Minimally Invasive Direct Coronary Artery Bypass (MIDCAB) is a surgical treatment for coronary heart disease that is a less invasive method of coronary artery bypass surgery (CABG). MIDCAB gains surgical access to the heart with a smaller incision than other types of CABG. MIDCAB is sometimes referred to as “keyhole” heart surgery because the operation is analogous to operating through a keyhole.
MIDCAB is a form of off-pump coronary artery bypass surgery (OPCAB), performed “off-pump” – without the use of cardiopulmonary bypass (the heart-lung machine). MIDCAB differs from OPCAB in the type of incision used for the surgery; with traditional CABG and OPCAB a median sternotomy (dividing the breastbone) provides access the heart; with MIDCAB, the surgeon enters the chest cavity through a mini-thoracotomy (a 2-to-3 inch incision between the ribs).
MIDCAB surgery is no more reserved for anteriorly placed single or double vessel diseases,because recently such lesion are usually managed by with angioplasty. Hence this surgery has recently been used in multi vessel diseases.
How is a MIDCAB done?
After the patient is under anesthesia, the surgeon makes a small transverse 2 inch long incision on the front of the chest, towards the left side. This incision is then deepened, dividing the pectoral muscles. When the rib cage is reached, a small portion of the front of the rib – called the “costal cartilage” – is removed.
Just beneath this cartilage lies the Internal Thoracic Artery (ITA). With great care, the surgeon dissects out this artery for a short length, making sure that all tiny branches are clipped to prevent bleeding later on. When an adequate length has been prepared, the ITA is divided and occluded with a clamp.
The surgeon makes an opening in the sheath covering the heart (called the pericardium). On the surface of the heart, directly under the incision, lies the Left Anterior Descending (LAD) coronary artery to which a graft will be placed.
Sewing together the ITA and LAD coronary artery, both of which measure around 1.5 millimeters, is difficult in the best of circumstances. With the heart still beating during a MIDCAB, the procedure becomes infinitely more difficult. Great manual dexterity and skill are required to create such a connection. Using a variety of techniques to stabilize the heart and reduce its movement, the two arteries are connected with hair-thin sutures. When the graft has been sutured, the clamp on the ITA is released, and blood can be seen to flow through the distal LAD coronary artery. Simple, isn’t it ?
Other grafts that have been placed using MIDCAB are : –
- Right ITA to the Right Coronary Artery (RCA)
- Right Gastro-epiploic artery (in the abdomen) to RCA branches
- Recently some surgeons have been able to graft the Left Circumflex Coronary Artery branches
Techniques used to immobilize the heart during MIDCAB
- Loop Sutures
- Special Clamps
- Utrecht Octopus Device
- Drug therapy