Myocardial Infarction (Heart Attack) PDF

# Myocardial Infarction ## Definition: - commonly known as a (heart attack) - irreversible death (necrosis) of heart muscle secondary to prolonged lack of oxygen supply (ischemia). ## Myocardial Infarction (Heart Attack) - An image of a heart with a blocked coronary artery, plaque, damaged tissue...

# Myocardial Infarction ## Definition: - commonly known as a (heart attack) - irreversible death (necrosis) of heart muscle secondary to prolonged lack of oxygen supply (ischemia). ## Myocardial Infarction (Heart Attack) - An image of a heart with a blocked coronary artery, plaque, damaged tissue, and a blood clot. ## Causes - Psychological stress or physical exertion, especially if the exertion is more intense than the individual usually performs. - Acute severe infection, such as pneumonia, can trigger myocardial infarction. - Trauma: this includes tears or ruptures in the coronary arteries. - Coronary artery spasm ## Risk factors - Tobacco smoking - High blood pressure - Family history of ischemic heart disease (IHD) - Obesity - **Age:** Men acquire an independent risk factor at age 45, Women acquire an independent risk factor at age 55. - Prolonged intake to high quantities of alcohol ## Pathophysiology - A myocardial infarction occurs when an atherosclerotic plaque slowly builds up in the inner lining of a coronary artery and then suddenly ruptures, occluding the artery and preventing blood flow downstream. - Ruptures resulting in total occlusion of the artery. Plaques can become unstable, and may promote a thrombus that occludes the artery; this can occur in minutes. When a severe enough plaque rupture occurs in the coronary vasculature, it leads to myocardial infarction. - Cellular injury occur when cells are denied adequate oxygen and nutrients, when ischemia lasting more than 20-45 minutes hypoxemic damage causes cellular death and tissue necrosis. - When large artery is compromised, collateral vessels connecting smaller arteries in coronary system dilate to maintain blood flow to the cardiac muscle, good collateral circulation can limit the size of MI. ## Signs and Symptoms - Chest pain: this can be mild and feel like discomfort or heaviness, or it can be severe and feel like crushing pain. It may start in chest and radiate to other areas like left arm, shoulder, neck, jaw, back or down toward waist. - Shortness of breath or trouble breathing - Fatigue - Trouble sleeping - Nausea or stomach discomfort, heartburn - Heart palpitations - Anxiety - Sweating ## Myocardial Infarction vs. Angina - **Myocardial Infarction**: Chest pain with damage to the heart. Pain is sudden, chest pain radiates to the neck and usually described as severe, steady. Hypotension, weak rapid pulse, and low-grade fever. - Chest Pain usually lasts for *more* than 15 minutes and occur at any time. - Symptoms persists after 15 minutes and not relieved by rest or nitro. - **Angina**: Chest pain with no damage to the heart. Pain is described as a tightness or pressure in the chest, and may radiate to the neck, lower jaw, left arm, and left shoulder. - Usually chest pain for *less* than 15 minutes, lasting 3-5 minutes. Occurs when engaged in physical activity or due to emotional stress. - Symptoms relieved by rest or nitro within 10-15 minutes. Lack of relief indicates an individual may be developing infarction. ## Diagnosis - **Electrocardiogram**: the primary purpose of the electrocardiogram is to detect ischemia or acute coronary injury. Because unstable ischemic syndromes have rapidly changing supply versus demand characteristics, a single ECG may not accurately represent the extent of the injury. - **Angiography**: A catheter is inserted into an artery (usually the femoral artery) and pushed to the vessels supplying the heart. A radio-opaque dye is administered through the catheter and a sequence of x-rays is performed. It allows visualization of narrowing or obstructions on the heart vessels and therapeutic measures can follow immediately. An image of a person with a heart and the path of the catheter, showing the aorta, aortic and anterior interventricular arteries. - A coronary angiogram allows visualization of narrowing or obstructions on the heart vessels and therapeutic measures can follow immediately. - An echocardiogram to help identify areas of the heart that aren't working properly. - A stress test to see how your heart responds to certain situations, such as exercise. - **Laboratory tests**: - **Serum Cardiac markers (enzymes)** - The cardiac troponins I is a protein found only in cardiac muscle. After myocardial injury, elevated serum troponin I concentrations can be detected within 3 to 4 hours; they peak in 4 to 24 hours and remain elevated for 1 to 3 weeks. Normal range less than 10. - Creatine kinase: is enzyme for cellular function found in cardiac muscles. It rise rapidly with damage to these tissues appearing in serum 4-6 hours after attack MI, and then declining over next 48 hours to 72 hours. - CK-MB are the most specific enzymes in cardiac tissues, it analyzed in acute MI, is detected in the blood within 3 to 5 hours after a myocardial infarction; levels peak in about 10 to 20 hours and normalize within about 3 days. Normal 60-400 units. - Myoglobin: is a small protein found in cardiac muscle, is rapidly released from damaged myocardial tissue and accounts for its early rise, within 1 to 3 hours after the onset of an acute MI. Myoglobin peaks in 4 to 12 hours and returns to normal in 24 hours. Normal range from 0-100 nano gram/ml - Complete blood count: shows an elevated white blood cells count due to inflammation of the injured myocardium. The erythrocyte sedimentation rate also rises because of inflammation. - **Physical examination**: - The general appearance of patients may vary according to the experienced symptoms; the patient may be comfortable, or restless and in severe distress with an increased respiratory rate. - A cool and pale skin is common. - Some patients have low-grade fever (38-39 °C). - Blood pressure may be elevated or decreased. - And the pulse can be become irregular. ## Complications - Congestive heart failure: A myocardial infarction may compromise the function of the heart as a pump for the circulation, a state called heart failure. - Myocardial rupture is most common three to five days after myocardial infarction, but may occur one day to three weeks later. Rupture occurs due to increased pressure against the weakened walls of the heart chambers. - Pericarditis; As a reaction to the damage of the heart muscle,. The inflammation may reach out and affect the heart sac. ## Management - **Pharmacological management**: - Thrombolytic therapy as; streptokinase, urokinase and alteplase. Thrombolytic therapy is indicated for the treatment of myocardium ischemia within 12 hours of the onset of symptoms, the effectiveness of thrombolytic therapy is highest in the first 2 hours. Because irreversible injury occurs within 2-4 hours of the infarction. - Analgesics: - Opiate analgesic therapy; as morphine sulphate, is given intravenously of 4-8 mg. it decrease pain and anxiety, also relaxes bronchioles to enhances oxygenation. - Demerol; is useful for pain management in patient with allergy to morphine. - Nitroglycerine; decrease myocardial work and oxygen demand through dilate veins, and dilate artery. - Beta adrenergic blocking agents; It reduce myocardial oxygen consumption which lead to decrease heart rate, decrease blood pressure and reduce myocardial contractility that provide balance between myocardial oxygen needs and supply of oxygen this help in control chest pain. - Atenolol (Tenormin) - Anticoagulation therapy used for prolonged bed rest to protect from deep venous thrombosis. - Calcium channel blocking agents; slow heart rate and decrease in strength of heart muscle contraction, these effects decrease workload of heart. It is also relax blood vessels causing decrease in blood pressure. - Verapamil, Felodipine. - Antidysrhythmics drugs; as lidocaine, it decrease ventricular irritability which occur after MI. - **Cardiac rehabilitation**: - **Objectives of cardiac rehabilitation**: - Limit effect and progression of atherosclerosis. - Return patients to work and pre illness life. - Enhance psychological status of the patient. These objectives accomplished by encouraging physical activity, educating patient and family. - **Phases of cardiac rehabilitation**: - **Phase I**: may begin with diagnosis of atherosclerosis, it include initial education for patient and family. - **Phase II**: occur after patient discharged, lasts for 4-6 week but may last up 6 month. This outpatient program consists of ECG monitoring, exercise training, support and guidance related to treatment of disease, education about life style. - **Phase III**: focus on maintaining cardiovascular stability and long term condition. Patient usually self direct during this phase. - **Priorities for education include**: signs and symptoms, medication regimen, rest and activity balance and follow up. Nurse must reassure patient that although coronary artery disease is lifelong disease but patient can resume normal life. - **Nursing process for patient with myocardium infarction**: - **Assessment**: Gather information regarding chest pain, onset and duration, location and radiation, precipitating and aggravating factors. Assess vital signs. - Observe patients for pallor, dyspnea, weakness, confusion. Evaluate cognitive, behavior and emotional status. - Intravenous sites are examined frequently to ensure that access is available for administer emergent medication. Avoid intramuscular injection due to delayed effect and risk for elevated serum enzymes. - **Nursing diagnosis, plan and intervention**: - **Ineffective cardiopulmonary tissue perfusion related to decrease coronary blood flow from coronary thrombus.** - **Goal**: relief chest pain and discomfort - **Intervention- balance cardiac oxygen supply with its oxygen demands**: - Oxygen should be administered with medication to assist in relief symptoms. It is given by nasal cannula and oxygen flow rate are documented (flow rate of 2-4 l/min is adequate to maintain oxygen saturation at 96-100%). - Assess vital signs frequently and other signs and symptoms of ischemia. - Physical rest in bed with back rest elevated or in cardiac chair help to decrease chest pain and discomfort. - Elevate the head: This is a benefit for decreasing venous return to the heart which decreases the work of the heart and improves drainage of the upper lung lobe. - Administer nitroglycerine and morphine based on vital signs, medication is required to accomplish this. - **Potential altered peripheral tissue perfusion related to decrease cardiac output from left ventricular dysfunction.** - **Goal**: promoting adequate tissue perfusion. - **Intervention**: - Monitor urine output hourly because decrease urine output indicate decrease in renal blood flow. - Monitor mental status because changes in it indicate decrease in cardiac output. - Limiting patient to bed or chair rest during initial phase of treatment to decrease myocardial oxygen consumption. - Oxygen is administered to overcome oxygen demand. - Take body temperature every 4 hours. - Monitor blood pressure every 2 hours because hypertension increase after load of heart, elevate oxygen demand. - Monitor respiration and lung every 2-4 hours as observe for dyspnea, orthopnea and pulmonary edema. - **Anxiety related to fear of death, chest pain.** - **Goal**: reducing anxiety - **Nursing care**: - These patients often fear loss of their roles within families so they are exposed to anxiety which worsen their condition. - Providing information about illness, treatment and method of preventing its progression is very necessary to decrease anxiety. - Various stress reduction methods should explore with patient as music therapy, relaxation technique. Ensure quiet environment, prevent interruption, using appropriate touch. - Give patients opportunity to express feeling and ask any question, and developing trusting relationship with patient is critical to decrease anxiety. - **Pain related to decrease oxygen supply to myocardium muscle.** - **Goal**: preventing pain - **Nursing care**: - The nurse assesses patients pain and if activity increase patients pain, plan activities according to ability of the patients. - Balance between rest and activity and rest is very important aspect of educational plan for patients and family. - Keep prescribed nitroglycerine tablets at the patient's side so one can be taken at the onset of pain. - **Risk for injury (bleeding) related to dissolution of protective clots** - **Goal**: preventing bleeding. - **Intervention**: take vital signs every 15 minutes during infusion of thrombolytic agents and then hourly. - Observe for signs of hematoma or skin breakdown.