Coronary Artery Disease
January 13, 2009 · 5 Comments
- Is characterized by the accumulation of plaque within coronary arteries, which progressively enlarge, thicken and calcify. This causes critical narrowing of the coronary artery lumen (75% occlusion), resulting in a decrease in coronary blood flow and an inadequate supply of oxygen to the heart muscle.
- Ischemia may be silent (asymptomatic but evidenced by ST depression of 1 mm or more on electrocardiogram (ECG) or may be manifested by angina pectoris (chest pain).
- Risk factor for Coronary Artery Disease include dyslipidemia, smoking, hypertension, male gender (women are protected until menopause), aging, non-white race, family history, obesity, sedimentary lifestyle, diabetes mellitus, metabolic syndrome, elevated homocysteine, and stress.
- Acute coronary syndrome is a complication of CAD due to lack of oxygen to the myocardium. Mnaifestations include unstable angina, non ST-segment elevation infarction, and ST-segment elevation infarction.
- Other causes of angina include coronary artery spasm, aortic stenosis, cardiomyopathy, severe anemia, and thyrotoxicosis.
- Character. Substernal chest pain, pressure, heaviness, or discomfort. Other sensations include a squeezing, aching, burning, choking, strangling, or cramping pain.
- Severity. Pain maybe mild or severe and typically present with a gradual buildup of discomfort and subsequent gradual fading away.
- Location. Behind middle or upper third of sternum; the patient will generally will make a fist over the site of pain (positive Levine sign; indicates diffuse deep visceral pain), rather than point to it with fingers.
- Radiation. Usually radiates to neck, jaw, shoulders, arms, hands, and posterior intrascapular area. Pain occurs more commonly on the left side than the right; may produce numbness or weakness in arms, wrist, or hands.
- Duration. Usually last 2 to 10 minutes after stopping activity; nitroglycerin relieves pain within 1 minute.
- Precipitating factors. Physical activity, exposure to hot or cold weather, eating a heavy meal, and sexual intercourse increase the workload of the heart and, therefore, increase oxygen demand.
- Associated manifestation. Diaphoresis, nausea, indigestion, dyspnea, tachycardia, and increase in blood pressure.
- Signs of unstable angina:
- A change in frequency, duration, and intensity of stable angina symptoms.
- Angina pain last longer than 10 minutes, is unrelieved by rest or sublingual nitroglycerin, and mimics signs and symptoms of impending myocardial infarction.
- Resting ECG may show left ventricular hypertrophy, ST-T changes, arrhythmias, and possible Q waves.
- Exercise stress testing with or without perfusion studies shows ischemia.
- Cardiac catheterization shows blocked vessels.
- Position emission tomography may show small perfusion defects.
- Radionuclide ventriculography shows wall motion abnormalities and ejection fraction.
- Fasting blood levels of cholesterol, low density lipoprotein, high density lipoprotein, lipoprotein A, homocysteine, and triglycerides may be abnormal.
- Coagulation studies, hemoglobin level, fasting blood sugar as baseline studies.
- Antianginal medications (nitrates, beta-adrenergic blockers, calcium channel blockers, and angiotensin converting enzyme inhibitors) to promote a favorable balance of oxygen supply and demand.
- Antilipid medications to decrease blood cholesterol and tricglyceride levels in patients with elevated levels.
- Antiplatelet agents to inhibit thrombus formation.
- Folic acid and B complex vitamins to reduce homocysteine levels.
- Percutaneous transluminal coronary angioplasty or intracoronary atherectomy, or placement of intracoronarystent.
- Coronary artery bypass grafting.
- Transmyocardial revascularization.
- Monitor blood pressure, apical heart rate, and respirations every 5 minutes during an anginal attack.
- Maintain continuous ECG monitoring or obtain a 12-lead ECG, as directed, monitor for arrhythmias and ST elevation.
- Place patient in comfortable position and administer oxygen, if prescribed, to enhance myocardial oxygen supply.
- Identify specific activities patient may engage in that are below the level at which anginal pain occurs.
- Reinforce the importance of notifying nursing staff whenever angina pain is experienced.
- Encourage supine position for dizziness caused by antianginals.
- Be alert to adverse reaction related to abrupt discontinuation of beta-adrenergic blocker and calcium channel blocker therapy. These drug must be tapered to prevent a “rebound phenomenon”; tachycardia, increase in chest pain, and hypertension.
- Explain to the patient the importance of anxiety reduction to assist to control angina.
- Teach the patient relaxation techniques.
- Review specific factors that affect CAD development and progression; highlight those risk factors that can be modified and controlled to reduce the risk.