What Is Bypass? How Is Bypass Surgery Performed?

Coronary bypass surgery is the procedure of creating a new blood flow pathway to the heart using healthy vessels taken from another part of the body in order to overcome narrowing or blockages in the vessels that supply the heart. This vital surgical operation is performed by opening the rib cage to access the heart and bridging the obtained replacement vessels just beyond the blocked area using precise techniques. The basic logic of the procedure is to build a completely new pathway through which blood can flow freely without touching the damaged original vessel. This intervention, which enables the heart muscle to regain uninterrupted access to the fresh blood and oxygen it needs, restores the heart to a healthy and safe circulation cycle.

What Is Coronary Bypass Surgery and Why Do Heart Vessels Become Blocked?

The human heart is an extraordinary engine that works continuously from the first moment of life until the final breath, carrying oxygen and nutrients to all organs in the body. However, just as every engine needs fuel to operate, the heart’s own muscle tissue also constantly requires clean blood and oxygen. These vital pathways that surround and nourish the heart muscle like a network are called coronary arteries. These vessels have an extremely delicate structure, and their diameters are only a few millimeters.

Over time, factors such as genetic predisposition, advancing age, smoking, high blood pressure, diabetes, poor nutrition, and a sedentary lifestyle cause damage to the inner walls of these thin vessels. Cholesterol and calcium in the body accumulate in these damaged areas and form structures called plaques. This process, known medically as atherosclerosis and commonly as hardening of the arteries, causes the inner space of the vessels to gradually narrow over the years.

When the narrowing in the vessels exceeds a certain level, the heart muscle cannot receive the extra blood it needs, especially while climbing stairs, walking uphill, or experiencing intense stress. This lack of oxygen manifests as pressure, burning, tightness in the chest, or pain radiating to the left arm. If the plaque in the narrowed area suddenly cracks or ruptures, a blood clot forms there within seconds and completely blocks the vessel. This condition is a heart attack, in which heart muscle cells begin to die rapidly. Coronary bypass surgery is one of the most established treatment methods used to restore blood flow to the heart before or after blockages cause a heart attack. This surgical procedure is based on the principle of building a new blood pathway beyond the blockage with a healthy vessel taken from another part of the body, without touching the blocked or narrowed vessel segment.

From Which Parts of the Body Are Replacement Vessels Taken for Bypass Surgery?

The word bypass is of English origin and means “bridging.” Plastic or artificial material is not used externally to route blood around the blocked pathway and deliver it to the target. Instead, replacement vessels that are entirely present in the person’s own body and whose removal does not cause any deficiency or loss of function in that area are preferred.

The quality of the replacement vessels used in surgery directly determines the long-term success of the operation. The left or right chest artery located inside the rib cage, very close to the heart, can be used for this purpose. Due to its structure, this vessel is incredibly resistant to atherosclerosis and can continue carrying blood without becoming blocked for decades. For other required bridges, the arm artery or leg veins may also be used.

The vessel sources preferred in bypass procedures are as follows:

• Chest artery
• Arm artery
• Leg vein

Arteries are much longer-lasting than veins due to their structures that are resistant to high blood pressure. Therefore, in current medical approaches, the use of chest arteries instead of leg veins is preferred whenever possible.

How Is Bypass Surgery Performed on a Beating Heart and a Stopped Heart?

Bypass surgeries are performed using two main methods according to medical requirements and the patient’s general health condition. The classical and most commonly used method is surgery performed on a stopped heart. In this method, the heart is accessed by opening the patient’s breastbone. However, the heart is a constantly beating, moving organ filled with blood. A motionless and bloodless operating field is needed to sew together millimetric vessels using sutures even thinner than a strand of hair. At this stage, the heart-lung machine comes into operation.

The patient’s entire blood circulation is transferred to this device through special tubes. During the surgery, the machine takes over the functions of oxygenating the blood in the lungs and pumping blood throughout the body. A special medicated solution is given to the heart to stop and paralyze it completely. Once the procedure is completed, the heart is restarted and the machine is removed from circulation.

The other method is beating-heart bypass surgery. Connecting to the heart-lung machine may create additional risks, especially in elderly and frail patients with chronic lung disease, kidney failure, or a previous stroke. To eliminate these risks, the heart is not stopped at all. Only the very small area where the vessel will be sutured is immobilized using special vacuum stabilizing instruments, while the rest of the heart continues pumping blood throughout the body. Although this method is technically more challenging for the surgeon, it accelerates the recovery process when applied to the right patient.

What Happens During the Preparation Process Before Bypass Surgery?

Once the decision for surgery is made, the process leading to the operating table is planned with great care. Comprehensive blood tests, chest X-rays, and kidney function assessments are first performed so that the body can tolerate this major intervention in the best possible way. Certain medications used by the patient, especially powerful blood thinners, must be discontinued or their doses adjusted a certain period in advance to prevent life-threatening bleeding during surgery.

Preparing the patient psychologically for this process and increasing respiratory capacity are also integral parts of treatment. It is critically important for patients who smoke to quit completely as early as possible before surgery for the postoperative awakening and independent breathing stages. Once preparations are completed, the surgery generally takes between three and six hours depending on the number of vessels to be treated.

How Does the Intensive Care Process Progress After Bypass Surgery?

After the operation is completed and the breastbone is closed with strong steel wires, the patient is taken directly to the intensive care unit. When the patient gradually emerges from anesthesia and opens their eyes, they feel quite tired, cold, and intensely thirsty. This is an entirely normal result of deliberately lowering body temperature during surgery and prolonged anesthesia.

The first hours in intensive care require patience and involve a monitoring process in which medical devices constantly sound alarms. Numerous tubes and cables are present on the patient’s body to observe and support recovery. Tubes that drain blood that may accumulate inside the rib cage, thin wire-shaped temporary pacemakers externally connected to the heart to keep the rhythm under control, and intravenous lines used for fluid support are all part of this process. Once the patient is seen to breathe comfortably on their own, the ventilator is removed. If everything proceeds well, liquid foods are usually started the next day, and the patient is generally transferred from intensive care to a regular hospital room by the end of the second day.

What Should Be Considered During the Recovery Process at Home After Bypass Surgery?

Discharge from the hospital does not mean that recovery is complete. For bypass patients, the period that truly requires patience is the convalescence process at home. Since the breastbone has been cut through the middle, it takes an average of six to eight weeks for this bone to fuse again and regain its former mechanical integrity. During this period, the patient must follow very strict rules. An imbalance in the load placed on the breastbone may cause the bones to heal incorrectly or lead to infection. This may open the door to other medical problems lasting for months.

Movements that must definitely be avoided during the recovery process are as follows:

• Lying on the side
• Lying face down
• Lifting heavy objects
• Stretching the arms backward
• Reaching asymmetrically

Patients must sleep only on their backs until the bone heals. However, these restrictions do not mean that the patient will be confined to bed. On the contrary, it is highly important for patients to take regular, light-paced walks every day inside the home or outdoors in suitable weather conditions to prevent blood clot formation and expand the lungs.

What Serious Surgical Risks Does Bypass Surgery Carry?

Although bypass surgery is a life-saving intervention, it also carries certain risks because it is major open surgery that deeply affects the integrity of the body. Even though the risk of death remains quite low in well-equipped centers and experienced hands, certain complications related to the use of the heart-lung machine and anesthesia may occur.

One of the most concerning conditions is the risk of stroke. Manipulation of the main vessel leaving the heart, the aorta, during surgery or the blood flow pressure of the machine may cause millimetric calcium particles on the vessel wall to break loose and reach the brain. In addition, rhythm disorders, which are the heart’s response while trying to adapt to the new circulation, are quite common. Fluid accumulation around the pericardium or psychological problems associated with prolonged hospitalization may also challenge patients.

The main risks associated with this major surgery are as follows:

• Stroke
• Bleeding
• Rhythm disorders
• Wound infections
• Fluid accumulation in the lungs
• Bone healing problems

Patients learning these risks in detail before the operation and establishing trust-based communication with the medical team help make the process psychologically easier to overcome.

Can the New Vessels Implanted During Bypass Surgery Become Blocked Again in the Long Term?

Patients often tend to believe that after bypass surgery they have completely recovered from cardiovascular disease and have a kind of “brand-new” heart. However, bypass is a mechanical solution that treats only the result of the disease, not its cause. The underlying atherosclerotic disease continues in the body.

Veins taken from the legs in particular are not naturally designed to carry high-pressure blood. These leg vessels, exposed to the forceful flow of arterial blood, begin to thicken in order to protect themselves. This cellular thickening process causes atherosclerosis to develop very rapidly inside the new vessel. According to statistics, a large proportion of bridges created using leg veins tend to become blocked again within ten years. This risk is much lower in arteries taken from the chest or arm.

For this second chance to become permanent, the patient must make fundamental lifestyle changes. Taking medications without interruption and adopting healthy habits determine the lifespan of the new vessels.

The factors that must be observed throughout life to keep the vessels open are as follows:

• Regular walking
• Ideal weight
• Blood pressure control
• Blood sugar control
• Smoke-free life

How Does the Heart Team Decide Between Bypass and Stent Treatment?

In a patient with multiple blockages in the heart vessels, narrowing in the left main coronary artery, which is the heart’s main vessel, or three-vessel disease, the most appropriate treatment is determined not by a single doctor’s decision but through the participation of multiple specialists in what is called the “Heart Team” or “Heart Council.”

In these councils, cardiovascular surgeons who perform bypass operations, interventional cardiologists who apply non-surgical treatment methods, imaging specialists, and anesthesiologists come together. The patient’s age, whether they have diabetes, kidney functions, the heart’s contractile strength, and the map of the vascular structure are evaluated. The risks of surgery and the benefits of non-surgical catheter-based methods are discussed, and the most suitable personalized treatment decision is made collectively.

How Does the SYNTAX Score Affect the Decision for Bypass Surgery?

The most scientific and objective tool used by the heart team when making decisions is the SYNTAX scoring system. This system is a type of complexity calculator. While angiography images are examined, factors such as the location of blockages in the vessels, the length of the narrowings, the amount of calcium in the vessel, and whether the vessels are tortuous are scored in a computer program.

The resulting score numerically indicates how anatomically complex the patient’s condition is. Patients with low scores are excellent candidates for non-surgical stenting procedures because they have localized and relatively simple blockages. Patients with intermediate scores are in the gray zone; in this group, the decision for surgery or stenting may be made according to the patient’s other diseases. A very high score indicates that the disease has spread in a heavily calcified form to almost the entire vascular network. While open surgery was the only option for high-scoring patients in previous years, today, thanks to advancing technology, even these challenging conditions have begun to become treatable with non-surgical methods.

What Alternatives Does Interventional Cardiology Offer Instead of Bypass Surgery?

The long recovery period required by bypass surgery, the cutting of the breastbone, and the burdens of general anesthesia naturally lead patients to seek alternative and less traumatic treatment options. This is where modern interventional cardiology comes into play. Interventional cardiologists are specialists who open vascular blockages under local anesthesia in a fully awake patient without the need for open-heart surgery.

These methods are generally applied by entering through the thin arteries in the groin or, much more commonly today, the wrist. Entry through the wrist provides tremendous comfort because the patient can stand up immediately after the procedure, the risk of bleeding is reduced almost to zero, and the patient can walk home the same day.

The modern tools offered by interventional cardiology are as follows:

• Drug-eluting stents
• Drug-coated balloons
• Atherectomy devices
• Intravascular ultrasound
• Shockwave balloons

How Are Modern Stents Applied Instead of Bypass Surgery?

The procedure of mechanically opening blocked vessels and supporting them from within is called angioplasty and stenting. When first-generation metal stents used years ago were placed inside the vessel, the vessel wall reacted to this metallic foreign body with a wound-healing response. As a result of this reaction, cells multiplied excessively and the inside of the stent became blocked again within a few months.

In today’s technology, only drug-eluting stents are now used. These thin and flexible stents are coated with a special drug layer that stops excessive cell proliferation. The stent placed inside the vessel slowly releases its medication and keeps the vessel smooth. After a short period, the body covers the stent with its own natural membrane, and the stent becomes a safe scaffold that prevents the vessel from collapsing for life.

In addition, drug-coated balloon technology is a revolutionary alternative for patients who do not want to carry a metal cage in their body for life or whose vessel diameter is very small. This special balloon is inflated at the blockage site, transfers the healing medication on its surface to the vessel wall, is then deflated and completely removed, leaving no material inside.

Why Are Cameras That Show the Inside of the Vessel Important Before a Bypass Decision?

A standard coronary angiography consists of an X-ray image taken from outside after a contrast agent is injected into the vessels. This procedure shows only the two-dimensional shadow of the vessel. By looking at the shadow, it is not possible to know exactly how calcified the inside of the vessel is or the true diameter of the narrowing. For correct treatment, it is necessary to turn on the light instead of moving forward blindly in the dark.

For this purpose, interventional cardiologists use highly advanced microscopic imaging technologies such as intravascular ultrasound (IVUS) or optical coherence tomography (OCT). Thanks to millimetric cameras inserted into the vessel, a 360-degree cross-sectional image of the vessel is displayed on the screen with cellular-level details. In this way, the true diameter of the vessel is measured, and it is checked whether the stent has fully adhered to the vessel wall with millimetric precision. Perfect placement of the stent inside the vessel almost completely eliminates the risk of future clot formation or restenosis.

What Pressure Measurement Methods Prevent Unnecessary Bypass Surgery Decisions?

Sometimes a blockage in a vessel may appear very alarming on the angiography screen. Making an immediate decision to place a stent or perform bypass surgery based solely on this image may lead to misleading results. What matters is not how the narrowing looks, but whether it truly reduces blood flow to the heart muscle. Intervening in a narrowing that does not impair flow may cause more harm than benefit to the patient.

To clarify this situation, an advanced technology called fractional flow reserve (FFR) is used. A special pressure wire even thinner than a strand of hair is passed beyond the narrowing. The wire simultaneously measures blood pressure before and after the blockage and calculates a mathematical ratio. The obtained value proves precisely and clearly how much the narrowing obstructs blood flow. Thanks to these intelligent wires, countless patients have been spared unnecessary bypass surgery or unnecessary stent placement.

How Are Completely Blocked Vessels Opened Without Bypass Surgery?

Vessels that have remained completely closed for months or even years are called chronic total occlusions (CTO). Over time, the inside of these vessels fills with a hardened, stone-like structure. For patients who were told in previous years, “this vessel is now dead, it cannot be opened, the only solution is bypass surgery,” medicine now offers almost a miracle.

In this field of interventional cardiology, which requires the highest level of experience, different strategies are applied to open hardened blockages that cannot be crossed through conventional routes. Sometimes special rigid wires and microcatheters are advanced directly toward the blockage. If this does not work, the small side vessels, known as collaterals, that the heart has developed to supply itself are used to travel around the back of the blockage and create a tunnel in the reverse direction. Thanks to these successfully opened vessels, heart failure is prevented, the patient’s shortness of breath disappears, and the need for open-heart surgery is completely eliminated.

Which Advanced Technologies Are Used Instead of Bypass in Calcified Vessels?

During the process of atherosclerosis, calcium deposits in the vessel wall cause the vessel to lose its flexibility and become almost like a rigid pipe. In severely calcified vessels, it is impossible to inflate standard balloons or place a stent because the calcium prevents the stent from expanding. Such patients were also frequently referred to surgery as a necessity.

Today, two remarkable technologies are used to break apart these calcified rocks. The first is the rotablator device, whose tip is coated with diamond particles and rotates tens of thousands of times per second to shave and pulverize the calcium inside the vessel. The second is shockwave technology, known as intravascular lithotripsy, which works according to the same principle as breaking kidney stones. Acoustic sound waves created inside the vessel crack only the calcium without damaging the vessel’s soft tissue. Thanks to the fractured calcium, the vessel regains its flexibility and can be safely stented.

How Are Blockages at the Bifurcation Points of Vessels Treated Without Bypass Surgery?

The coronary arteries that supply the heart continuously divide into two like the branches of a tree and spread across the surface of the heart. The formation of vascular blockages at these division, or bifurcation, points is an anatomical problem that makes medical intervention quite difficult. The risk of closing the side branch while placing a stent in the main branch complicates treatment.

For such lesions, interventional cardiologists apply special techniques using multiple wires and balloons simultaneously to preserve the anatomical shape of the vessel. When necessary, both vessels are kept open using advanced weaving techniques in which two separate stents are placed inside one another at perfect angles. At the end of the procedure, the natural shape of the vessel is perfectly reconstructed with the kissing balloon technique, in which the balloons in both vessels are inflated simultaneously.

Frequently Asked Questions

Prof. Dr. Kadriye Kılıçkesmez

Prof. Dr. Kadriye Orta Kılıçkesmez is one of the leading figures in the field of Turkish cardiology. She was born on January 24, 1974, in Tekirdağ. After completing her undergraduate education at Istanbul University Cerrahpaşa Faculty of Medicine, she chose cardiology as her specialty and received her specialist training at the Cardiology Institute of the same university. In 2015, she was appointed by the university to establish the Şişli Etfal cardiology clinic and Angio laboratory. Becoming a professor in 2017, Kadriye Kılıçkesmez established the cardiology clinic and Angio laboratory of Prof. Dr. Cemil Taşçı Hospital in 2020 and ensured that the clinic became a training clinic.