Feature

DISEASES OF THE BLOOD VESSELS OF
THE HEART

Nicolas W. Shammas, MS, MD, FACC, FACP
Nicolas W. Shammas, MS, MD, FACC, FACP
LEARN ABOUT YOUR HEART...MADE SIMPLE 19 How does the heart receive its blood supply? The heart is a pump that continuously beats at 60 to 100 beats per minute during the life of a person.This pump requires oxygen and nutrients to achieve its tasks.These are delivered to the heart via blood vessels called the coronary arteries (see Figure 1). There are 3 or 4 major coronary arteries that deliver blood to the heart.These supply the top (left anterior descending artery), the side (left circumflex artery), and the bottom (right coronary artery) of the heart.Any interruption of blood supply to any of those coronary arteries can lead to heart damage to a correspondent part of the heart muscle. How do the coronary arteries fill with plaque and become obstructed? The coronary arteries are covered on the inside by a lining called the endothelium, a single layer of cells that covers every single blood vessel in our body. It has been estimated that if this DISEASES OF THE BLOOD VESSELS OF THE HEART Nicolas W. Shammas, MS, MD, FACC, FACP C H A P T E R 3 Left Main Coronary Artery Circumflex Artery Left Anterior Descending Artery Right Coronary Artery Figure 1. Heart with major coronary arteries. Chapter03Shammas.qxd 10/27/05 5:29 PM Page 19 20 LEARN ABOUT YOUR HEART...MADE SIMPLE DISEASES OF THE BLOOD VESSELS OF THE HEART lining of all the blood vessels from a single individual is spread on a flat surface, it could cover 2 tennis courts in size.This single layer of cells, however, separates the blood vessels from health and disease. Any damage to the endothelium can lead to its invasion by blood elements called monocytes. These monocytes penetrate under the lining of those blood vessels and absorb fat from the bloodstream.They become enlarged in size and are called foam cells. These foam cells promote a complex reaction under the endothelium, which subsequently causes inflammation and attracts various other cells to the plaque area. The plaque expands and starts to impinge on the opening of the blood vessels that supply the heart (see Figure 2). It is well known that the process of plaque formation starts very early in childhood. Autopsies on young soldiers who died in wars have shown that the blood vessels of their bodies already show the buildup of fat under the endothelium. Over twothirds of people over the age of 40 show the buildup of plaque in the blood vessels that supply their heart, as seen by ultrasound scanning of those blood vessels. What is angina? Angina is a symptom of chest pain—also described as chest pressure, a heavy feeling in the chest, or a squeezing sensation in the chest—that is caused by a lack of blood supply to a part of the heart muscle.Angina is described as either stable or unstable. A narrowing in 1 of the blood vessels of the heart by plaque Intima Layer Adventitia Media Layer Plaque Blockage Figure 2. Artery with plaque buildup. Chapter03Shammas.qxd 10/27/05 5:29 PM Page 20 LEARN ABOUT YOUR HEART...MADE SIMPLE 21 DISEASES OF THE BLOOD VESSELS OF THE HEART buildup causes stable angina. Stable angina occurs when a person is active and doing physical exertion. It typically resolves within two to three minutes of resting.This type of angina does not occur at rest. As a person becomes active and exerts himself or herself, the heart has to pump faster and stronger.With the increase in the heart rate, there is a need to increase the blood supply to the heart to continue to match its demands. If plaque buildup is severe enough to narrow the coronary arteries, the blood supply to the heart cannot increase at the rate needed by the heart. A mismatch of demand and blood supply occurs.This generates discomfort in the heart—angina. Once the patient rests and the demands of the heart for blood supply returns to normal, the pain resolves. In contrast to stable angina, a rupture of the plaque inside the blood vessels causes unstable angina. This leads to a subsequent accumulation of a clot at the area of the plaque rupture, which abruptly interrupts the blood supply to the heart. Angina then occurs with very minimal activity or at rest. This type of angina requires immediate medical attention. How does the patient perceive angina? Angina is perceived as chest pressure, tightness, a squeeze, or heaviness in the chest.This could radiate to the arm and the jaw, the shoulders, the back, or the abdomen.The pain can be associated with an increase in shortness of breath, a feeling of nausea, and occasional vomiting. Also, patients break out in a sweat, which is called diaphoresis. Lightheadedness and anxiety accompany these symptoms. Patients might describe 1 or more of these symptoms, without any chest discomfort on many occasions. Women and people with diabetes tend to present with atypical symptoms without chest pain. What should you do if you experience chest pain or other symptoms of angina? If you experience chest pain or any of the previously described symptoms, it is important that you not attempt to self-diagnose. In this situation, it is very important to seek immediate medical attention. If the pain occurs at rest, this is essentially an emergency and driving to the hospital or having someone drive you Chapter03Shammas.qxd 10/27/05 5:29 PM Page 21 22 LEARN ABOUT YOUR HEART...MADE SIMPLE DISEASES OF THE BLOOD VESSELS OF THE HEART can be very dangerous.The best way to deal with your rest angina is to call 9-1-1 and allow paramedics to transport you to the hospital. The first hour of the onset of chest discomfort is the most dangerous. Electrical disturbances in the heart can occur, and the heart could cease pumping blood to the brain and the vital organs of the body. This can be corrected easily if you are being transported to the hospital with trained professionals. However, sudden cardiac death can occur if you are still at home or you are in a regular car on your way to the hospital. A sudden change in symptoms—such as the occurrence of nausea or vomiting, sudden worsening of breathing, or the occurrence of chest pain—warrants immediate hospital evaluation. If chest pain or the anginal symptoms have been occurring primarily with exertion or activity but never at rest, this tends to be somewhat less of an emergency. However, evaluation should be performed relatively soon. Calling your doctor and getting evaluated relatively soon is important. The symptoms of pain with exertion are classic anginal symptoms, and they have a high chance of being related to obstructive plaque in the coronary arteries. How does a patient die from a heart attack? The most common cause of death from heart attack is electrical instability to the heart. Once the blood supply is interrupted, the electrical conduction inside the heart becomes disturbed. Abnormal electrical circuits are generated in the bottom chambers of the heart. These lead to quivering of the heart muscle. The heart muscle becomes inefficient in pumping blood. These arrhythmias are called ventricular tachycardia or ventricular fibrillation.The blood will be able to generate minimal to no blood supply to the vital organs of the body, including the brain. A person loses consciousness usually within 5 to 10 seconds of the occurrence of this event. Death occurs if the electrical system of the heart is not restored back to its normal condition within 5 to 6 minutes of the electrical disturbance. Rarely, heart failure resulting from the heart attack leads to death. By far, the majority of deaths are related to this electrical instability. Paramedics and hospitals are equipped with machines called defibrillators that are capable of aborting those electrical Chapter03Shammas.qxd 10/27/05 5:29 PM Page 22 LEARN ABOUT YOUR HEART...MADE SIMPLE 23 DISEASES OF THE BLOOD VESSELS OF THE HEART heart rhythms by delivering an electrical shock to the chest. Automatic external defibrillators are now widely placed in public places, such as airports, schools, and large business centers. Operation Heartbeat, a program of the American Heart Association, has intended to extend the use of automatic external defibrillators in public places in order to save lives of heart attack victims. Cardiopulmonary resuscitation (CPR), which includes artificial respiration and chest compression, can sustain enough blood circulation for the first 10 minutes after the electrical instability has occurred. However, without the more definitive therapy of defibrillation using the defibrillator, CPR alone is inadequate to restore a normal heart rhythm. In fact, survival rate after 6 minutes of the arrhythmia is slim despite CPR and without defibrillation. What does my doctor do when I come to the emergency room with chest pain? Your doctor will evaluate you with a full history and physical exam. Details of the chest pain, such as its onset, severity, radiation, and association with other symptoms or with activity, will all be important information to provide.A physical exam to listen to your lungs and heart will be important. Based on all the information gathered, including blood testing, your physician will attempt to determine whether your symptoms could be related to your heart or are noncardiac in origin. If it is a possibility that these symptoms are heart-related, you will be asked to stay in the hospital. Many hospitals have a chest pain unit where you will be observed for several hours on a monitor. Serial blood testing will be obtained to rule out the possibility of heart injury. An electrocardiogram also will be obtained. Eventually, if all your tests are unremarkable, a stress test will be performed. All these tests will help your doctor decide whether to admit you to the hospital for further testing, such as a coronary angiogram. On the other hand, if your chest pain has occurred at rest and continues to do so in the emergency room, your doctor will have to assume that this is an unstable anginal symptom. You will then be directly admitted to the hospital and placed on Chapter03Shammas.qxd 10/27/05 5:29 PM Page 23 24 LEARN ABOUT YOUR HEART...MADE SIMPLE DISEASES OF THE BLOOD VESSELS OF THE HEART medical treatment. If the suspicion for cardiac-related symptoms is high, your doctor might proceed directly with an angiogram. What is a cardiac catheterization or a coronary angiogram? A cardiac catheterization is essentially the same as a coronary angiogram.This procedure is performed in the cardiac catheterization laboratory. During this procedure, a small plastic tube is inserted in the blood vessel in the groin, called the common femoral artery.This small plastic tube or catheter is placed under a local anesthetic.Through this catheter, plastic tubes are placed inside the blood vessels under x-ray guidance. These go to the heart, where a contrast dye is injected.The dye is injected directly in the heart’s chamber as well as in the blood vessels of your heart. As the dye is being injected in those blood vessels, a camera takes multiple pictures of your heart, which will allow your physician to see your coronary arteries and determine the location of the blockages, if present. The angiogram is considered an invasive procedure. It carries some risks with it.These risks vary depending on the condition of the patient.Patients with heart failure and reduced heart function, diabetes, or kidney problems tend to be at exceptionally high risk. Patients with previous history of heart attacks, strokes, and blockages in the blood vessels of the legs are also at higher risk. However, the overall risks of the procedure remain small. In a non-emergent angiogram, the risk of death should be less than 1 in 1,000, risk of strokes 1 in 500, and the risk of major bleeding from the insertion site of the catheter should be less than 1%. Obviously, these risks also vary if the angiogram is only for diagnostic purposes to identify the location of the blockage or for treatment purposes to treat the blockage. During the treatment of blockages, large amounts of blood thinners are administered, which increases the risk of bleeding and complications. Other risks of the angiogram also include infection, damage to the nerves in the groin area, damage to the arteries of the heart themselves, as well as the aorta, the main artery that comes out of the heart and supplies blood to the rest of the body.Your doctor will weigh carefully all those risks compared to the potential benefits of the test. Chapter03Shammas.qxd 10/27/05 5:29 PM Page 24 LEARN ABOUT YOUR HEART...MADE SIMPLE 25 DISEASES OF THE BLOOD VESSELS OF THE HEART Typically, an informed consent—a legal contract that authorizes the physician to proceed with the test—is obtained after you understand these risks and your questions and concerns are answered. Signing a consent form essentially acknowledges your understanding of these risks and your willingness to proceed with the test.You should treat it seriously, carefully read it, and understand it.The physician or the nurse should be available to answer any questions you might have. How do we treat blockages in the coronary arteries once they are found? Blockages in the blood vessels of the heart are treated in 3 different ways. 1.Your doctor might decide that your coronary blockages are only borderline in nature or insignificant, and preventative therapy and medical therapy might be advised. 2. If your blockages, however, are severe, the treatment can be done by either an angioplasty or a bypass surgery. During an angioplasty, your cardiologist passes a balloon into the blocked arteries. Once the balloon is inflated at the area of the blockage (see Figure 3), the blockage will be compressed and the artery is stretched. A stent, or a stainless steel mesh, is most frequently deployed in the area of treatment to keep the artery widely open and prevent it from collapse.The choice of the stent depends on the type of blockages, their location, and the ability to deliver the stent to that part of your coronary arteries. Although the current standard of treating blockages is with Artery (section removed to view stent) Stent Balloon Flexible Guidewire Figure 3. Stent, mounted on a balloon, being implanted in an artery. Chapter03Shammas.qxd 10/27/05 5:29 PM Page 25 26 LEARN ABOUT YOUR HEART...MADE SIMPLE DISEASES OF THE BLOOD VESSELS OF THE HEART the use of a stent, some blockages are not amenable to stenting because of their size or the difficulty of delivering the stents to a particular blockage because of blood vessel tortuosity and calcification. Current stents also have medications in them. These medications prevent the recurrence of blockages within the area of the treatment.The choice of the stents is also guided by certain rules that your doctor might follow. Currently, the majority of the blockages are managed through the angioplasty process. 3.However, some blockages might be in locations too dangerous to treat with angioplasty or might be extensive for an angioplasty procedure.They might be complex in nature, particularly if they occur in a person with diabetes. Currently, the trend is to treat those blockages with a bypass operation. During the bypass operation, a blood vessel under the collarbone or a vein derived from under the skin of the legs is utilized to bypass the area of the blockage (see Figure 4). How long does it take to recover from the treatment of a blockage in the heart? If an angioplasty is utilized as the primary method of treating a blockage, generally you stay in the hospital for 23 hours. Within 72 hours, you should be able to drive and resume your normal activities. The exception to this is if you have had a heart attack. After a Right Coronary Bypass Graft Circumflex Bypass Graft Left Anterior Descending Bypass Graft Veins are grafted from the aorta to the native vessel, bypassing the blocked areas in the native vessels. Figure 4. Heart with veins bypassing blocked coronary arteries. Chapter03Shammas.qxd 10/27/05 5:29 PM Page 26 LEARN ABOUT YOUR HEART...MADE SIMPLE 27 DISEASES OF THE BLOOD VESSELS OF THE HEART heart attack, typically a patient cannot drive for 2 weeks and should be undergoing cardiac rehabilitation for a minimum of 4 weeks prior to release back to work.Your doctor will decide on the size of heart attack that you had, the extent of cardiac rehabilitation required, and the optimal time for you to return to work. On the other hand, bypass surgery would require that you stay in the hospital for an average of 5 to 6 days.This can be significantly more prolonged if complications occur.The recovery phase is in the range of about 6 weeks. For about 3 months, you should avoid carrying any weight that exceeds 10 pounds and avoid any form of exertion that requires pulling and pushing. It is also important to minimize any trauma to the area of the wound in the middle of the chest. Driving typically is not permitted during the first month after bypass surgery. There are many exceptions to the above rules based on your condition, complications occurring during surgery, and your recovery. What is the long-term outcome following treatment of blockages in the heart? Following the treatment of a blockage with an angioplasty, there is an immediate inflammation that occurs at the site of the treatment. This response of the blood vessel to the injury that the balloon has caused triggers the formation of scar tissue at the site of the treatment. Patients develop scar tissue to a different extent for unclear reasons.The scar tissue that develops within the stent can potentially cause a recurrence of a blockage in the area of the treatment. When balloon angioplasty alone is utilized without stenting, the recurrence of the blockage is in the range of about 40%. When a stent is used, the recurrence of a blockage is in the range of 15 to 20%. Higher rate of recurrence occurs in people with diabetes, patients with small blood vessels, and those with long areas of blockages. With the advent of stents loaded with drugs that suppress these blockages (drug-eluting stents), the rate of recurrence of scar tissue is currently about 5 to 9%. It is typical for scar tissue to form within the first 6 months Chapter03Shammas.qxd 10/27/05 5:29 PM Page 27 28 LEARN ABOUT YOUR HEART...MADE SIMPLE DISEASES OF THE BLOOD VESSELS OF THE HEART following an angioplasty. If this does not occur within the first 6 months, it is extremely less likely that it will occur afterward. Your doctor might elect to proceed with a stress test at about 4 to 6 months following an angioplasty to determine whether enough scar tissue has occurred to block the artery again. The decision to do this stress test is generally a clinical one and physician- dependent. The overall outcome of the patient, however, from the standpoint of preventing a heart attack is mostly dependent on preventative measures rather than the angioplasty process itself. In other words, angioplasty for blockages that have caused no symptoms or only stable symptoms generally does not affect a person’s survival.The major impact of angioplasty is on improving the quality of life and lessening the need for medications. In order to prevent death or a heart attack long-term, strict control of cardiac risk factors becomes important.This includes controlling blood pressure, cholesterol, blood sugar, and weight and avoiding smoking. Dietary modification, exercise, and stress reduction also become very important.These will be covered in detail in the preventative chapter of this book. Following a bypass surgery, the procedure’s long-term success depends on the continued normal functioning of the bypass grafts. It is known that 10 to 15% of bypass grafts can deteriorate within the first year of surgery. Also, at about 10 years from a bypass, two-thirds of all bypasses are expected to have significant buildup of plaques and blockages. There has been a lot of progress made recently in the treatment of those bypass grafts. However, again, the overall long-term survival and benefit is highly dependent on preventative measures. Several studies have indicated that the viability of bypass grafts and their overall health is related to taking blood thinners, such as aspirin or clopidogrel, and the use of some cholesterol-lowering medications, such as statins. Research is continually ongoing to find ways to preserve those bypasses and prevent them from deteriorating or blocking shortly after the surgery. What is a heart attack and how does it happen? Heart attack happens when there is a sudden interruption of the blood supply to a part of the heart muscle.This leads to death of Chapter03Shammas.qxd 10/27/05 5:29 PM Page 28 LEARN ABOUT YOUR HEART...MADE SIMPLE 29 DISEASES OF THE BLOOD VESSELS OF THE HEART the muscle tissue.A heart attack leads to symptoms similar to angina. However, these symptoms tend to be more prolonged and generally are more than a half hour in duration.The interruption of the blood supply to the heart occurs because of a plaque rupture. A plaque, irrespective of severity, can break, exposing the inside of the plaque to the blood elements.The blood forms a clot on the top of the ruptured plaque. If the clot does not block the artery entirely, unstable angina certainly will occur, as described previously. However, if the interruption in the blood supply is complete because of a full clot, the muscle of the heart supplied by this particular blood vessel will be deprived of nutrients and oxygen and will die. The most important step in the management of a heart attack is to restore the blood supply to the heart muscle as quickly as possible. The current guidelines strongly suggest that the artery should be opened with the angioplasty procedure within 90 minutes of a patient’s arrival to the emergency room. If the angioplasty procedure is not available to this particular emergency room and hospital, a clot-dissolving (or thrombolytic) medicine needs to be used immediately, within 30 minutes of arrival to the emergency room. Most hospitals are able to initiate the use of these thrombolytic drugs within about 20 minutes of a patient arriving to the emergency room. Current data strongly suggest, however, that angioplasty is a more effective way of opening up an artery in a heart attack situation and probably leads to better short- and long-term outcomes. Therefore, it is imperative that when the pain starts or when symptoms of a heart attack start, the patient needs to be transported to an emergency room as soon as possible.Time is extremely precious, and the longer the delay in opening a closed artery, the more damage will happen to the heart muscle. In fact, in 4 to 6 hours after the artery is closed, the damage is essentially complete. There is strong data to suggest that the earlier the artery is opened, the higher the likelihood of survival from a heart attack. What medications should I expect to be on following a heart attack? Following the acute treatment of a heart attack, which is primarily restoring the blood supply to the heart muscle, a patient is Chapter03Shammas.qxd 10/27/05 5:29 PM Page 29 30 LEARN ABOUT YOUR HEART...MADE SIMPLE DISEASES OF THE BLOOD VESSELS OF THE HEART placed on several medications to reduce the chance of another heart attack and reduce mortality. The standard therapy consists of the use of a beta blocker that has been shown to reduce heart failure and arrhythmias and prevent stretching and dilatation of the heart muscle following a heart attack. In addition, the patient is expected to be on a statin, which is a cholesterol-lowering medication that has also shown to substantially prevent the chance of another heart attack.The use of blood thinners, such as aspirin and clopidogrel (Plavix), has become standard therapy to also reduce the chance of another cardiac event. The use of an angiotensin-converting enzyme (ACE) inhibitor in patients following a heart attack and reduced left ventricular function is also now a standard to prolong life and reduce the chance of further cardiovascular events. With the use of a beta blocker, an ACE inhibitor, aspirin, clopidogrel, and a statin, one would expect that the chance of recurrence of a heart attack should be reduced to less than 3% per year on this preventative therapy. In addition to pharmacologic therapy, the patient will be strongly advised to adhere to strict dietary restrictions, weight control, exercise, and a no-smoking policy. All these changes require significant lifestyle modifications, which at times can be challenging. However, a patient striving for better health and prevention of another heart attack generally adheres to these guidelines. How important is cardiac rehabilitation after a heart attack or a bypass surgery? Cardiac rehabilitation in a structured format, with the patient being monitored, has been shown to substantially improve quality of life. Data also suggest an improvement in survival. Cardiac rehabilitation allows patients to gain confidence in their ability to do things, gradually increases their fitness level, and helps them develop a habit to exercise routinely on a long-term basis. The importance of exercise is mostly in its cardiovascular fitness and conditioning that allows a stronger ability of the body to extract oxygen from the blood, as well as improve the overall efficiency of the heart. A trained and fit individual tends to have Chapter03Shammas.qxd 10/27/05 5:29 PM Page 30 LEARN ABOUT YOUR HEART...MADE SIMPLE 31 DISEASES OF THE BLOOD VESSELS OF THE HEART a slower heart rate at rest and a lower adrenaline blood level. These are very protective elements overall to the heart. Cardiac rehabilitation is very strongly recommended to cardiac patients after an angioplasty, a heart attack, or bypass surgery. Many patients see a tremendous improvement in their sense of well-being and an improvement in their depression after a heart attack.This, in itself, also has significant protective effect to their overall health as well as cardiovascular health. The second phase of cardiac rehabilitation is the outpatient phase that follows a heart attack and is generally monitored under the guidance of cardiac rehabilitation nurses or technicians. The patient is generally placed on a monitor, and different kinds of exercises are encouraged, with close monitoring of the heart rates and the blood pressure, as well as the heart rhythm.A gradual increase in the target heart rate is done under the guidance of the primary cardiologist. The third phase of cardiac rehabilitation is a less-monitored phase where a person joins a group of heart patients and exercises on a routine basis. Phase III provides significant group support to the heart patient and allows uninterrupted, continued exercise with minimal supervision but with some form of continued guidance. Chapter03Shammas.qxd 10/27/05 5:29 PM Page 31