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Interview with Dr. Michael Conte: Peripheral Artery Disease

Hear a Patient Power interview with Dr. Michael Conte, who talks about the importance of early diagnosis and treatment of peripheral artery disease (PAD). Peripheral artery disease is a progressive narrowing of the blood vessels that affects up to 20 percent of those over age 55. Diabetics in particular are two to four times more likely to develop the condition. Still, it is under diagnosed and under treated, leading to limb amputation, heart attack and stroke.

Interview Transcript

Introduction

Andrew Schorr:

Hello and welcome to Patient Power. I'm Andrew Schorr. This is where we tackle significant medical topics with leading experts from UCSF Medical Center. One of the conditions that affects so many millions, maybe 23 million Americans and many millions more around the world, is diabetes. Now people know you want to control your blood sugar, and they may know that you're at higher risk for heart problems and even stroke, but of course another condition that can go with it is diabetic neuropathy, circulation problems, and certainly peripheral artery disease, and we're going to learn more about that with Dr. Michael Conte, who is chief of Vascular and Endovascular Surgery at the UCSF Heart and Vascular Center.

Dr. Conte led the largest multi-center clinical trial to date examining the outcomes of leg bypass surgery in patients with severe peripheral artery disease, and we're also going to learn about the whole range of treatments and evaluation that's so important for people with diabetes.

Dr. Conte, thank you so much for being with us. Let's talk about diabetes. People may know that they're at risk for problems in their feet, but they may not understand the risks related to peripheral artery disease for diabetics and also how it could even be a signal that they have even life-threatening conditions that could be developing. Help us understand that.

Dr. Michael Conte:

Sure Andrew. Diabetes and smoking are the two strongest risk factors for peripheral artery disease. I think it's widely understood that patients with diabetes are at increased risk for heart disease and stroke, and require close monitoring on that basis.

Peripheral artery disease (PAD) occurs as a result of blockages in the arteries in the leg. This disease is seen in a high percentage of patients with diabetes, perhaps as other risk factors like smoking, diabetes puts patients at particularly increased risk for PAD and its most severe complication, which is loss of the limb. All patients with risk factors such as diabetes need to be aware of the importance of PAD.

Diagnosing Peripheral Artery Disease

Andrew Schorr:

What are the signs of this, and are some people in a situation where it's developing but they don't even know it?

Dr. Michael Conte:

In general most patients with PAD do not have symptoms, at least initially. That is, one can develop blockages in the arteries of the leg but until they reach a very critical level you may not have any signs or symptoms whatsoever. The earliest symptom of PAD is often that of pain or fatigue when walking. The pain can be in the calf muscle or in the thigh muscle, and is called claudication, and that is one of the cardinal signs of early PAD.

When the disease progresses to involve more arteries farther down the leg, then the symptoms can be more severe, such as pain in the foot, the development of ulcerations, or advanced changes such as gangrene in the toes. These developments imply that the foot is in danger if something is not done to increase blood flow. This more serious stage is far less common, but indicates an urgent situation.

Andrew Schorr:

Are there simple ways where a doctor can check to see if someone's at risk for this or maybe that it's developing even if there are no symptoms?

Dr. Michael Conte:

Yes, most definitely we can make the diagnosis of PAD in the office 90 percent of the time with very simple physical examination and testing. First of all, patients who are at increased risk for PAD, and that includes all patients with diabetes, as well as people who smoke, the elderly, and those with known heart disease should undergo a complete vascular examination.

The basic examination includes feeling of pulses in the leg all the way down to the foot and examination of the feet. The simple and most reliable test beyond that is to use a hand-held ultrasound instrument called a Doppler, and measure the pressure in the ankle in comparison to the pressure in the arm. That test is called an ankle-brachial index or ABI. The ABI, although it does have some areas where it's in error, is considered the best and simplest test to make a rapid screen for PAD.

Andrew Schorr:

Dr. Conte, some people who develop PAD are maybe older patients, and they may say, "Well it's more difficult to walk" or "I get this fatigue" or "I get this pain in my leg or thighs when I walk because I'm getting older." And they just kind of discount it and don't go further, but they could be risking much more serious events couldn't they?

Dr. Michael Conte:

That's an excellent point Andrew. The importance of making the diagnosis of PAD is two-fold.

First and most importantly, it's because making the diagnosis of PAD may be the first sign that a patient has atherosclerosis in their bodies. Because PAD is strongly associated with heart disease and stroke, these patients need to be treated aggressively from a medical standpoint to avoid cardiovascular complications like heart attack and stroke. So the implications are much greater than just the leg itself. In fact the risk to the leg is really not that high overall for the population with PAD, but the diagnosis does imply a significant amount of cardiovascular disease.

The second reason to make the diagnosis of PAD is to monitor people and treat them in a timely and aggressive fashion to avoid progressive loss of function in the leg, or worst case to avoid amputation. Making the diagnosis of PAD does not necessarily mean that a procedure needs to be done in the leg at that time. What it does mean is that those patients and their limbs need to be watched much more closely over time.

Andrew Schorr:

There are a couple of points I wanted to underscore from that. One is someone may have a fear if they're seeing changes in their leg or problems and if they know maybe somebody previously with diabetes they say, "Oh my god I am risking amputation" and they just don't want to go there and so they don't get the early care, but as you were saying that's usually not the case. If you can get early intervention, you're not risking the loss of a limb and there are many interventions that can be explored, right?

Dr. Michael Conte:

Yes absolutely. All of us who take care of diabetic patients and patients with PAD know that amputation is one of the greatest fears. Amputation is far more common in diabetic patients in general not only because of their vascular disease but also because they can get peripheral neuropathy which affects nerve function.

Neuropathy by itself can lead to the development of sores in the feet that can ultimately lead to infection and amputation. So diabetic patients are at increased risk for amputation, and it's a justifiable fear. What we want to do with education is avoid having patients turn that fear into denial to seek out appropriate therapy. What most of these patients really require is just good foot care, very careful attention to their medical risk factors, avoidance of smoking, certain simple measures to avoid problems with their feet and close monitoring, and with these basic measures we can very likely make a strong impact on avoiding amputation.

The other key point is that there are multiple types of treatments available when the disease gets more severe in the leg. Making the right judgment about picking the right treatment at the right time is really the best way to preserve function long term. However avoiding treatment altogether often unfortunately results in patients showing up too late, with a situation that becomes harder to salvage.

Treatment Options and Research

Andrew Schorr:

So that brings us to the UCSF Heart and Vascular Center story. You have a multidisciplinary team there. You're a vascular surgeon. You have cardiovascular specialists of all types who all work together to try to determine what's right for Mrs. Smith or Mr. Jones and their individual situations over time. Tell us about the benefit of that. You're also a research institution, and I know as we said at the outset, you led a multicenter trial about the research and how that could apply to somebody with this condition.

Dr. Michael Conte:

Sure. We just mentioned that for many patients with PAD simply making the diagnosis, monitoring, and instituting appropriate medical therapy is really all that's required. So many patients with PAD, diabetic or not, need to just be put on the right program of modifying their risk factors, using appropriate targets for their sugar and for their cholesterol, which by the way are now being increasingly made lower, and the drugs are very effective, and appropriate foot care and shoes. That's really what we do for a large percentage of patients.

One of the misconceptions is that if I have a blocked artery in my leg, it has to be opened, and that's not the case. We don't treat patients based on their arteries. We treat them based on their symptoms and how it affects their overall level of function. There are many, many treatment options now that involve less invasive approaches using catheters such as balloons and stents and lasers and other devices that can clean out plaque. In the right patient, they can be effective at improving leg function, but I would say that there are more procedures than there is evidence to support where and how they should be used and how effective and durable they are.

That's why it's really important to have a multidisciplinary team with specialists who are experienced, competent, and have good judgment and are able to offer a variety of these approaches. The best decision, we feel, is made by a combined team approach and by taking into account, not just the immediate outcome, but the best chance at preserving the leg for the patient's life. This requires careful selection of the procedure and timing.

The most effective and durable treatment — when a patient's blockages are severe enough to warrant doing something — is surgery, to perform a bypass around the blocked artery. This tends to be the longest lasting and provide the greatest amount of increased circulation in the foot. However, it is an operation that does have some risk up front, and even bypass surgery done with a patient's veins, which is the best material to use, can fail over time.

Use of balloons and stents and other procedures offer a less-invasive approach, but it has a much higher rate of failure; as many as fifty-percent of these may fail within the first one to two years.

The point is that all of these procedures have some failure rate over time. One of the key areas of research is to avoid or reduce scar tissue that can build up, that can result in re-narrowing of the vessels, the problem that we call restenosis. That is something we are researching to develop new drugs that can be applied to stents or balloons or to the veins themselves to reduce the scar tissue that forms after the procedure and enable a higher percentage of these to stay open for five to 10 years or longer as long as the patients need them.

By the way, patients with cardiovascular disease are living longer in general, and so maintaining the long-term outcome of these procedures becomes even more important. Needing a repeat procedure is often a harder thing for the patient to go through. So preventing the scar tissue, the restenosis, is a No. 1 scientific problem that we are working on here at UCSF.

The second area is there are patients who just don't have good options because the disease is so severe in their leg that they're essentially running out of arteries. They can't be reopened with catheters, and there's nothing left to bypass to, or they don't have a vein available to use for a bypass in the leg. In those cases, the avenues that are being developed are to try to encourage the body to develop its own alternative blood vessels in a more rapid fashion. All of us will develop what's called collateral vessels in our legs if we develop blockages, but they may not be adequate. Researchers here and at other places have been exploring a variety of ways to encourage this so-called angiogenesis process and its companion process, which is arteriogenesis, the development of larger vessels to reroute blood flow around the leg.

This area of research is a little bit early in its timeline to reach clinical fruition but is a very active area of research.

Finally, the last area which affects the PAD patient is to somehow create better materials to use for bypasses when patients don't have veins. The currently available artificial grafts do not really work very effectively when we have to do these operations to the smaller vessels down the leg and down into the ankle and foot area. There is continued need for developing alternative materials to work with, and that's a final area of important research here.

Andrew Schorr:

Dr. Conte, as I listen to this as a lay person I'm impressed with the fact that if somebody in my family has diabetes I'm going to insist that they get evaluated to see how their circulation is to their extremities and their legs, and if there is some indication there or if they're having any symptoms but even before that that we get it dealt with early. I'm also impressed with the fact that at the UCSF Heart and Vascular Center, your team approach, may be very right on target for someone not only today but with your research and your variety of procedures and how they're developing over time. So it makes a lot of sense to me, and I know you have a concern personally about how in diabetics this condition is underdiagnosed, so I hope wherever people are listening they get checked for it and get the appropriate care.

Dr. Michael Conte:

Yes, I think I would like to leave off with that message, that this is a disease with complications that can often be prevented by early recognition and the appropriate use of aggressive strategies in a timely fashion. Many patients do not require aggressive or invasive procedures, but when they do cross that threshold then picking the right procedure and doing it early is the best way to avoid the endpoints that we don't want to see.

Andrew Schorr:

Dr. Michael Conte, thank you so much for being with us, chief of Vascular Surgery at the UCSF Heart and Vascular Center, and for our listeners if you want to get more information about Dr. Conte, the whole group there, related to PAD and treatment for diabetes and many other conditions, call the UCSF Physician Referral Line, and that is (888) 689-UCSF (888-689-8273). I'm Andrew Schorr. You've been listening to Patient Power brought to you by UCSF Medical Center.

Recorded January 2009

 

Reviewed by health care specialists at UCSF Medical Center.

This information is for educational purposes only and is not intended to replace the advice of your doctor or health care provider. We encourage you to discuss with your doctor any questions or concerns you may have.

Related Information

UCSF Clinics & Centers

Heart & Vascular Center

Vascular & Endovascular Surgery
400 Parnassus Ave., Suite A-6110
San Francisco, CA 94143
Phone: (415) 353-2357
Fax: (415) 353-2669

Vascular Laboratories at Parnassus
505 Parnassus Ave., Eighth Floor, Room M-830A
San Francisco, CA 94143
Phone: (415) 353-1286
Fax: (415) 353-8706

Limb Preservation Center
400 Parnassus Ave., Room A-6110
San Francisco, CA 94143
Phone: (415) 353-2357
Fax: (415) 353-2669

Key Treatments