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Friday, November 28, 2014

Heart Attack, Part One: A Patient Guide

Introduction

The Heart Attack Patient Guide is a simple explanation of what a person is likely to experience when having a heart attack. The guide describes how a person is treated immediately during the attack, upon arrival at the hospital, to months and years later. The first part of the guide discusses the basics of heart function, heart attack symptoms, emergency care, medications, tests and treatments performed in the hospital. The second part is a comprehensive guide that covers short-term recovery in the cardiac care unit of the hospital, including details about bypass and angioplasty recovery, discharge from the hospital, cardiac rehabilitation, exercise, long-term recovery, medication, depression, and lifestyle modification.

Heart function

The heart works as a muscular pump with blood vessels leading in and out. The blood flows from your lungs, where it picks up oxygen, into the pump (your heart) and is pumped out to the rest of the body. Once the blood has delivered oxygen to the tissues, it returns to your heart and gets pumped back out to the lungs.

Blood flow during a heart attack

The heart muscle requires oxygen to function properly. The blood inside your heart does not supply oxygen to the heart muscle. Special blood vessels on the outside of the heart, called coronary arteries, feed the heart muscle. Three major vessels and many smaller vessels do this job. When one or more of the major vessels is obstructed (usually due to blood clot formation in the blood vessel lumen), blood cannot reach the heart muscle beneath the block, restricting the supply of oxygen. Within 20 minutes of not receiving blood and oxygen, some heart muscle cells begin to die. The death of heart muscle cells is called a heart attack.  A heart attack results in the loss of some of the function or contractility portion of the heart that has been damaged.

Symptoms of a heart attack

The symptoms of a heart attack may vary greatly. For some people, a heart attack is quite obvious, an intense, vice-like squeezing chest pressure or a feeling of a heavy weight having been placed on the chest. For others, a heart attack is more subtle, often felt as a mild chest discomfort or dull ache. Some individuals report a stabbing, knifelike, or burning sensation. The pain is usually prolonged and typically lasts for at least 30 minutes. The pain, however, may also greatly fluctuate in intensity during the period of a heart attack, and at times, appear to nearly completely dissipate. The intensity of heart attack-related chest pain does not usually alter with changes in body position. Even rest will not typically relieve this type of chest pain. Some people may not experience any pain in the chest but may experience it elsewhere. It is not at all unusual for people to describe pain radiating down the arms (either one, or both) with a tingling sensation in the wrist, hand, and fingers, or in the shoulders, neck, and jaw. The pain can also radiate to the teeth, the gums, or through to the back. Additional symptoms may include indigestion, nausea, vomiting, palpitations, cold perspiration, weakness, dizziness, cough, breathlessness, fainting, anxiety, or a sense of impending doom. In general, men and women experience similar symptoms of a heart attack. Although most heart attack victims report some form of chest pain, others may report none at all. While individuals who are elderly or have diabetes are generally at highest risk for an absence of chest pain during a heart attack (this is known as a silent heart attack), all persons should recognize this risk. In particular, individuals with unexplainable new onset indigestion, nausea, or shortness of breath should consider seeking prompt medical attention. Heart attacks can cause of sudden death in adults and may occur with absolutely no warning signs at all.

Emergency Care

Prior to arrival at the hospital

If you are experiencing chest discomfort and any of the aforementioned symptoms, you or someone close to you should call an ambulance immediately. Use 911 or your local emergency number. If you are not sure if you are having a heart attack, call your doctor immediately. There is a strong tendency to deny the possibility of a heart attack. Denial and delaying medical treatment can cost you your life. Research shows that one in three people die from a heart attack within the first few hours of experiencing chest pain. Making the decision to get to a hospital as early as possible is often the single most important factor in determining your likelihood of survival.

If your doctor has previously prescribed nitroglycerin tablets for you, put one under your tongue when the symptoms begin and repeat at five-minute intervals for a total of three doses. If the symptoms have not disappeared within 15 minutes, call an ambulance immediately. Do not take nitroglycerin tablets unless directed by a doctor. In patients with a condition known as aortic stenosis, taking nitroglycerin tablets can precipitate death. If you do have this condition, clearly understand from your doctor how you should respond in the event that you do develop worrisome chest pain. Do not take nitroglycerin if you have recently taken medicine for erectile dysfunction. The combination of nitroglycerin and such medicines can cause death.

As soon as you think you are having a heart attack, take one adult strength aspirin (325 mg), unless you have a specific allergy to it or a condition that makes taking aspirin highly risky. While perhaps the most inexpensive of all heart related therapies, aspirin is also one of the most effective.

Unlike a heart attack, if you believe you are having a stroke, aspirin may not be beneficial and may even prove harmful. This is because not all strokes are due to blood clots. Some are due to bleeding. Aspirin may worsen a stroke if it is due to bleeding.

If you are with someone whose heart has stopped beating, call 911 or your local emergency number. Administer cardiopulmonary resuscitation (CPR) immediately. CPR will supply oxygen to parts of the body until the ambulance arrives. It is important to have a family member or caretaker trained in CPR, especially if there is diagnosed heart disease in the family. Local community centers, the Red Cross and hospitals can provide information on CPR training.

In the emergency department

Treatment goals at the emergency department are to decrease the demands on your heart and prevent and treat complications. An IV (intravenous catheter) will be placed in a vein. This is the best way to administer fluids and medications. Even if blood levels of oxygen are normal, oxygen will be administered to decrease the workload of the heart. A urinary catheter might be inserted to help monitor the input and output of fluid from the body.

Your doctor will use the following information to determine the severity of your condition and treatment of choice: previous medical history, physical examination, an electrocardiogram (ECG or EKG), and the level of certain chemicals in your blood.

Physicians will want to know what type of chest pain you may have experienced previously. They will also want to know whether you have had a heart attack in the past, surgeries, and if you take any medications. (It is useful if a family member has knowledge of medication dosages.) This information will help physicians determine whether the pain you are feeling is due to a heart attack.

The physical examination will concentrate on checking your blood pressure and heart rate and listening to your heart and lungs for abnormal sounds. The ECG (or EKG) is a test that records the electrical rhythm of your heart. Wires (or leads) are attached to the chest, arms, and legs using pads with gel or tape. This procedure is not painful. Specific changes in the ECG may alert the physician if a heart attack is occurring. EKG monitoring is generally started immediately since life-threatening dysrhythmias (defective rhythm) are the leading cause of death during the first several hours following an acute heart attack. Sometimes an echocardiogram will be required. This is a test done by ultrasound. A transducer (a device that looks a bit like a microphone) will be placed against your chest in order to visualize the beating heart. This is totally painless, and you can actually watch the screen. Using the echocardiogram we can see whether the valves are working properly, and whether the heart muscle is functioning as it should. This device does not visualize the coronary arteries however. Occasionally CT (computerized tomography, a form of x-ray), or MRI or MRA (magnetic resonance imaging, magnetic resonance angiography) or transesophageal echocardiography may be required.

Blood tests provide an indication of heart muscle damage. When some of the heart muscle dies, the dead cells release chemicals into the blood. One chemical that is routinely evaluated is creatinine phosphokinase (CPK), specifically the MB isoform. Another set of chemicals belongs to the troponin family of proteins (troponin I and troponin T). All of these chemicals have high specificity for heart muscle and when they are significantly elevated, confirm a heart attack diagnosis. The CPK MB and troponins provide important information about the extent and severity of your heart attack, when your heart attack might have occurred, and your prognosis.

Heart Attack Medicines

If ECG results determine that you are having a heart attack, your doctor will use medications to help the heart. Several of these drugs are specifically designed to prevent further blood vessel obstruction (aspirin, heparin, low-molecular weight heparin, glycoproteins 2b/3a inhibitors, and clopidogrel). Others, such as oxygen and beta-blockers, improve oxygen utilization by the heart and decrease the heart's workload. Nitrogylcerin and morphine are used to decrease chest pain and reduce heart strain. If you have an arrhythmia during the course of your heart attack, you may also be placed on an antiarrhythmic (other than beta blockers which are, by themselves, effective antiarrhythmics). Diuretics such as Lasix (furosemide) may be prescribed if you have fluid accumulation in your lungs. Cholesterol-lowering agents such as statins and antihypertensive, anti-remodeling agents such as angiotensin-converting enzyme inhibitors (ACE inhibitors) are important adjunctive therapies that may also be used early in the course of your therapy.

If your doctor finds convincing evidence that you are having a heart attack you will be prescribed some form of reperfusion therapy. Reperfusion therapy refers to using intravenous medication (thrombolytic), a percutaneous catheterization-based technique (angioplasty), or surgery to reestablish blood flow to an occluded artery. The decision to receive one of these therapies is dependent upon a number of important factors including how long ago your heart attack started, the severity and instability of your heart attack, and the available resources and experience of the cardiovascular specialists at the hospital at which you are being treated. Each of these therapies has their own unique advantages and disadvantages that will be discussed with you during the very initial phases  in the emergency room. If the emergency team has decided during your en route trip to the hospital that you will receive a thrombolytic, you may be started on such medication in the ambulance. Along with reperfusion therapy, heparin and/or 2b/3a inhibitors may be prescribed to reduce the clotting tendency of your blood.

Tests and Treatments for heart attack: the following tests and treatments are usually not performed in the emergency room.

Cardiac catheterization

A thin catheter (plastic tube) is inserted through an artery in the arm or leg and is guided into the coronary arteries of the heart. A skilled doctor usually injects dye through the catheter into the origins of the coronary arteries and identifies arterial obstructions by observing dye flow. This test can provide information about functioning of the heart muscles and valves as well as the arteries.

Angioplasty

As briefly mentioned, your doctor may decide to treat you with angioplasty to establish reperfusion when he/she feels that thrombolytic therapy is either not primarily indicated or was ineffective in relieving your heart attack symptoms. Angioplasty can be performed during a cardiac catheterization. The technique consists of a small balloon being placed at the site of the coronary blockage and blown up with air. This causes the material forming the blockage to be compressed along the wall of the vessel. The inflated balloon can also cause the vessel to stretch, making it wider so more blood can flow through. It can also cause cracks in the blockage that will allow more blood to flow through. In order to keep the blood vessel open a small device called a stent may be placed in the coronary artery. A stent is a small tubular scaffolding that is inserted with the help of the catheter. Some of these stents are made of bare metal; others have a coating of a drug that will be absorbed by the blood vessel over time (these are called drug eluting stents). The decision of what type of device to use, or whether to use a device is dependant upon the anatomy of the lesion. Interventional cardiologists are experts in deciding what fits best for you.

You will be mildly sedated during angioplasty, and most people report feeling only minor discomfort. Like a catheterization, your doctor will inject dye into your arteries that will allow him/her to monitor your blood flow and determine the site(s) of blockage. The tube carrying the balloon, regarded as the catheter, is inserted at the site of artery access, usually in the groin area. The catheter is moved along the artery until it reaches the blockage. The balloon is then inflated for a period of a few seconds to a few minutes and then deflated. Blood flow is monitored to ensure adequate reperfusion or restoration of blood flow. Sometimes the balloon will be reinflated at the same site or at another site.

Usually a stent is placed at the site of the balloon. A stent is a rigid tube that prevents the vessel from collapsing or a blood clot from forming at the site of the blockage. Great advances in stent technology have led to markedly improved outcomes for people who undergo angioplasty at the time of their heart attack, or shortly thereafter.

Bypass surgery

If angioplasty proves unsuccessful, the position of the block is too difficult to access by angioplasty, or you have severe blockages in multiple major vessels, the doctors may recommend bypass surgery.

Bypass surgery is a major operation. If you undergo this operation, you will receive general anesthesia, and thus be completely asleep during the surgery. Pre-operative medications are often administered to bypass patients by mouth, muscular or subcutaneous injection, or IV. During bypass surgery, the chest bone (sternum) is separated, and the ribs are spread apart to allow visible and physical access to the heart. During surgery, blood circulation and breathing functions will be taken over by a heart-lung machine. The operation usually lasts between two and six hours. A bypass graft is performed to reroute blood flow around the blockage. Veins used in bypass surgery are usually taken from one of the legs or an artery is usually taken from the chest wall (internal mammary artery), or forearm (radial artery) to complete the graft.

A newer technique, minimally invasive bypass surgery, requires a much smaller incision in the chest (only three inches) instead of sawing through the chest bone. An artery from the chest is used to bypass the blockage. While fewer patients are candidates for this type of surgery, the technique is less painful and leads to a shorter hospital stay than the usual bypass surgery.