CAD and ACS
Diagnostic Tests
* 12 Lead EKG - PRIORITY * Troponin - highly specific to myocardial tissue CK-MB - increases with cardiac necrosis Myoglobin - first cardiac biomarker PT/INR CXR - rule out pneumonia CBC and Chem7 - White blood cell count would increase in the first days after myocardial infarction because of the inflammatory response associated with myocardial cell death. C-Reactive Protein - is a marker for inflammation and elevated levels can predict cardiac disease. D-Dimer - rule out PE CT - rule out PE Echo - ejection fraction Stress Test - on a treadmill to see changes in EKG With acute coronary syndrome, ECG changes indicating myocardial injury and infarction occur within minutes. Because treatment for ACS usually involves actions to restore blood flow to the myocardium as rapidly as possible, it is essential that the ECG be done and evaluated immediately. The other tests are also appropriate but will be done after the ECG. Changes in the chest radiograph will occur if there is cardiac enlargement, pericardial effusion, or heart failure secondary to myocardial infarction. Troponin T will increase in an average of 4 to 6 hours with myocardial infarction. CK-MB starts to increase at about 6 hours after myocardial infarction.
Pathogenesis of Atherosclerosis
1. Chronic endothelial injury; damage to endothelium allows lipids to leak into intima - HTN, tobacco use, hyperlipidemia, hyperhomocysteinemia, diabetes, infections, toxins 2. Fatty streak; lipids are oxidized and then consumed by macrophages via scavenger receptors, resulting in foam cells (leads to fatty streak) - lipids accumulate and migrate into smooth cells 3. Fibrous plaque; inflammation and healing lead to deposition of extracellular matrix and proliferation of smooth muscle (leads to fibromuscular cap), thickening of the the arterial wall -collagen covers fatty streak, vessel lumen is narrowed, blood flow is reduced, and fissures can develop 4. Complicated lesion; as fibrous plaque grows, continued inflammation can result in plaque instability, ulceration, and rupture. Once it ruptures, platelets accumulate in large number, leading to further narrowing or total occlusion. - plaque rupture, thrombus formation, and further narrowing or total occlusion of vessel
Types of Angina
Angina - chest pain, is the clinical manifestation of myocardial ischemia. Is caused by either an increased demand for O2 or a decreased supply of O2 ----------------------------------------------------- Silent ischemia - Ischemia that occurs in absence of any subjective symptoms. Associated with diabetic neuropathy affecting the nerves that innervate the cardiovascular system. Confirmed by ECG changes (ST depression and/or T wave inversion). Prinzmetal's angina (Varient Angina) - Rare, occurs at rest and not with increased physical demand. Can be seen in patients with a Hx of migraine headaches, Raynaud's phenomenon, and heavy smoking. Spasm (strong contractions of smooth muscle) of a major coronary artery results from increased intracellular calcium. Spasms could be due to alcohol, cocaine, medications that narrow blood vessels, or cold weather exposure. Coronary vasospasm. Microvascular angina - Syndrome X (MVD). Chest pain occurs on the absence of significant CAD or coronary spasm of a major coronary artery and is related to myocardial ischemia associated with atherosclerosis or spasm of the small distal branch vessels or the coronary microcirculation (MVD). Prevention and treatment follows CAD recommendations. Often angina is prolonged and brought on by physical exertion (usually a positive stress test). Myocardial ischemia from microvascular disease affecting the small, distal branches of the coronary arteries.
Cardiac Catheterization Laboratory (Cath Lab)
Cardiac Catheterization and Coronary Angiography Visualize blockages (diagnostic) Open blockages (interventional) - percutaneous coronary intervention (PCI) - balloon angioplasty and stent; goal is 90 min Management: monitor for recurrent angina frequent VS, including cardiac rhythm Monitor catheter insertion site for bleeding Neuromuscular assessment Acute renal failure Bed rest per institutional policy REPERFUSION IS CRITICAL
cardiac catheterization (CC)
Cath Lab A procedure in which a thin, flexible tube (catheter) is guided through a blood vessel to the heart to diagnose or treat certain heart conditions, such as clogged arteries or irregular heartbeats. For STEMI patients, within 90 min of presentation For UA or NSTEMI patients, during hospitalization to diagnose and evaluate the extent of the disease
coronary angiography
Cath Lab A procedure that uses X-ray imaging to see your heart's blood vessels. The test is generally done to see if there's a restriction in blood flow going to the heart. Coronary angiograms are part of a general group of procedures known as heart (cardiac) catheterizations.
Chronic Stable Angina
Chest pain that occurs intermittently over a long period with the same pattern of onset, duration, and intensity of symptoms Etiology: Myocardial ischemia (usually from CAD) caused by an O2 supply/demand mismatch It is often provoked by physical exersion, stress, or emotional upset. Usually only lasts a few minutes and often subsides when the precipitating factor subsides (resting, calming down, using sublingual nitroglycerin). Episodic pain. With ischemia, 12-lead ECG shows ST segment depression and/or T wave inversion. This represent inadequate supply of blood and O2 to the heart muscle. Controlled by drugs. Since chronic stable angina it is often predictable, drugs are timed to provide peak effects during the time of day when the angina is liking to occur. The goal is to either decrease O2 demand and/or increase O2 supply. - Short acting nitrates, long acting nitrates, Angiotensin-converting enzyme inhibitors (ACE) and Angiotensin receptor blockers (ARBs), B-Blockers, Calcium channel blockers, and lipid lowering drugs - this decreases cardiac workload PQRST Assessment P - Precipitating events: events or activities precipitated the pain or discomfort (argument, exercise, resting) Q - Quality of Pain: what does the pain feel like (pressure, dull, aching, tight, squeezing, heaviness) R - Region and Radiation: the location and where is it radiating to (back, neck, arms, jaw, shoulder, elbow) S - Severity of pain: on a scale of 0 - 10 T - Timing: when did it start, has it changed since then, has it happened before
12 Lead EKG/ECG
Definitive ECG changes occur in leads that face the area of ischemia, injury, or infarction. Reciprocal changes may occur in leads facing opposite the area of ischemia, injury, or infarction
Cardiac troponins
Elevations of troponin I and T levels are indicative and specific for cardiac muscle damage as would occur with STEMI. Cardiac troponins are released into circulation within hours after myocardial injury or infarction, and elevation in troponin levels helps determine that the client is experiencing ACS. Will be most important for the nurse to monitor to determine whether a client with chest pain has acute coronary syndrome (ACS)
Coronary Artery Bypass Graft (CABG)
Is a procedure that uses your own veins (usually from the legs) or arteries (usually from the chest or arm) to bypass narrowed areas and restore blood flow to heart muscle. Generally, blood vessels can be obtained from four areas of the body: the chest, leg, arm, and abdomen. With coronary artery bypass graft (CABG) surgery, a leg vein or an artery taken from the chest or arm is grafted from the aorta (the major blood vessel exiting the heart) onto the coronary artery, beyond the narrowed segment. This bypasses the diseased section and restores blood flow to the area of the heart muscle supplied by that artery. Often, more than one graft is placed. Requires sternotomy and cardiopulmonary bypass (CPB) Complications related to CPB - oxygenator failure, pump malfunction, clotting in the circuit, tubing rupture, gas supply failure and electrical failure due to which hand cranking must be available at all times. Management: ICU for first 24 - 36 hours Assess patient for bleeding Monitor hemodynamic status Pleural/mediastinal chest tubes Continuous ECG ET tube with MV Epicardial pacing wires Urinary catheter NG tube Replace blood and electrolytes PRN Assess fluid status Restore temperature (must be cold during surgery) DVT prevention
ECG evolution with ACS
Ischemia - ST depression, T wave inversion Injury - ST elevation, physiologic Q wave Infarction - Pathologic Q wave (abnormally wide (>0.2 second) or abnormally deep (>5 mm)), ST elevation, and T wave inversion
CAD risk factors
NONMODIFIABLE -Age -Gender -Ethnicity -Family Hx -Genetic predisposition MODIFIABLE -Smoking/second hand smoke -Hypertension -Obesity -Cholesterol/increased serum lipids -Physical inactivity CONTRIBUTING MODIFIABLE -Diabetes -Metabolic Syndrome -Psychologic stress -Homocysteine level (amino acid) -Substance abuse
Unstable Angina (UA)
Non-ST segment-elevation myocardial infarction (NSTEMI) Is chest pain that is new in onset, occurs at rest, or occurs with increasing frequency, duration, or less effort than the patients chronic stable angina pattern Lasts 10 minutes or more May develop from chronic stable angina or be the first clinical sign of CAD. Development from chronic stable angina, it is usually described as a significant change in pattern of angina. Occurs with increasing frequency and is easily provoked by minimal exertion, during sleep, or even at rest. Unpredictable and must be treated immediately ECG often includes ST depression and/or T wave inversion (ischemic changes) Symptoms in women are often under-recognized
When a client comes to the emergency department with moderate substernal chest pain that is unrelieved by rest and nitroglycerin, which prescribed action has the highest priority? Administer morphine sulfate. Transfer to the coronary care unit. Obtain a 12-lead electrocardiogram (ECG). Have a blood specimen drawn for troponin studies.
Obtain a 12-lead electrocardiogram (ECG). Current guidelines state that an ECG should be done and reviewed by the health care provider within 10 minutes of the arrival of a client with possible acute coronary syndrome. The other actions are also essential: Administration of morphine sulfate will be done to relieve pain, but the ECG has priority, because the presence or absence of ECG changes will determine whether the client needs immediate interventions such as percutaneous coronary intervention or thrombolysis. The client will be transferred as quickly as possible to the coronary care unit, but the ECG would be done in the emergency department. Obtaining blood for troponin should be done as quickly as possible, but presence or absence of elevated troponin will not affect decision-making about the client's immediate care.
MI clinical manifestations
PAIN - Severe chest pain not relieved by rest, position change, or nitrate - common locations are substernal and epigastric area, may be mistaken as acid reflux/indigestion - may radiate to the neck, lower jaw, and arms or to the back Catecholamine release and stimulation of SNS - norepinephrine and epinephrine - results in diaphoresis, increased HR and BP, and vasoconstriction of peripheral blood vessels - skin may be ashen clammy, and cool to the touch Cardiovascular - Initially, increased HR and BP, then decreased BP because of a decrease in CO - Crackles, SOB - JVD, hepatic engorgement, and peripheral edema may mean right ventricular dysfunction - Abnormal heart sounds (S3 and S4, LV dysfunction) N/V - reflux stimulation due to severe pain Fever - may increase to 100.4 F (38 C) within 24 - 48 hours and may last for 4 - 5 days - increase in temperature is due to a systemic inflammatory process caused by the death of myocardial cells
When a client who is admitted for coronary artery bypass graft (CABG) surgery asks the nurse about the purpose of pacemaker wires inserted during surgery, which explanation will the nurse give? Defibrillation of the heart after surgery Prevention of slow heart rate after surgery Maintenance of rate of at least 100 beats/minute during surgery Inhibition of too-rapid heart rate during the postoperative period
Prevention of slow heart rate after surgery Pacing wires are sometimes placed during CABG so that pacing is rapidly available in case of bradycardia during the postoperative period. Pacing wires are not use for defibrillation. The heart is usually placed into cardiac arrest during CABG to facilitate the suturing of grafts into place. Medications to slow heart rate would be used rather than overdrive pacing during the postoperative period after CABG.
Which intervention would the nurse perform when caring for a client in the emergency department reporting chest pain? Select all that apply. One, some, or all responses may be correct. Providing oxygen Assessing vital signs Obtaining a 12-lead EKG Drawing blood for cardiac enzymes Auscultating heart sounds Administering nitroglycerin
Providing oxygen Assessing vital signs Obtaining a 12-lead EKG Drawing blood for cardiac enzymes Auscultating heart sounds Administering nitroglycerin The nurse would provide oxygen to a client with chest pain, as the heart may be getting insufficient oxygen as a result of occluded coronary vessels. The nurse would also assess the client's vital signs, obtain a 12-lead EKG, and auscultate heart sounds to determine rhythm changes related to cardiac ischemia. The nurse would need to draw blood for evaluation of cardiac enzymes. Changes in the levels of these enzymes (including troponin, creatine kinase, and myoglobin) can indicate damage to heart tissue. Nitroglycerin is administered to promote coronary vasodilation.
Which finding for a client who has just returned to the nursing unit after an emergency cardiac catheterization would be most important to report to the primary health care provider? Anxiety about the results of the procedure ST-segment elevation on the electrocardiogram Pain at the femoral artery catheter insertion site Premature atrial contractions on the cardiac monitor
ST-segment elevation on the electrocardiogram Embolization of plaque or injury to the coronary artery during catheterization may cause acute myocardial infarction. ST-segment elevation is a sign of acute myocardial injury and would be reported immediately because actions such as emergency coronary artery stent placement may be needed. Anxiety about test results is a common concern, but does not require immediate action by the health care provider. Pain at the arterial puncture site is attributable to entry and cannulation of the artery and is a common complaint after a cardiac catheterization. Premature atrial contractions usually do not require treatment, although the nurse will continue to monitor for dysrhythmias.
Serum Cardiac Biomarkers
are proteins released into the blood from necrotic heart muscle after an MI and are important in the diagnosis of MI ------------------------------------------------ Troponin - cTnT and cTnI - are highly specific indicators of MI and have greater sensitivity and specificity for myocardial injury than Creatine-kinase MB (CK-MB) - Troponins are released into circulation within 2 to 4 hours after myocardial infarction (MI) and are not found in healthy adults, so elevated troponin levels indicate myocardial necrosis. CK-MB - CK levels, especially the creatine phosphokinase (MB) subunit, increase with myocardial necrosis within 3 to 6 hours, but are not as sensitive as troponin testing for acute myocardial necrosis. - CK-MB is found in cardiac muscle and levels increase with myocardial cell death. Myoglobin - first serum cardiac biomarker, but lacks cardiac specificity - Although myoglobin is one of the first cardiac markers to increase after an MIMI, it lacks cardiac specificity.
Atherosclerosis
condition in which fatty deposits called plaque build up on the inner walls of the arteries lipid deposits within the intimate of the artery, it is a major cause of CAD endothelial injury and inflammation play a major role in the development athere - "fatty mush" skleros - "hard"
Myocardial Infarction (MI)
heart attack; occurs due to an abrupt stoppage of blood flow through a coronary artery with a thrombus caused by platelet aggregation. - Preexisting CAD or STEMI (occlusive thrombus) causes irreversible myocardial cell death (necrosis) beyond the blockage due to ischemia (loss of blood flow) as a result of an occlusion of a coronary artery; usually caused by atherosclerosis ST-segment-elevation myocardial infarction (STEMI); Total occlusion of the coronary artery infarction: obstruction of the blood supply to an organ or region of tissue, typically by a thrombus or embolus, causing local death of the tissue.
12 Lead EKG/ECG Placement
limb leads (RA: right arm, LA: left arm, RL: right leg, LL: left leg) and chest leads (V1, V2, V3, V4, V5, V6). RA: Placed on the right arm or right below the right clavicle LA: Placed on the left arm or right below the left clavicle RL: Placed on the right leg or upper right quadrant LL: Placed on the left leg or upper left quadrant V1: Placed in the fourth intercostal space to the right of the sternum V2: Placed in the fourth intercostal space to the left of the sternum V3: Placed directly between leads V2 and V4 V4: Placed in the fifth intercostal space in the mid-clavicular line V5: Placed level with V4 at the left anterior mid-axillary line V6: Placed level with V5 at the mid-axillary line
Acute Coronary Syndrome (ACS)
may develop when chest pain from ischemia that is prolonged and not immediately reversible Non-ST elevation acute coronary syndrome; Partial occlusion of coronary artery - Unstable Angina (UA) - Non-ST segment-elevation myocardial infarction (NSTEMI) ST-segment-elevation myocardial infarction (STEMI); Total occlusion of the coronary artery -------------------------------- Elevation or depression of the ST segment is indicative of ACS because of changes in cardiac electrical activity that occur with ischemia and injury. P wave changes are not used to diagnose ACS. Changes in the QRS complex do not occur with ACS. Changes in the PR interval are not diagnostic of ACS.
Coranary Artery Disease (CAD)
type of blood vessel disorder that is considered in the general category of atherosclerosis; a chronic and progressive disease caused by plaque formation of cornary arteries, leads to restricted blood flow to the heart tissue. Leads to chronic stable angina and acute coronary syndrome. Can lead to unstable angina and non-ST segment-elevation MI OR ST-segment-elevation MI other descriptions of CAD: Arteriosclerotic heart disease ASHD, Chronic valvular heart disease CVHD, ischemic heart disease IHD, coronary heart disease CHD