What Is Double Bypass Surgery?

Double bypass surgery is a type of open-heart surgery that redirects blood around two partially or fully blocked arteries in the heart (called coronary arteries).

The procedure, known specifically as coronary artery bypass graft (CABG) surgery, involves the harvesting of an artery from another part of the body. The artery is then grafted into the heart to bypass the blockage and restore blood flow.

It is called a "double bypass" because two coronary arteries need to be bypassed. If three vessels are bypassed, it is called a triple bypass, four bypasses are called a quadruple bypass, and so on. The quintuple bypass involving five blocked vessels is rare.

CABG surgery is a serious but fairly common procedure used to treat coronary artery disease (CAD) characterized by reduced blood flow to the heart. It may also be used for people who have suffered a heart attack or who have heart failure.

This article explains what to expect before, during, and after double bypass surgery.

Why It Is Done

CABG surgery is one treatment option for a blocked coronary artery. The main cause of this is atherosclerosis, a condition in which fatty deposits in blood vessels cause them to narrow and harden.

There are several reasons why CABG surgery may be needed:

• Angina: This is chest pain caused by the narrowing of arteries that supply the heart. When angina causes debilitating pain at rest or with light activity, bypass surgery may be a reasonable option.
• Left-sided heart failure: If you have more than one diseased coronary artery and the left ventricle of your heart isn't pumping blood as it should, a bypass may be necessary. The left ventricle is the chamber of the heart that pumps blood for circulation throughout the body.
• Arterial stenosis: This is the narrowing of an artery due to atherosclerosis and other causes. A bypass may be needed if your left main coronary artery is severely narrowed as this is the vessel that supplies most of the blood to the left ventricle.
• Failed angioplasty: A bypass may be needed when a procedure called angioplasty with stenting has failed. Angioplasty with stenting involves the inflation of a tiny balloon to widen an artery, which is then held open with a wire mesh tube (called a stent).

CABG surgery may also be used in emergency situations, such as a heart attack if you are not responding to other treatments.

Preparations for a Double Bypass

Before undergoing double bypass surgery, you would need tests to determine which blood vessels can be safely harvested for the graft.

Since veins in the legs are most commonly used for this, a physical exam would be performed to check for varicose veins and other abnormalities. If the veins in your legs are not viable, others may be harvested from your arm or chest wall.

Several days before the surgery, all anticoagulant drugs (blood thinners) would be stopped to prevent excessive bleeding. This includes drugs like Coumadin (warfarin), Plavix (clopidogrel), and aspirin.

The site of the graft will then be mapped with an angiogram, an imaging scan that shows the flow of blood through the heart. The type most commonly used is computed tomography angiography (CTA), which combines multiple X-rays to create three-dimensional "slices" of the heart.

Double bypass surgery is an inpatient procedure, meaning that you will be hospitalized for treatment and postoperative recovery.

Before the Surgery

A double bypass is performed by a cardiothoracic surgeon with the assistance of an anesthesiologist, a surgical nurse, a cardiac perfusionist (who operates the bypass machine), and others.

The surgery is performed under general anesthesia to put you fully to sleep. In order for you to breathe, an endotracheal breathing tube will be placed into your throat and connected to a mechanical ventilator. Your vital signs (including pulse, blood pressure, and blood oxygen) will be monitored to ensure that you remain stable throughout the procedure.

Heparin, a type of blood thinner, will be administered intravenously (into a vein) to prevent blood clotting.

There are two types of CABG surgery your surgeon may perform:

• On-pump: This is when you are connected to a cardiopulmonary bypass machine that maintains blood circulation while your heart is in arrest (not pumping). The machine takes over the function of the heart and lungs, maintaining blood circulation and oxygen levels.
• Off-pump: This is done while your heart is still beating and sections of your heart have been stabilized so that the graft can be placed accurately. This method is mainly used for older people and those with medical conditions in whom stopping the heart may be dangerous.

During the Surgery

CABG surgery involves the harvesting of a vein to be grafted and the grafting of the vein into the heart (anastomosis).

Once you are sedated, the surgeon will perform a sternotomy in which a cut is made along the breastbone with a scalpel. Tools are then used to open the ribcage and expose the heart. In most cases, your heart will be temporarily stopped with medications and placed on a cardiopulmonary bypass machine.

Blood vessels are taken from another area of the body, typically the leg, and grafted onto the existing coronary artery to reroute blood flow around the blockage. In some instances, the sternotomy and harvesting may be done simultaneously by the surgeon and an assistant, respectively.

After the graft is placed, the heart will be restarted and checked for any signs of leakage. Once everything has been checked, your chest will be closed and your skin sutured or stapled shut.

Chest tubes are usually placed to drain fluids from the chest cavity, either with gravity or gentle suction. This prevents the build-up of blood and fluid around the heart.

After the Surgery

Once CABG surgery is over, you are wheeled to a cardiac intensive care unit (ICU) to recover. 

Unlike most procedures, the anesthesia used for CABG surgery is not reversed with medications.  Instead, the anesthesia is allowed to wear off over the course of four or more hours, allowing you to slowly and gently wake up.

In most cases, you will be kept in ICU until the following day and transferred to a bed in the surgical ward. If there are no complications, you can usually be discharged in four days and provided with care instructions for you and your caregivers.

You will also be prescribed drugs to prevent postoperative complications, including:

• Dobutrex (dobutamine): Used to increase blood output from the heart
• Low-dose aspirin: Used to prevent blood clots and graft failure
• ACE inhibitors or ARB blockers: To maintain optimal blood pressure
• Beta-blockers: Used to prevent atrial fibrillation

You may experience postoperative side effects like insomnia, poor appetite, depression, and memory problems, but these tend to subside within six to eight weeks. A tailored exercise and diet plan will be provided to aid with your recovery.