November 17th, 2010
05:10 PM ET

What causes new blockages to form so quickly?

Every weekday, a CNNHealth expert doctor answers a viewer question. On Wednesday, it's Dr. Otis Brawley, a chief medical officer for the American Cancer Society.

Question asked by Angi Garton of Chariton, Iowa:

My mother had triple bypass surgery one year ago. She was having chest pain again and hospitalized. There are more blockages, one right below a bypass and 70 percent blockage through a bypass. Also one bypass has failed. Her cholesterol and blood pressure are in good ranges and under control. What would have caused the new blockages so quickly from a year ago?

Expert answer

Unfortunately, it is rather common for a patient to have blockages in the coronary arteries and in the bypass after a coronary artery bypass graft (or CABG).

The heart muscle is threatened when one or more of the arteries carrying oxygenated blood through it is partially or completely blocked. It can be blocked by a cholesterol plaque, a blood clot or a combination of the two. Heart muscle beyond the blockage cannot get enough oxygenated blood. This can cause the chest pain called angina. Prolonged decreased blood flow can cause death of heart muscle which is referred to as a myocardial infarction or a heart attack.

Minor blockages of the coronary artery are treated with medications that dilate the arteries and lower blood pressure which decreases the workload and oxygen requirement of the heart. More severe blockages have to be treated with an angioplasty, angioplasty and placement of a stent, or with a coronary artery bypass graft. Angioplasty is when a catheter is passed, usually from the femoral artery in the groin up to the heart and a balloon-like device is placed in the coronary artery to the level of the partial occlusion and inflated to open the blockage. A stent, a tiny tube, can be left behind to keep the artery open. A coronary artery bypass is an open-chest surgery. A surgeon takes a piece or graft of artery or vein from elsewhere in the body. The graft is then stitched into the coronary artery so that blood can detour around the blockage. Think of a CABG as creating a detour or alternative route for blood flow around a partial or completely blocked artery. All of these treatments are designed to allow muscle beyond the blockage to get oxygenated blood.

When CABG is done the surgeon may choose to use the saphenous vein from the leg or the internal mammary artery (IMA) from the chest and armpit for the bypass graft. The condition of the patient is factored into the decision to use one or the other. In surveys more than 80 percent of CABGs are done with the right or left internal mammary artery. In the first five years after surgery, the internal mammary artery grafts are less likely to occlude compared with the saphenous vein.

In studies of several thousand people getting CABG using the saphenous vein, 10 percent have graft occlusion within the first few weeks to a year after surgery. It occurs in 35 to 40 percent by five years after the operation and 40 to 50 percent at 10 years. Factors that predispose to saphenous vein graft disease, include the size of the vein graft. Smaller diameter veins being at higher risk. Remember women are likely to have smaller vein grafts and are thus at higher risk than men. Other risk factors include length of the vein grafted (longer being at higher risk), smoking history before and after surgery, hypertension in the weeks after surgery, and lipid abnormalities in the weeks after surgery. Interestingly diabetes and poor blood sugar control appear to have little role as a risk factor for early occlusion of the grafts but is a risk factor later.

One percent of left internal mammary artery grafts and six percent of right IMA graphs develop blockages within three months of surgery. Over the long term, 10 to 15 percent of internal mammary grafts develop occlusion. Factors that increase risk of IMA occlusion include the area of the heart that needs to be grafted and the severity of the blockages being bypassed. A more severe blockage in a coronary artery correlates with decreased chances of a blockage in the graph presumably because of higher blood flow in the graph.

IMA grafts are generally preferred because they have a higher long-term patency rate. Sometimes the internal mammary artery cannot be used, necessitating the use of the saphenous vein. In select cases, some surgeons are now using the radial artery from the forearm or the the right gastroepiploic artery (from the stomach).

Studies show that one can decrease risk of occlusion of both the veinous and arterial grafts and the coronary arteries by aggressively reducing LDL-cholesterol with statin therapy and possibly through blood pressure control to low normal levels. Patients also generally benefit from low-dose aspirin therapy, some doctors prefer the antiplatelet agent clopidogrel instead of aspirin. Avoidance of smoking, controlling the serum glucose in diabetes is also important. Unfortunately these reduce but do not eliminate risk of occlusion.

I will discuss angioplasty and cardiac stents next week.

soundoff (25 Responses)
  1. sri

    thats some heavy doctory type stuff...whoa...its making me all tingly and stuff

    November 17, 2010 at 17:50 | Report abuse | Reply
  2. irsh man

    i got a block cok or a cok block. Is there a stent to clear up that block ? his name is randy marsh

    November 17, 2010 at 17:51 | Report abuse | Reply
  3. Vick

    The majority of Americans eat a high-glycemic diet (foods that spike your blood sugar); this causes inflammation in arteries, capillaries and increases Fibrinogen which forms clots. This info is in reliable medical issue but too often bypassed in this country.

    November 17, 2010 at 18:30 | Report abuse | Reply
  4. Oncologist or Cardiologist?

    He is a real doctor people..........

    .Is it a typo stating he is an oncologist but actually he is a cardiologist?

    He is spot on with the answer though and I was trying to find mistakes too.

    Sorry doctor....

    CNN has been passing off some psuedo -doctors lately...

    November 17, 2010 at 18:33 | Report abuse | Reply
  5. Buster Bloodvessel

    I have the heart of a twenty-one-year-old. I keep it in a jar under my desk.

    November 18, 2010 at 13:55 | Report abuse | Reply
  6. Dave

    "Avoidance of smoking" is easily the most important thing in this response and should not be relegated to the bottom paragraph. I fix arteries all the time with bypasses and stents and routinely tell people that if they continue to smoke, they are essentially wasting my time– that greatly increases the risk of recurrent blockages.

    There is a small group of folks who don't do well with *any* arterial intervention, but most people aren't that.

    The "glycemic diet causing inflammation" is complete garbage... unless of course you are talking about uncontrolled diabetes with blood sugars above 300. That'll land you in the ER eventually.

    December 3, 2010 at 01:26 | Report abuse | Reply
  7. Thurston Murray

    I wish to take up for the physician who discussed stents and CABAGE Surgery. My cardiologist tried a stent with me and in the proces he accidently knicked the blood vessel above the stent–making a new blockage. This resulted in my having to endure CABAGE Surgery. That bypass occluded after about a month. I was extremely disapointed with the outcomes from my procedures. So now I am on a Beta Blocker, Asprin, and Crestor inj generic form. I have reasonable concern about my future, even though at this time I exercise, eat right, and get plenty of rest. Please keep advancing Robotic Surgery as fast as possible for all CABAGE Surgery. If necessary, I would consider that, Thanks for the article.

    December 15, 2010 at 10:06 | Report abuse | Reply
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  9. jack b

    I have a 10% blockage, seems minimal but is it serious? Thanks for the help

    August 25, 2015 at 22:04 | Report abuse | Reply
    • joseph

      NO, a 10% blockage is not dangerous , lol

      September 10, 2017 at 20:35 | Report abuse |
  10. Timothy A Gigliotti

    I started having a blockage one night 12 years ago after lifting something extremely heavy on a night job. It took over a month to get in at our local hospital to have a stress test. Then they said I had to have a stent right now or die. They couldn't get through the artery so they took me into surgery. Could only do one By-pass instead of all three they said i needed cause my veins were to small or something. After surgery my Sternum Bone never healed it always moves. I couldn't even do re-hab after 35 days,never did do it. Went back to work in six or eight weeks no more blockage, quit smoking, work 10 hrs a day 6 days a week.Always in pain, don't have any stamina can't stand and hold a gal milk very long. Now the Blockage is there again i feel it some everyday, everytime I lay down and also when i'm up. Sometimes its not as bad as others. 65 yrs old, trying to work until july when SS checks start the another year of full time work with the SS to pay off Bills. I'm scared to tell the doctor cause I can't afford to go back to hospital sick pay isn't enough to cover all the bills. They prob can't fix it anymore anyway. All I can do is trust God to keep me going until it's time for me to go.

    December 7, 2015 at 08:41 | Report abuse | Reply
    • Lawrence Semprevivo MSW

      Mainstream medicine has it all wrong with respect to heart disease. Stents and bi-pass are huge money makers but the wrong approach in all but the most extreme cases. If you want to get well u can. Dr. Esselstein MD cardiologist from the Cleveland Clinic in Ohio wrote a book reversing heart disease. His program has empirical evidence that demonstrates that diet can open occluded arteries and restore heart function and make u completely heart attack proof. There is no need to be butchered and suffer for the profit of Big Pharma and Big medicine. Get his book follow the plan and u will never suffer from heart disease again. Stents and surgery are only temporary fix but the disease process is never addressed. Its all diet.
      Drop the carbs drop the sugar, drop processed foods, forget processed vegetable oils, make the bulk of your diet greens, and veggies berries pastured meats pastured eggs wild caught salmon clean water and stress reduction and exercise and you will never get heart disease again. Dr's promote heart disease as does the American heart Association's recommended diet it will kill. Statins cause systemic arterial calcification, reduction in stem cell production, diabetes, cognitive impairment, loss of cardiac function due to decreased CO Q10 and ATP production. The efficacy of statin use is a statistical manipulation and will only harm u. Save yourself by changing your diet taking targeted supplements like fish oil vitamin K2 D3 alpha lipoic acid, Berberine and Tummeric and your health will quickly return.

      November 15, 2017 at 10:10 | Report abuse |
  11. atul mishra

    sir,my dad had been an angiography few days before doctor said that he needs to go under angioplasty as there is a blockage in ramus. when my dad consulted it with other doctor he said heart is very strong and that blockage is can be depleted by medicine. can you plz suggest me are there any terms of faking or fake can be done in angiography ?

    February 15, 2016 at 03:02 | Report abuse | Reply
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  13. bobbie moncilovich

    I had stints in both my legs, I have pad, I went back to my dr. 5 months later, because I had pain in both legs, now he says I need surgery again, because both legs have severe blockage, even the upper groins, and in my stomach, why did it get that way in five months, I thought the stints would take care of my problems, now I am in severe pain, much worse now than I was before the surgery, please leave me a message and your thoughts on my e mail, thanks

    October 26, 2016 at 03:20 | Report abuse | Reply
  14. Justin

    My father in law had cabg x 8 and he is having some issues and doctors are saying that they can not do anything for him. Is this true??? 10-11 years ago was the surgery.

    March 18, 2017 at 23:41 | Report abuse | Reply
  15. Name*Tina

    My surgeon made a comment after my quad bypass. He said one and done. I have to admit it has stayed with me. I have genetically high cholesterol first being seen in blood tests going back to age 12. My daughter was tested in 7tb grade does as well. I'm a bit fearful. Can you explain one and done?

    April 23, 2017 at 17:40 | Report abuse | Reply
  16. Name*claudia

    My mom had 3 bypass surgery in December and now she's having pain in chest that has been going on since February. It's April and after coming in for chest pain to hospital. They performed an exam that shows a blockage or a non functioning by pass. Dr. says the heart is strong and has blood flow thru other veins. Has anyone had this can something. E done??

    April 29, 2017 at 15:16 | Report abuse | Reply
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  19. Pankaj arora

    Dear sir

    My mother had undergone bypass surgery from max hospital, mohali, india. Now again after 3 months after ct angio it shows 100 percent blockage in one artery and other two are 80 percent block in 3 months time, how it is possible, my mother has hypertension that too controlled and no other diaease also she do not take even a single pinch of salt and fat.
    What should we do know, dr said angioplasty is high risk

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