- 16/April/2019
CABG Types & Procedure facts - Ananthapuri Hospitals, Trivandrum
Coronary artery bypass grafting (CABG), also called ‘heart bypass surgery’ or simply ‘bypass surgery’, is a surgical procedure to improve blood supply to the heart in people whose hearts are not receiving enough blood supply.
Doctors perform this procedure on people who have a severe obstruction of their coronary arteries, a condition called coronary heart disease (CHD). The coronary arteries are the vessels that supply oxygenated blood to your heart.
Bypass Surgery is aimed at ensuring that the blood flows optimally to the heart by creating another route to bypass the blocked coronary artery. It is one of the most common open-heart surgeries and it is done by specially-trained doctors called cardiothoracic surgeons.
During bypass surgery, arteries or veins may be used as grafts to create a bypass route for occluded coronary arteries. However, arteries are preferred.
Why are Arterial Grafts Preferred?
Doctors usually use arterial grafts instead of venous grafts because of low risk of recurrent fat buildup in the vessel, thereby low risk of future occlusion, and thereby better outcome for the patient!
Doctors may, however, combine arterial and venous grafts for some patients with multiple coronary arteries. The saphenous vein, a long vein which runs along the inside of each leg, is the most common vein used for bypass surgery.
Types of Arterial Grafts
Doctors obtain grafts from different arteries in the body to bypass the obstructed coronary artery. Examples of arteries used include:
- Internal mammary artery, which is the most common artery used for this procedure
- The radial artery from the forearm, supplying blood to the hand
Using the internal mammary artery for coronary bypass surgery has been linked with excellent long-term outcomes and is the most common artery used. Other arteries are also associated with good long-term results but to a lower degree than the internal mammary arteries.
The questions now are: how do doctors make the choice of the most suitable arterial grafts and what is responsible for the difference in results between different arterial grafts? The difference is in the biological properties of these vessels.
Factors that Influence the Choice of Arterial Grafts
There are some other factors your doctor may consider before choosing an arterial graft for you. These factors include:
Age of Patient
Arterial grafts are generally preferred because of their superior patency rates; however, age may be a limitation.
All patients with coronary heart disease should receive internal mammary grafts, except if there’s a contraindication. Radial artery grafting can be used for all age groups, but more preferably, people younger than 70 years. As a general rule, if a patient is expected to live for more than 10 years, an arterial graft is preferred.
Internal mammary and radial artery can be used in composite configurations for Bypass grafting avoiding handling the Aorta. In elderly patients aorta has cholesterol deposits and manipulating the aorta can cause neurological injury. Arterial grafting without aortic manipulation thus reduces the chance of stroke in older patients undergoing CABG
Severity of Occlusion of Coronary Artery
The degree of occlusion of the native coronary artery also determines whether the artery is suitable for graft purposes. Arterial grafts work better when the block is more than 90%
What to Expect During Arterial Grafting
Coronary artery bypass graft surgery usually takes about 3 to 6 hours, depending on the number of coronary arteries to be bypassed. Of course, you won’t be awake during the procedure. The anesthesiologist will administer general anaesthesia that will put you to sleep before the procedure commences.
For a traditional CABG procedure, the surgeon will make an incision from the top of your chest down the centre to the bottom of your chest. Once this cut is made, the surgeon will use a device to separate your ribs so to gain access to your heart.
The required grafts (eg: Internal mammary artery, Radial Artery ) are then harvested
Depending on the number & location of bypass required, the surgeon will connect the mammary artery & Radial artery to create a different configuration ( Eg Y graft )
The blocked coronary artery is then identified based on the coronary angiogram.
A special device ( eg Octupus, Acrobat ) is placed in the surface of the beating heart to immobilise the part the grafting needs to be done. This is continued till all blocked arteries are bypassed.
This technique ensures the heart is beating at all times and blood supply is maintained even while grafting is done.
What to Expect After Arterial CABG
After the procedure, you will be transferred to the Intensive Care Unit (ICU), where your vital signs – respiratory rate, heart rate and heart rhythm, blood pressure, and oxygen saturation levels – will be continuously monitored.
For arterial grafts, your doctor will administer other intravenous medicines that prevent spasms in the artery used. After discharge from the hospital, you will keep taking these medicines orally for at least 6-12 months to prevent spasms and re-occlusion.
In the ICU, you will continue to receive medicines, through an intravenous line, to control these vital indices. You will also likely have a tube inserted in your chest to drain fluid. In addition, you may also receive oxygen treatment if necessary. You will also receive pain medications to numb the pain. You may not be allowed to eat or drink anything while in the ICU.
You will spend 1-2 days in the ICU, after which, if all vital indices are stable, you will be transferred to the hospital ward. You may be discharged home after 3-5 days in the hospital ward. However, this depends on how fast you recover.
Ananthapuri Hospitals | Advantages of Beating Heart Arterial CABG
- Less incidence of neurological complications
- Less incidence of kidney failure.
- Less chance of abnormal Heart Rhythm.
- Less need for blood & blood product transfusion.
Risks of Arterial CABG
As with any other surgery, arterial grafting does have risks. These risks include:
- Complications of anaesthesia used
- Wound infection
- Excessive bleeding during and after the procedure
- Fever
- Pain
- Breathing difficulty
- Chest infection, called pneumonia
- Heart attack from poor reperfusion of the heart
- Stroke
- Kidney failure
- Trouble remembering things
- Death
Your age, the severity of the coronary heart disease, how many bypass grafts you receive all influence what complications arise after your surgery. Also, the risk of these complications is much higher if the procedure is done as an emergency treatment and if you have other medical conditions, such as diabetes and kidney disease, that affect the heart and blood vessels.
Biological Properties of Various Arterial Grafts
Although arterial grafts are superior to venous grafts because of the lower risk of future occlusion, lower risk of vascular damage, and in turn, long-term patency of the vessels, different arterial grafts yield different results. The biological properties of these arteries yield varying results for each when used for grafting.
Structure of the Artery
Structural differences between these arteries confer differences in the results they yield; one of such structural differences is the elasticity of the vessels. The more elastic the vessel, the longer it may last as a graft for coronary bypass.
Contractility
The contractility of an artery is the measure with which it tightens or constricts. Contractility often occurs in response to certain stimuli and these arteries respond to these constrictive factors differently. This may lead to a recurrent occlusion and another “coronary” heart disease.
Endothelial Function
The inner lining of an artery is called the endothelium. There are chemicals that bind to proteins in the endothelium, causing the artery to relax. Some studies have revealed that the internal mammary artery responds more to these chemicals than most other arteries and the saphenous vein.
Incidence of Fat Plaques
The buildup of fat plaques in arteries is called atherosclerosis and the risk of atherosclerosis in a blood vessel determines its effectiveness for a coronary bypass graft. Some arteries have a low risk of atherosclerosis. For instance, the internal mammary artery generally has a low risk of atherosclerosis than other arteries. Even 15 to 20 years after grafting with the internal mammary artery, the risk of atherosclerosis is still low.
Arterial grafts are conductance vessels, which have been shown to have superior long-term patency rates, better patient outcome, and a lower risk of re-occlusion in comparison to venous grafts. However, the choice of which arterial grafts to use should be based on certain objective factors, including the biologic properties of the graft, the general condition of the patient, and technical considerations.
Cardiovascular Centre at Ananthapuri Hospitals & Research Institute
The Cardiovascular centre of Ananthapuri Hospitals has been functioning with full-fledged facilities ever since the inception of the hospital in July 2005. Our team comprises of surgeons credited with extensive experience as professors and Senior Consultants in leading medical colleges and tertiary care centres. They bring a unique wealth of clinical expertise and surgical craft from home and abroad. In addition to that, our department has state of the art technology to diagnose and treat patients with diverse types of cardiac problems and is equipped with gadgets capable of performing complex interventions. We stay true to our mission of providing service with sincerity and solicitude.
To book an appointment, call us at +91 9400332777 or visit our hospital at Chacka, NH Bypass, Thiruvananthapuram.