What is cardiac surgery?

Science and Profession

Cardiac surgeons are part of the broader field of thoracic surgery that includes all physicians who perform surgery on organs in the chest. Thoracic surgeons specialize in surgery of the chest that includes the lungs, the area between the lungs, the esophagus, and the chest wall. Surgery on the heart and the large vessels near the heart are performed by cardiac surgeons.

Cardiologists are also physicians who specialize in heart disorders. However, cardiologists do not perform open-heart surgeries. They diagnose and treat heart ailments using medications and cardiac catheterization procedures, in which a thin, flexible tube is inserted into a major blood vessel in the arm, upper thigh, or neck and threaded to the heart. If major surgery is needed, then a cardiologist refers the patient to a cardiac surgeon.

One of the major diseases treated by cardiac surgeons is coronary artery disease, in which the arteries that supply blood to the heart muscle become blocked with fatty deposits. Failure to treat coronary artery disease adequately can result in a heart attack. Heart valve problems are also surgically repaired by cardiac surgeons. If a heart valve allows blood to leak back in the wrong direction or is blocked, then the valve can be repaired and normal blood flow can be restored. Heart failure in its early stages is managed by a cardiologist. In its later and more severe stages, heart failure is treated by cardiac surgeons, who can either put in a ventricular assist device that helps to pump the blood or perform a heart transplant. These procedures will help the heart pump the amount of blood necessary to keep the patient alive and improve quality of life.

Another condition treated by cardiac surgeons is atrial fibrillation, in which the upper chambers (atria) of the heart contract so fast and chaotically that they fail to pump extra blood into the lower chambers (ventricles). In its early stages, atrial fibrillation is managed by cardiologists. Prior to the refinement of cardiac catheterization techniques, cardiac surgeons would perform the Maze procedure, in which the conducting pathways of the atria are interrupted by intentionally damaging the tissue to form scar tissue that can interrupt unwanted electrical impulses. Cardiologists can now perform this procedure using catheterization, but when other procedures that require open-heart surgery are needed, the Maze procedure can be done at the same time by the cardiac surgeon.

An aneurysm is a weakening in the wall of the heart or a blood vessel. A major concern is the rupture of the aneurysm and the subsequent loss of blood through the opening. One common location where aneurysms are found is in the aorta, the major artery that carries blood from the left ventricle of the heart. If the aneurysm gets too large, then a cardiac surgeon can repair it. As with other heart ailments, a cardiologist generally manages the treatment until the condition becomes severe and then surgery is performed by a cardiac surgeon.

Becoming a cardiac surgeon requires extensive education and training. Typically, four years of undergraduate education is followed by four years of medical school. In the last year of medical school, students apply for a general surgery residency program. During this five-year program, residents complete rotations in various surgical specialties, including cardiothoracic surgery. In the fourth year of the general surgery residency, the student must apply for another residency in cardiothoracic surgery, which will last another two to three years. Upon completion of the residency program, the newly trained surgeon must pass the American Board of Thoracic Surgery exams. To specialize in cardiac surgery, an additional fellowship of one to two years is required. The actual years of training at the various levels may be slightly different in the many training programs available.

Diagnostic and Treatment Techniques

Most diagnostic testing for heart conditions is performed by cardiologists. Cardiac surgeons deal primarily with the surgical treatment of heart ailments. A major intervention performed by cardiac surgeons is coronary artery bypass graft surgery. The purpose of this procedure is to restore adequate blood flow through coronary arteries that have blockages from coronary artery disease. The surgeon will open up the chest by sawing through the bones of the rib cage and then stop the heart. Blood is pumped by a heart-lung machine during the surgery. A blood vessel is removed from another part of the body, usually the upper leg. The coronary artery is cut above the blockage, and the transplanted vessel is sutured at the incision. The coronary artery is then cut below the blockage, and the other end of the transplanted vessel is sutured to the coronary artery. The result is a bypass around the blockage and through the grafted vessel, restoring normal blood flow to the heart muscle. The heart is restarted, and the incision is closed. If there are multiple blockages, then multiple bypass grafts can be performed in one surgery.

Another common surgery performed by cardiac surgeons is valve repair or replacement. The procedure begins like coronary artery bypass surgery by opening the chest and stopping the heart. If the valve can be repaired, then the surgeon may sew a ring around the valve opening to strengthen it. Sometimes the surgeon modifies the valve to make it function better by cutting and separating tissue. In more severe cases, the valve can be replaced with a biological or mechanical valve. Biological valves come from pigs, cows, or human donors. Mechanical valves are made from synthetic materials. Mechanical valves last longer than biological valves but require blood-thinning medication for life so that blood clots do not form. After the damaged valve is removed and the new valve is sutured in place, the heart is restarted and the chest is closed.

Aortic aneurysms that have a risk of bursting can be repaired by a cardiac surgeon. Usually the surgeon will open the chest. The location of the incision is dependent upon the location of the aneurysm. When the aneurysm is exposed, the surgeon replaces the affected area with a synthetic graft. The material of the graft is stronger than the damaged aorta, thus eliminating the bulge.

Sometimes cardiac surgeons perform the Maze procedure, usually in conjunction with other open-heart surgeries. Maze surgery begins by gaining access to the atria of the heart. When performed by cardiac surgeons the chest is opened and the patient is placed on a heart-lung machine. Some patients are able to have the surgery without a heart-lung machine. This is called off-pump surgery and is performed while the heart is beating. In either case, the surgeon makes small incisions in the left and right atria. These lesions will interrupt unwanted electrical impulses through the atria. After the procedure is completed, the chest is closed.

When the heart muscle is damaged, often due to a heart attack, it becomes weaker and begins to lose its shape. Cardiac surgeons can reform the ventricle with a surgical procedure called ventricular remodeling. The surgeon first opens the chest and stops the heart. A heart-lung machine pumps and oxygenates the blood. The correct size and shape of the ventricle is calculated, and a balloon of the appropriate size is inserted. A patch and circular sutures are used to bring the ventricle back to its preferred shape. A mesh stent may also be inserted to help the vessel remain open. The balloon is removed, and the heart maintains the new, optimal configuration. Then the heart is restarted and the chest is sutured shut.

If the damage to the heart is extensive, then ventricular remodeling may not be possible. In severe cases, patients may need a ventricular assist device or a heart transplant. Candidates for a heart transplant must go on a waiting list for a donor match. When a match is found, the surgery is scheduled. The cardiac surgeon opens the chest and connects the great vessels to the heart-lung machine. Then the patient’s heart is removed. The donor heart is sutured to the patient’s great vessels and then started. The heart-lung machine is removed and the chest is closed. If a donor is not available, then a ventricular assist device can be implanted. This device weighs one to two pounds and is placed in the chest. The pump is connected to the major vessels. Generally a tube is passed through the skin to connect it to batteries and controls. Sometimes the pump is placed outside the body with the controls and batteries. The ventricular assist device may be temporary until a donor is found or can be permanent.

Some traditional open-heart surgeries can be performed using minimal-access cardiac surgery. Cardiac surgeons, instead of opening the chest, use scopes to reach the heart through smaller openings in the chest cavity. This technique can be used for bypass surgery on one or two vessels, some valve repairs and replacements, Maze surgery, and some types of aortic aneurysms. If minimal-access procedures can be used, then there is generally a quicker recovery and less time in the hospital for the patient.

Perspective and Prospects

Surgeries on the heart date back to the late 1890s. They were generally to repair penetration wounds to the heart. Open-heart surgery has been performed since 1960, when an effective heart-lung machine was developed. The heart-lung machine made many heart procedures possible. Heart surgeries increased in numbers and types through the late twentieth century and into the twenty-first century because of this machine. In the 1990s, off-pump heart surgeries were developed, so that the heart continues to beat during surgery. Techniques to stabilize the moving heart made this advance possible, but not all patients are candidates for this surgery.

Minimally invasive heart surgery techniques have been developed as well. These surgeries can be performed with three small incisions. The instrument used is a robot controlled by the cardiac surgeon with three scopes that are inserted through the holes. Minimally invasive techniques are expensive, but the recovery time for patients is much less.

Another technique that is reducing the need for open-heart surgery is cardiac catheterization. Cardiac catheterization was first used on humans in the 1930s. Over the years, more applications to heart surgeries have been discovered. New catheterization techniques continue to be developed to replace open-heart surgeries because they are less expensive, have fewer risks, and require shorter recovery times. In the future, open-heart surgeries will continue to be replaced by minimally invasive and catheterization procedures.

The techniques used by cardiac surgeons continue to evolve, and as the population ages, more people will likely need heart surgeries. Cardiac surgeons will continue to have patients in need of surgery and better surgical techniques to correct the various heart conditions.

Bibliography

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