Coronary artery disease (CAD) is the condition in which the coronary arteries cannot deliver adequate blood supply to the heart muscle to meet the tissue demand. This condition is characterized by obstruction or narrowing of the vessel lumen.
Coronary artery disease has been linked with certain "risk factors." In general, the more risk factors associated with an individual, the greater the chance for development of CAD. Some risk factors cannot be changed, while other risk factors can be modified or eliminated. Patient education is an important aspect of the nursing care of patients with CAD because the educated patient can take steps to improve his condition.
a. Risk factors that cannot be changed (non-modified) are age, sex, race, genetic make-up, and family history.
b. The major risk factors, however, fall into the category of modifiable risk factors. Hypertension, elevated serum cholesterol levels, and cigarette smoking have been identified as the three major risk factors. These factors can be modified and controlled by taking prescribed blood pressure medication, modifying eating habits, and giving up cigarettes.
c. Additional modifiable risk factors include weight, activity level, and stress levels. These factors can be controlled by maintaining an appropriate weight, making life style adjustments to reduce stress, and increasing physical activity.
a. Arteriosclerosis is the primary cause of CAD. Arteriosclerosis is defined as hardening or thickening of the arteries. Arteriosclerotic disease is characterized by thickening and loss of elasticity of the arterial walls.
b. Atherosclerosis is the most common form of arteriosclerosis. Deposits of yellowish plaques (called atheromas) are formed within the medium and large sized arteries. These atheromas are made up of cholesterol, lipoid material, and lipophages (cells that ingest or absorb fat).
a. Coronary heart disease (CHD) is a collective name for a number of ischemic diseases of the myocardium. Coronary heart disease is the eventual clinical manifestation of the effects of CAD.
b. The major diseases of CHD are: angina pectoris, cardiac dysrhythmias, myocardial infarction, congestive heart failure, and sudden cardiac death.
a. Angina pectoris is a clinical syndrome of ischemic heart disease, manifested by paroxysmal pain in the chest and adjacent areas. This disorder is considered to be an early warning of CV deterioration. The symptoms occur as a result of myocardial oxygen demand that exceeds the ability of the coronary arteries to deliver oxygen. (The coronary arteries supply the myocardium with the oxygenated blood it needs to work effectively.) The main cause for this inability to meet oxygen demand is the presence of aterosclerosis that causes advanced occlusion or stenosis of one or more of the three major branches of the coronary artery tree. The coronary arteries are illustrated in Figure 1-3.
b. When the heart is stressed, it must rely on increased coronary blood flow to meet the increased oxygen demand of the cardiac tissue. Coronary blood flow is determined by the amount of pressure in the aorta and the amount of resistance in the coronary arteries. If atherosclerosis is present in the coronary vascular system, coronary blood flow is decreased because of the increased resistance in the coronary arteries.
c. The pain of angina pectoris occurs when the heart is stressed or worked to a point where the oxygen demand is greater than the amount of oxygen that can be delivered. This usually occurs with some type of exertion, such as mowing the lawn, climbing stairs, or doing heavy housework. In the affected patient, the onset of pain will occur with exertion, and relief will normally occur with rest. Rest will decrease the workload on the heart, thereby decreasing the heart's oxygen demand and relieving the pain.
d. Unstable angina pectoris is a term used to describe the exacerbation of the symptoms of angina pectoris. This syndrome is characterized by increased severity of symptoms, increased ease in provoking attacks of angina, and less predictability in controlling angina attacks. Symptoms may be severe enough to mimic an acute myocardial infarction. Crescendo angina and acute coronary insufficiency are also terms used to describe unstable angina.
e. In either case, medical management is the same. The patient is educated about the nature of the disease so that it may be controlled with diet, medication, exercise, and risk factor modification. When the condition advances to the stage where it can no longer be controlled in this manner, surgical intervention may be indicated. Two surgical possibilities include the coronary artery bypass graft (CABG) and transluminal coronary angioplasty (balloon compression).
a. Acute myocardial infarction (AMI) results from an imbalance between oxygen demand and oxygen supply to the myocardium. In 90 percent of the cases of AMI, this imbalance is preceded by atherosclerosis and decreased blood flow in the coronary arteries. The inadequate blood flow results in decreased oxygen delivery to the heart muscle, which causes ischemia, injury, and death of a portion of the myocardium (infarction).
b. Myocardial infarctions are described as being anterior, inferior, or posterior, depending upon the location of the infarcted area of the heart muscle. Infarcts can be further classified as being transmural or non-transmural. A transmural infarct (Non Q- Wave MI) is one that involves damage to the full thickness of the myocardium. A nontransmural MI involves only a partial thickness of the muscle.
c. In the majority of patients with AMI, chest pain is the major presenting symptom. The pain is usually substernal and may radiate to the neck, shoulders, arms, or epigastric area. The pain is described as heaviness, constriction, burning, or similar to indigestion. It is important to remember, however, that there may be little or no pain present at all. AMI can be very subtle, and often difficult to distinguish from angina. In addition to chest pain, symptoms of MI include shortness of breath, diaphoresis, weakness, fatigue, anxiety, nausea, vomiting, abnormal blood pressure, and abnormal heart rate.
d. Pain, anxiety, and arrhythmias occur in the early stages of MI. Ventricular fibrillation is the greatest threat to life in the first hours after MI. Medical management includes ECG monitoring, bedrest to reduce the workload of the heart, and intravenous therapy. Medications include morphine to reduce pain and relieve anxiety, vaso- dialators, beta blocker, calcium channel blockers and lidocaine as antiarrhythmic therapy.
e. Nursing management of a patient with AMI is intensive in nature, requiring close monitoring of the patient's status and progress, along with concurrent patient education. The nursing staff works closely with the physician, physical therapist, and dietician to develop an individualized rehabilitation plan for the patient. This post myocardial infarction rehabilitation plan, often referred to as the "MI protocol," takes the patient from complete bed rest during the first days of his MI to discharge from the hospital several weeks later. The protocol is a plan of progressive, monitored "steps" of increased activity and exercise, accompanied by intensive patient education. The rehabilitation plan is implemented upon physician's orders once the patient's condition is stable. Rehabilitation is advanced by the physician, who bases his decisions upon daily review of the patient's status and the information recorded by the nursing staff. Important information regarding patient tolerance and acceptance of the rehabilitation process is obtained by the nursing staff and recorded in the patient's chart.
f. Nursing care is directed toward three major considerations: observation and prevention of further myocardial damage and complications, promotion of an environment that allows for maximum comfort and rest, and patient education to fully prepare the patient for discharge.
(1) Observation and prevention include the following nursing considerations:
(a) Frequent monitoring of the patient's vital signs and ECG.
(b) Observation for signs of impending heart failure by close monitoring of intake and output, daily weight, breathe sounds, and serum enzymes.
(c) Careful assessment and documentation of each episode of chest pain to include severity, duration, medication given, and relief obtained.
(2) Promotion of a restful and comfortable environment includes the following nursing considerations:
(a) Provide emotional support to reduce anxiety and stress.
(b) Orient the patient to the coronary care unit (CCU) routine and environment. Take time to explain procedures.
(c) Schedule patient care activities carefully to avoid interrupting the patient's sleep.
(3) Patient education is necessary to prepare the patient for resuming life outside the hospital setting. The following nursing considerations should be included:
(a) Promote compliance with prescribed medications, diet, and other treatment measures by thoroughly explaining the need for each and the possible consequences of noncompliance.
(b) Review all activity limitations and restrictions.
(c) Counsel the patient on the action that should be taken when he is confronted with chest pain or other symptoms.
a. Heart failure is the clinical state in which there is inadequate cardiac output, resulting in poor perfusion of all organ systems.
b. In left sided heart failure, the pumping action of the left ventricle is compromised, but the right ventricle continues to function normally. There is an imbalance between the out-put of each ventricle. The right heart continues to pump blood into the lungs to be oxygenated. The failing left heart, however, is unable to return that same volume of blood to the systemic circulation. The result is an accumulation of blood in the pulmonary blood vessels. Increased pressure in the pulmonary vessels causes fluid to leak into the interstitial lung tissue, compromising gas exchange. This condition is called pulmonary edema.
c. Right sided heart failure usually follows left sided failure. The increased pressure in the pulmonary vessels causes "back pressure" to the right side of the heart. This interferes with venous return, and consequently, the organs of the body become congested. This condition, known as congestive heart failure (CHF), is manifested by neck vein distention and body edema.
d. Right sided failure may occur without left sided failure. This condition, called corpulmonale, may be caused by pulmonary hypertension secondary to lung disease or by the presence of pulmonary emboli.
e. Medical management of heart failure is twofold. The first concern of treatment is to stabilize the failure, relieving the edema and congestion. The second concern is to discover and treat the underlying cause of the failure.
f. Nursing care of the patient with heart failure involves two major areas: nursing intervention during the acute phase of illness and patient education to prepare the patient for discharge.
(1) During the acute phase, nursing considerations include the following:
(a) Monitoring fluid retention by weighing the patient daily.
(b) Monitoring intake and output.
(c) Frequent assessment of vital signs.
(d) Frequent monitoring of electrolytes.
(e) Promoting mental and physical rest to reduce the workload of the heart.
(f) Administration of prescribed medications to improve the heart's effectiveness as a pump.
(g) Administration of prescribed dietary restrictions (sodium and fluids).
(2) Patient education should include the following nursing considerations:
(a) Instruction on effective coping mechanisms that will reduce stress in daily living.
(b) Compliance in taking prescribed medications.
(c) Compliance in following the prescribed dietary and fluid restrictions.
(d) The importance of regular check-ups.
a. Hypertension (HTN) is defined as persistent levels of blood pressure with the systolic pressure greater than 150 mmHg and the diastolic pressure greater than 90 mmHg. Hypertension is a major cause of heart failure, kidney failure, and stroke.
b. Hypertension is classified as primary and secondary.
(1) Primary (or essential) HTN has no identifiable cause. Increased peripheral resistance is the basic cause for the elevated blood pressure, but the cause of the increased resistance is not understood. Drug therapy is aimed at decreasing the peripheral resistance, thereby lowering the blood pressure.
(2) Secondary HTN is the result of a specific cause or disease process. Kidney disease, adrenal tumors, thyrotoxicosis, and preeclampsia are just a few examples. Therapy is aimed at both treating the elevated pressures and treating the primary cause.
c. Hypertension is called the "silent killer" because it is often symptom free. When symptoms do occur, they are often mistakenly associated with other causes. Symptoms include headache, fatigue, nervousness, irritability, dyspnea, and edema.
d. Continued HTN is damaging to the body. Medical management is aimed at lowering the blood pressure to alleviate the symptoms and to slow the progression of damage to the body.
e. Nursing management involves intensive patient education to help the patient understand the nature of his disease and his role in keeping it under control. The nursing staff should reinforce the importance of the following:
(1) Taking medications as prescribed.
(2) Decreasing the use of tobacco and stimulants, such as caffeine.
(3) Eliminating table salt and avoiding foods high in sodium, such as pickles, potato chips, cold cuts, and processed foods.
(4) Controlling serum cholesterol levels by modifying the diet to avoid saturated fats.
(5) Maintaining a weight appropriate to height and body type.
(6) Altering one's lifestyle to minimize stress.
(7) Following a regular exercise program.
a. The function of the heart's valves is to maintain the forward flow of blood from the atria to the ventricles and from the ventricles into the great vessels.
b. Valvular damage interferes with this forward flow by stenosis (narrowing) of the valve or by impaired closure of the valve that allows a backward leakage of blood. This is called valvular insufficiency or regurgitation.
c. If the heart muscle itself remains strong, the circulatory mechanisms can adjust and compensate for a bad valve. These modifications are called compensatory changes.
d. Valve deficiencies cause two basic types of stress on the heart. If the stress produced is greater than the heart's ability to compensate, eventual deterioration will occur. The two types of heart stress associated with valve deficiencies are:
(1) Pressure overload (associated with valvular stenosis).
(2) Volume overload (associated with valvular insufficiency and regurgitation).
a. Infective (bacterial) endocarditis is a microbial infection of endocardial tissue. The endocardium is the layer of tissue that lines the heart's cavities and covers the flaps of its valves.
b. When an area of endocardium becomes inflamed, a fibrin clot called a vegetation may form. This clot will later form into a mass of scar tissue. The scarred endothelium becomes stiff, thick, and deformed. Vegetations on the valves may eventually cause chronic valvular disease.
c. Endocarditis is categorized as either acute or subacute. This is determined by the virulence of the causative organism.
(1) In acute infective endocarditis, the infecting organism is highly virulent, causing rapid and severe complications.
(2) In subacute infective endocarditis, the infecting organism is of low virulence. Severe complications do not occur until late in the illness, if at all.
d. Because standard medical treatment for infective endocarditis involves intravenous antimicrobial agents for a period of 4-6 weeks, the patient will require nursing intervention to prevent depression and alleviate the boredom that will result from the lengthy hospitalization. As the patient begins to feel better, he will feel confined and restricted by intravenous (IV).
e. Nursing management of patients with endocarditis includes the following:
(1) Obtain a history of allergies prior to the administration of antibiotics.
(2) Ensure patency of IV and prevent the complications of long- term IV therapy.
(3) Observe for signs and symptoms of complications such as CHF, renal failure, or emboli.
(4) Educate the patient about his condition and the need for continued treatment and prophylactic antibiotics.
(5) Teach the patient to recognize the symptoms of endocarditis and to seek medical assistance should symptoms recur.