Heart Function

Emergency Care

Tests and Treatments

Heart Attack Patient Guide-2

I.Heart function

The heart works like a large pump and consists of a bag comprised of muscle with blood vessels leading in and out. The blood flows from your lungs, where it picks up oxygen, into your heart and gets pmped out to the rest of your body. Once the blood has delivered its 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 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 to the heart . Within 20 minutes of not receiving blood and oxygen, the heart muscle begins to die, leading to a heart attack. A heart attack results in the loss of function or contractility of the damaged portion of the heart.

Symptoms of a heart attack
The symptoms of a heart attack can be greatly varied. Some heart attacks are blatantly obvious, with affected people describing an intense, vice-like squeezing chest pressure or a feeling of a heavy weight having been placed on their chest. Other heart attacks are much more subtle, often beginning slowly as a mild chest discomfort or dull ache. Some individuals may 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. Finally, some patients may not experience any chest pain.Some patients describe pain radiating down the arms (usually the left arm) with a tingling sensation in the wrists, hands, and fingers. Others report pain in the shoulders, neck, and jaw. The pain can also radiate to the teeth and back. Additional symptoms include indigestion, nausea, vomiting, palpitations, cold perspiration, weakness, dizziness, cough, fainting, dry mouth, anxiety, or a sense of impending doom. In general, men and women experience the same symptoms of a heart attack. Although many 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 experiencing no 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.Finally, acute heart attack is a major cause of sudden death in adults and may occur with absolutely no warning signs at all.

II.Emergency Care 

Prehospital care
If you are experiencing chest discomfort and any of the aforementioned symptoms, you or someone close to you should call an ambulance immediately. 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.

In the emergency department
Treatment goals at the emergency department (emergency room) 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 usually the best way to administer fluids and medications. Even if blood levels of oxygen are normal, oxygen is generally administered to decrease the workload of the heart and make oxygen readily available to the body. 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 pertinent 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 thepast, 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.

If you are having a heart attack, a rapid pulse, changes in blood pressure, crackles in lungs, and abnormal heart sounds might be found on physical examination. 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 alert the physician that 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.

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 belong 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.

Medicines
If ECG results determine that you are having a heart attack, your doctor will try to 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 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 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 enough convincing evidence that you are having a heart attack, then you will be prescribed some form of reperfusion therapy. Reperfusion therapy refers to using intravenous medication (thrombolytics), 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 where 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 of your hospitalization. If the caring emergency team has decided during your en route trip to the hospital that you will receive thrombolytics, 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.

III. Tests and Treatments

The following tests and treatments are usually not performed in the emergency room. Patients are usually admitted at this point.

Cardiac catheterization
Your physician may request a cardiac catheterization. A thin catheter (plastic tube) is inserted through a vein or artery in the arm or leg and is guided into the coronary arteries of the heart. This test can accurately measure how much oxygen is in your blood, your blood pressure, and can provide information about functioning of the heart muscles, valves and arteries. A skilled doctor usually injects dye through the catheter into the origins of the coronary arteries and identifies arterial obstructions by observing dye flow.

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.

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 which 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. In this procedure, a piece of vein taken from the leg or an artery taken from the chest is used to form a bypass conduit to enable blood to go around the blockage. Several blocks can be bypassed at the time of 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 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.