MIDCAB is a minimally invasive version of the traditional coronary artery bypass graft (CABG). Like CABG, MIDCAB creates a detour for blood to flow around a blocked coronary artery but with minimal invasion into the patient's chest area. It also does not require the use of a heart-lung machine , which has been associated with a number of potential complications. The surgery is used to treat coronary artery disease and is designed to help relieve symptoms such as angina ( chest pain , pressure or discomfort). By improving blood flow through the coronary arteries, the MIDCAB also lowers the risk of heart attack or other potentially fatal events. The MIDCAB offers a number of advantages over the standard CABG. For example, it is less traumatic, less expensive and requires smaller incisions. On the other hand, it is rarely used when blockages are present in multiple arteries. Patients will be given strict instructions regarding eating, drinking and smoking before the procedure and can expect to spend at least three days in the hospital. Variations of MIDCAB include port access bypass surgery , off-pump bypass surgery , keyhole surgery (also called buttonhole surgery or laparoscopic bypass) and robotic visualization techniques. An experimental technique currently being researched is PICVA . More information on these procedures can be found in the section: Variants of the MIDCAB .
Like the traditional coronary artery bypass graft (CABG), MIDCAB (minimally invasive direct coronary artery bypass) creates a detour for blood to flow around a blocked coronary artery , but with minimal invasion into the patient's chest area. The detour is usually created around a left anterior descending coronary artery (LAD) that has signs of atherosclerosis – the hardening and narrowing of the artery as a result of plaque build-up and calcification . Untreated, the plaque can completely block the flow of oxygen-rich blood through the hardened artery, cut off the flow of blood and nutrients to the heart muscle, and potentially result in a heart attack . Both the CABG and the MIDCAB reduce the risk of a potentially fatal event (e.g., heart attack), and each has its own advantages and disadvantages. In contrast with the CABG, the MIDCAB offers the following advantages:
Not all surgeons are qualified to perform minimally invasive techniques, which require greater skill and experience. Patients interested in determining their eligibility for these techniques and/or finding a qualified surgeon to perform the surgery may wish to seek a second opinion. For additional information about seeking a second opinion, click on the following: Getting a Second Opinion . 
What happens before a MIDCAB? Patients should prepare in advance for a hospital stay of about three days. The patient is usually admitted on the scheduled date of the MIDCAB. In the hospital, the patient will undergo a pre-operative assessment that includes following:
Immediately before surgery, the patient will be given specific pre-operative medications and then "prepped" for surgery. First, the chest area is shaved. Next, the surgical team creates a sterile environment by swabbing the patient's chest with an antiseptic solution and covering the operative area with sterile surgical drapes. An intravenous (I.V.) line will also be started, usually in the forearm or back of the hand. The patient is then given a sleep-inducing medication through the intravenous (I.V.) line. Once asleep, the patient will continue to breathe a mixture of oxygen and anesthetic gas (general anesthesia ) to make sure that he or she remains asleep throughout the entire surgery.
What happens during a MIDCAB? After the patient is asleep, a device called the Swan-Ganz catheter is often inserted into the jugular vein (in the neck) and threaded to the pulmonary artery (which goes from the heart to the lungs ). The catheter can be used to give medication, to measure the oxygen levels in the blood and to measure pressures in the heart. A breathing tube ( endotracheal tube) will also be inserted into the mouth and down the windpipe ( trachea ) to maintain an airway. The surgeon will then make an incision about 4 to 6 inches long on the left side of the chest. Through this incision, the surgeon can identify the mammary artery (also known as the internal thoracic artery ), which will be used for the graft. The artery is located and part of it is retrieved for use ( harvested ). If the surgeon finds the mammary artery to be unusable for this purpose, or if other complications are revealed (e.g., the LAD shows severe calcification ), then the surgeon might proceed with a standard CABG from that point. Whereas CABG requires a heart-lung machine to take over the heart's functions so that the heart can be carefully stopped, MIDCAB only requires the heart rate to be slowed down with the use of medications. Once the heart rate has been slowed, blood flow to the LAD is temporarily clamped off. The mammary artery is then attached directly to the LAD beyond the blockage. Since the heart is still beating throughout this process, a piece of equipment called a heart stabilizer is an important part of MIDCAB. The stabilizer restricts the heart's range of motion to only 1 millimeter, creating a work area for the surgeon as he or she completes this very delicate surgery. Once the procedure is finished, blood can flow freely through the LAD beyond the blockage, restoring blood flow to the heart muscle. When the surgeon is satisfied that complete blood circulation has been restored to the heart, the chest incisions are closed ( sutured ). The procedure takes approximately two hours.
What is the recovery process after MIDCAB? Following the MIDCAB, the patient will spend some time in the recovery room, where simple exercises will be performed to restore normal breathing, circulation and movement. Heart and blood flow will be continuously monitored. Within 24 hours, the patient will be transferred to a regular hospital room. Routine medications and additional pain medications may be administered and food will be given as tolerated by the patient. An average hospital stay after a MIDCAB procedure is approximately three days. After discharge, patients are encouraged to engage in light exercise , such as walking; however, strenuous exercise is discouraged.
What are the benefits and risks of a MIDCAB? Clinical tests have shown that MIDCAB is a highly successful procedure with a lower risk of serious complications than a conventional bypass surgery . A successful MIDCAB will result in the resumption of normal blood flow through the left anterior descending coronary artery (LAD). A segment of the LAD will still be blocked, but the blood will be able to flow freely through the detour and around the damaged area via the newly grafted mammary artery. What is the future course of action after MIDCAB? After undergoing a MIDCAB, patients are strongly encouraged to make lifestyle changes that can prolong the effectiveness of the procedure as well as the patient's overall health. These changes include the following:
Variants of the MIDCAB There are a number of variants of the MIDCAB. One variant is a hybrid between the standard MIDCAB and the traditional coronary artery bypass graft (CABG). It is called a port access surgery. Port-access surgery involves making several very small incisions in the chest through which the surgeon will perform the operation. The surgeon is able to view what he or she is doing through the use of fiberoptic endoscopes positioned in the chest and uses small, specially designed surgical instruments during the procedure. The sternum is not split and the chest is not opened. More than 98 percent of patients undergoing this procedure have had successful outcomes, a faster recovery and less pain. Port-access surgery does, however, require the use of the heart-lung machine to take over the functions of the heart so that the heart can be safely stopped. The ports are held open during surgery with 1.5-centimeter tubes that provide a workspace for tools and scopes to access the heart and coronary arteries. A catheter is inserted through the groin and fed through the femoral vein and/or femoral artery to assist with the diversion of the blood flow to the heart-lung machine. In contrast with the standard MIDCAB, the advantages of port-access surgery include the following:
Another variant of the MIDCAB is the off-pump coronary artery bypass (OPCAB). The OPCAB is a compromise technique that is being used more and more by today’s surgeons to perform coronary artery bypass surgery. With this technique, the patient's chest is opened as in conventional open-heart surgery. However, no heart-lung machine is used, and the surgery involves stabilizing only that area of the heart on which the surgeon is operating. The entire heart still beats on its own. A recent study compared heart patients undergoing their bypass surgery either with or without the heart-lung machine. Those “off” the heart-lung required fewer blood transfusions during surgery; sustained less heart damage; had less weight loss; and had a shorter hospital stay. It is also believed that this technique carries a lower risk of neurological injury, whether it be stroke, confusion or depression. A final variant of the MIDCAB is the use of robotic visualization techniques. This strategy involves a voice-activated robot at the operating table and a cardiac surgeon one room away. The hand motions of the surgeon are processed and digitized from the controls to a computer. The computer, in turn, directs the robot where to cut and sew inside the chest. The surgeon directing the operation can view the procedure via an endoscope (a slim optical tube with an attached camera that is positioned inside the chest cavity). The advantage of using a robot is that the "hands" are smaller than human hands and require a much smaller incision. These techniques are reported to be safe and reliable, causing less pain to the patient, less surgical trauma and a shortened recovery time. Tele-robotic heart surgery is still in the embryonic stage and is currently used in less than 15 percent of cases involving coronary artery disease. The procedure, which has been approved in several European countries, is still being tested in the United States and has not been approved by the Food and Drug Administration. Other minimally invasive methods of coronary artery bypass are continually being explored. A recent issue of Circulation (May 29, 2001) reported the success of the first non-surgical bypass operation in Germany. Named percutaneous in situ coronary venous arterialization (PICVA), the procedure basically redirects blood flow around a blocked artery by diverting it to an adjacent vein. An ultrasound catheter system guides a needle into the blocked artery and through the artery wall into a nearby vein. This creates a channel into the vein, redirecting the flow of blood around the blockage. The procedure had been performed in 1999 on a patient with severe chest pain and coronary artery disease who was not a candidate for traditional bypass surgery or balloon angioplasty. A year after the procedure, the patient was still free of heart-related chest pain. Further studies are needed to determine the safety and long-term effectiveness of this procedure.
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