HYBRID CORONARY REVASCULARISATION
WHAT IS HYBRID REVASCULARISATION ?
This is a procedure that combines both minimally invasive bypass surgery with percutaneous angioplasty (balloon and stenting). This type of procedure is not new and has been done since the mid 1990s.
WHY NOT COMPLETE ANGIOPLASTY OF ALL BLOCKED VESSELS ?
There are three main arteries of the heart. They are the left anterior descending artery (LAD), right coronary artery (RCA) and left circumflex artery (Lcx). The LAD artery runs down the front of the heart and in the majority of people is the most important of the three arteries as it supplies the bulk of the muscles of the left heart chamber.
Present evidence gained from many years of experience still suggests that certain types of grafts used in bypass surgery can last longer than using stents. In particular, a graft taken from the breast bone called the left internal mammary artery (LIMA) when connected to the left anterior descending artery (LAD) of the heart provides a long lasting result. Such grafts have also proven to increase life span. The expected failure rate of the LIMA to LAD graft is only about 10% after 10 years.
Stents on average may have a re narrowing rate of up to 20% by the first 6 months. Even drug coated stents have rates of re narrowing that are at best about 5-10% by the 1st year. In addition, narrowings in the artery that are not stented have a chance of progressing to become more narrowed with time. Drug coated stents also have a down side which is called thrombosis (sudden formation of blood clots) that can occur after the initial stenting. This is rare, occurring in about 0.5-0.6% of people per year who have have drug coated stents placed. However, a stent in the LAD artery which suddenly clots has a high likelihood of causing death.
WHY NOT TRADITIONAL BYPASS SURGERY ?
While the LAD artery lies on the front surface of the heart, the other two arteries run a course to the back and bottom of the heart. To do a full bypass of all three arteries, the patient is usually placed on a heart-lung bypass machine and the heart is made to stop beating. The increased manipulation of the heart during operation can lead to increased risk of complications. Another problem termed “pump head” can occur when patients are placed on the heart-lung bypass machines. This is due to small showers of debris that can cause tiny “strokes” and may result in memory loss and forgetfulness after the operation.
Grafting of the other two arteries (RCA and Lcx) are also usually performed by using veins taken from the legs. These veins are not as robust as the LIMA artery with blockage rates of up to 20% by the first year after operation.
HOW IS HYBRID REVASCULARISATION DONE ?
Essentially beating heart surgery is done and the LIMA artery is grafted to the LAD artery. This avoids the need to stop the heart and therefore the need to place a patient on heart-lung bypass. Excessive manipulation of the heart is also avoided as the LAD artery lies on the front surface of the heart. The scars following such surgery is also much smaller and there is no need to take veins from the legs.
Narrowings that may be present in the other two arteries can then be done by angioplasty following surgery. Presently, drug coated stents can be placed which provide low rates of re narrowing. If clots formed in such stents, they would usually be less dangerous than would have occurred if the stents were in the LAD artery.
WHO SHOULD GO FOR HYBRID REVASCULARISATION ?
The approach of bypass surgery alone or angioplasty alone remain the mainstream ways of improving blood flow in blocked heart arteries. Hybrid revascularisation should only be considered in patients with appropriate types of blockages and/or who may be too high risk for the more traditional approaches. Hybrid revascularisation requires surgeons and cardiologists to work closely together and co-ordination of such approach needs to be carefully arranged. In the majority of patients, there may not be an added advantage for this hybrid approach due to the increased need for procedures and cost involved. There are also specific advantages and disadvantages of this hybrid approach. Patients considering such an approach should have a careful discussion with both their surgeon and cardiologist before a decision is taken to undergo this form of procedure.