Coronary Artery Bypass Surgery: The Life-Saving Procedure for Narrowed Coronary Arteries

When medication or stents are no longer sufficient to ensure blood flow to the heart, bypass surgery is often the last and most effective option. Every year, this procedure is performed thousands of times in Germany to prevent fatal heart attacks and maintain the heart’s pumping capacity.

The main cause for bypass surgery is coronary heart disease (CHD). In this condition, fats and calcium build up in the walls of the blood vessels. This atherosclerosis leads to what are known as coronary stenoses (narrowings). When these calcified areas severely obstruct blood flow, the heart muscle receives insufficient oxygen.

Based on scientific evidence, the indication for surgery is usually established in cases of:

• A severe stenosis of the main trunk of the left coronary artery (main trunk stenosis).
• “Three-vessel disease” (when all three main branches of the coronary arteries are affected).
• Patients with diabetes mellitus, in whom stents often yield poorer long-term results than surgery.
• Acute myocardial infarction, when dilation via cardiac catheterization is technically not possible.

The goal is always revascularization—that is, the restoration of blood flow. The surgery restores an adequate supply of oxygen-rich blood to the affected area.

Principle of bypass surgery: Arterial (red) and venous (blue) bypassing of the narrowed areas.

The principle of the surgery is mechanically simple but surgically highly complex: The narrowed section of the artery is not removed but bypassed. A so-called bypass is created. To do this, the surgeon needs a replacement vessel (graft), which is harvested from another part of the body. This vessel is sutured onto the coronary artery as a “vascular bypass” behind the narrowed area. This allows blood to bypass the blockage and flow freely again.

Only the body’s own tissue is used for the bypasses. The choice of vessel has a major impact on long-term durability (prognosis).

1. Arterial bypasses (the gold standard) The internal mammary artery (which runs along the inner side of the chest wall) is most commonly used.

• Advantage: Arterial bypasses can withstand the high pressure in the arterial system and remain open for a very long time. Patients under the age of 70 benefit particularly from the use of both mammary arteries (BIMA).
• Total arterial revascularization: In this procedure, the surgeon completely avoids using veins and uses only arteries, which can further improve life expectancy.

2. Venous bypass Often, a vein from the leg (saphenous vein) is also harvested. It is well-suited for use as a venous bypass to bridge longer distances to the aorta. However, veins are more likely to reclose over the years, as they are anatomically designed for lower blood pressure.

A classic bypass surgery typically lasts three to four hours. In modern cardiac surgery, there are two established treatment procedures, which are selected on a case-by-case basis depending on the patient:

1. Conventional Coronary Bypass Surgery (with CPB) This is the most common standard procedure worldwide. The heart is stopped for the duration of the suturing of the bypass grafts (cardioplegic arrest).

• Use of the heart-lung machine: During this time, the machine takes over the functions of the heart and lungs, oxygenates the blood, and pumps it through the body.
• Advantage: This allows the surgeon to work with the utmost precision on the delicate blood vessels—often only 1–2 mm in diameter—while the heart is still and bloodless.

2. Off-Pump Coronary Artery Bypass (OPCAB) In this procedure, the surgery is performed on a beating heart, i.e., without a heart-lung machine. A special stabilizer (“Octopus”) holds still only the small area of the heart wall where suturing is currently taking place.

• Advantage: This method is gentler on the brain and kidneys and reduces the risk of a stroke.
• Disadvantage: It is technically more demanding and is not suitable for all heart conditions.

Although coronary bypass surgery is routine today, it remains a major heart operation. The risk depends heavily on age, reduced cardiac output, and comorbidities such as diabetes or kidney failure. Possible complications include:

• Wound infections on the chest (sternum) or leg (harvest site).
• Postoperative bleeding in the chest cavity.
• Heart rhythm disturbances (e.g., atrial fibrillation).
• Neurological events (stroke), often triggered by calcium deposits from the aorta.

Nevertheless, if left untreated, coronary heart disease remains the leading cause of death in industrialized countries. The surgical risk is very low today in specialized centers (e.g., the German Heart Center) and is usually significantly lower than the risk of another heart attack without surgery.

The prognosis following successful bypass surgery is good. Typical symptoms such as angina pectoris (chest pain) disappear immediately in most patients. Physical endurance returns. Studies show that bypass surgery prolongs survival compared to stents, particularly in cases of complex conditions. The goal is to improve blood flow beyond the stenosis and protect the heart muscle.

Important for life expectancy: The surgery restores blood flow but does not cure the underlying condition, atherosclerosis. A healthy lifestyle (quitting smoking, exercise, a healthy diet) is crucial to prevent the new bypasses from becoming blocked again.

How long does rehabilitation take after bypass surgery?

The hospital stay usually lasts 10 to 14 days. This is almost always followed by a three-week period of follow-up treatment (rehab). It takes about 2 to 3 months for the chest to heal completely and for the patient to be able to resume full physical activity.

Is a stent or a bypass better?

That depends on the findings. For isolated narrowings, a stent (vascular support) is often sufficient. However, if multiple blood vessels are affected, the main coronary artery is narrowed, or the patient has diabetes, scientific evidence suggests that coronary bypass surgery is the safer and more sustainable solution.

What is minimally invasive coronary artery bypass surgery (MIDCAB)?

With the MIDCAB method, access is gained not by cutting through the sternum, but through a small incision between the ribs. However, this is usually only possible if only the anterior descending artery is affected and only a single bypass is needed.

Where can I find specialists?

Major heart centers and university hospitals have the most experience in bypass surgery. In the Leading Medicine Guide, you’ll find selected experts in the treatment of coronary heart disease.