General Heart Diseases

General Heart Diseases

• Myocardial Infarction (Heart Attack)
  • Atherosclerosis
  • Coronary Thrombosis
• Aortic Dissection
• Cardiac Arrhythmia (Irregular Heart Beat, or Arrhythmia)

1. Myocardial Infarction (Heart Attack)

The proper use of the non-medical term "heart attack" is "Myocardial Infarction". Either term is scary. "Myocardial Infarction" (abbreviated as "MI") means there is death of some of the muscle cells of the heart as a result of a lack of supply of oxygen and other nutrients. This lack of supply is caused by closure of the artery ("coronary artery") that supplies that particular part of the heart muscle with blood. This occurs 98% of the time from the process of arteriosclerosis ("hardening of the arteries") in coronary vessels.

Although it once was felt that most heart attacks were caused from the slow closure of an artery, say from 90 or 95% to 100%, it is now clear that this process can occur in even minor blockages where there is rupture of the cholesterol plaque. This in turn causes blood clotting within the artery, blocking the flow of blood. This sort of event is illustrated above. The heart muscle which is injured in this way can cause irregular rhythms which can be fatal, even when there is enough muscle left to pump plenty of blood. When the injured area heals, it will leave a scar. While the heart won't be able to pump quite as much as before, there is often plenty of good muscle left to take care of the job, and recovery can be quite complete.

While heart attacks are clearly scary, with modern techniques, patients survive most of them. Furthermore, most can have a long and satisfying life, perhaps more satisfying than before.

Causes

Predisposing factors include:

❑ positive family history

❑ hypertension

❑ smoking

❑ elevated levels of serum triglycerides, total cholesterol, and low-density lipoproteins

❑ diabetes mellitus

❑ obesity or excessive intake of saturated fats, carbohydrates, or salt

❑ sedentary lifestyle

❑ aging

❑ stress or a type A personality (aggressive, ambitious, competitive, addicted to work, chronically impatient)

❑ drug use, especially cocaine.

Men and postmenopausal women are more susceptible to an MI than premenopausal women, although incidence is rising among females, especially those who smoke and take a hormonal contraceptive.

The site of the MI depends on the vessels involved. Occlusion of the circumflex branch of the left coronary artery causes a lateral wall infarction; occlusion of the anterior descending branch of the left coronary artery, an anterior wall infarction.

True posterior or inferior wall infarctions generally result from occlusion of the right coronary artery or one of its branches. Right ventricular infarctions can also result from right coronary artery occlusion, can accompany inferior infarctions, and may cause right-sided heart failure. With a transmural MI, tissue damage extends through all myocardial layers; with a subendocardial MI, only in the innermost and possibly the middle layers.

Symptoms:

Common Heart Attack Warning Signs

• Uncomfortable pressure, fullness, squeezing or pain in the center of the chest lasting more than a few minutes
• Pain spreading to the shoulders, neck or arms.
• Chest discomfort with lightheadedness, fainting, sweating, nausea or dyspnea (shortness of breath).

Other signs of myocardial infraction may include:

• Sweating
• Jaw pain
• Heartburn or indigestion
• Upper back pain
• General feeling of illness

A recent survey reported by the American Heart Association reveals that the majority of American women do not understand the true threat of cardiovascular disease. Despite the fact that heart disease is the leading cause of death among women, a nationwide survey revealed that only 8% of women perceive heart disease as the greatest threat to their health. More than six out of 10 women falsely believe that they are more likely to develop cancer than heart disease.

Diagnosing Myocardial Infarction (Heart Attack)

When symptoms are presented, patients should be evaluated quickly with blood tests and an electrocardiogram. After the patient is stabilized, an echocardiogram and nuclear medicine exam may be performed.

• Blood work: Blood tests will be performed to detect levels of creatine phosphokinase (CPK), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and other enzymes released during myocardial infarction.

• Electrocardiogram (ECG or EKG): An electrocardiogram makes a graphic record of the cardiac activity, either on paper or a computer monitor. An ECG can be beneficial in detecting disease and/or damage.

• Echocardiogram (heart ultrasound): This diagnostic technique is an excellent first step in investigating congenital heart disease or in evaluating abnormalities of the heart wall. Echocardiography is a non-invasive exam in which images are acquired and viewed in real time without the use of radiation. Echocardiography is often useful in studying the beating heart and provides some information on functional abnormalities of the heart wall, valves and blood vessels. Doppler ultrasound can be used to measure blood flow across a heart valve. Abnormal operation of the valves can be detected by studying the opening and closing function versus normal valve function. Echocardiography may also be used to study congenital heart defects such as a septal defect (a hole in the wall that separates the two chambers of the heart).

• Nuclear medicine: Nuclear medicine (also called radionuclide scanning) allows visualization of the anatomy and function of an organ. The patient will be given a radionuclide which will assist in the acquisition clear images of the heart with a gamma camera. Nuclear medicine imaging may be used to detect coronary artery disease, myocardial infarction, valve disease, heart transplant rejection, check the effectiveness of bypass surgery, or to select patients for angioplasty or coronary bypass graft.

Duration of a Heart Attack:

A heart attack itself may last several minutes when the symptoms are present. However, because of the damage it causes and the way the heart tries to cope with it, in those people who survive a heart attack, the consequences last a lot longer. This may mean there is a risk of more abnormal heartbeats (arrhythmias) for several hours or days following. For some patients there can be further risk several months later because they may go on to develop heart failure or other problems. This is why special care and medicines are needed for a long time, to reduce the chances of this happening.

• Following recovery from a heart attack there is damage to the heart muscle, which takes some time to repair.
  
  
• The repair to the heart muscle is not always complete and scarring is usually present.
  
  
• There is always a chance of a recurrence due to the continued presence of diseased coronary arteries that caused the heart attack.
  
  
• There is also the risk of heart failure developing over a period of weeks as the heart reacts to the injury it has sustained.
  
  
• For these reasons it is necessary for patients to be monitored carefully and to receive the appropriate treatment to reduce the risk of further disease progression and other heart attacks.

Treatment of a Heart Attack:

Medical treatment is aimed to open the blocked artery and restore blood flow to the affected area of heart muscle (doctors call this reperfusion). Treatment is also aimed at preventing further damage and the chance of repeat heart attacks in the future.

• Once the artery is open, the heart attack is generally halted and the patient becomes pain free.
  
  
• The patient is most likely to make a good recovery if reperfusion can be established in the first 4-6 hours of a heart attack.
  
  
• Anti-platelet medicines, for example aspirin, reduce the tendency of platelets (a type of blood cell) in the blood to clump and clot. These medicines help to prevent the arteries from becoming blocked again.
  
  
• Nitroglycerin, a vasodilator (blood vessel dilator), widens the blood vessel by relaxing the muscular wall of the blood vessel.
  
  
• ACE (angiotensin converting enzyme) inhibitors, another type of vasodilator, improve the heart muscle healing process. They do this by blocking the production of a hormone (chemical signal carried in the blood) called angiotensin II.
  
  
• Beta-blocking agents interfere with the nerves controlling the heart by blocking the action of a chemical they release called noradrenaline. They also block a hormone (chemical carried in the blood) called adrenaline. This makes the heart beat more slowly and less forcibly, which decreases the amount of muscle damage and can help to prevent serious arrhythmias.

After a heart attack, many other recommendations may be made including changes in diet, lifestyle, stopping smoking and so on. The aim of these is to try to reduce the chance of having another heart attack. If specific conditions are discovered that have contributed to the heart attack, like high cholesterol or high blood pressure for example, then specific treatments might be needed for these.

Any medical information on this website is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.

Special considerations

❑ Care for patients who have suffered an MI is directed toward detecting complications, preventing further myocardial damage, and promoting comfort, rest, and emotional well-being. Most MI patients receive treatment in the coronary care unit (CCU), where they’re under constant observation for complications.

❑ On admission to the CCU, record the patient’s blood pressure, temperature, and heart and breath sounds, and monitor them regularly. Also, obtain an ECG.

❑ Assess and record the severity and duration of pain; administer an analgesic. Avoid I.M. injections; absorption from the muscle is unpredictable.

❑ Check the patient’s blood pressure after giving nitroglycerin, especially the first dose.

❑ Frequently monitor the ECG to detect rate changes or arrhythmias. Place rhythm strips in the patient’s chart periodically for evaluation.

❑ During episodes of chest pain, obtain ECG, blood pressure, and pulmonary artery catheter measurements for changes.

❑ Watch for signs and symptoms of fluid retention (crackles, cough, tachypnea, and edema), which may indicate impending heart failure. Carefully monitor daily weight, intake and output, respirations, serum enzyme levels, and blood pressure.

❑ Auscultate for adventitious breath sounds periodically (patients on bed rest frequently have atelectatic crackles, which may disappear after coughing) and for third or fourth heart sounds.

❑ Organize patient care and activities to maximize periods of uninterrupted rest.

❑ Ask the dietary department to provide a clear liquid diet until nausea subsides. A low-cholesterol, low-sodium, caffeine-free diet may be ordered.

❑ Provide a stool softener to prevent straining during defecation, which causes vagal stimulation and may slow the heart rate. Allow use of a bedside commode, and provide as much privacy as possible.

❑ Assist with range-of-motion exercises. If the patient is completely immobilized by a severe MI, turn him often. Antiembolism stockings help prevent venostasis and thrombophlebitis.

❑ Provide emotional support, and help reduce stress and anxiety; administer a tranquilizer, if needed.

❑ Explain procedures, and answer questions. Explaining the CCU environment and routine can ease anxiety. Involve the patient’s family in his care as much as possible.

To prepare the patient for discharge:

❑ Promote adherence measures by thoroughly explaining the prescribed medication regimen and other treatment measures.

❑ Warn the patient about adverse reactions to drugs, and advise him to watch for and report signs and symptoms of toxic reaction (anorexia, nausea, vomiting, and yellow vision, for example, if the patient is receiving digoxin).

❑ Review dietary restrictions with the patient. If he must follow a low-sodium or low-fat and low-cholesterol diet, provide a list of foods that he should avoid. Ask the dietitian to speak to the patient and his family.

❑ Counsel the patient to resume sexual activity progressively.