Opening the heart for surgery requires cutting through the breastbone in a procedure called a sternotomy, the standard approach for most major heart operations. The breastbone (sternum) is about 6 inches long in adults, and splitting it down the middle gives surgeons the widest, most direct access to the heart and surrounding structures. While minimally invasive alternatives exist for some procedures, a full sternotomy remains the most common route for bypass surgery, valve replacements, and repairs to the aorta.
Why Open-Heart Surgery Is Needed
Open-heart surgery is typically reserved for blockages or damage too severe for catheter-based procedures. For coronary artery bypass grafting, the most common open-heart operation, guidelines call for surgery when a major coronary artery is more than 70% blocked, or when the left main artery supplying most of the heart has more than 50% blockage. It’s also recommended when two or three major vessels are significantly narrowed, or when a patient continues to have serious chest pain despite medication.
Valve disease, aortic aneurysms, and certain congenital heart defects also require the full exposure that a sternotomy provides. In some cases, a less invasive approach through a smaller incision is attempted first but must be converted to a full sternotomy. This happens in roughly 3% of minimally invasive cases, usually due to unexpected bleeding.
Step by Step: How the Chest Is Opened
The surgeon begins with a scalpel, cutting through the skin in a straight vertical line starting between the two collarbones and ending where the breastbone tapers off near the upper abdomen. Once the skin and tissue are parted, a specialized sternal saw cuts through the bone from top to bottom. This is a precise, controlled cut down the center of the sternum.
A metal retractor is then placed between the two halves of the split breastbone and slowly cranked open, spreading the chest wide enough to see and reach the heart. In children, the thymus gland sitting in front of the heart may be partially or fully removed to improve the surgeon’s view.
The heart itself sits inside a protective sac called the pericardium. The surgeon cuts this sac open to expose the heart directly. At this point, the surgical team can see the beating heart and begin the planned repair.
How the Heart Is Kept Still During Surgery
For most open-heart procedures, the heart needs to be temporarily stopped so the surgeon can work on a motionless, bloodless surface. A heart-lung machine (also called a bypass machine) takes over the job of circulating and oxygenating blood while the heart is out of commission.
Tubes are inserted into the right side of the heart to drain blood out of the body and into a reservoir. Gravity pulls the blood down based on the height difference between the patient and the machine. The blood then passes through an oxygenator, a device with a thin membrane that lets oxygen flow in and carbon dioxide flow out, mimicking exactly what the lungs normally do. A pump pushes this freshly oxygenated blood back into the patient’s arteries through another tube, keeping every organ supplied with oxygen throughout the operation.
This setup lets the surgical team work on a heart that is still and drained of blood, which is essential for delicate tasks like stitching new blood vessels onto coronary arteries or replacing a damaged valve.
Closing the Chest
Once the heart procedure is complete, the surgeon wires the two halves of the breastbone back together using 8 to 12 stainless steel wires. These wires are permanent in most cases. If the bone is especially dense, small holes are drilled to thread the wires through. The overlying tissue and skin are then closed in layers.
The sternum heals much like a broken bone. Full fusion takes about six weeks in most patients, though the wires provide structural support throughout the healing process and beyond.
What Recovery Looks Like
Most people start feeling noticeably better four to six weeks after surgery, though full recovery takes longer. The American Heart Association recommends building activity gradually, doing a little more each day than the day before.
The biggest restriction during the first six weeks is protecting the healing breastbone. You should avoid lifting, pulling, or pushing anything over 10 pounds. Reaching behind your back or raising your arms above your shoulders is also off limits during this window. Some guidelines extend weight restrictions up to 12 weeks depending on the surgeon’s assessment of bone healing.
Driving is restricted for six weeks because of the physical demands of steering and the risk of a seatbelt impact in a sudden stop. You can ride as a passenger immediately, but on long trips, get out and walk around every two hours. Most people feel ready to return to light work somewhere between 6 and 12 weeks after surgery, though this varies by the type of work and the complexity of the procedure.
Survival and Risk Factors
For first-time open-heart surgery in otherwise stable patients, outcomes are generally favorable. The risk picture changes significantly for patients who need a second or third operation. In a study of 250 patients undergoing repeat open-heart surgery, the 30-day mortality rate was 13.6%, rising to 21.2% at one year. Each subsequent reoperation was associated with lower survival. Age alone did not strongly predict outcomes when patients were grouped by procedure type.
The higher risk in repeat surgeries comes partly from scar tissue that makes accessing the heart more difficult and increases the chance of bleeding or injury to existing grafts and structures. This is one reason surgeons aim to get the most durable result possible during the first operation.
Minimally Invasive Alternatives
Not every heart procedure requires a full sternotomy. Some valve repairs and replacements can be done through a smaller incision between the ribs, avoiding a complete split of the breastbone. These approaches typically mean less pain, shorter hospital stays, and faster recovery.
However, minimally invasive options aren’t available for everyone. Patients with significant buildup of plaque in the aorta face higher risks from the alternative tube-placement sites used in keyhole procedures, including the risk of dislodging plaque and causing a stroke. Complex multi-vessel bypass surgery, emergency cases, and operations requiring access to multiple heart structures almost always call for a full sternotomy. Your surgical team determines the approach based on the specific anatomy and the complexity of what needs to be repaired.