What are the main risks of bypass surgery? 

Coronary artery bypass graft (CABG) surgery is a major clinical operation that carries certain risks. While it is a life saving procedure for many people with severe heart disease, it is important for patients and their families to understand the potential complications. In the UK, surgical teams perform thousands of these operations every year with high success rates, but like any major surgery involving the heart and general anaesthesia, there are inherent clinical risks. 

In this article, you will learn about the short term risks during and immediately after surgery, as well as the long term considerations for heart health. We will also discuss how the clinical team works to minimize these risks and the factors that might increase the likelihood of complications for certain patients. 

What We’ll Discuss in This Article 

• Common clinical risks encountered during the surgical procedure. 

• Potential complications that can arise in the early recovery phase. 

• Factors that increase the risk of infection or delayed wound healing. 

• The risk of heart rhythm problems like atrial fibrillation after surgery. 

• Neurological considerations including the risk of stroke or memory changes. 

• Long term risks related to the durability of the bypass grafts. 

• How patient age and other health conditions impact the overall risk profile. 

What are the most common short term risks? 

The most common clinical risks associated with bypass surgery occur in the first few days following the procedure. Bleeding is a primary concern because the surgery involves major blood vessels and the heart itself. While some bleeding is expected, in rare cases, a patient may need a second operation to stop persistent bleeding or require a blood transfusion. 

Another common risk is an irregular heart rhythm, specifically atrial fibrillation. This is often caused by the heart muscle being slightly irritated during the operation. While it can feel alarming, it is usually temporary and is managed effectively with medication. The clinical team in the intensive care unit and on the cardiac ward monitors your heart rhythm constantly to detect and treat these changes immediately. 

• Bleeding during or shortly after the operation. 

• Atrial fibrillation in about 20% to 30% of patients. 

• Low blood pressure requiring specialized intravenous medications. 

• Fluid build up around the lungs or heart. 

Risks of infection and wound healing 

Because a bypass operation involves a large incision in the chest and potentially other incisions in the legs or arms, there is a risk of infection. Wound infections can occur at any of these sites. The most serious type is a deep chest wound infection affecting the breastbone. While this is rare in UK hospitals, it requires intensive treatment with antibiotics and sometimes further surgery to clean the wound. 

Several factors can increase the risk of infection, including having diabetes or being a current smoker. The clinical team takes extensive precautions, such as giving preventive antibiotics before the surgery and using sterile techniques, to minimize this risk. After surgery, keeping the wound sites clean and dry as they heal is the most important step you can take to prevent infection. 

• Minor skin infections at the leg or arm harvest sites. 

• Deep sternal wound infection which is rare but serious. 

• Pneumonia or other lung infections due to reduced breathing depth after surgery. 

• Urinary tract infections from the use of a catheter during surgery. 

Neurological risks and cognitive changes 

A major concern for many patients is the risk of neurological complications, such as a stroke. This can happen if a small piece of plaque or a blood clot is dislodged during the surgery and travels to the brain. In the UK, the risk of a significant stroke during bypass surgery is generally low, typically around 1% to 2% for most elective patients. 

Some patients also experience temporary cognitive changes, often referred to as pump brain if a heart lung bypass machine was used. This can include mild memory loss, difficulty concentrating, or feeling slightly confused in the days or weeks following the operation. For the vast majority of people, these symptoms are temporary and resolve fully as the body recovers from the effects of the surgery and anaesthesia. 

• Risk of stroke is minimized through careful surgical technique. 

• Temporary confusion or mood changes in the early recovery phase. 

• Long term cognitive issues are rare in the modern surgical era. 

• Detailed neurological monitoring is part of the standard postoperative care. 

How do other health conditions impact risk? 

A patient overall health significantly influences the level of risk associated with bypass surgery. Clinical triggers that increase risk include advanced age, significant kidney disease, or severe lung conditions. If the surgery is being performed as an emergency following a severe heart attack, the risks are also higher than for a planned elective procedure. 

Surgeons use specialized scoring systems to calculate your individual risk before the operation. This takes into account your age, heart function, and other medical history. By understanding these factors, the surgical and anaesthetic teams can tailor their approach to make the procedure as safe as possible for you. 

• Diabetes can slow wound healing and increase infection risk. 

• Poor kidney function may require extra monitoring of fluid balance. 

• Pre existing lung disease increases the risk of postoperative breathing issues. 

• Emergency surgery carries a higher risk profile than elective surgery. 

Long term risks and graft durability 

While the immediate surgery has risks, there are also long term considerations regarding the durability of the bypass grafts. Over time, the new vessels can become narrowed or blocked, a process similar to the original disease. Vein grafts taken from the leg are more prone to this than arterial grafts taken from the chest or arm. 

To reduce the risk of graft failure, it is essential to manage the underlying coronary heart disease for the rest of your life. This involves taking your heart medications exactly as prescribed and making significant lifestyle changes. If a graft does fail years later, it can often be treated with a stent or a change in medication, but preventing this through good heart health is always the clinical priority. 

• Vein grafts have a higher long term risk of narrowing than arterial grafts. 

• Smoking is the leading cause of premature graft failure. 

• High cholesterol and blood pressure must be strictly managed for life. 

• Regular follow up with a GP or cardiologist is vital for monitoring graft health. 

Conclusion 

Bypass surgery is a major operation with recognized risks, including infection, bleeding, and heart rhythm issues. However, for most patients, the long term benefit of improved blood flow and reduced heart attack risk far outweighs these potential complications. By understanding the risks and working closely with your clinical team, you can take proactive steps to ensure a safe and successful recovery. 

If you experience severe, sudden, or worsening symptoms, such as intense chest pain, heavy bleeding from a wound, or fainting, call 999 immediately. 

Authority Snapshot 

This article was written by Dr. Rebecca Fernandez, a UK trained physician with an MBBS and extensive experience in cardiology, general surgery, and intensive care. Dr. Fernandez has managed critically ill patients and stabilized acute cardiac cases within the NHS. This guide follows the latest clinical standards from NICE and the British Heart Foundation to provide safe and accurate information regarding the risks of bypass surgery.