Disorders of myocardial blood supply

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Information about Disorders of myocardial blood supply
Health & Medicine

Published on October 1, 2014

Author: Binabdallah4

Source: slideshare.net


disorders of myocardial blood supply

Department of Nursing Sciences, Faculty of Medicine, Ahmadu Bello University, Zaria. Topic; Disorders of myocardial blood supply By; ABDULLAHI Abbas (student 400level)

OUTLINE a) Blood supply to the heart b) Risk factors of coronary artery diseases c) Coronary artery diseases(C.A.D) d) Myocardial infarction e) Angina pectoris

Blood supply to the heart View slide

Coronary Circulation Coronary arteries; Right coronary artery; originates from the right aortic sinus, descends along the anterior side of the heart towards the right along the inferior border of the right auricle, then wraps posteriorly around the heart; gives rise to the following branches:  SA nodal artery- usually branches from the right coronary artery; supplies the SA node View slide

 Right marginal branch- supplies the right border of the heart  AV nodal artery- supplies AV node  Posterior interventricular artery- supplies both ventricles and the interventricular septum from the posterior side of the heart

Left coronary artery; originates from the left aortic sinus, descends along the anterior side of the heart towards the left, courses between the pulmonary trunk and the left auricle then bifurcates into the following branches:  Anterior interventricular branch (LAD)- descends along the anterior surface towards the apex supplying the left ventricle and interventricular septum  Circumflex branch- wraps posteriorly around the heart in the coronary sulcus, gives rise to the left marginal artery which supplies the left border of the heart.

Cardiac veins Coronary sinus; courses along the posterior side of the heart in the coronary sulcus; drains blood from the following cardiac veins to the right atrium;  Great cardiac vein (anterior interventricular vein)- ascends from the apex along the anterior side of the heart in the anterior interventricular sulcus.  Middle cardiac vein (posterior interventricular vein)- ascends from the apex along the posterior side of the heart in the posterior interventricular sulcus.

 Small cardiac vein- (right marginal vein)- courses with the right marginal artery, wraps around the right border of the heart in the coronary sulcus.  Anterior veins- originate on the anterior surface of the right ventricle, course over the coronary sulcus to drain directly into the right atrium.

CORONARY ARTERY DISEASE(C.A.D)  Is an abnormal accumulation of lipid or fatty substances and fibrous tissues in the lining of the coronary arterial vessels walls which lead to blockage and narrowing of the vessels in a way that reduces blood flow to the myocardium (muscles of the heart).

Risk factors of coronary artery diseases  Age and gender  Family history and genetic  Diabetes  Hypertension  Tobacco use  Sedentary lifestyle  hyperlipidemia  Obesity  Stress  Poor diet etc.

Clinical manifestation  Asymptomatic.  Chest pain (angina) because of decreased blood flow to heart muscle and/or increase in myocardial oxygen demand resulting from stress. Chest pain lasts between 3 to 5 minutes.  Chest pain can occur when the patient is resting.  Pain may radiate to the arms, back, and jaw.

 Chest pain occurs after exertion, excitement, or when the patient is exposed to cold temperatures because there is an increase in blood flow throughout the body, raising the rate.  Some times shortness of breath(dyspnea)  Fatigue  Anxiety  restlessness

pathophysiology Cholesterol, calcium and other elements Deposited on the coronary artery wall Narrowing of the artery and reduction of blood flow Impedes blood supply to the heart muscle Deposits start as fatty streaks and eventually develop into plaque

Diagnosis  History taking  Chest x-ray  Electrocardiograph  Cardiopulmonary angiography  Blood chemistry

Management  Treatment consists of;  Risk factor modification,  Life style changes,  Medications and,  revascularization.

 Weight loss.  Diet change: lower sodium, lower cholesterol and fat, decreased calorie intake, increased dietary fiber.  Administer low doses of aspirin.  Administer beta-adrenergic blockers to reduce workload of heart: metroprolol, propranolol, nadolol.  Administer calcium channel blockers to reduce heart rate, blood pressure,and muscle contractility; helps with coronary vasodilation; slows AV node conduction.

 Administer nitrate if patient has symptomatic chest pains to reduce discomfort and enhance blood flow to myocardium.  Platelet inhibitors:dipyridamole clopidogrel and ticlopidine.

 Administer HMG CoA reductase inhibitors (statins)—lowers cholesterol: a) lovastatin b) simvastatin c) atorvastatin d) fluvastatin e) pravastatin f) rosuvastatin  Fibric acid derivatives reduce synthesis and increase breakdown of VLDL particles: gemfibrozil.

Nursing diagnosis  Acute pain  Activity intolerance  Impaired gas exchange

Angina Pectoris  A narrowing of blood vessels to the coronary artery, secondary to arteriosclerosis,  results in inadequate blood flow through blood vessels of the heart muscle, causing chest pain.

Types of angina  Stable angina pectoris; pain is relieved by rest or nitrates and symptoms are consistent.  Unstable angina pectoris; pain occurs at rest; is of new onset; is of increasing intensity, force, or duration; isn't relieved by rest; and is slow to subside in response to nitroglycerin.  Prinzmetal angina pectoris; usually occurs at rest or with minimal formal exercise or exertion; often occurs at night.

causes  An episode of angina is typically precipitated by physical activity, excitement, or emotional stress.also due to diseases such as;  Coronary atherosclerosis  Anaemia  Polycythaemia  Aortic stenosis  Extreme cold  Smoking

pathophysiology . • Narrowing of coronary artery . • Inadequate blood flow through the heart ‘ • Reduced myocardial oxygenation that leads to discrepancy btw the oxygen and energy expended • Causing chest pain, which also radiate to left or both shoulders, arms, neck and jaws

Clinical manifestation  Chest pain lasting 3 to 5 minutes—not all patients get substernal pain; it may  be described as pressure, heaviness, squeezing, or tightness. Use the patient’s  words.  Can occur at rest or after exertion, excitement, or exposure to cold—due to  increased oxygen demands or vasospasm.  Usually relieved by rest—a chance to re-establish oxygen needs.

 Pain may radiate to other parts of the body such as the jaw, back, or arms—  angina pain is not always felt in the chest. Ask if the patient has had similar  pain in the past.  Sweating (diaphoresis)—increased work of body to meet basic physiologic  needs; anxiety.

 • Tachycardia—heart pumping faster trying to meet oxygen needs as anxiety  increases.  • Difficulty breathing, shortness of breath (dyspnea)— increased heart rate  increases respiratory rate and increases oxygenation.  • Anxiety—not getting enough oxygen to heart muscle, the patient becomes  nervous.

diagnosis  History taking  Electrocardiography  Echocardiograph  Coronary angiography  Radionuclide imagine  Basic screening; a) Fasting blood glucose b) Serum lipids including high density lipoproteins (HDL) and triglycerides c) Full blood count d) Blood urea and electrolytes e) Serum urates

management  The goal of treatment is to deliver sufficient oxygen to the heart muscle to meet its need, 2 to 4 liters of oxygen.  Administer beta-adrenergic blocker e.g. propranolol, nadolol, atenolol, metoprolol.  Administer nitrates—aids in getting oxygenated blood to heart muscle. a) Nitroglycerin—sublingual tablets or spray; timed-release tablets. b) Topical nitroglycerin—paste or timed-released patch.  Aspirin for antiplatelet effect.  Analgesic

Nursing diagnoses  Anxiety  Decreased cardiac output  Acute pain

Myocardial Infarction commonly known as heart attack Is when blood supply to the myocardium is interrupted for a prolonged time due to the blockage of coronary arteries resulting in insufficient oxygen reaching cardiac muscle,causing cardiac muscles to die (necrosis).

causes  Coronary atherosclerosis  Coronary thrombosis  Coronary embolism  Hypovolemic shock

pathophysiology Blockage of the coronary artery Resulting to insufficient oxygen supply Leading to death of the cardiac muscle(necrosis)

Clinical manifestation  Chest pain that is unrelieved by rest or nitroglycerin, unlike angina  Pain that radiates to arms, jaw, back and/or neck  Shortness of breath, especially in the elderly or women  Nausea or vomiting possible  Maybe asymptomatic, known as a silent MI, which is more common in diabetic patients  Heart rate >100 (tachycardia) because of sympathetic stimulation, pain, or low cardiac output

 Variable blood pressure  Anxiety  Restlessness  Feeling of impending doom  Pale, cool, clammy skin; sweating (diaphoresis)  Sudden death due to arrhythmia usually occurs within first hour

diagnosis  History taking  Electrocardiography(ECG)  Erythrocyte sedimentation rate(ESR)  Echocardiography  Radionuclide imaging  Cardiac enzyme analysis; creatinine phosphokinase, lactic dehydrogenase, and aspartate aminotransferase.

management  Treatment is focused on reversing and preventing further damage to the myocardium.  Early intervention is needed to have the best possible outcome  Administer oxygen, aspirin.  Administer antiarrhythmics because arrhythmias are common as are conduction disturbances. a) Amiodarone. b) Lidocaine. c) Procainamide.

 Electrical cardioversion for unstable ventricular tachycardia. An initial shock is administered to the heart to re-establish sinus rhythm.  Administer antihypertensive to keep blood pressure low e.g Hydralazine.  Percutaneous revascularization

 Administer thrombolytic therapy within 3 to 12 hours of onset because it can re-establish blood flow in an occluded artery, reduce mortality, and halt the size of the infarction. a) Alteplase. b) Streptokinase. c) Anistreplase. d) Reteplase.  Heparin following thrombolytic therapy.  Administer calcium channel blockers as they appear to prevent reinfarction and ischemia, only in non–Q-wave infarctions. e.g. Verapamil, Diltiazem.

 Administer beta-adrenergic blockers because they reduce the duration of ischemic pain and the incidence of ventricular fibrillation; decreases mortality. Propranolol. E.g. Nadolol, Metroprolol.  Administer analgesics to relieve pain, reduce pulmonary congestion, and decrease myocardial oxygen consumption.e.g. Morphine.  Administer nitrates to reduce ischemic pain by dilation of blood vessels; helps to lower BP.e.g Nitroglycerin.  Place patient on bed rest in CCU.  No bathroom privileges. Bedside commode only.  Low-fat, low-caloric, low-cholesterol diet.

Nursing diagnoses  Ineffective tissue perfusion  Decreased cardiac output

General complications of myocardial blood supply disorders  Myocardial ischemia  Pericarditis  Cardiogenic shock  Depression etc.


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