, you may need to stop this treatment before your operation to lower the risk of blood clotting complications.
For some medications, like ACE inhibitors, angiotensin receptor blockers (ARBs), or antiplatelet drugs (like clopidogrel and ticagrelor), your doctor may advise a break before your CABG to minimize potential problems such as excessive bleeding during surgery.
Finally, if you’re a smoker, adopting a strict no-smoking policy and getting help with depression care and cardiac rehab can significantly help your recovery. It is important to remember that each patient’s needs are individual, so the medication care plan can differ based on your unique medical history and current conditions. Be sure to ask your doctor any questions you may have about your preoperative preparation and postoperative care.
How is Coronary Artery Surgery performed
CABG, or Coronary Artery Bypass Grafting, is a procedure that improves blood flow to the heart. Essentially, it creates a new path for blood to flow around, or “bypass,” a blocked part of your heart’s blood vessels. This is done by using a blood vessel from another part of your body, known as a conduit, to divert blood around the blocked area.
The goal of this operation is to make sure blood flow is restored entirely to the affected vessel. The way the bypass is built is crucial for successful surgery and the patient’s recovery. This is because if it blocks up, it shouldn’t cut off blood flow through the heart’s own vessels.
One piece of technology that helps during the operation is the cardiopulmonary bypass pump. This device helps make the surgical area almost bloodless and keeps the heart still for finer surgical work. It also helps protect heart muscle cells during the operation.
There are a few different types of blood vessels that can be used as conduits in the bypass operation. The internal mammary artery, a vessel located near your chest, is the best to use because it lasts longest and has the lowest chance of developing blockages. The left side of this artery is most commonly used, but some surgeons may use both sides simultaneously.
The radial artery, which travels along your arm, can also be used as a conduit. There are benefits and drawbacks to this; it can last a long time but it also has a risk of narrowing (vasospasm). Consequently, it should only be used if the blockage being bypassed causes more than 70% narrowing of the heart’s blood vessel.
The greater saphenous vein, a large vein in your leg, is another possible conduit. Despite it being commonly used, it does not last as long as other options. Although this is partly related to the natural diseases that affect veins, the harvesting (collecting) process and the change in blood pressure may be linked to reduced life span of this conduit.
Surgeons can choose to perform the CABG operation with or without the use of a bypass pump. While using a pump helps avoid some side effects like inflammation, kidney failure, and depressive symptoms, it does not seem to change overall outcomes or quality of life.
Finally, during the operation, some doctors may also perform a procedure called coronary endarterectomy to help improve the condition of complex blockages. This procedure involves making a cut near the blocked part of the vessel and removing the plaque (fatty buildup that causes the blockage) from the inside of the vessel. Afterwards, the CABG process continues as before. However, this is not a common procedure, as more evidence is needed to ensure its safety and effectiveness.
Possible Complications of Coronary Artery Surgery
Coronary artery bypass graft (CABG, pronounced ‘cabbage’) surgery helps improve blood flow to the heart. Various health organizations have been studying the results of this surgery for over thirty years. This surgery has many benefits in the long-term, but like all surgeries, there are some risks.
The risk of death shortly after surgery is small. The rates vary, with some studies reporting rates of 1.7% and 3.5%. Unfortunately, the mortality rate increases over time, with a reported 6 to 8% mortality rate after one year and 11 to 23% after three years. However, if a patient needs emergency surgery, needs to repeat the surgery, or is in shock, this risk increases. Despite this, most patients fare just as well two years after surgery as other patients do.
The heart may experience some problems after surgery, like a heart attack or low heart output that requires medication and a medical device called an intra-aortic balloon pump to keep up the blood pressure. After surgery, 20 to 50% of patients experience abnormal heart rhythms, which can increase the risk of death and stroke. To lower this risk, surgeons will often give medication to prevent it from occurring.
Stroke, or brain damage due to a lack of blood flow, is another risk of CABG surgery with a reported incidence of 1.4% to 3.8%. This high risk increases mortality ten-fold. The stroke can be due to emboli, or clots, that can get lodged in the brain’s blood vessels during surgery or due to reduced blood flow to the brain during or after surgery. Doctors use various strategies, like optimal medical support, separate surgeries to unblock blood vessels, and surgical supports like ultrasounds, to lower this risk.
Acute kidney injury, where the kidney is damaged due to reduced blood flow, inflammatory reactions, or possibly low blood count, also occurs in 2 to 3% of CABG patients, with 1% requiring dialysis. Similarly, patients might experience bleeding because they need blood thinners during the heart-lung bypass during surgery. This bleeding is problematic because transfusions can negatively affect the heart and further increase the risk of death.
The surgical wound that’s created when the doctors access the heart can also cause complications. The superficial wound incidence is reported 2 to 6%, with a deeper wound occurrence of 0.5 to 5%, which considerably increases risk of death. Such wounds are not surprising, considering the loss of blood flow to the region during surgery. Because of this, patients with diabetes could have more wound issues due to their already compromised wound healing. Hence there is emphasis on optimal blood sugar control during and after surgery.
What Else Should I Know About Coronary Artery Surgery?
Coronary artery bypass graft (CABG), which is a type of heart surgery that improves blood flow and oxygen to the heart, is thought to be one of the most beneficial and life-saving surgeries available. There have been many studies that back up these assertions.
There were three major studies conducted in the 1970s that compared CABG to medication therapy for people with heart disease caused by clogged arteries. These studies did not find a difference in overall survival rates, but they did show that specific groups of patients with more serious heart disease found significant benefits from CABG. For example, the Veterans Administration (VA) Coronary Artery Bypass Surgery Cooperative Study Group found that patients who had the procedure because they suffered from chest pain due to coronary artery disease had extended survival rates, especially in the case of individuals who had clogged left main and triple vessel arteries. However, this survival advantage disappeared after approximately 11 years when the grafts, which were mainly created from leg veins, became obstructed.
Over the years, many other studies have compared CABG with the various forms of Percutaneous Coronary Interventions (PCI), which are non-surgical procedures used to treat the stenotic (narrowed) coronary arteries of the heart. PCI uses angioplasty (using a balloon to open up a blocked blood vessel) and stents (tiny wire cages that prop open blood vessels after angioplasty) to improve blood flow. The general consensus from these studies is that CABG is better.
One notable study was the FREEDOM trial. It included 1,900 diabetic patients with blocked coronary arteries who were treated with either drug-eluting stents or CABG. After five years, those who had PCI were more likely to experience death, heart attack, and stroke than those who had surgery (27% vs. 19%).
The SYNTAX trial was another important study. It included 1,800 patients with three blocked coronary arteries or a blocked left main artery. They were treated with either drug-eluting stents or CABG. After a year, fewer patients who had had CABG reached the primary endpoint (a measure of effectiveness), primarily due to the need for further procedures to reopen their vessels (12% vs. 18%).
In light of medical advancements, newer studies have started to compare revascularization (restoring blood flow to the heart), via CABG or PCI, with medication therapy as was done in the 1970s. One such study, the BARI 2D trial, examined CABG, PCI, and medication therapy and found that, for diabetic heart disease patients with a mid to high-risk SYNTAX score (a scoring system that measures the appearance of the coronary vessels), CABG reduced major adverse cardiac events compared to medication therapy. There weren’t any differences between PCI and medical treatment.
In general, the studies indicate that CABG can be recommended over other treatment plans for certain groups of patients. However, all data and treatment plans should be considered on an individual basis, with the individual’s unique medical history in mind.
