Myocardial Infarction Flashcards
What happens in MI?
An MI is when there has been compromised blood flow to the myocardial tissue that leads to cell death.
In a MI, The heart’s myocardial tissue layer dies from decreased blood flow due to what causes:
Blockage in the coronary artery from coronary artery disease (most common)
Coronary spasms from illicit drug usage drugs like cocaine or hypertension. This causes constriction of the coronary artery and stops blood flowing to the heart muscle.
Damage to the coronary artery due to coronary artery dissection. This is a tear in the inner layer “tunica intima” of the artery which causes blood to leak in the “tunica media”. This restricts the flow of blood through the coronary artery. It can happen spontaneously and occurs more likely in young, active women.
Blockages in the _________________-coronary arteries can cause the worst damage from a myocardial infarction
Why is this ?
left
This is because blockages in the left coronary artery can cause anterior wall death which affects the left ventricle. Anterior MIs affect the most myocardial tissue, especially if the blockage occurs before it branches off and this can extend into the septum and lateral wall.
supplies right and left ventricle and septum. This is the most common site for blockages.
Left anterior descending artery
supplies the left atrium and ventricle
left circumflex
supplies the right
atrium and ventricle
Right coronary artery
supplies the right ventricle and septum
right marginal artery
What happens to the heart muscle after a MI?
When a coronary artery becomes 100% blocked the muscle cells die. Cell death is irreversible after about 30 minute. The cells are gone forever and can never be replaced.
Myocardial cell death is irreversible after about __________ minutes
30 minutes
What are early signs of an MI?
no physical changes to heart muscle yet (until about 6-8 hours), but when the myocytes die cardiac enzymes are released: CK-MB (4 to 6 hours after MI), troponin (2-4 hours…most regarded) myoglobin (1 hours after injury…show injury but not too specific).
Within ________________ hours inflammation sets in and _______________- come on the scene and congregate at the damaged tissue site. This causes complication of possible _________________. In addition, within 24 hours the heart fails to __________efficiently (cardiogenic shock) and ______________ can develop (atrial and ventricular dysrhythmia along with AV blocks).
24-36; neutrophils; pericarditis; pump; arrthymias
Within 10 days, _______________occurs when the macrophages come on the scene. They are WBCs who’ve come to clean up the dead cells and other components. However, the new tissue formed from granulation is not well formed and is ______________. This increases the chance of cardiac ____________.
granulation; weak ; rupture
Within __________ months scarring occurs, and the heart is affected in size and functionality due to increased collagen.
2 months
other complications of MI
Heart failure, depression, and ventricular aneurysm
signs & symptoms of MI : mnemonic CRUSHING
Chest pain (intense, heavy)
Radiating chest pain that goes to left arm, jaw, back
Unrelieved by nitroglycerin or rest (chest pain)
Sweating (cold)
Hard to breathe (shortness of breath)
Increased heart rate, blood pressure or irregular heart rate
Nausea with vomiting
Going to be anxious and scared
MI and women
Women can present differently by not having “heavy” chest pain. Their chest pain may be felt in the lower part of the chest, experience shortness of breath, and feel extremely fatigued. They may not seek immediate help because they think they are “just ill” with a sickness.
Silent MI’s - what are they and within whom do they mainly occur ?
this is where the patient has no symptoms of chest pain. Mainly occurs in diabetics due to diabetic neuropathy where the nerves that feel pain are damaged in the heart.
When the heart muscle is injured it releases ___________overtime. This will help the health care provider know that something is going on along with a 12-lead EKG (and other tools).
cardiac markers;
this is the gold standard cardiac marker used by most hospitals in assessing for an MI
Troponins -
It is a protein released from the heart when damage is present from a myocardial infarction.
Troponin levels will elevate ___________ hours after injury
2-4 hours
What is the nurses role when it comes to Troponin levels ?
How soon do they elevate ?
The nurse’s role is to collect levels and monitor them for an upward trend. If levels are increasing, the physician will need to be notified.
They are drawn in a series (troponin levels will elevate 2-4 hours after injury). They are usually drawn every 6 hours for 3 sets.
this is an early cardiac marker released after heart injury (1 hour after injury); however, it is not very ……….
MYOGLOBIN - not very cardiac specific…used in early detection..will need more blood tests to further evaluate
How soon does CK-MB levels elevate after heart injury?
4-6 hours
What is CK ?
What is CK-MB?
How soon does it elevate after injury?
CK is protein released when there is muscle damage (not specific to just the heart)…so CK-MB may be ordered to tell if it is the heart since CK-MB represents heart muscle (it elevates 4-6 hr after injury).
What other tools are used to diagnose an MI?
Echocardiogram, Stress Test, Heart Cath, EKG
this is an ultrasound of the heart to look at the heart to see if there is damaged from an MI.
Echocardiogram
a procedure where a special dye is injected into the coronary arteries and an X-Ray is taken to see if there are any blockages, their locations, and if there is any muscle damage. If there is a blockage, the cardiologist will assess the need for stent placement or other techniques used to open the artery.
Heart Catheterization
This diagnostic test assesses how the heart responds to stress and evaluates the blood flow to the myocardial muscle.
Stress test with Myocardial Perfusion
What is the nurses role in EKG and MI diagnostics?
Nurses role: obtaining EKG (or delegating it to be done) looking for any EKG changes and notifing md of them
Compare newly obtained EKG to previous EKGs
The various leads of the 12 lead EKG offer ________________ of the heart
different views
Regarding MI, what are you looking for on the EKG ?
ST-segment elevation - indicates injury
ST segment depression - indicates ischemia
T-wave inversion or hyperacute - indicates ischemia
Pathological Q-wave - indicates current or prior infarction
Know the views of the heart based on an EKG reading:
I, AVL, V5, V6: Lateral
II, III, AVF: Inferior
V 1, V2: Septal
V 3, V4: Anterior
Nursing Interventions for Myocardial Infarction: what kinds of things will you be doing ?
Monitoring & Assessing Cardiovascular system:
- Obtain a 12-lead EKG, have continuous bedside cardiac monitoring
- Monitoring blood pressure and heart rate
Place on oxygen via nasal cannula per MD order 2-4 L
Working IV access (multiple…may start drips and administer other IV medications)
Monitor respiratory system: lung sounds “crackles”..represent heart failure
Strict bedrest (activity puts strain on heart)
Collect cardiac enzymes as ordered by the physician
Administering medications per MD order:
A client who has had a myocardial infarction asks the nurse why she should not bear down or strain to ensure having a bowel movement. The nurse provides education to the client based on which physiological concept?
Bearing down as if straining to have a bowel movement can stimulate a vagal reflex. Stimulation of the vagus nerve causes a decrease in heart rate and cardiac contractility.
Stimulation of the sympathetic nervous system has the opposite effect. These two branches of the autonomic nervous system oppose each other to maintain homeostasis.
Mnemonic for Administering Medications for Myocardial infarction
Acute Angina Means Nasty Artery Blockages And Cardiac Complications
Antithrombotic Agents
Antiplatelets
Morphine
Nitrates
Ace Inhibitors
Beta Blockers
ARBS
Cholesterol Lowering medications
Calcium Channel Blockers
these meds prevent the formation of clots
Antithrombotic Agents/ Anticoagulants
