Coronary artery bypass surgery is usually reserved for patients with multiple sites of disease in their coronary arteries. Patients with diabetes and poor heart function may do better with bypass surgery than with angioplasty, according to MayoClinic.com. Heart bypass surgery requires the surgeon to use pieces of vein from the legs or other extremities and place them on the heart to bypass the blocked vessels. Sometimes the surgeon uses the internal mammary artery for bypass as well. This major surgery does have potential complications.
Sternal Infection
In order to access the heart, traditionally an incision is made from the top of the chest bone--the sternum--to the bottom.Then it is necessary to saw the sternum open. If the internal mammary artery will be used for a bypass, it is dissected away from the chest wall to use as a new vessel for the heart. Disrupting this blood flow to the chest wall, and the trauma that occurs during opening of the chest, can result in an infection of the chest bone and surrounding tissues. This complication can be devastating and result in the removal of the sternum if long-term antibiotics fail. Sternal infection is a rare complication but potentially life-threatening.
Bleeding
The cardiopulmonary bypass machine,also known as the CPM or the heart-lung machine, is used to maintain circulation to the body while the heart is stopped during the procedure. This machine takes the patient's blood through a system of tubes placed in the aorta and right atrium and cleans the toxins and oxygenates the blood. The blood is subsequently returned to the patient. Use of this machine can create bleeding because as the blood passes through the machine, it is diluted with extra fluids, thereby diluting the necessary clotting factors. In addition, the platelets, which are also necessary for clotting, can become damaged as they pass through the CPM. Finally, heparin, a blood thinner, is used to prevent the blood from clotting while passing through the tubing, but this can also lead to undesired bleeding later.
Arrhythmias
The significant handling of the heart during surgery can affect the conduction system of the heart. About 15 to 40 percent of patients will have atrial fibrillation about two to three days after surgery, states the Merck Manual. Nonsustained ventricular tachycardia, a fast, chaotic, heart rhythm, is seen in about 50 percent of patients. This rhythm can quickly switch to a sustained ventricluar tachycardia and become life-threatening. About 1 percent of patients will have a heart attack after the operation.
Organ Failure
The blood reacts to the tubing of the CPM by releasing special proteins called cytokines into the blood. These cytokines are responsible for creating a system-wide inflammatory response. Cytokines travel in the bloodstream and when they pass through the organs, they can cause organ damage or failure. Cytokines can cause the lungs to react with acute respiratory distress syndrome or cause kidney failure.
References
- MayoClinic.com: Coronary Artery Disease: Angioplasty or Bypass Surgery?
- BMC: Superficial and Deep Sternal Wound Infection after more than 9000 coronary artery bypass grafts, incidence, risk factors and mortality. Abbas Salehi Omran, MD and et.al. BMC Infectious Disease. 2007
- The Merck Manual Online Medical Library.com: Coronary Artery Bypass Grafting (CABG)
- Sage Journals Online: Understanding Cytokines Part I: Physiology and Mechanism of Action.
- MedlinePlus: Acute Respiratory Distress Syndrome
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