Bilateral Internal Mammary Artery Grafts in CABG: Benefits and Patient Selection

Bilateral internal mammary artery grafting is a coronary bypass technique that uses both internal mammary arteries to improve blood flow to the heart muscle. It can offer durable results for carefully selected patients, but the decision depends on overall health, coronary anatomy, and the risk of wound-healing complications.

Overview

Bilateral internal mammary artery grafts are used in coronary artery bypass grafting, commonly called CABG, to restore blood flow around narrowed or blocked coronary arteries. The internal mammary arteries, also called internal thoracic arteries, run along the inside of the chest wall. In this approach, both the left and right internal mammary arteries are used as bypass conduits to carry blood beyond coronary blockages.

CABG is usually considered when coronary artery disease is extensive, when symptoms continue despite medication, or when the pattern of artery narrowing is better treated with surgery than with stents. In standard coronary artery bypass surgery, surgeons may use a combination of arteries and veins, most often the left internal mammary artery and leg vein grafts. Bilateral internal mammary artery grafting, often shortened to BIMA or BITA, uses a second chest wall artery to increase the proportion of arterial grafting.

The main reason this technique is discussed is durability. Arterial grafts tend to remain open longer than vein grafts, particularly when the left internal mammary artery is connected to the left anterior descending coronary artery. However, using both internal mammary arteries is not automatically the best choice for every patient. The decision is individualized and should be made by an experienced cardiac surgery team after assessing both heart-related and general health factors.

How Bilateral Internal Mammary Artery Grafting Works

During CABG, the surgeon creates new pathways for blood to reach the heart muscle. One end of an internal mammary artery usually remains attached to its natural blood supply, while the other end is connected to a coronary artery beyond the blockage. This allows blood to flow around the narrowed segment and supply oxygen-rich blood to the heart muscle.

In many operations, the left internal mammary artery is connected to the left anterior descending artery, a major vessel that supplies a large part of the heart. When both internal mammary arteries are used, the right internal mammary artery may be routed to another important coronary branch, such as a vessel on the left side of the heart or the right coronary system, depending on the patient’s anatomy. Surgeons may use the right internal mammary artery in its natural position or as a free graft, according to the surgical plan.

The arteries can be harvested in different ways. A “pedicled” harvest takes the artery together with surrounding tissue, while a “skeletonized” harvest removes the artery more selectively. Skeletonized harvesting may help preserve more blood flow to the breastbone, which can be helpful in patients with a higher risk of wound-healing problems. The most suitable technique depends on the surgeon’s experience, the patient’s risk profile, and the goals of the operation.

Potential Benefits of Using Both Internal Mammary Arteries

The potential benefit of bilateral internal mammary artery grafting is improved long-term graft function. Internal mammary arteries are naturally resistant to atherosclerosis compared with leg vein grafts, and they tolerate the pressure and flow conditions of the coronary circulation well. For some patients, this may reduce the likelihood of needing another procedure years later because of graft narrowing.

Many observational studies have suggested that patients receiving two internal mammary artery grafts may have better long-term outcomes than similar patients receiving only one internal mammary artery plus vein grafts. Randomized trial evidence has been more nuanced, partly because real-world surgical practice includes crossover between techniques, differences in expertise, and the use of other arterial grafts such as the radial artery. For patients, the practical message is that BIMA can be valuable, but its advantage depends on careful selection and high-quality surgical execution.

Patients who may benefit most often include those with multivessel coronary artery disease, good overall functional status, and a reasonable life expectancy in which long-term graft durability is especially meaningful. Younger patients, active older adults with low wound risk, and people whose coronary anatomy allows good targets for arterial grafting may be considered. The final choice is not based on age alone, but on a balanced review of overall health, coronary anatomy, and surgical risk.

Risks and Limitations to Consider

Like all forms of heart bypass surgery, BIMA grafting carries the usual risks of major cardiac surgery, including bleeding, rhythm disturbances, infection, stroke, kidney stress, and complications related to anesthesia. These risks vary widely from person to person and are estimated before surgery using clinical assessment and risk models. The additional issue specific to using both internal mammary arteries is the effect on blood supply to the breastbone, or sternum.

The sternum needs good blood flow to heal after it is divided during open-heart surgery. Because the internal mammary arteries contribute to sternal blood supply, taking both arteries can increase the risk of sternal wound complications in some patients. These may include delayed healing or, less commonly, deeper infection. Modern harvesting techniques, careful glucose control, smoking cessation, and meticulous wound care can help reduce these risks.

The technique may also take longer and require specific surgical expertise. In some cases, the coronary targets may not be suitable for a second internal mammary artery because of vessel size, location, or the degree of blockage. If a graft is placed on a coronary artery with only moderate narrowing, competitive blood flow can reduce graft function. For this reason, the decision involves both patient factors and detailed review of coronary imaging.

Patient Selection: Who May Be a Good Candidate?

Patient selection is the central question in bilateral internal mammary artery grafting. A good candidate is not simply someone who needs CABG; it is someone likely to gain long-term benefit while having an acceptable risk of wound and surgical complications. The heart team considers coronary anatomy, symptoms, heart pumping function, other medical conditions, and the patient’s recovery potential.

Factors that may support BIMA grafting include multivessel coronary artery disease, a strong target vessel for the second arterial graft, good mobility before surgery, and absence of major wound-healing risk factors. Patients with a longer expected lifespan may gain more from graft durability. Good control of blood pressure, cholesterol, and blood sugar also supports long-term graft health after surgery.

Factors that require extra caution include:

• Diabetes, especially if blood sugar control is poor or insulin treatment is required
• Obesity or a high risk of sternal wound complications
• Current smoking or chronic lung disease with frequent coughing
• Advanced kidney disease or dialysis
• Severe frailty, malnutrition, or reduced ability to heal
• Previous chest radiation or prior sternotomy
• Long-term steroid or immunosuppressive medication use

These factors do not always rule out bilateral internal mammary artery grafting. Instead, they guide a careful discussion about alternatives, such as using one internal mammary artery with another arterial graft or with vein grafts. The safest and most durable plan is the one tailored to the individual patient.

Preoperative Evaluation and Surgical Planning

Before CABG, patients usually undergo a detailed evaluation that includes coronary angiography, echocardiography, blood tests, medication review, and assessment of lung, kidney, and vascular health. The angiogram helps the surgeon identify which coronary arteries are suitable targets for bypass grafts. Echocardiography shows how well the heart pumps and whether valve disease or other conditions should be addressed at the same time.

Planning for BIMA grafting also includes assessment of sternal wound risk. The team may review diabetes control, body weight, smoking history, nutritional status, and any history of chest surgery or radiation therapy. Some patients need additional imaging or testing if there are concerns about the aorta, peripheral arteries, or lung function. Medication adjustments are also made, especially for blood thinners, diabetes medicines, and drugs that affect blood pressure.

The surgeon explains the proposed graft strategy, including which arteries or veins may be used and why. Patients are encouraged to ask whether both internal mammary arteries are planned, what alternatives exist, and how the surgical team reduces wound risk. Shared decision-making helps patients understand that CABG is not one standardized operation; it is a personalized reconstruction of blood flow to the heart.

Recovery, Long-Term Care, and Self-Care

Recovery after CABG is gradual. In the hospital, the care team monitors heart rhythm, breathing, wound healing, pain control, kidney function, and mobility. After discharge, patients continue recovery at home with follow-up appointments, medication management, and instructions for caring for the chest incision. The breastbone usually needs time to heal, so lifting and upper-body strain are limited according to the surgeon’s guidance.

Long-term success depends not only on the grafts but also on controlling coronary artery disease. Medications may include antiplatelet therapy, cholesterol-lowering treatment, blood pressure medicines, and diabetes treatment when needed. Patients should not stop or change heart medicines without medical advice. Lifestyle care is equally important, including not smoking, following a heart-healthy eating pattern, staying active as advised, and maintaining a healthy weight.

Cardiac rehabilitation is often recommended because it provides supervised exercise, education, and support for returning safely to daily life. A structured cardiac rehabilitation program can help patients build confidence, improve fitness, and strengthen habits that protect the heart. At Acibadem International, multidisciplinary cardiac specialists in JCI-accredited hospitals evaluate and treat coronary artery disease for international patients, including patients who may be candidates for advanced CABG strategies.

When to See a Doctor

People with known or suspected coronary artery disease should seek medical evaluation if they have chest pressure, shortness of breath with activity, reduced exercise tolerance, palpitations, dizziness, or symptoms that interfere with daily life. These symptoms do not always mean surgery is needed, but they should be assessed by a qualified clinician. Early evaluation allows doctors to choose the most appropriate treatment, which may include medication, stenting, CABG, or a combination of approaches.

After CABG, patients should contact their care team if they notice fever, increasing redness or drainage from the chest incision, worsening chest wound pain, new shortness of breath, fainting, persistent irregular heartbeat, leg swelling, or sudden weight gain. Any new or severe chest discomfort should be treated as urgent and assessed promptly. Patients should follow their discharge instructions and emergency guidance from their surgical team.

A consultation is also appropriate when a patient has been advised to undergo bypass surgery and wants to understand graft choices. Asking about single versus bilateral internal mammary artery grafting, radial artery grafts, and vein grafts can clarify the reasons behind the recommended plan. Informed discussion with a heart team helps align the operation with the patient’s anatomy, health status, and long-term goals.

Frequently asked questions

What are bilateral internal mammary artery grafts?

Bilateral internal mammary artery grafts use both chest wall arteries to bypass blocked coronary arteries during CABG. The left internal mammary artery is commonly used for the main front artery of the heart, and the right internal mammary artery may be used for another important coronary vessel. The goal is to provide durable blood flow to the heart muscle.

Are bilateral internal mammary artery grafts better than vein grafts?

Internal mammary artery grafts generally have better long-term durability than leg vein grafts. However, the best graft strategy depends on the patient’s anatomy, age, other medical conditions, and surgical risk. Some patients benefit from two internal mammary arteries, while others are safer with one internal mammary artery plus another graft type.

Who is most likely to benefit from BIMA grafting?

Patients with multivessel coronary artery disease, good target vessels, and a longer expected lifespan may be more likely to benefit. Good overall health and a low risk of sternal wound complications also support this approach. The decision should be made after a heart team reviews the full clinical picture.

Why is diabetes important when considering bilateral internal mammary arteries?

Diabetes can affect wound healing and may increase the risk of sternal wound complications after open-heart surgery. This does not automatically exclude a patient from BIMA grafting, especially if diabetes is well controlled. Surgeons consider diabetes together with weight, smoking status, kidney function, and other risk factors.

Does using both internal mammary arteries make recovery longer?

Recovery is similar in many respects to standard CABG, but careful attention to chest wound healing is especially important. Some patients may have a slightly higher wound-healing risk depending on their health profile. Following lifting restrictions, wound care instructions, and cardiac rehabilitation guidance supports safer recovery.

Can BIMA grafting be done in all CABG patients?

No, it is not suitable for every CABG patient. Some patients have coronary anatomy that is not ideal for a second internal mammary artery, while others have health factors that make wound complications more likely. A personalized surgical plan is usually safer than applying one technique to everyone.

What should patients ask their surgeon before CABG?

Patients can ask which grafts are planned, why those grafts are recommended, and whether bilateral internal mammary artery grafting is appropriate. They may also ask about wound risk, alternatives such as radial artery or vein grafts, and what steps reduce complications. Clear discussion helps patients understand both the benefits and limitations of the proposed operation.

References

• American Heart Association
• European Society of Cardiology
• Society of Thoracic Surgeons
• American College of Cardiology
• National Institute for Health and Care Excellence

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.