Coronary artery bypass grafting (also known as CABG) is a surgical procedure that improves blood flow to the heart in people with coronary artery disease (CAD). In CAD, plaque builds up within the coronary arteries—the blood vessels that supply the heart with oxygen-rich blood—narrowing or blocking those arteries. This reduces or stops blood flow to the heart muscle, which can result in chest pain, heart attack, and, over time, heart failure. With CABG, healthy blood vessels taken from elsewhere in the body are used to reroute blood around narrowed or blocked sections of affected coronary arteries to restore blood flow to the heart.

Off-pump coronary artery bypass grafting (known as off-pump CABG or OPCAB) is a type of CABG in which the heart remains beating, and a heart-lung bypass machine is not used during the procedure. By contrast, in conventional CABG surgery, the heart is stopped, and a heart-lung bypass machine (sometimes referred to as the “pump”) takes over the function of the heart and lungs. Because traditional CABG involves the use of a heart-lung bypass machine, it is also called on-pump CABG.

Both off-pump and on-pump CABG can effectively restore blood flow to the heart, resulting in improved heart function, reduced chest pain, lower risk of heart attack, and overall better long-term survival in people with CAD. While the majority of CABG procedures in the United States are on-pump, off-pump CABG is often used to treat people who are at risk for complications from conventional CABG, including those at higher risk of stroke due to significant plaque buildup within the aorta (the large artery that transports blood from the heart to the coronary arteries and the rest of the body), those with a weaker heart, and those with chronic lung or kidney disease.

Off-pump CABG is a type of heart bypass surgery that improves blood flow to the heart. Unlike on-pump CABG, the heart is not stopped, and a heart-lung bypass machine is not used. Instead, the procedure is performed while the heart is still beating, with the help of special heart stabilizers.

In an on-pump CABG procedure, the patient’s heart is connected to a heart-lung bypass machine, and the patient’s heart is stopped using certain medications. The patient’s blood is then delivered to the machine, which adds oxygen to the blood, and then pumps the resulting oxygen-rich blood around the patient’s body.

The use of a heart-lung bypass machine during CABG allows the surgeon to operate on the heart while it is immobilized and bloodless. The machine preserves blood circulation throughout the body, thereby maintaining blood flow to organs and tissues during the procedure. However, the use of the heart-lung bypass machine can cause inflammation throughout the body, resulting in problems with the functioning of multiple organs.

Additionally, during on-pump CABG, a cannula (tube) is inserted into the aorta and the aorta is usually cross-clamped to cut off blood flow. Cannulating and clamping the aorta can cause plaque to dislodge from it. The plaque can travel to the brain and, in some cases, cause a stroke.

Off-pump CABG was developed to avoid complications associated with the use of a heart-lung bypass machine and manipulation of the aorta. A large body of scientific evidence suggest that decreasing aortic manipulation in CABG is associated with overall better outcomes.

Off-pump CABG has several advantages over on-pump CABG, including:

• A significantly decreased risk of stroke and cognitive decline after surgery
• A lower risk of renal dysfunction and respiratory failure
• A lower risk of requiring a blood transfusion
• A lower risk of irregular heart rate in the days after surgery
• A shorter hospital stay and quicker recovery

However, for the surgeon, off-pump CABG is more technically challenging than traditional CABG, in large part because the heart is still beating during the procedure. This means the surgeon has to sew blood vessels while the heart is still moving (though special stabilization devices are used to reduce movement in the part of the heart the surgeon is working on).

In addition to the short-term advantages discussed above, the use of multiple arterial bypass grafts provides a significant long-term benefit. Traditionally, CABG is performed using one arterial graft (the internal mammary artery from within the chest wall) and several vein grafts (harvested from the leg).

Decades of experience with CABG surgery have shown that patients receiving multiple arterial grafts have reduced chances of requiring a second procedure and live longer. To facilitate multiple arterial grafting, the surgeon will harvest both right and left internal mammary arteries from within the chest wall and the radial artery usually from the non-dominant arm.

Off-pump CABG is used to treat people with CAD, the most common type of heart disease in the United States. According to the Centers for Disease Control and Prevention (CDC), around 1 out of every 20 adults ages 20 and over have CAD.

Off-pump CABG may be used to treat people with CAD who have certain health conditions that could increase the risk of complications from traditional on-pump CABG, including:

• Substantial atherosclerosis or calcification of the aorta
• Significant blood vessel blockages elsewhere in the body
• Kidney disease
• Lung disease
• Decreased heart function
• Previous stroke

During the procedure, patients are placed under general anesthesia so they will not be awake or feel pain.

Off-pump CABG may be done via open-heart surgery or using minimally invasive techniques.

Open-heart off-pump CABG. At the beginning of the procedure, the surgeon makes an incision in the front of the chest above the sternum (the breastbone). The surgeon divides the breastbone and uses a device called a retractor to separate the two sides of the breastbone and hold them apart, providing access to the heart.

Next, the surgeon opens the pericardium, the sac that surrounds the heart. One or more healthy blood vessels are harvested, or removed, from the arm, leg, or chest. The number of blood vessels harvested depends on how many bypasses are needed.

Because the patient’s heart is beating during the procedure, the surgeon uses a stabilization device to immobilize the sections of the heart and blood vessel they are working on. The surgeon then sews one end of a harvested blood vessel—known as a graft—to the affected coronary artery past the point where it is narrowed or blocked. With special surgical techniques, it is possible to construct “composite grafts” and provide blood inflow to the entire heart without manipulation of the aorta. In this way, the surgeon creates a new route for oxygen-rich blood to flow to the coronary artery and, ultimately, to the heart.

The surgeon will repeat this process for each narrowed or blocked coronary artery. Two, three, four, or more arteries may need to be bypassed. These procedures are known as double, triple, or quadruple bypasses, respectively.

At the end of the procedure, the surgeon will place the pericardium over the heart, close the breastbone, and wire it together. Skin incisions are then stitched closed. Tubes are left in the chest for one to three days to drain fluid.

Minimally invasive techniques. Minimally invasive options that do not involve dividing the breastbone may be an option. Minimally invasive off-pump techniques include:

• Minimally invasive direct coronary artery bypass (MIDCAB). In MIDCAB procedures, the surgeon makes a small incision in the left side of the patient’s chest and accesses the heart and the coronary arteries through the ribs. Robotic-assisted MIDCAB, a MIDCAB procedure in which the surgeon performs the surgery using robotic arms, may be used in some cases.
  
  A related procedure called MICS-CABG (minimally invasive cardiac surgery CABG) is done via an incision above the ribs and may be more suitable than MIDCAB for people who have more than one coronary artery that needs to be bypassed.
  
  The MIDCAB procedure may be used in combination with percutaneous coronary intervention (PCI), a nonsurgical procedure that improves blood flow through narrowed or blocked coronary arteries. This is known as a hybrid coronary artery revascularization procedure (HCR).
• Totally endoscopic coronary artery bypass (TECAB). This procedure is performed via three small incisions above the ribs using an endoscope—a thin tube equipped with a camera, light, and surgical tools—and robotic arms.

Compared to open-heart off-pump CABG, minimally invasive techniques typically involve smaller incisions, a shorter hospital stay, and a speedier recovery.

The risks of off-pump CABG are overall similar to the risks of traditional “on-pump” CABG and include:

• Infection
• Bleeding
• Heart attack
• Stroke
• Atrial fibrillation
• Kidney failure
• Need for a repeat CABG procedure (because the CABG procedure may not bypass all segments of a coronary artery that are narrowed or blocked and/or because the grafts used in the procedure may become narrowed or blocked, thereby reducing blood flow to the heart)

After the procedure, you may spend one to two days in the intensive care unit (ICU) and a total of roughly one week in the hospital. If complications occur or if additional procedures were performed, your hospital stay may be longer.

Initially, you will have tubes in your chest to drain fluids and a catheter in your bladder to drain urine. In most cases, the chest tubes are removed after one to three days. In the hospital, health care providers may check your bandages, monitor your heart rhythm using an electrocardiogram (ECG), and check your blood oxygen level, blood pressure, and heart rate. You may also be given supplemental oxygen via a tube connected to nose prongs or a mask. After the procedure, you may be given various medications including drugs to manage pain and to lower the risk of blood clots and heart arrhythmias.

In most cases, after the surgery, people are able to sit in a chair the next day, and over the next day or two, they can usually walk. At five to six days after the procedure, they are typically able to go up and down stairs.

When you leave the hospital, your doctor will discuss which medications you should continue taking and how to continue to care for your surgical wound.

A cardiac rehabilitation program can help you recover from off-pump CABG. These structured programs involve guided exercises, as well as education on lifestyle habits that can help you lower stress, improve your quality of life, and lower the risk of future heart problems.

In all, full recovery from off-pump CABG may take up to three months, though recovery from minimally invasive off-pump procedures is usually faster. You should stay in touch with and continue to see your doctor to monitor your recovery from off-pump CABG.

The outlook for people who undergo off-pump CABG can vary based on a number of factors, including the severity of CAD and the patient’s overall health.

By restoring blood flow to the heart, off-pump CABG can effectively relieve chest pain caused by CAD and help people with CAD lead active lives. Full recovery from the procedure typically takes three months.

Over time, coronary arteries or grafts can become narrowed or blocked after the surgery. Following certain lifestyle habits, such as exercising regularly, following a healthy diet, keeping blood pressure and high cholesterol levels under control, and not smoking, can slow the development of narrowed or blocked coronary arteries and grafts.

The Division of Cardiac Surgery at Yale School of Medicine offers beating heart CABG at both Yale New Haven Hospital and Bridgeport Hospital to patients affected by CAD in need of a bypass operation.

“With a true multidisciplinary approach, every case is discussed by the Heart Team, which is composed of a cardiologist and cardiac surgeon, to offer the best approach specifically tailored to the individual’s needs, in order to make our patients live better and longer,” says Fabio Ramponi, MD, a Yale Medicine cardiac surgeon who specializes in heart, lung, and vascular surgery.

Yale Medicine offers state-of-the-art techniques to deliver world class care via a carefully orchestrated coordination involving multiple providers, including cardiac surgeons and physician assistants, cardiac anesthesiologists and clinical perfusionists. Post-operative care is coordinated between the cardiac surgery and the intensive care team.