What is Open-Heart Surgery?
Open-heart surgery refers to operations performed on the heart that require a patient being placed on the heart-lung bypass machine.
The heart-lung bypass machine takes over the function of the heart and lungs to provide oxygenated blood to the body.
The heart can be stopped with a solution called "cardioplegia." Cardioplegia is a cold, high-potassium solution. It also protects the heart muscle while it is stopped.
The heart itself can then be opened and repair can be accomplished in a bloodless, still environment. In some situations, when on the cardiopulmonary bypass machine, the heart can be operated upon while still beating, but emptied. This usually occurs when the repair is on the right side and there are no holes between the left and right sides of the heart.
Open-Heart Surgery Use
The repair of many cardiac defects such as atrial septal defects, ventricular septal defects, AV canals, transposition of the great arteries, tetralogy of Fallot and other complex anomalies requires the use of cardiopulmonary bypass, stopping the heart, and opening the heart. Most pediatric heart procedures are open-heart procedures.
Description of Open-Heart Surgery
To get access to the heart, the surgeon has to open the chest. To do so, he or she has to cut through the breast bone (sternum). This is referred to as the sternotomy. The skin incision is generally smaller in size than the length of the breast bone, since the skin can be stretched to some extent. For repeat incisions (a redo-sternotomy) often the length is a little longer than the previous scar.
For many parents, the concept of a sternotomy raises much concern. Most parents are surprised to hear that a sternotomy is one of the safest and more comfortable incisions performed during surgery. Performing a sternotomy is nothing but an artificial fracture; at the end of the operation the two edges of the breast bone are put back together with steel wires. This usually does not lead to any deformities of the chest wall, even as a child grows. At the same time, performing a sternotomy does not prevent the progression of already existing chest wall deformities (e.g., "pigeon chest").
Pain is sensed by the nerve endings in the affected tissues. In the bone, pain arises from movement at the site of a fracture. Infants don't have much chest wall muscle mass to move the sternal edges and develop pain. For that reason, not surprisingly, most infants are discharged home on just ibuprofen and Tylenol.
After the chest is opened, a part (or all) of the thymus gland is removed. The thymus gland is involved in the immune system; however, its removal has not been shown to lead to any immune compromise. The removal of the thymus is necessary to allow the surgeon to see and operate on the heart. The heart sits in a thin, leather like sac called the pericardium. To get access to the heart, the pericardial sac has to be opened. The surgeon often removes a small portion of the pericardium, to be used later to patch holes in the heart or patch vessels to make them bigger. Often the removed piece is treated with a chemical called glutaraldehyde to increase the stiffness of the pericardium, making it easier to work with during surgery.
The removed pericardial piece is used during the operation as patch material for a variety of holes or defects within the heart. The removed piece of pericardium does not need to be replaced.
Preparing Your Child for Open-Heart Surgery
Patients requiring open-heart surgery will have had a complete evaluation by their cardiologist and cardiac surgeon.
The evaluation usually includes blood work, chest X-ray, an electrocardiogram, an echocardiogram and possibly a cardiac catheterization. All of this information helps guide the surgery and peri-operative care.
Blood is crossmatched to be available in the operating room or to prime the bypass machine if necessary.
Decision to Perform Open-Heart Surgery
When a patient's cardiologist feels surgery may be indicated, the patient is discussed at Cincinnati Children's Heart Institute's weekly combined Cardiology-Cardiothoracic Surgery Case Management Conference.
The patient's medical history, physical exam findings and all studies that have been performed are reviewed. The group then discusses your child’s case and decides on a treatment plan for your child. If surgery or alternate procedure (e.g., cath intervention) is recommended, the timing and type of procedure are then decided.
Often, the operation needed is clear-cut. However, more complex defects may have different possible approaches for either correction or palliation. Such cases benefit greatly from the input of many experts. Also, regardless of how good the pre-operative assessment, the anatomy is never really known until the surgeon is looking at the heart. Therefore, sometimes the operation done may change because of intra-operative findings.
Open-Heart Surgery Complications & Risks
All open-heart procedures carry risks related to the use of cardiopulmonary bypass. The safety of cardiopulmonary bypass has improved significantly over the years. Major complications are now exceedingly rare. Bypass times up to four to eight hours are well tolerated.
The risks of bypass itself include inadequate perfusion of organs or tissues, activation of a systemic inflammatory response, and embolization of air or particles. Especially concerning is the potential of embolization to the brain, but this risk should be quite low – less than 1 percent in most cases.
“Inadequate perfusion of organs and tissues” means that the bypass machine is not as efficient of a pump as your own heart, so some organs and tissues get a little less blood flow during surgery than they would normally. These organs protect themselves by slowing down. However, this is rare during modern cardiopulmonary bypass.
“Activation of a systemic inflammatory response” means that the heart-lung machine activates the body to release chemicals and cells that cause inflammation. This is why children after cardiopulmonary bypass can be somewhat swollen and their lungs can become “wet.” Lasix (a medicine that helps your child get rid of fluid by urinating) is usually given after surgery. “Embolization” occurs when a particle breaks loose and travels from one location in the body to another. Both air and clots can break lose and embolize and can cause a potentially dangerous event (such as stroke). A potentially significant, yet rare, complication of cardiopulmonary bypass is neurologic injury resulting in stroke or seizures.
Bleeding is also a risk after open heart surgery. Due to the use of Heparin (a blood thinner) during bypass, bleeding sometimes occurs where we have placed sutures. Usually, the bleeding is minimal and easily controlled with medications and bandages. The need for re-operation for bleeding following open-heart operations is low, about 2 percent.
In addition to the risks of bypass, the heart itself can be affected. First, the heart undergoes a period of cold ischemia (no blood flow) during most open-heart operations. Myocardial function may be compromised by this period of ischemia despite efforts to protect the heart muscle using cardioplegia and cooling. Second, the heart’s function may be decreased or “depressed” after surgery. The heart needs time to adapt to new anatomy and physiology after repair. Last, the heart rhythm may also be affected by open-heart procedures. Some patients require temporary or even permanent pacing (stimulation of the heart to assure a normal rhythm).
Incidence of Open-Heart Surgery in Children
At Cincinnati Children's Hospital Medical Center, more than 300 open-heart operations are performed each year.
In the United States, approximately 22,000 pediatric open heart procedures are performed each year. These procedures are done safely in younger children.
Currently nearly 25 percent of children undergoing open heart surgery are under a month of age, and nearly 70 percent are under 1 year of age.
Open-Heart Surgery Success
Success of open-heart surgery is highly dependent on the particular defect being operated upon.
Corrective procedures such as atrial septal defect and ventricular septal defect closures are highly successful with a near-zero percent mortality (or death rate).
Somewhat more complex lesions -- yet ones that are performed often, such as AV canal defects, transposition of the great vessels and tetralogy of Fallot -- carry a risk less than 5 percent.
More complex lesions, such as single ventricle defects, may carry a higher risk in the range of 15 to 20 percent, because one of the ventricles or valves is hypoplastic (underdeveloped).
Other factors can affect these results. For instance, a prematurely delivered newborn suffering from low birth weight and end-organ injury (i.e., kidney failure or liver injury) is at increased risk from open heart surgery.