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Understanding the Cardiovascular System
Cardiovascular System Disorders
Coronary Artery Disease
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.
Risk Factors promoting Coronary Artery Disease
Risk factors that cannot be changed (non-modified) are age, sex, race, genetic make-up, and family history.
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.
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.
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.
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).
Coronary Heart Disease
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 coronary artery disease.
The major diseases of CHD are:
Angina Pectoris: A clinical syndrome of ischemic heart disease.
Myocardial Infarction: An imbalance between oxygen demand and oxygen supply to the myocardium.
Congestive Heart Failure: A condition in which the heart's function as a pump is inadequate to meet the body's needs.
Sudden Cardiac Death: The sudden cessation of the heartbeat and circulation.
Angina pectoris is a clinical syndrome of ischemic heart disease, manifested by paroxysmal pain in the chest and adjacent areas.
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.
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 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.
Angina Pectoris (Continued)
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.
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.
Acute Myocardial Infarction
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).
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.
Acute Myocardial Infarction (Continued)
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.
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.
This diagnostic method is recognized for precision in detecting congenital cardiac defects. Individual chambers of the heart are visualized, pathways for the blood stream are demonstrated, and chamber enlargement can be seen.
The opaque medium may cause a flushing sensation as it flows through the body. If necessary, the studies may be conducted under mild anesthesia. After one complete circulation, the opaque media is so diluted that it is no longer visible by x-ray.
No special preparation of the patient is necessary unless anesthesia is to be given. In that event, food may be withheld prior to the studies. A record of the patient's weight should be sent to the x-ray department with him.
Heart failure is the clinical state in which there is inadequate cardiac output, resulting in poor perfusion of all organ systems.
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.
Right sided heart failure
Right Sided Heart Failure
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.
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.
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.
Hypertension is classified as primary and secondary.
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.
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.
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.
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.
Nursing management of a patient with hyper tension 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:
Taking medications as prescribed and decreasing the use of tobacco and stimulants, such as caffeine.
Eliminating table salt and avoiding foods high in sodium, such as pickles, potato chips, cold cuts, and processed foods.
Controlling serum cholesterol levels by modifying the diet to avoid saturated fats.
Maintaining a weight appropriate to height and body type.
Altering one's lifestyle to minimize stress and following a regular exercise program.
END of UNIT
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