I cannot give you a definitive answer, because it depends to a large
part on individual factors. The information I have found suggests
that, in the worst case, there is a 50% chance of requiring a repeat
bypass after 10-12 years. On the other hand, the anonymous writer of
an article on bypass surgery for Heartpoint.com, who appears to be a
cardiac surgeon, while giving the 50% figure, also says:
How long do the bypasses last? I think I've heard more poor
information about this than about any other topic in cardiology.
Bypass grafts can last for really long periods of time. I have seen
many instances where the graft looks almost "brand new" on angiograms
done 15-20 years later.
Mark Anderson MD, Surgical Director of the Cardiopulmonary
Transplantation and Ventricular Assistance Program at Robert Wood
Johnson University Hospital, gives the following opinion:
"Bypass operations have a limited life span. This varies with
individual patients but it can range from 10 to 20 years. When a
bypass fails, many patients can be managed with medicine. If a patient
has a more significant problem, often it can be treated with
angioplasty. In selected cases, repeat bypass operations may be
performed. Some patients may require a heart transplant. The prognosis
for patients with CAD remains good."
The type of graft that was used is a significant factor, because
arterial grafts generally have a longer life span than venous grafts.
Basically, the graft degenerates through the action of two processes.
The first is called intimal thickening, which means that the lining of
the internal wall of the blood vessel used for the graft become
thicker through the growth of new tissue. The second process is the
formation of atherosclerotic plaques on the internal walls of the
vessel. Both of these processes result in the vessel becoming
narrower, and ultimately can cause total blockage, necessitating a
repeat bypass or other revascularization procedure. Arterial grafts
have been found to be less susceptible to both these processes.
Here is an extract from the guidelines of the American College of
Cardiology and American Heart Association. The extract refers to
patency, which is is defined by the American Heritage Dictionary as
The state or quality of being open, expanded, or unblocked:
Another area of evolving technology is the use of arterial and
alternate conduits. The 5-year patency of coronary arteryvein bypass
grafts is 74%, and at 10 years, just 41%. Contrariwise, patency rates
of the internal mammary artery implanted into the LAD are as high as
83% at 10 years.
Recently, the radial artery has been used more frequently as a conduit
for coronary bypass surgery. Five-year patency appears to be in the
range of 85% (compared with nearly 90% for the internal mammary
ACC/AHA Guidelines for Coronary Artery Bypass Graft Surgery: Executive
Summary and Recommendations : A Report of the American College of
Cardiology/American Heart Association Task Force on Practice
Guidelines (Committee to Revise the 1991 Guidelines for Coronary
Artery Bypass Graft Surgery)
Published in Circulation, 1999, volume 100, pages1464-1480.
Full text: http://circ.ahajournals.org/cgi/content/full/100/13/1464
The good news is that aggressive management of cholesterol levels
through diet and medication will help to slow down the process of
atherosclerosis and thus prolong the life of the graft. A 1997 press
release from NIH reports on the Post Coronary Artery Bypass Graft
(Post CABG) study carried out by the National Heart, Lung, and Blood
bypass patients treated with higher doses of two cholesterol lowering
drugs -- lovastatin and cholestyramine -- and who achieved greater
reductions in their LDL cholesterol had a significantly lower average
percentage of grafts per patient showing progression of
atherosclerosis than patients treated with a more moderate regimen (28
percent versus 39 percent).
About 50 percent of saphenous bypass grafts (from the leg) become
blocked 10 to 12 years after surgery, particularly in patients with
high cholesterol levels. As a result, these patients may need a repeat
bypass or another revascularization procedure called angioplasty.
NIH press release Aggressive Cholesterol Lowering Reduces
Atherosclerosis Progression in Bypass Grafts
High blood triglyceride (fat) levels in bypass patients were found to
be especially significant if diabetes is also present, and "[diabetic]
Women faced a particularly high risk, the researchers note. For them,
high triglyceride levels carried nearly a 50% higher risk of heart
attack, death, or repeat surgery."
Reuters report of a study published in Diabetes Care 2000, VOl. 23,
pages 1648- 1653
I hope this is the information you were seeking. Please request
further clarification of the answer if required.
1. "repeat bypass" after years
2. time before repeat bypass
3. venous arterial graft occlusion bypass
4. "repeat bypass" women