Open Heart surgery is done to:
- Perform Coronary Artery Bypass Grafting
- Repair or replace valves that control blood flow through the heart
- Repair abnormal or damaged structures in the heart
- Implant medical devices that regulate heart rhythms or support heart function and blood flow
- Replace a damaged heart with a healthy heart from a donor
Traditional heart surgery is done by opening the chest wall to operate on the heart. Almost always, the chest is opened by cutting through a patient’s breastbone.
Once the heart is exposed, the patient is connected to a heart-lung bypass machine. Cardiopulmonary bypass (CPB) is a technique that temporarily takes over the function of the heart and lungs during surgery, maintaining the circulation of blood and the oxygen content of the body. The CPB pump itself is often referred to as a heart-lung machine or “the pump”. Cardiopulmonary bypass pumps are operated by perfusionists in association with surgeons who connect the pump to the patient’s body.
During an open-heart surgery (like bypass or valve surgery) the heart-lung machine takes over the functions of the heart and lungs. This allows the heart surgeon to stop the heart while rest of your body continues to receive blood and oxygen. It is now possible to operate inside the heart (or outside on the very small coronary arteries).
Before starting CPB, the patient is administered heparin to prevent clotting, and protamine after the operation is finished to reverse the effects of heparin. Depending on what procedure is performed, the blood is sometimes also cooled during CPB and then returned to the body. The cooled blood slows the body’s basal metabolic rate, decreasing its demand for oxygen.
Oxygenator: The oxygenator is designed to transfer oxygen to infused blood and remove carbon dioxide from the venous blood.
After its development in the 1950s, CPB has become very save and is used in most heart surgeries. However, there are potential problems (like with any man-made product) that may occur, especially in patients with extensive cardiac risk factors such as severe atherosclerosis.
Risks include the formation of small (micro) blood clots and/or particulate matter in the blood that the machine processes, which (despite filtering) can cause complications such as a stroke. More commonly, problems with temporary confusion or memory loss have also been reported in some cases.
The risk of serious complications related to being placed on cardiopulmonary support depends on the age of the patient, co-morbidities and the complexity of the surgery. In most cases the risk of a CPB related complication is less than one percent. The risk of stroke is quite variable and depends upon the nature of the patient’s heart problem, the condition of the patient themselves (in particular, the patient’s age) and the type of procedure being performed. A small percentage of patients complain of mental changes that may be the result of new mini-strokes. Recent studies suggest that cognitive decline after open heart surgery may be caused by underlying patient factors. These risk factors include :
- Older age
- Previous stroke or “mini-strokes” or TIAs (transient stroke warning symptoms)
- Evidence of cognitive dysfunction before surgery
- Atherosclerosis or “hardening of the arteries” involving the aorta, the blood vessels supplying the brain (carotid arteries) or the limbs (peripheral vascular disease)
- Chronic kidney failure
- High blood pressure
- Chronic alcohol use
In patients undergoing cardiac surgery with CPB, a systemic inflammatory reaction occurs when the blood is taken out of the body and circulated through the CPB machine. This maytrigger an inflammatory process that can damage many of the body’s systems and organs, called post-cardiotomy syndrome. Additionally, post-operative bleeding may be a serious complication, occasionally requiring a return to the operating room, but that may be associated with other issues such as pre-operative medications like Plavix.
To avoid these risks, cardiac surgeons have developed minimally invasive techniques for heart surgery that do not involve the use of a heart-lung machine. While the traditional “open heart” procedure is still performed and often preferred in many situations, newer, less invasive techniques have been developed to bypass blocked coronary arteries.
“Off-pump” procedures, in which the heart does not have to be stopped, were developed in the 1990’s. Other minimally-invasive procedures, such as key-hole surgery (performed through very small incisions) and robotic procedures (performed with the aid of a moving mechanical device), are also being used sometimes in combination with a heart lung machine, for instance for robotic valve replacements.