Benefits and Risks of Off Pump Coronary Artery Bypass Surgery

Summary

Off Pump Coronary Artery Bypass Surgery is an open surgical procedure done to overcome blockages, due to plaque deposits, in coronary arteries. Unlike the more common Coronary Artery Bypass Grafting (CABG) in which the heart is not beating and circulation is maintained by a heart-lung machine, in an Off Pump procedure, the heart continues to beat. But its movement and blood-flow are stabilized using certain devices. The procedure requires shorter incisions compared to a CABG, so recovery is quick. In this article, we will learn more about the procedure.

Introduction

Atherosclerosis is a condition in which cholesterol and other material found in the blood deposit on the inner walls of arteries. As the deposits grow, they can narrow down the artery, and thereby restrict blood-flow (situation called as stenosis). Over time, these deposits harden and are called plaque now. The hard plaque can break off sometimes and cause tears in the wall of the artery. In response to the tear, platelets rush to the site of tear and block the spot to prevent blood-leakage. Normally, blood-clots disintegrate eventually, once the wound is healed, so there is no concern.

However, quite often, these clots break away from the spot, and start circulating in the blood. In the process, they can end up clogging coronary arteries in the heart, or arteries anywhere in the body. But since the heart is responsible for non-stop pumping of blood, such a blockage can cause serious consequences such as heart attacks. In addition to clots, even pieces of plaque that break away, can circulate and clog up an artery. So, the blockage, caused by either or both materials, must be resolved at the earliest.

How are such blockages resolved?

If medication, and angioplasty with stenting, does not resolve the blockage over time, a Coronary Artery Bypass Surgery (CABS) is done. In this procedure, a vein or artery taken from anywhere in the body (but generally from the heart) is used to create a bypass for the blood-flow, around the blockage. This way, normal blood-flow is resumed and that portion of artery which has the blockage eventually becomes dead. CABS is of 2 types:

1. Coronary Artery Bypass Grafting (CABG): This is the more common procedure. Also called cardiopulmonary bypass with cross-clamping of the aorta. In this, a cardiopulmonary bypass pump (or ‘heart-lung machine’) is used. The blood circulation within the heart and from the heart is temporary stopped. The blood from the heart is diverted to an external machine where oxygen is added and the blood circulated through the rest of the body (other than the heart). The surgeon then takes a piece of another vein or artery from the heart which is clear, and grafts it on to the artery which has a blockage, thereby creating a loop or bypass around the blockage. The blood-flow will eventually resume through the new bypass while the piece of artery with the blockage, becomes defunct. The intention of stopping blood-flow through the heart temporarily, is to make it easy for the surgeons to complete the procedure.

 

2. Off Pump Coronary Artery Bypass (OPCAB): In this procedure, there is no heart-lung machine used, hence the name Off Pump CAB. In this procedure, the heart continues to beat throughout the procedure, hence the other name for OPCAB is ‘beating-heart surgery’. However, to make it easy for the surgeons, the heart’s beating and the blood-flow are controlled, using stabilization devices and cross-coronary shunting. The surgeon then takes a piece of vein or artery from the heart or chest-well, attaches one end to the aorta (the main artery supplying pure blood to the body). The other end is attached to the artery which has the blockage, thereby creating a bypass for the blood-flow.

Why is OPCAB required?

So why is OPCAB done? Why do we have two types of CABS?

CABG or the on-pump procedure has the advantages that it presents a clear field or area for surgery, to the surgeons involved. The lack of motion and perfusion (blood-flow) in the heart makes it easy to resolve blockages and examine other possible heart conditions. However, it comes with its own disadvantages.

• Inflammation: the circulation in the body that happens due to contact with a heart-lung machine causes inflammation in the body. Blood in people who have had a CABG, has been examined and found to have high levels of markers for inflammation. Inflammation can cause swelling in some parts of the body.
• Impaired haemostasis: Haemostasis is the body’s natural reaction to an injury which causes it to create clots at the spot of injury and prevent uncontrolled blood-leakage. People who have had a CABG may show impaired haemostasis for some time after the procedure.
• Cognitive impairment: Patients who are woken up after the procedure exhibit confusion and memory loss, for some time.
• Infections, due to blood-contact with an extracorporeal (‘outside the body’, or external) machine
• Arrhythmias or irregular heart-beats, for a fairly long time after the procedure
• Bleeding, and blood-clots, in the days after the procedure. This increases the risk of heart-attack or stroke
• Kidney failure, especially in patients who are already suffering from chronic kidney disease (CKD)

Further, not everyone is a candidate for CABG. Patients suffering from the following conditions, are advised to go in for OPCAB:

• Atherosclerosis in the aorta, the master artery of the heart
• Cerebrovascular disease: a range of conditions that affect blood-circulation to, and inside the brain
• Chronic lung disease
• Chronic kidney disease
• Cirrhosis of the liver
• An earlier bypass surgery

Benefits or Advantages of OPCAB

OPCAB overcomes many of the limitations of CABG and offers the following benefits:

• Reduced risk of infection and inflammation, as no extracorporeal machine is used here
• Lesser damage to kidneys or reduced renal-dysfunction (impairment of kidney function)
• Reduced risk of stroke and cognitive issues
• Reduced risk of coagulopathy (improper blood-clotting) and hence reduced requirement of blood-transfusion due to blood-loss following an injury
• Reduced morbidity and mortality (the risk of disease and death from that disease), especially in women and high-risk patients
• Reduced injury to the heart: OPCAB procedures in recent years use shorter and multiple incisions compared to CABG. Advanced hospitals in the west even use minimally-invasive and robotic surgery. All these reduce injury, and collateral damage to nearby tissues.
• Reduced hospital stays and faster recovery: due to the previous point
• Reduced risk of arrhythmias

Risks or Disadvantages of OPCAB

• Bleeding, due to incisional surgery
• Infection, due to the open nature of surgery
• Stroke, due to blood-clots caused by the bleeding
• Kidney failure, in patients with advanced CKD
• Lung complications, in some cases
• Complexity: OPCAB requires highly skilled surgeons who have enough experience and expertise in this procedure.
• A repeat bypass surgery in the future

The extent of risk will depend on various factors such as age of the person, whether he/she is a smoker or not and the history of smoking, the quality of heart-function, the presence and severity of conditions like diabetes, chronic lung disease and chronic kidney disease.

So, which is better?

The choice of whether to go in for a CABG or OPCAB is not for the patient to make. This will be decided by the case doctors involved after a thorough evaluation of various parameters, and conducting certain diagnostic-tests. In fact, doctors have extensive decision-making algorithms or flow-charts to arrive at a conclusion. Rest assured, they will make the right decision which is in the patient’s best interest.

How is the procedure done?

• If the patient is a smoker, he/she is advised against smoking for a week or more before the procedure.
• If he/she takes certain medications, especially anti-coagulants, the same will be temporarily discontinued.
• He/she must avoid eating or drinking anything after midnight before the day of surgery.
• Patient will be admitted to the hospital the previous night or few hours before the surgery.
• The area of incision will be shaved in case of male patients.
• Anaesthesia will be administered and the patient rendered unconscious.
• The surgeon will make an incision down the middle of the sternum or chest-bone, to access the heart. Depending on the location of the blockages, the incision may even be made between the ribs, or multiple, small incisions may be made.
• A device is used to stabilize the heart.
• A torniquet or a tight bandage is tied around the blocked artery to stop blood-flow in it.
• A piece of another vein or artery taken from the heart is grafted, with one end attached to the aorta and another to the blocked artery, thereby creating a bypass.
• The torniquet is removed, sternum is closed, and the incision stitched up.
• Once the patient is awake, he/she will find a tube in the throat to help him/her breathe, and a tube in the chest to drain out fluids.
• The patient is observed for a day or two, and once stable, he/she is discharged. The doctor will provide clear dos and don’ts which the patient must follow strictly, to speed up recovery.

Kauvery Hospital is globally known for its multidisciplinary services at all its Centers of Excellence, and for its comprehensive, Avant-Grade technology, especially in diagnostics and remedial care in heart diseases, transplantation, vascular and neurosciences medicine. Located in the heart of Trichy (Tennur, Royal Road and Alexandria Road (Cantonment), Chennai (Alwarpet & Vadapalani), Hosur, Salem, Tirunelveli and Bengaluru, the hospital also renders adult and pediatric trauma care.

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