Structure & Function of the Heart:
Risk factors for Coronary Artery disease:
Coronary Artery Disease:
Emergency Complications of Heart Attack:
Coronary Artery Bypass Grafting (CABG):
Rheumatic Fever and Heart Valve Diseases:
Heart Transplantation and Assisted devices
Choice of Grafts for Coronary Artery Bypass Grafting (CABG)
If the decision has been made that your coronary artery disease is going to be treated with coronary artery bypass graft surgery, one important thing is to decide which grafts will be used to bypass your blocked arteries. There are 3 types of grafts, venous grafts, arterial grafts and synthetic grafts.
During your operation, the surgical team will need to harvest and prepare a vein from elsewhere in the body to use as a graft. The most commonly used vein is the long saphenous vein. The long saphenous vein is a very long vein which runs on the inner surface of your leg starting from the ankle and moving up till it ends in the groin. The saphenous vein is long enough and if its whole length is taken, it can be used to bypass at least three coronary arteies. The good news is that when this vein is taken, nothing harmful happens to our leg except for some swelling, tingling and numbness.
If the long saphenous vein is diseased with varicosities, another vein on the back of your leg named the short saphenous vein can be used.
Although the saphenous vein is generally a good-quality blood vessel and can reach any coronary arteries, there is about a 5 percent chance per year that it will become narrow or totally blocked. Thus, its patency rate over time (or chance of the vein staying open with time) is not as good as that of some other grafts.
The saphenous vein graft is usally harvested by the physician assistant and can be taken through a long skin incision or recently by the endoscope (EVH). Benefits of endoscopic vein harvesting include more cosmetic incision and lower incidence of infection.
Certain arteries in the body can be harvested without doing much problems to the areas they were taken from. Here are examples of some of the arteries which can be harvested:
The left internal mammary artery: very commonly used vessel which is also called the left internal thoracic artery. It runs under the breastbone (sternum) on the left side. When the left internal mammary artery is harvested, it is usually freed in its lower part and its upper part is kept attached to its branch of origin from the aorta where it gets the blood from. After freeing its lower part , it is sutured to the left anterior descending coronary, which generally is the most important coronary artery for bypass.
The very good thing about the left internal mammary artery is its excellent patency rate in which there is about a 95 percent chance it will remain open for twenty or more years later.
Sometimes its size is a disadvantage. It may only be a millimeter or less in diameter which is smaller than the coronary artery being bypassed, and sometimes the blood flow through it is inadequate. Occasionally, the internal mammary artery will not reach the point on the coronary that it needs to be grafted. That obstacle can frequently be overcome by disconnecting the upper end and sewing one end to the coronary and one to the aorta or another artery.
The right internal mammary: run under the breastbone on the right side, and is also frequently used to bypass blockages in the coronary arteries. This artery usually reaches the right coronary, the left anterior descending and some branches of the circumflex. If it does not, the approach is generally the same. The upstream end of the artery is disconnected, and one end is sewn on the coronary artery and the other is attached to the aorta or to another bypass graft.
One of the disadvantages of harvesting the internal mammary arteries is that they are the arteries which give blood supply to the breastbone. In some patients the healing of the breastbone, which is opened during surgery, is delayed and can be infected as well.
Radial Artery: which is located in the arm and runs from the elbow to the wrist towards the thumb.. Although some surgeons were using this artery for coronary bypass twenty-five years ago, recently it has become popular again. There is a single main artery in the upper arm called the brachial artery, which divides into two main branches near the elbow. One branch, the radial artery, runs along the inner forearm toward the thumb. The other branch, the ulnar artery, runs along the outer edge heading toward the little finger. Before harvesting the radial artery, surgeons will do special tests and sometimes Doppler ultrasound to make sure that the ulnar artery can take over and supply the hands when the radial artery is removed.
The patency rates with radial arteries so far indicate that it has a greater chance of staying open longer than saphenous vein grafts but not quite as long as the left internal mammary artery.
One of the disadvantages of the radial artery is that it can develop some spasm and narrowing after harvesting. This can be overcome by bathing the artery in some solutions after harvesting and by giving you special intravenous drugs in the ICU that will protect the artery from this spasm
Doctors sometimes use an abdominal vessel called the gastroepiploic artery as the bypass graft. To use this artery, the abdomen must be opened. When using this artery, one end of it can be left attached to the stomach while the other end is threaded through a hole in the diaphragm, or breathing muscle, and joined to the appropriate coronary artery. The gastroepiploic artery can also be used as a free graft when both ends are disconnected. In this case, the other end is sewn to the aorta or another coronary bypass graft. The gastroepiploic artery graft seems to have a better patency rate than the saphenous vein graft but a somewhat poorer patency rate than the left internal mammary artery. The disadvantage of using this artery is that the surgeon has to make a second major incision to open the abdomen and take part of the blood supply of a portion of the stomach.
In certain other cases, veins from a human cadaver have been used, but, again, the patency rates are not very good. This may be because of a rejection process that occurs from using tissue from another human.
Synthetic grafts made of Dacron or other material have also been used. These grafts generally work quite well in other areas of the body, particularly in the larger arteries and the aorta, but the patency rates for coronary artery grafting have not been very good, and these synthetic arteries are not routinely used.
A new concept, called total arterial revascularization, is now emerging in which arterial grafts are only used because of their patency rates. However lot of surgeons still believe in using the left internal mammary artery for bypassing the left anterior descending artery and using saphenous vein grafts to bypass other coronary arteries.
Symptoms and signs of heart disease:
NonInvasive diagnostic tests For heart disease:
Invasive Diagnostic Tests for heart disease:
Cardiac Arrythmias and Pacemakers:
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