Atherosclerosis

Atherosclerosis, an inflammatory process that causes narrowings in many of our arteries. These narrowings are known as plaques. The main risk factors for atherosclerosis are smoking, high blood pressure, high cholesterol, and diabetes. Atherosclerotic plaques can progressively restrict blood flow to downstream vascular territories, which leads to various symptoms depending on the vascular territory that is affected. Occasionally a blood clot can form on an atherosclerotic plaque, or the plaque itself can break down, sending showers of particles downstream that may cause sudden blockages in small branches of the artery affected. A plaque may progress to a complete blockage of the artery affected. Atherosclerosis is also sometimes called arteriosclerosis.

Aneurysms

Aneurysms, dilations of blood vessels that also result from inflammation in the wall of the affected blood vessel. The inflammation causes the wall of an artery to become weak, so it starts to dilate under the arterial pressure. Dilatation further increases the tension in the wall of the artery, and if the artery dilates enough, the artery can eventually rupture if it is not treated. Aneurysms most commonly affected the aorta but can affect the lower extremity arteries, carotid arteries, and branches of the aorta such as the renal arteries and splenic artery. Risk factors for aneurysms included smoking, high blood pressure, and high cholesterol.

Dissections

Dissections, a condition whereby the layers of the wall of an artery suddenly separate, such that the inner two layers pull away from the outer layer. This can occasionally lead to rupture of an artery but more commonly leads to compromise of blood flow in the artery affected, or in a downstream branch. Dissections most commonly affect the aorta but can affect other arteries. They most frequently occur spontaneously in patients with severe hypertension, but can occur as a result of blunt or penetrating trauma. Dissections can also present as a bruise in the wall of the artery known as an intramural hematoma, or as a penetrating ulcer.

Carotid Artery Atherosclerosis

The carotid arteries are located in the neck and they provide blood flow to the brain and face. By far the most common condition of the carotid arteries that we treat is a buildup of atherosclerotic plaque that occurs in the common carotid artery just below the jaw, where it divides into the internal carotid artery (a straight pipe that goes to your brain) and the external carotid artery (a pipe with many branches that takes blood flow to your face and scalp). This plaque buildup can lead to stroke if the plaque breaks down and parts of the plaque, or small blood clots that may form on the surface of it, travel up the internal carotid artery and plug secondary branches in the brain. “Hard” symptoms of stroke may include loss of vision in an eye, inability to form words or understand people speaking to you, drooping of one side of the face, or weakness of an arm or a leg. “Soft” symptoms include numbness or tingling in parts of the body, balance disturbances, or falls. Sometimes a patient may experience temporary symptoms lasting only a few minutes or hours as a result of very small particles from the plaque traveling to the brain and causing temporary spasm of secondary branches, that briefly affects the function of the part of the brain supplied by these branches. This condition is called a transient ischemic attack, or TIA. The main predictors of risk of stroke or TIA from a carotid plaque included the degree of narrowing (also called stenosis), the presence or absence of symptoms at the time of presentation, the presence of ulcers in the plaque, and the presence of bilateral carotid disease. If a patient has symptoms at the time of presentation, that person is at much higher risk of having a stroke than a person with a comparable plaque but no symptoms. This makes sense since the plaque is starting to become unstable.

Carotid Plaques

Carotid plaques are most commonly treated with an operation called a carotid artery endarterectomy (CEA). Most of these operations are performed by vascular surgeons but they may be performed by neurosurgeons, cardiac surgeons, and general surgeons. A CEA may be performed under local or general anesthesia, with equivalent results. An incision is made in the neck, the artery is opened after it is clamped, the plaque is cleaned out, and the artery is closed again, usually with a patch of prosthetic material so it is less likely to narrow again in the future. A tube called a shunt is usually placed in the carotid artery so that blood keeps flowing through the artery while the artery is being worked on. Studies have shown that outcomes are better with surgeons who have specialized training in this operation and who perform high volumes of carotid surgery. Risks of CEA include stroke, heart attack, bleeding, or injury to nerves supplying innervation to the tongue, voice box, muscles around the mouth, or the esophagus. The incidence of these complication is usually less than 5% and the risk of death (usually from a major heart attack or stroke) is approximately 1%. CEA is approved for treating both symptomatic and asymptomatic carotid blockages, providing certain conditions are met – not all patients with carotid stenosis benefit from CEA. The first CEA was performed in 1954 and over 100,000 CEAs are performed annually in the US. Most patients spend one night in hospital and can return to normal activities only a few days later. The wound is typically not very painful and can frequently be hidden in a skin crease, so that it is not even noticeable by others.

Another technique that may be used to treat carotid plaques is a technique called carotid stenting, where a cylinder made of wire mesh called a stent is placed inside the carotid artery, usually through a puncture in an artery in the groin. Carotid stenting is advantageous in certain situations such as prior carotid surgery or prior neck surgery, prior neck irradiation, or severe cardiac disease. However, most studies show the risk of carotid stenting is significantly higher compared to CEA, and as a result carotid stenting is not approved for treating asymptomatic carotid stenosis. As with CEA, not all patients with carotid stenosis benefit from carotid stenting.

Aortic Aneurysms and Dissections

Aneurysms are caused by weakening of arterial walls that result in dilation of the artery. The main risk factors for aneurysms are smoking, high blood pressure and high cholesterol. The most commonly affected artery is the abdominal aorta, but aneurysms can affect the thoracic aorta, the renal and mesenteric arteries, the lower extremity arteries, the carotid arteries in the neck and intracranial arteries. As an artery dilates, the tension in the wall of the artery increases. This can lead to rupture of the artery. In the case of abdominal aortic aneurysms, this risk starts to become significant when the diameter of the aorta approaches 5 cm (2 inches); the normal diameter of the abdominal aorta is 2-2.5 cm. Aneurysms may be found on physical exam or on screening tests such as an aortic ultrasound or a CT scan. An ultrasound is the preferred test to diagnose and follow aneurysms since it is an inexpensive, reliable, and completely noninvasive test. CT scans are typically used in patients who cannot be imaged adequately with ultrasound, or in whom treatment is planned since ultrasound does not give enough detail about a patient’s anatomy to plan intervention.

Approximately 30,000 abdominal aortic aneurysm repairs are performed each year in the US. Most of these are now performed with a minimally invasive procedure called an endovascular repair, using a device called an aortic stent graft. A stent graft is a wire cylinder covered with a water-proof fabric that comes “shrink wrapped” on a flexible pole that is introduced into the aorta over a wire from the arteries in the groins, which are accessed with small incisions or sometimes just punctures. The device comes in several pieces that are assembled inside the aneurysm, under guidance with an X-ray machine called a flouroscope. Once in place, blood flows through the device and pressure is taken off the aneurysm. Patients usually spend one night in hospital. After discharge they have no limitations, but may have some groin pain or leg swelling. This technology is FDA approved and has been available since 1999. Approximately a dozen companies make aortic stent grafts that are available for use in the US.

Not all patients with abdominal aortic aneurysms are candidates for standard endovascular repair. In most cases this is due to the patient’s anatomy, where the aneurysm extends too close to other im-portant branches, such as those providing blood flow to the kidneys (renal arteries) or pelvis (iliac arteries). In some cases where the aneurysm extends very close to the renal arteries, the AAA may still be repaired with an advanced endovascular procedure using a device called a fenestrated stent graft. This device has a custom made component that allows the endovascular repair to include the portion of the aorta that involves the renal arteries. Separate stent grafts are placed in the arteries providing blood flow to the kidneys or other abdominal organs as required, through specially designed openings in the sides of the main aortic component. Only one company currently has a device approved for use in the US. This procedure is available through Advanced Vascular Therapy, LLC.

CT and intraoperative angiogram of patient with juxtarenal aneurysm treated with fenestrated stent graf

Most patients who are not candidates for endovascular repair are still candidates for open surgical repair. Excellent results can still be expected but the complication rates, as well as the length of stay and recovery period are longer. At Advanced Vascular Therapy, we have extensive experience with open AAA repair and can offer this treatment to patients who do not qualify for endovascular repair.

Aortic dissections usually involve the thoracic aorta, or the part of the aorta in the chest. Dissections commonly start at a site called an entry tear, where the inner 2 layers of the wall of the aorta pull away from the outer layer. The entry tear is usually located just above the heart in the ascending aorta, or just beyond the branch that goes to the left arm (the left subclavian artery), in the descending aorta. Most dissections of the ascending aorta require urgent open surgery by cardiac surgeons. Most dissections of the descending aorta can be managed medically with strict blood pressure control, but if medical treatment fails they can often be treated with stent grafts designed specially for the thoracic aorta. The first thoracic aortic stent grafts become available in 2007. At least four companies make FDA approved thoracic stent grafts. These devices can also used to treat aneurysms of the descending thoracic aorta. These procedures are also available at Advanced Vascular Therapy, LLC.

Mesenteric Artery Disease

The abdominal organs get their arterial supply from three main arteries, called the celiac artery, the superior mesenteric artery, and the inferior mesenteric artery. The celiac artery provides blood flow to the liver, the stomach and the spleen. The superior mesenteric artery provides blood flow to the small bowel and approximately two-thirds of the colon. The inferior mesenteric artery provides blood flow to the distal third of the colon. If blockages form in these arteries, particularly the superior mesenteric artery, patients may develop abdominal pain after eating, when the demand for blood flow goes up to help the gut digest the food and transport the resulting products to the liver. If there are blockages in these arteries, they may not meet this increased demand. Lactic acid can build up and irritate the nerves, resulting in abdominal pain. This process is very similar to what happens when cardiac patients develop chest pain due to inadequate blood flow in the coronary arteries, so it is often called intestinal angina but clinicians usually refer to it as mesenteric ischemia. The abdominal pain can lead to food avoidance and significant weight loss. Untreated, the bowel may eventually lose its blood supply and die, a condition that can lead to emergency abdominal surgery and death.

Mesenteric ischemia is frequently diagnosed late, or not at all until patients present with an acute abdominal catastrophe. It is a diagnoses that even gastroenterologists may fail to consider when evaluating patients for abdominal pain. If you have chronic abdominal, you should make sure this diagnosis has been considered by your treating physicians. Blockages of the mesenteric arteries can be detected with a duplex ultrasound, but this is a very difficult study to do and should be performed by an experienced vascular sonographer in a dedicated vascular lab.

Narrowings or stenoses of the mesenteric arteries can usually be treated with catheter based interventions with good results. Complete blockages, on the other hand, usually must be treated with a major surgical operation, either a bypass or endartectomy. Therefore it is ideal to identify and treat symptomatic disease as early as possible, while the plaque is only causing a narrowing and not a complete blockage. Here at Advanced Vascular Therapy, LLC we have the expertise to perform both catheter based and surgical interventions for symptomatic mesenteric artery occlusive disease. There is no indication to treat asymptomatic blockages that are identified incidentally on diagnostic studies. Other causes of abdominal pain should be ruled out, preferably by a gastroenterologist, before an intervention is performed on mesenteric artery occlusive disease.

Angiogram of symptomatic stenosis of superior mesenteric artery, stented in the office with complete relief of symptoms.

Renal Artery Disease

The most common problem affecting the renal arteries is atherosclerosis causing renal artery stenosis. Mild or even moderate stenoses usually are asymptomatic and do not need treatment. High grade renal artery stenoses can result in high blood pressure that may be resistant to treatment with medications. High grade stenoses may also result in progressive loss of kidney function and even total loss of a kidney if the stenosis progresses to a complete occlusion. Renal artery stenoses are frequently treated with stents in a safe outpatient procedure. Recurrent or complicated renal artery disease may need to be treated surgically. Examples of more complicated renal artery disease are fibromuscular dysplasia and renal artery aneurysms.

Left Renal Artery Stint

Angiogram of left renal artery stenting performed in the office for renovascular hypertension

Lower Extremity Arterial Disease

Lower extremity arterial disease is a very common clinical problem that is frequently undiagnosed or under-diagnosed. Symptoms result from insufficient blood flow to the legs as a consequence of narrowings or complete blockages that can form in arteries in the abdomen, pelvis, or the legs. These narrowings result from atherosclerotic plaques that build up in the arterial wall. The main risk factor for these blockages are smoking, high blood pressure, high cholesterol, and diabetes. Symptoms may vary depending on the location of the blockage or blockages. If the blockages occur in the abdomen or pelvis, patients may present with crampy pain in the buttocks or hips, and men may experience erectile dysfunction. If the blockages occur in the leg, patients usually experience crampy pain or early fatigue in the muscles in the calf or thigh. This symptom is called claudication. Patients initially experience claudication when walking long distances but it will gradually occur at shorter and shorter distances as the disease progresses. Untreated, symptoms may progress to more serious situations where patients experience pain at rest, or develop ulcers or even gangrene. These more serious symptoms are known as critical limb ischemia or CLI. CLI is more common in patients with diabetes, and who have blockages in the arteries in the lower leg, called the tibial arteries. Untreated, these symptoms may lead to amputation. All diabetics with foot ulcers should have arterial testing, if not a consult with a vascular surgeon.

Abnormal blood flow can be detected with simple noninvasive screening test, starting with a physiologic arterial study where the blood pressure is measured in the legs and compared to the best blood pressure in the arms to generate a ratio called an ankle brachial index or ABI. A normal ABI is at least 0.9. People with CLI will usually have an ABI of 0.4 or less. Sometimes people will have partial blockages that are well compensated, and the ankle brachial index will be normal at rest, but become abnormal if patients are asked to exercise, similar to a stress test for coronary disease in cardiac patents. If the resting or post-exercise ABI is abnormal, further testing is indicated. This usually begins with a special ultrasound of the arteries called a duplex ultrasound. This test is performed in diagnostic labs that are dedicated to treating arterial disease. A skilled sonographer can identify the location and extent of most arterial blockages, which a treating physician can use to make treatment decisions. This test may be followed by an arteriogram or a CT scan.

Treatment for claudication begins with conservative treatment including risk factor modification and exercise. Risk factor modification includes quitting smoking, as well as controlling blood pressure, cholesterol, and blood sugars. These actions are the most important part of controlling peripheral artery disease. Aggressive exercise can sometimes result in dramatic improvement in the distance people can go before they claudicate, much like an athlete can train to go farther distances. However many people have other medical problems such as heart disease, lung disease, or joint problems that prevent them from aggressively exercising. It can take several months to see results and if patients stop exercising, their symptoms return.
Pharmacologic treatment is also available. Two drugs are approved by the FDA, Trental and Pletal, but Trental has been shown to be no better than a placebo so should not be prescribed. Pletal may help but is expensive and has frequent side effects such as headache or nausea. In addition, it must be taken twice a day and many claudicants are already on a lot of other medicines so they have little interest in adding another medication to their list. Most patients with claudication are candidates for drug therapy but compliance is an issue and treatment failures are common.

When conservatives measure fail, most patients are eligible for a procedure where their blockages can be corrected with a minimally invasive, catheter based intervention. Treatment may involve a combination of techniques including balloon angioplasty, stenting, or atherectomy. Angioplasty is where a balloon is inflated inside a blockage. Stenting is where a wire cylinder is placed inside a blockage to keep it propped open. Atherectomy involves debulking plaque with one of several types of devices such as a drill, a laser, or a scraper. These procedures are typically outpatient procedures. At Advanced Vascular Therapy, LLC we offer these interventions right here in the office in a clean, pleasant, professional environment. Most blockages can be successfully opened but blockages can return after a few years or even less, as a result of inflammation that occurs in the arterial wall in response to the intervention. This inflammation is especially likely to recur if patients continue to smoke and do not comply with medical therapy. Much research is being devoted to prolonging the life span of these interventions, and results are improving all the time. Examples of recent innovations include drug-coated balloons and stents which expose the arterial wall to anti-cancer drugs that suppress inflammation in the artery. Dissolvable stents are also being developed.

Sometimes a blockage is too extensive to be treated with catheter based interventions, or a recurrent blockage is not treatable with additional catheter based interventions. In these instances a patient may by eligible for a procedure such as an endarterectomy or a bypass. An endarterectomy is a procedure where a plaque is physically removed from an artery. A commonly performed endarterectomy is on the femoral artery in the groin. Many different bypasses are performed depending on the location of the blockage that needs to be bypassed. Examples including aorto-femoral bypass, axilla-femoral bypass, iliofemoral bypass, femoral-femoral bypass, femoral-popliteal bypass, femoral-tibial bypass, and popliteal-tibial bypass. Bypasses can be performed with prosthetic materials or a vein harvested from the patient, typically a superficial vein in the leg called the greater saphenous vein.

Angiogram showing complete occlusion of left iliac artery stented in the office with complete relief of claudication.

Angiogram of patient with critical limb ischemia due to distal occlusion of popliteal artery and single vessel reconstitution of the anterior tibial artery, treated successfully in office with atherectomy and angioplasty.