Unit 2: Myocardial Infarction (MI) Flashcards
Acute Myocardial Infarction
destruction of heart muscle from lack of oxygenated blood supply
-common cause of obstruction = atherosclerosis
Risk Factors for Heart Disease and MI
-cigarette smoking
-high LDLs
-type 2 diabetes
-elevated adrenaline (catecholamines)
-obesity
-inactivity
-hypertension
-male gender
-post menopausal female
-family hx
>can occur at any time
>most dangerous time = early morning hours; may be d/t higher levels of circulating adrenaline at this time
Atherosclerosis
gradual build up of plaque inside the wall of the artery
- rupture of plaque = thrombus formation and obstruction of coronary artery flow = ischemia and death of heart muscle
- heart muscle damaged by inadequate blood supply cannot maintain normal cardiac function = decrease in cardiac output (CO)
- systemic symptoms associated w/ MI = chest pain and poor peripheral perfusion
Stable Angina
episodes of intermittent chest pain present when artery is narrowed 60 to 70%
- associated w/ activity or exercise
- relieved by rest
- not associated w/ damage to heart muscle
- warning sign for potential heart muscle damage
Acute Coronary Syndrome
umbrella term -used when there is concern for myocardial ischemia >unstable angina (UA) >non-ST elevation MI (NSTEMI) >ST elevation MI (STEMI)
Unstable Angina
pain not associated w/ exercise
- not relieved by rest
- may present w/ ECG changes
- no elevation in cardiac markers
- may present w/ nonspecific or transient ST segment depressions or elevations
- emergency = requires immediate tx
Non-ST elevation MI (NSTEMI)
partial occlusion of a major coronary vessel or complete occlusion of a minor coronary vessel
- causes reversible partial thickness heart muscle damage
- ST depressions (0.5 mm at least) or
- T wave inversions (1.0 mm at least)
- w/o q waves in 2 contiguous leads w/ prominent R waves or AR/S ratio > 1
- elevated cardiac markers
ST Elevation MI (STEMI)
complete occlusion of a major coronary vessel
- results in irreversible full thickness heart muscle damage
- ST elevations
- elevated cardiac markers
Clinical Manifestations
-Chest Pain (angina); from obstructed blood flow to the heart muscle
-Angina can be stable or unstable
>Stable (exertional) angina: occurs during activity, has predictable pattern, goes away w/ rest
>Unstable (rest) angina: more serious; can occur at rest w/ no specific pattern, not relieved by change in activity, medical emergency
-angina is a warning sign of impending MI
Symptoms in addition to Chest Pain when there is a complete occlusion of the vessel resulting in an MI and muscle damage
- shoulder and arm pain (more on left)
- jaw and tooth pain
- shoulder blade pain
- upper back pain
- SOB
- nausea and vomiting
- sweating
- generalized fatigue
Things to consider w/ person to person
- symptoms can vary significally from person to person
- women are more likely to have neck, shoulder blade, jaw, and abdominal pain
- diabetes are more likely to have SOB and fatigue
- geriatrics tend to have co-morbidities may mimic angina; may experience dyspnea, syncope, weakness, or confusion
Right MI
right coronary artery/ventricle
- Jugular Vein Distention (JVD)
- Hypotension
- Bradycardia r/t damage to SA node
- Nausea and vomiting
Left MI
left coronary artery/ventricle
-worse prognosis; high risk of sudden death and congestive heart failure
-dyspnea
-tachycardia
-hypertension
>tachycardia and hypertension result from the loss of CO b/c of damage to the left ventricle and subsequent stimulation of sympathetic compensatory mechanisms
-hypotension will quickly evolve
Laboratory Testing
- Creatinine kinase (CK)
- Creatinine Kinase Myocardial Bands (CK-MB)
- Troponin (I and T)
- CMP, CBC, Coagulation, and ABGs
Laboratory Testing: Creatinine Kinase (CK)
general marker of cellular injury
-released from cells in the brain, skeletal muscle, and cardiac tissue after muscle damage has occurred
Laboratory Testing: Creatinine Kinase Myocardial Bands (CK-MB)
0-3 mg/dl
- CK isoenzyme marker specific to cardiac tissue
- when myocardial damage occurs, CK-MB is released from the cells
- can remain elevated for up to 36 hours before returning to normal
- increased levels can be seen at 3 hours after injury
Laboratory Testing: Troponin (T and I)
proteins expressed almost exclusively in the heart; specific marker of cardiac muscle damage
-less than 0.4 mg/ml (<0.4 mg/ml)
-can elevate within 4 hours of injury
-levels can stay elevated for up to 10 days
(b/c it stays elevated longer than CK-MB, it is a valuable marker when attempting to diagnose injury in recent past
-blood test of choice
Laboratory Testing: CMP
complete metabolic profile (CMP)
- electrolytes
- tests of organ system functioning (eg. Renal values: BUN + Creatinine)
Laboratory Testing: CBC
complete blood count (CBC)
-tests hemoglobin, hematocrit, and WBC
Laboratory Tests: Coagulation
- Prothrombin time (PT): 10-13 sec
- Activated Partial Thromboplastin Time (aPTT): 25-35 sec
- INR: <2.0
Diagnostic Tests for MI
Invasive + Noninvasive
- ECG
- Echocardiogram
- Stress testing
- Coronary Angiography
Electrocardiogram (ECG)
-gold standard for diagnosis of MI
-inexpensive, easy to perform, safe, painless
>ST depression = ischemia
>ST elevation = infarction
>Q wave = confirms MI (later on)
Echocardiography
- used to evaluate the ventricular functions (ejection fraction [EF])
- assists in diagnosing an MI by looking at specific areas of heart muscle that are not contracting (wall motion abnormalities)
Stress Testing
- not done during time an MI is evolving
- another way to evaluate heart function
- types: exercise stress test, dobutamine/adenosine test, stress echo, nuclear stress test
- dependent on pts needs and condition
- looks at coronary blood flow
- looks at left ventricular function and wall motion abnormalities
Nuclear Stress Test
best for diagnosing myocardial ischemia; reveals amount of viable heart muscle
Coronary Angiography
gold standard for the diagnosis of flow-limiting coronary artery disease
-allows visualization of any obstruction or narrowing of the coronary arteries
-involves catheter insertion into radial or femoral artery, and advanced up to the heart
-radiopaque dye injected through the catheter into the coronary artery while sequences of x-rays (fluoroscopy) are obtained
>a ventriculogram can also be performed; positioning the catheter to allow injected dye to enter the left ventricle; demonstrates how efficiently the left ventricle fills and pumps blood, how well blood flows through the aortic and mitral valves, and size of left ventricle
Treatment for MI
- maximizing oxygenation
- administering medications to control pain, dilate the coronaries, prevent clots, and decrease myocardial workload
- then therapies to increase blood flow to cardiac tissue, or reperfusion therapy (within 90 minutes)
Immediately upon arrival to the hospital, what should the patient recieve?
- Oxygen
- Sublingual (SL) nitroglycerin
- Aspirin
- Pain medication (morphine sulfate) if pain is not relieved by the SL nitroglycerin
Supplemental Oxygen
- recommended for all patients w/ a suspected MI
- used if in respiratory distress, if arterial saturation is less than 90%
- for patients w/ high risk of hypoxia
Nitroglycerin
dilates coronary arteries; increasing blood flow to the heart in an attempt to limit myocardial muscle damage and control pain
- one tablet sublingual q 5 minutes for a max of 3 doses as long as the patient maintains adequate BP
- if pain not controlled with 3 doses, IV nitroglycerin will be started
Aspirin
given to help prevent platelets from enlarging the existing clot or new clots from forming
Morphine Sulfate
can be given to control pain
- relieves chest pain
- masks pain symptoms; not improving coronary blood flow, potentially worsening MI
- used only if pain is not relieved by Nitroglycerin
Beta Blockers
> Metoprolol (Lopressor)
Atenolol (Tenormin)
-to decrease sympathetic nervous system response
-decreases myocardial workload and myocardial oxygen consumption
-not used in right coronary artery MI experiencing bradycardia
Heparin
heparin sodium infusion
- helps prevent new clot formation
- anticoagulant
Commonly Prescribed Medications for MI
- Antiplatelet: Aspirin, Clopidogrel (Plavix), Eptifibatide (integrilin)
- Anticoagulants: Heparin, Enoxaparin (Lovenox), Factor XA inhibitors
- Narcotics: Morphine Sulfate, Hydromorphone (Dilaudid)
- Beta Blocker: Metoprolol (Lopressor), Atenolol (Tenormin)
- Nitrates: (Nitroglycerin)
- Thrombolytics: (Alteplase (Activase), Reteplase (Retavase)
Thrombolytics
> Alteplase (Activase)
Reteplase (Retavase)
revascularization of the heart muscle by dissolving clots in arteries
Reperfusion Therapy
- Percutaneous Coronary Intervention (PCI)
- Fibrinolytic Therapy
Percutaneous Coronary Intervention (PCI)
most preferred method for opening blocked vessels that cause MI
- done within 90 minutes of arrival to hospital
- catheter w/ small balloon on its tip is inserted into an artery (radial or femoral) and advanced under fluoroscopy up to the left side of the heart and coronary arteries
- balloon is inflated and deflated to open the lumen of the blocked artery
- lumen opened –> a stent may be advanced to the location to hold the artery open and maintain adequate blood flow
- risk of bleeding
- femoral approach: need to lie flat w/o bending leg for 2 to 6 hours to allow artery to heal
- radial preferred; risk for internal bleeding eliminated; external bleeding easily compressed
- radial artery catheter removal–> compression device placed; no requirement for pt to remain immobile
Fibrinolytics
medications that accomplish revascularization through fibrinolysis of the existing clot
- administered within 30 minutes of arrival to hospital
- considered if not contraindicated and immediate PCI not available
Contraindications for Fibrinolytics
- recent surgery or bleeding
- presence of peptic ulcer
- uncontrolled hypertension
- pregnancy
- non-compressible vascular punctures
Complications of Fibrinolytics
- bleeding
- increased risk of intracranial hemorrhage
Coronary Artery Bypass Grafting (CABG)
surgical revascularization intervention that bypass blockages in the coronary arteries causing the myocardial muscle damage
-not first line; PCI and Fibrinolytics much quicker and do not require a surgical procedure
>in CABG, a healthy artery or vein is grafted to the blocked coronary artery; one end attached to the aorta while the other end is attached to the blocked coronary distal to the occlusion; by passing the blocked portion of the artery allowing blood to flow to the cardiac tissue
Indications for CABG
- unsuccessful PCI or not a candidate for PCI
- failure of medical management
- critical left main or 3 vessel disease
Complications of CABG
- bleeding
- dysrhythmias
- MI
- stroke
- nonunion of sternum
- sternal infection
- renal failure b/c of decreased renal blood flow
- heart failure
Complications of Bypass
- induction of a systemic inflammatory response resulting in vasodilatory shock
- heparin-induced thrombocytopenia
- activation of platelets
- complications associated w/ cross clamping the aorta during the procedure
Secondary Prevention
- cardiac rehabilitation after acute cardiovascular event (MI), percutaneous intervention, or surgical revascularization
- supervised exercise program
- education regarding diet, weight management, medication purpose and side effects, psychosocial support
- Goal: improve recovery from event; improve quality of life
- evaluated by cardiac specialists
Complications of MI
- Heart Failure
- Arrhythmias
- Cardiogenic Shock
Complication of MI: Heart Failure
when an MI causes a large amount of heart muscle to die, there is decreased left ventricular function
-inability to produce an adequate cardiac output (CO) to maintain body’s metabolic demands
Complication of MI: Arrhythmias
> Asystole
Symptomatic bradycardia
Heart Block
Ventricular arrhythmias
-asystole, symptomatic bradycardia, and heart block are associated w/ sinoatrial (SA) node dysfunction; most common after an inferior wall MI b/c the right coronary artery supplies the SA node (located in R atrium)
-temporary pacemaker may be used to prevent asystole
-ventricular arrhythmias occur in first 48 hours of MI
-immediate defibrillation tx of choice for v-fib and pulseless ventricular tachycardia
Nursing Management: Assessment + Analysis of MI
the clinical manifestations of MI is r/t lack of oxygen delivery to the heart and resulting decrease of cardiac output
- chest pain
- shortness of breath
- nausea/vomiting
- dizziness
- diaphoresis and pallor
Women may present w/ clinical manifestations of:
- neck, shoulder blade, and jaw pain
- abdominal pain
Older Adults/ Geriatrics may show clinical manifestations of:
- dyspnea
- syncope
- weakness
- confusion
- pts can be tachycardic w/ borderline low BP
Nursing Assessments for MI
- Vital signs
- Pulse Oximetry
- Characteristics of Pain
- Assess ECG changes
- Assess for restlessness
- Skin color and temperature, diaphoresis
- Peripheral pulses
- Urine output
- Asses Troponin, CK, CK-MB Levels
Assessments: Vital Signs + Pulse Oximetry
-tachycardia w/ a borderline low BP and decreased Sp02 = inadequate CO and oxygen delivery (DO2)
Assessments: Characteristics of Pain
> location, radiation, duration, intensity, precipitating/alleviating factors
use 1 to 10 pain scale
-chest pain is an indication of MI
-continued or changing pain characteristics can be indicative of a worsening condition
Assessments: ECG Changes
- ST-segment depression = ischemia
- ST segment elevation = injury
- if present, Q wave is diagnostic for MI
Assessment: Assess for Restlessness
- may be found in early stages of MI
- progression to severe anxiety and sense of doom is a late-stage symptom
Assessment: Skin color, Temperature, Peripheral pulses, Diaphoresis
- decreased pulses and cold, clammy, pale skin
- signs of inadequate tissue perfusion and inadequate CO
- activation of the sympathetic nervous system w/ low BP will stimulate diaphoresis
Assessment: Urine Output
decreased or absent urine output is a sign of decreased renal perfusion r/t decreased CO
Assessment: Troponin, CK, CK-MB
> Troponin: protein released from damage cardiac muscle; elevates within 4 hours; can stay elevated for up to 10 days
CK-MB: the CK isoenzyme marker specific to cardiac tissue is released from cells w/ cardiac muscle damage; increased levels seen at 3 hours; remain elevated for 36 hours
Post CABG Assessments
- Monitor HR and BP continuously w/ an arterial catheter at least q 15 minutes initially, then q 4 hours when stable
- Hemodynamic monitoring
- Continuous cardiac monitoring
- Assess heart tones
- Monitor breath sounds and continuous Sp02
- Monitor core temperature hourly
- Assess LOC, pupils and responsiveness
- Hourly intake and output
- Skin color, temperature, pulses, edema, capillary refill
- chest tube output, color, and volume hourly
- hemoglobin, hematocrit, electrolytes, creatinine and BUN, glucose
- incision for drainage, warmth, redness, or swelling
Post CABG Assessment: Monitor HR and BP w/ an arterial catheter q 15 min initially, q 4 hours when stable
-tachycardia, bradycardia, hypotension, or hypertension may be signs of decreased CO or compensatory mechanisms
Post CABG Assessment: Hemodynamic monitoring
-decreased preload (CVP, PAOP), Sv02 may indicate decreased CO; poor tissue perfusion
Post CABG Assessment: Continuous cardiac monitoring
-dysrhythmias common after CABG
Post CABG Assessment: Heart tones
- muffled may = tamponade
- S3, S4 and crackles may = heart failure
Post CABG Assessment: Breath sounds and continuous Sp02 monitoring
- decreasing saturation may = pulmonary complications
- diminished or unilateral absent breath sounds may = atelectasis, pleural effusions, or pneumothorax
Post CABG Assessment: Monitor core temperature hourly
- hypothermia during surgery reduces metabolic rate and risk of organ ischemia
- re-warming may produce hypotension from vasodilation
- core temp most reliable
Post CABG Assessment: Assess LOC, pupils and responsiveness
- assess effectiveness of sedation
- evaluates neurological function
Post CABG Assessment: Hourly intake and output
- notify provider for output less than 30 ml/hr for 2 hours
- decreased urine output may be a sig of renal damage or decreased CO
Post CABG Assessment: Assess skin color, temperature, pulses, edema, capillary refill
- pale, cool skin w/ delayed capillary refill and weak pulses may = decreased CO
- edema can be expected response after CABG r/t fluid resuscitation during surgery
Post CABG Assessment: Monitor Chest tube output, color, and volume hourly
-sudden increases in output greater than 100 to 200 mL not associated w/ position changes or increased bright red drainage may = hemorrhage and the need to return to OR
Post CABG Assessment: Assess Hemoglobin, hematocrit, electrolytes, creatinine and BUN, Glucose
- changes may indicate bleeding, fluid shifts, and renal dysfunction
- tight glucose control associated w/ improved outcomes
Post CABG Assessment: Assess incision site for drainage, warmth, redness, swelling
may = infection
Nursing Actions for an MI
-Administer oxygen
-Insert 2 large bore-IVs (medication delivery, fluid resuscitation)
-Administer medications:
>Aspirin and Heparin: prevent new clot formation
>Nitroglycerin SL: dilates coronary arteries; increasing blood flow and decreasing pain
>Morphine: narcotic given for pain relief if nitroglycerin not effective
>Beta Blockers: decrease sympathetic response to an MI, decreasing cardiac workload and oxygen consumption
>Fibrinolytics: work to dissolve clots
-Continuous ECG monitoring
-Bed Rest: to decrease oxygen and cardiac demands
Nursing Actions Post CABG
- Maintain tight BP control
- Administer fluids + Meds as ordered (vasodilators, vasoconstrictors, inotropes, and diuretics)
- Rewarm patients slowly w/ warm fluids, blankets, or airflow devices. Prevent shivering
- Administer pain medication and continuous sedation medication
- Pulmonary hygiene while intubated (reposition frequently, suction PRN, oral care q 4 hours)
- Pulmonary hygiene after extubation (incentive spirometry, cough and deep breathe q 1 to 2 hours while awake; chest splinting when coughing)
- Plan for and initiate early mobility or ambulation
- Wound Care: initial dressing to be removed or changed by provider, then change daily or PRN
Nurse Teaching for MI
- immediately report s/s of MI: chest pain, chest discomfort, or increased SOB
- purpose, dose, and side effects of meds
- AHA “Life’s Simple 7”
Nurse Teaching Post CABG
- infection
- sternal precautions
- cardiac rehab
Sternal Precautions for Post CABG
- do not lift weight over 10 lbs
- do not raise arms overhead
- do not bend at waist
- do not participate in vigorous activity until cleared
Participate in Cardiac Rehab
- medical evaluation
- exercise training and physical activity counseling
- coronary risk factor reduction/secondary prevention
- nutritional counseling + weight management
- purpose of medications
- medication side effect
- effects on exercise tolerance
- reinforce medication adherence
Evaluating Care Outcomes
- free from pain
- normal vital signs
- improved Sp02
- signs of decreased perfusion from inadequate CO (cool extremities, weak pulses, decreased urine output) are resolving
AHA “Life’s Simple 7”
- No smoking of cigarettes or other tobacco products
- Maintain normal body weight
- Exercise for at least 150 minutes w/ moderate-intensity activity, or 75 minutes of vigorous-intensity or combo of both each week
- Eat a healthy diet
- Maintain total cholesterol less than 200 mg/dl
- Keep BP less than 120/79 mmHg
- Fasting glucose less than 100 mg/dl
