Acute Coronary Syndromes & Cardiac Surgery

Question 1

MI - Epidemiology

• More than 1 in 3 adults lives w/1 or more types of CVD
• Contributing risk factors for heart disease & MI include
  > cigarette smoking, hyperlipidemia, type 2 diabetes
  > elevated adrenaline (catecholamines), obesity, inactivity, HTN

Question 2

Pathophysiology

• Atherosclerosis is the gradual buildup of plaque inside the wall of the artery from CHRONIC INFLAMMATION
• Rupture of this plaque results in thrombus formation & obstructs coronary artery flow

Answer 2

• Ischemia & death of heart muscle are the eventual outcomes
• Heart muscle damaged by inadequate blood supply cannot maintain normal cardiac function, which results in decreased CO & systemic sx’s assoc w/MI

Question 3

Recognize Cues/MI Risk Factors - Non-modifiable

• Age
• Gender
• Fhx
• Ethnic background

Answer 3

Modifiable

• Elevated serum cholesterol
• Cigarette smoking
• HTN
• Impaired glucose tolerance/DM
• Obesity
• Excessive alcohol
• Limited physical activity
• Adrenaline/catecholamine increases (stress/fright)

Question 4

Coronary Artery Disease (coronary heart disease)

• Is a disease in which a waxy substance called plaque builds up inside the coronary arteries
• These arteries supply O2-rich blood to the heart muscle
• When plaque builds up in the arteries, the condition is called atherosclerosis

Answer 4

• Hardened plaque narrows the coronary arteries & reduces the flow of O2-rich blood to the heart
• If plaque ruptures, a blood clot can form on its surface; large blood clot can mostly or completely block blood flow through a coronary artery
• Angina is a chest pain or discomfort; may feel like pressure or squeezing in the chest

Question 5

• Over time, CHD can weaken the heart muscle & lead to HF & arrhythmias

Answer 5

Plaque & clot formation

• Lesion or inflammation in arteries
• Body sends in cholesterol to help heal inflammation
• Inflammation & clot formation block blood flow to the heart tissue & tissue begins to die

Question 6

Continuum of CAD

?

Is an insufficient oxygen supply to meet requirements of myocardium

Answer 6

Ischemia

Question 7

?

Is necrosis or cell death that occurs when severe ischemia is prolonged & decreased perfusion causes irreversible damage to tissues

Answer 7

Infarction

Question 8

Angina

• Stable
• Unstable
• Variant (Prinzmetal’s)
• Microvascular

Answer 8

• Typically no changes in troponin or CK levels
• Responds to nitroglycerin (NTG) (3x every month)
• Typically no ST changes on 12-lead EKG

Question 9

Angina

• Sometimes called angina pectoris
• Happens when there’s 60-70% blockage in coronary arteries - not typically associated w/damage to heart muscle but are warning signs

Question 10

?

• Most common type
• Happens when heart is working harder than usual; has a regular pattern
  > “Pattern” being how often the angina occurs, how severe it is & what factors trigger it
• You could learn the pattern & when pain will occur; usually goes away a few min after rest or angina rx (likely NTG which opens up the arteries & increases blood flow)

Answer 10

Stable angina

! Isn’t an MI but suggests that & MI is more likely to happen in the future
> Make radical lifestyle changes

Question 11

?

• Rare; caused by a spasm in the coronary arteries
• Occurs while @ rest; pain can be severe
• Usually happens between midnight & early morning; rx’s can help

Answer 11

Variant (Prinzmetal’s) angina

Question 12

?

• Type that doesn’t follow a stable pattern
• Can happen w/ or w/o physical exertion, & rest or rx may not relieve pain
  ! Very dangerous & needs treatment; an MI could happen

Answer 12

Unstable angina

! Can happen more often & be more severe than stable angina

Question 13

?

• Can be more severe & lasts longer than other types; rx may not relieve this
• Newer studies state women have this type

Answer 13

Microvascular angina

Question 14

! Other conditions that cause CP besides CHD include PE, a lung infection, aortic dissection, hypertrophic cardiomyopathy, pericarditis, & a panic attack

Answer 14

NTG can be taken in 5-min increments; a total of 3 doses can be given to relieve angina pain
> Usually responds to NTG but if taking 3 sublingual tablets one after another doesn’t help, an MI may be happening

Question 15

?

Is a myocardial muscle protein released into the bloodstream w/injury to myocardial muscle

Answer 15

Troponin

Question 16

Troponin T & and I aren’t found in healthy pts, so any rise in values indicates cardiac necrosis or acute MI

Have a wide diagnostic timeframe; are useful for pts who present several hrs after CP onset

Answer 16

! Troponin is more sensitive than myoglobin & creatine kinase

Question 17

Troponin T < ___ ng/mL

Troponin I < ___ ng/mL

Answer 17

0.10

0.03

Question 18

• Cardiology sources state that the troponin is the only biomarker that’s recommended to be used for dx of acute MI @ this time b/c of its superior sensitivity & accuracy

Answer 18

• Pts w/elevated troponin lvls but negative creatinine-kinase-MB (CK-MB) values who were formerly dx’d w/unstable angina or minor myocardial injury are now reclassified as non-ST segment elevated MI (NSTEMI), even in absence of diagnostic ECG changes

Question 19

?

Is an enzyme specific to cells of the brain, myocardium, & skeletal muscle

• Appearance in the blood indicates tissue necrosis or injury, w/lvls following a predictable rise & fall during a specified period

Answer 19

Creatinine kinase (CK)

Question 20

3 isoenzymes of CK

CK-MM - found in ___

CK-MB - found in ___
> Is most specific for MI & shows a predictable rise & fall during 3 days; peak lvl occurs ~24 hrs >CP onset

CK-BB - found in ___

Answer 20

skeletal muscle

myocardial muscle

brain

Question 21

?

Is a low-molecular-weight heme protein found in cardiac & skeletal muscle; is earliest marker detected - as early as 2 hrs >MI w/rapid decline >7 hrs

• Is not cardiac specific so usefulness is more limited than troponin

Answer 21

Myoglobin

Question 22

?

Has been the most studied marker of inflammation

• Any inflammatory process can produce this in the blood
• Elevations also seen w/HTN, infection, & smoking

Answer 22

hsCRP (highly sensitive C-reactive protein)

Question 23

hsCRP

Low risk = < ___ mg/dL; over ___ mg/dL puts pt @ risk for heart disease

Answer 23

1; 3

! CRP is very helpful in determining treatment outcomes in pts @ risk for coronary dz & in managing statin therapy >an acute MI
> Most useful time to measure appears to be for risk assessment in middle-age or older

Question 24

hsCRP

Lower risk: <2.0 mg/L

Higher risk: > or = 3.0 mg/L

Answer 24

Acute inflammation: >10.0 mg/L

Question 25

? Means that there's still some flow in the cardiac arteries

Answer 25

NSTEMI

Question 26

* Infarction is a dynamic process that takes time * Cardiac cells can withstand ischemic conditions for approx 20 min before cell death begins * Earliest tissue to become ischemic is the ___ (innermost layer of tissue in cardiac muscle) > Is b/c it's too far away from the blood in the ventricular cavity & the O2 from the carotid artery

Answer 26

subendocardium

Question 27

* Doesn't usually progress to a Q wave & is sometimes called a non Q wave MI

Answer 27

Cardiac markers of NSTEMI vs STEMI - CK-MB, troponin I and T all elevate in both cases > Elevation mild in NSTEMI compared w/STEMI ! Needs intervention to enhance perfusion - usually PCI w/stents

Question 28

NSTEMI or NSTE-ACS * NON ST elevation MI aka Non ST elevation Acute Coronary Syndrome * ST and T wave ___, typically indicating ischemia * Cardiac enzymes initial WNL, then ELEV over 3 to 12 hrs (slower process than STEMI) * Causes: PARTIAL OCCLUSION of blood flow to coronary arteries

Answer 28

depression

Question 29

? Represents complete blockage of the coronary artery usually from thrombus formation; causes transmural damage meaning that necrosis goes through all levels of the muscle

Answer 29

STEMI

Question 30

* STEMI shows ST segment elevation in ECG d/t full thickness injury of heart muscle & later progresses to a Q-wave > Also called a Q wave MI * Ultimate ECG findings of STEMI are ST-segment elevation & elevated troponin levels

Answer 30

* If ischemia persists, it takes approx 4-6 hrs for entire thickness of heart muscle to become necrotic

Question 31

! **Thrombus causes can abrupt 100% occlusion to the coronary artery, is a medical emergency, & requires immediate revascularization of the blocked coronary artery** ! Intervention needed = PCI within 120 min of sx onset; also undergo clot busting and/or CABG

Answer 31

! **After 48 hrs infarcted area turns gray w/yellow streaks as neutrophils invade tissue & begin to remove necrotic cells** > **By 8-10 days** >infarction, granulation tissue forms at edges of necrotic tissue > **Over 2-3 month period**, necrotic area eventually develops into a shrunken, thin, firm scar

Question 32

* Scar tissue permanently changes the size & shape of the entire left ventricle, called **ventricular remodeling** * Remodeling may decrease left ventricular function, cause HF, and increase morbidity & mortality

Answer 32

* **Scarred tissue doesn't contract or conduct electrically**, thus is why this area is often the cause of chronic ventricular dysrhythmias surrounding the infarcted zone

Question 33

Sx's of Complete Occlusion MI Right Coronary Artery > ___ > ___ > ___

Answer 33

JVD Hypotension Bradycardia

Question 34

LCA or Left Ventricle Infarct * Worse prognosis; highest risk of sudden cardiac death; CHF > Dyspnea > Tachypnea > HTN

Question 35

Analysis: Analyze Cues & Prioritize Hypotheses * Acute pain d/t an imbalance between myocardial oxygen supply & demand * Decreased myocardial tissue perfusion d/t interruption of arterial blood flow

Answer 35

* Potential for dysrhythmias d/t ischemia & ventricular irritability * Potential for HF d/t left ventricular dysfunction

Question 36

ACS: Planning & Implementation: Generate Solutions & Take Action * Managing acute pain * Increasing myocardial tissue perfusion * Identifying & managing dysrhythmias * Monitoring for & managing HF

Answer 36

* Before giving NTG, ensure that the pt hasn't taken any phosphodiesterase inhibitors (PI's) for ED, like sildenafil, tadalafil, avanafil, or vardenafil, within past 24-48 hrs > Concomitant use of NTG w/these inhibitors can cause profound hypotension > Some PI's are used in the treatment of PAH & pts w/PAH can't stop taking the PI (! NTG contraindicated)

Question 37

NTG - Increases collateral blood flow - Redistributes blood flow toward the subendocardium - Dilates coronary arteries - Decreases myocardial O2 demand by peripheral vasodilation which decreases preload & afterload

Answer 37

* Morphine may also be given to pain unresponsive to NTG

Question 38

! Re: O2 Use - Oxygen use in the ABSENCE of hypoxemia has been shown to INCREASE coronary vascular resistance, DECREASE coronary blood flow, & INCREASE mortality

Question 39

CAD: Older Adult Considerations * Recognize that CP may not be evident in the older pt. Examples of assoc sx's are unexplained dyspnea, confusion, or GI sx's * Although older adults have a greater reduction in mortality rate from MI w/the use of fibrinolytic therapy, they also have the most severe side effects * Dysrhythmia may be a normal age-related change rather than a complication of MI. Determine whether the dysrhythmia is causing significant sx's. Then notify the HCP.

Answer 39

* If beta blockers are used, assess the pt carefully for the development of side effects. Exacerbation of the depression some older adults have is a sig problem w/beta blockade. * Plan slow, steady increases in activity. Older adults w/minimal previous exercise show particular benefit from a gradual increase in activity. * Older adults should plan longer warm-up & cool-down periods when participating in an exercise program. Their pulse rates may not return to baseline until 30 min or longer >exercise.

Question 40

Expected outcomes are that patient will: * State that pain is alleviated * Have adequate myocardial perfusion * Be free of complications such as dysrhythmias & HF

Answer 40

Sx's ! Ask about radiating pain also; jaw/mouth/throat, arm/back ! Pts w/diabetes may not present w/CP (may have damage to nerve conduction)

Question 41

Nursing Process: Assessment * Restlessness * Pain characteristics * Focused cardiac assessment * ECG changes > ST segment changes indicative of ischemia or injury > Presence of Q wave diagnostic for MI

Answer 41

* Troponin levels > Elevates within 4 hrs & can stay elevated for days * VS/oximetry > Tachycardia w/a borderline low BP & dec O2 sat is a sign of inadequate cardiac output & O2 delivery * Skin/peripheral pulses > Dec pulses & cold, clammy, pale skin are signs of inadequate tissue perfusion & inadequate CO; activation of SNS w/low CO will stimulate diaphoresis * Urine output > Decreased or absent urine output is a sign of dec renal perfusion r/t dec cardiac output

Question 42

Assess, Take Action, Evaluate Outcomes, Repeat * Monitor ABCs, VS, LOC, heart & breath sounds, cardiac rhythm, & O2 sat * Assess & record response to rx's (e.g., decrease in CP), & re-medicate or titrate rx's (e.g., NTG) as needed * Provide reassurance & emotional support to pt & caregiver * Explain all interventions & procedures to pt & caregiver in simple terms

Answer 42

* Anticipate need for intubation if respiratory distress is evident * Prepare for CPR & defibrillation if indicated * Anticipate the need for transcutaneous pacing if indicated

Question 43

Question 44

MI - Potential Complications * Dysrhythmias * HF * Cardiogenic shock * Embolism * Papillary muscle dysfunction

Answer 44

* Ventricular aneurysm * Pericarditis * Dressler syndrome - a pericarditis following MI, trauma, or surgery

Question 45

Cardiac Rehab * 2-8 wks up to 6 mos * Specific to the type & degree of injury & type & degree of treatment * Assess educational needs of pt & family & readiness to learn

Answer 45

* Risk modification * Diet, exercise, complementary, drug therapies, sexual activity * Community resources