How Bypass Surgery Works — What Patients Need to Know

Most people know that bypass surgery involves the heart. Fewer know what actually happens in the operating theatre, why the surgery takes hours, or what makes it different from angioplasty. This guide covers the full picture — from the blocked artery that leads to the recommendation, to the moment the chest is closed.

Why Bypass Surgery Becomes Necessary

The heart is a muscle. Like all muscles, it needs a continuous blood supply to function. That supply comes through the coronary arteries — three main vessels (right coronary, left anterior descending, and circumflex) that wrap around the outside of the heart and send branches into the muscle.

When cholesterol-containing plaques build up inside these arteries over years — atherosclerosis — the arteries narrow. Blood flow drops. The heart muscle gets less oxygen, particularly during exertion when demand is highest. The result is chest pain or pressure (angina), shortness of breath, or in severe cases, heart attack.

When the blockages are severe, numerous, in difficult locations for angioplasty, or in patients with diabetes and multi-vessel disease, bypass surgery produces better long-term outcomes than placing stents.

What "Bypass" Actually Means

The operation does not fix the blocked arteries. It routes blood around them.

The surgeon creates new channels — grafts — that carry blood from before the blockage to after it, bypassing the narrowed section entirely. The heart muscle, now receiving adequate blood through these new routes, recovers its function.

A double bypass means two grafts. A triple bypass means three. The number refers to how many blockages are being bypassed, not the severity or danger of the surgery.

The Graft Vessels — Where They Come From

Two main sources:

1. Internal mammary artery (IMA): A vessel that runs down the inside of the chest wall. The left IMA is the preferred graft for the left anterior descending artery — the most critical coronary vessel. IMA grafts have outstanding long-term patency; studies show over 90 percent still working at ten years. When a surgeon uses the IMA rather than vein grafts, the long-term results are meaningfully better.

2. Saphenous vein: The long vein running down the inside of the leg. Harvested through a separate incision (or endoscopically through small cuts), it provides additional graft material when more than one or two bypasses are needed. Vein grafts have lower long-term patency than IMA — around 50 to 60 percent at ten years — but still provide excellent symptom relief.

The Operation — Step by Step

The patient is under general anaesthesia. The surgeon makes an incision down the centre of the chest and divides the breastbone (sternotomy) to access the heart. Simultaneously, a second surgeon or assistant harvests the graft vessels from the chest wall or leg.

The heart is connected to a cardiopulmonary bypass machine — a pump oxygenator that takes over the circulation while the heart is stopped. Cold cardioplegia solution is delivered into the coronary arteries to arrest the heart and protect the muscle during the procedure.

With the heart still and bloodless, the surgeon sews the grafts into place. The distal end of each graft is attached to the coronary artery beyond the blockage. The proximal end is connected to the aorta, the main artery leaving the heart, to source the new blood supply.

Once all grafts are sewn, the cross-clamp is removed. The heart receives warm blood again. It usually restarts spontaneously or with a small electrical shock. The bypass machine is weaned off as the heart takes over circulation again. Temporary pacing wires are placed on the heart surface in case the rhythm needs support after surgery. Chest drains are inserted to remove any blood or fluid that accumulates after closure.

The sternum is wired shut with stainless steel wires that stay permanently. The soft tissue layers and skin are closed. The operation typically takes three to six hours total.

Off-Pump Bypass — When the Heart-Lung Machine Is Avoided

In selected patients, surgeons perform bypass surgery on the beating heart without cardiopulmonary bypass. The surgeon uses mechanical stabilisers to hold still the small section of heart being worked on while the rest continues beating.

Off-pump CABG reduces some complications associated with the bypass machine — particularly stroke risk in patients with aortic calcification, and kidney dysfunction in patients with pre-existing renal disease. It is technically more demanding and not suitable for all coronary anatomy. Available at Fortis Memorial Research Institute and other centres in Prime Medical's network.

After the Operation — The Recovery Stages

Day 0–1: Patient wakes in the cardiac ICU on a ventilator. As consciousness returns and breathing becomes independent, the breathing tube is removed — usually within four to eight hours of surgery. Monitoring lines, drains, and pacing wires are in place.

Days 2–3: Chest drains removed when output is low. Patient sits up, takes first steps with physiotherapy support. Moved out of ICU to the cardiac ward.

Days 4–8: Increasing mobility. Wound checks daily. Medications established — aspirin, statin, beta-blocker, blood pressure control as needed.

Discharge: Most patients go home at five to eight days. International patients at Prime Medical's partner hospitals remain in India for a further two to three weeks of outpatient monitoring before the cardiac team clears them to fly.

Six to eight weeks: The sternum heals. During this period, no lifting more than two to three kilograms, no driving. Most patients are back to gentle walking from week two.

Three months: Most patients return to normal daily activities. Cardiac rehabilitation — supervised exercise and lifestyle education — significantly improves long-term outcomes.

Cardiac Surgery Hospitals in Prime Medical's Network

Artemis Hospital, Gurugram (JCI, NABH) — Prime Medical partner. Strong cardiac surgery department. Off-pump CABG available. Personal environment compared to very large campuses.

Fortis Memorial Research Institute, Gurugram (JCI, NABH, NABL) — Advanced cardiac programme. Off-pump and robotic-assisted cardiac surgery. Complex multi-vessel cases.

Max Super Speciality Hospital, Saket, Delhi (JCI, NABH, NABL) — Dr. Balbir Singh leads cardiology. Full cardiac surgery programme. Treats patients from Ethiopia, Uganda, Gambia, and Tanzania regularly.

Indraprastha Apollo Hospital, New Delhi (JCI, NABH) — Over 15,000 cardiac procedures annually. Africa desk. Full bypass and valve programme.

For patients from Addis Ababa, Hawassa, Bahir Dar, Kampala, Dar es Salaam, or Banjul who have an angiogram showing coronary artery disease: share the report with Prime Medical Solutions. A cardiac specialist reviews within 48 hours and advises whether bypass or angioplasty is more appropriate for the specific anatomy.

To book a consultation, call the number on our website.