| MIDCAB (minimally invasive direct conorary artery bypass) surgery was developed as a less-invasive alternative to conventional coronary artery bypass graft (CABG). During a conventional CABG, the surgeon “cracks” the patient’s chest by making an incision through the breastbone and spreading the ribs. This gives the surgeon excellent access to the heart, but it results in a long recovery for the patient. Also, the incision is more prone to infection and other complications. MIDCAB addresses these concerns by using a smaller incision in the side of the chest. Working through this smaller incision, the surgeon is able to sew bypass grafts onto diseased coronary arteries. This technique reestablishes blood flow to the heart with much less trauma to the patient and a reduced risk of infection at the site of the surgical wound. On average, patients who undergo MIDCAB may be released from the hospital within 3 to 7 days and can often return to normal activities within two weeks. By contrast, patients undergoing CABG often spend two weeks in the hospital and several months in recovery. MIDCAB surgery may be performed with or without use of the heart-lung machine. If it is performed with the heart–lung machine, the surgeon stops the heart through use of cardioplegia solution, then uses a special system of clamps and shunts to redirect blood flow around the heart. This may be called port access surgery, after the device that is used to reroute blood flow. This technique gives the surgeon the ability to work on a still, empty heart, which increases the level of control over the operation. If the surgery is performed without the heart-lung machine, the surgeon uses a special system of clamps and stabilizers to hold the heart still while the bypass grafts are sewn into place. MIDCAB is used to treat the symptoms of conorary artery disease, including angina (chest pain and pressure). By reestablishing blood flow to the heart, the risk of heart attack is also reduced. Compared to conventional CABG, MIDCAB has a number of advantages and disadvantages. It offers the following advantages: - It is less costly.
- The risk of serious complications, including infection, can be minimized because of the smaller incision.
- It does not require the trauma of “cracking the sternum” and opening the entire chest. Because much smaller surgical incisions are used, there is less pain and trauma to the patient.
- It usually requires a shorter operation, hospital stay and recovery period.
There are also some limitations to the MIDCAB: - MIDCAB techniques can only be used in a very small subset of patients. To date, MIDCAB has been performed only in either very high-risk patients who could not withstand balloon angioplasty or conventional CABG, or very low-risk patients whose coronary artery disease was limited to the left anterior descending coronary artery (LAD), which lies on the front of the heart. In some cases, MIDCAB can be used on the right coronary artery or for multiple bypasses, but these procedures are far less common.
- Several studies have noted that MIDCAB may not be as effective over the long term as the standard CABG. Follow-up data revealed that patients who had undergone MIDCAB were more likely to have blockages in their new grafts than patients who had undergone CABG. It must be noted when interpreting this data that MIDCAB requires greater skill of the surgeon, and these studies were done when MIDCAB was still a new technique.
- Difficulty in accessing the LAD or an inability to use the mammary artery as the graft may disqualify the use of this procedure in some patients.
Efforts have been made to address MIDCAB’s main limitation, which is its limited usefulness in patients with multiple vessel disease. In some cases, it has been used successfully in conjunction with a catheter-based procedure such as balloon angioplasty. In this case, disease of the LAD will be corrected with a MIDCAB graft, while blockages in other arteries may be treated with balloon angioplasty and stenting. Results for these hybrid procedures are comparable to classic CABG for multi-vessel disease. 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. Before the MIDCAB procedure | Patients should prepare in advance for a hospital stay of about three days. The patient is usually admitted on the scheduled date of the minimally invasive direct conorary artery bypass (MIDCAB). In the hospital, the patient will undergo a pre-operative assessment that includes: - Urine and blood tests. These are done to ensure that the patient is in good overall health for undergoing surgery. Blood tests to assess blood clotting (coagulation tests) include an INR or prothrombin time (PT), partial thromboplastin time (PTT), bleeding and clotting times, and a platelet count.
- Electrocardiogram (EKG). A recording of the heart’s electrical activity as a graph on a moving strip of paper or video monitor.
- Echocardiogram. This test uses sound waves to visualize the structures and functions of the heart. A moving image of the patient’s beating heart is played on a video screen, where a physician can study and measure the heart’s thickness, size and function. The image also shows the motion pattern and structure of the four heart valves, revealing any potential leakage (regurgitation) or narrowing (stenosis).
- Chest x-ray. A radiation-based imaging test that offers the physician a picture of the general size, shape, and structure of the heart and lungs.
Eight hours before surgery, all patients are placed on NPO (non per os; nothing by mouth) status. That means that they are not permitted to eat, drink or take anything by mouth until after their surgery. Smokers will have been instructed to completely avoid smoking for at least two weeks before their surgery to prevent problems in breathing, reduce secretions and facilitate necessary coughing. Certain medications may need to be reduced or stopped temporarily, so patients should discuss their medication schedules with their cardiologist before surgery. 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 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. During the MIDCAB procedure | 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 may proceed with a standard bypass surgery from that point. Whether the heart is stopped or not depends on the particular patient and the surgeon. If the heart is stopped, a cardioplegia solution is administered and special incisions (ports) are made to accommodate the port access system. The ports are held open during surgery with 1.5-centimeter (1-inch) 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. During the surgery, the heart is still and empty of blood. This enables the surgeon to reach more of the heart than during a “beating heart” surgery. If the heart is not stopped, specialized clamps and stabilizers are used to hold the heart in place. To prevent ischemia, or lack of blood flow to the heart, a temporary shunt is put in place. Once this has been accomplished, blood flow to the left anterior descending artery (LAD) is temporarily clamped off. The mammary artery is then attached directly to the LAD beyond the blockage. 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. After the MIDCAB procedure | Following the minimally invasive direct coronary artery bypass (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. Strenuous exercise is discouraged. | | | |
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