Download Acute Myocardial Infarction

Acute Myocardial
Infarction
Prepared by:
BSN, Level IV
Sarah Jane A. Cristobal
Definitions
• Is the medical term for an event commonly
known as a heart attack. An MI occurs when
blood stops flowing properly to a part of the
heart, and the heart muscle is injured because
it is not receiving enough oxygen. Usually this
is because one of the coronary arteries that
supplies blood to the heart develops a
blockage due to an unstable buildup of white
blood cells, cholesterol and fat. The event is
called "acute" if it is sudden and serious.
Definitions
• Myocardial infarction occurs when myocardial
ischemia, a diminished blood supply to the
heart, exceeds a critical threshold and
overwhelms myocardial cellular repair
mechanisms designed to maintain normal
operating function and homeostasis. Ischemia
at this critical threshold level for an extended
period results in irreversible myocardial cell
damage or death.
Anatomical Structure
Signs & Symptoms
• A person having an acute MI usually has
sudden chest pain that is felt behind the
breast bone and sometimes travels to the left
arm or the left side of the neck.
• Additionally, the person may have shortness
of breath, sweating, nausea, vomiting,
abnormal heartbeats, and anxiety.
Signs & Symptoms
• Women experience fewer of these symptoms
than men, but usually have shortness of
breath, weakness, a feeling of indigestion, and
fatigue. In many cases, in some estimates as
high as 64%, the person does not have chest
pain or other symptoms. These are called
"silent" myocardial infarctions.
Risk factors
• Important risk factors are previous
cardiovascular disease, old age, tobacco
smoking, high blood levels of certain lipids
(low-density lipoprotein cholesterol,
triglycerides) and low levels of high density
lipoprotein (HDL) cholesterol, diabetes, high
blood pressure, lack of physical activity,
obesity, chronic kidney disease, excessive
alcohol consumption, and the use of cocaine
and amphetamines.
Physical exam
The parts of the physical exam that are most
helpful in diagnosing heart failure are:
• Measuring blood pressure and pulse rate.
• Checking the veins in the neck for swelling or
evidence of high blood pressure in the veins
that return blood to the heart. Swelling or
bulging veins may indicate right-sided heart
failure or advanced left-sided heart failure.
Physical exam
• Listening to breathing (lung sounds).
• Listening to the heart for murmurs or extra
heart sounds.
• Checking the abdomen for swelling caused by
fluid buildup and for enlargement or
tenderness over the liver.
• Checking the legs and ankles for swelling
caused by fluid buildup (edema).
• Measuring body weight.
Normal
• Lung and heart sounds are normal, blood
pressure is normal, and you have no sign of
fluid buildup or swollen veins in the neck.
• You may have further exams or tests to check
for other causes of symptoms.
Abnormal findings that suggest heart
failure:
• High blood pressure (140/90 mm Hg or above)
or low blood pressure is present. Low blood
pressure could be a sign of late-stage heart
failure.
• An irregular heart rate (cardiac arrhythmia)
Abnormal findings that suggest heart
failure:
• A third heart sound (indicating abnormal
movement of blood through the heart) is
heard. Heart murmurs may or may not be
present.
• The impulse normally felt from the lower tip
of the heart (apex) is not felt in its normal
position on the chest wall, suggesting
enlargement of the heart.
Abnormal findings that suggest heart
failure:
• You have a swollen liver or have pain in the
right upper abdomen, loss of appetite, or
bloating. This suggests that blood may be
backing up into the body.
• You have swelling in your legs, ankles, or feet
or in the lower back when you lie down, and it
is clearly not caused by another condition.
Fluid buildup first occurs during the day and
goes away overnight.
Abnormal findings that suggest heart
failure:
• Swollen neck veins or abnormal movement of
blood in the neck veins suggest that blood
may be backing up in the right ventricle.
• Noises (pulmonary rales) such as bubbling or
crackling are heard, which may point to fluid
buildup in the lungs. Your doctor uses a
stethoscope to hear these noises while you
take deep breaths.
Diagnostic Procedures
• The main way to determine if a person
has had a myocardial infarction are
electrocardiograms (ECGs) that trace the
electrical signals in the heart and testing
the blood for substances associated with
damage to the heart muscle.
Diagnostic Procedures
• . Common blood tests are troponin and
creatine kinase (CK-MB). ECG testing is
used to differentiate between two types
of myocardial infarctions based on the
shape of the tracing. An ST section of the
tracing higher than the baseline is called
an ST elevation MI (STEMI) which usually
requires more aggressive treatment.
Diagnostic Procedures
• A cardiac troponin rise accompanied by either
typical symptoms, pathological Q waves, ST
elevation or depression, or coronary
intervention is diagnostic of MI.
Diagnostic Procedures
• Clinical history of ischaemic type chest pain
lasting for more than 20 minutes
• Changes in serial ECG tracings
• Rise and fall of serum cardiac biomarkers
• At autopsy, a pathologist can diagnose an MI
based on anatomopathological findings.
Pathopysiologic Mechanism
Acute myocardial infarction (MI)
generally refers to segmental (regional) myocardial
necrosis, typically endocardium-based, secondary
to occlusion of an epicardial artery. In contrast,
concentric subendocardial necrosis may result from
global ischemia and reperfusion in cases of
prolonged cardiac arrest with resuscitation. Areas
of myocardial infarction may be subepicardial if
there is occlusion of smaller vessels by
thromboemboli originating from coronary thrombi.
In the majority of patients, there is obstructive
coronary disease at angiography.
Pathopysiologic Mechanism
The area of infarct occurs in the
distribution of the occluded vessel. Left main
coronary artery occlusion generally results in a
large anterolateral infarct, whereas occlusion of
the left anterior descending coronary artery
causes necrosis limited to the anterior wall.
There is often extension to the anterior portion
of the ventricular septum with proximal left
coronary occlusions.
Pathopysiologic Mechanism
In hearts with a right coronary
dominance (with the right artery supplying the
posterior descending branch), a right coronary
artery occlusion causes a posterior (inferior) infarct.
With a left coronary dominance (about 15% of the
population), a proximal circumflex occlusion will
infarct the posterior wall; in the right dominant
pattern, a proximal obtuse marginal thrombus will
cause a lateral wall infarct only, and the distal
circumflex is a small vessel.
Pathopysiologic Mechanism
The anatomic variation due to
microscopic collateral circulation, which is not
evident at autopsy, plays a large factor in the
size of necrosis and distribution. Unusual
patterns of supply to the posterior wall, such as
wraparound left anterior descending or
posterior descending artery supplied by the
obtuse marginal artery, may also result in
unexpected areas of infarct in relation to the
occluded proximal segment.
Pathopysiologic Mechanism
A proximal occlusion at the level of
an epicardial artery results in a typical
distribution that starts at the subendocardium
and progresses towards the epicardium (the socalled wavefront phenomenon).[1] Therefore, an
area of necrosis or scarring is considered to have
an "ischemic pattern" if it is largest at the
endocardium, with a wedge-shaped extension
up to the epicardial surface.
Pathopysiologic Mechanism
Ischemic injury, however, may be
located in the mid myocardium or even the
subepicardium if the level of the coronary occlusion
is distal within the myocardium. Therefore, in cases
of thromboemboli from epicardial thrombi
(especially plaque erosions), there may be patchy
infarction, often associated with visible thrombi
within the myocardial vessels, not centered in the
endocardium but occurring anywhere in the
myocardium, including midepicardial and
subepicardial locations
Complications of AMI
 Reperfusion injury
 Acute heart failur
 Aneurysm of heart
 Cardiac muscle cells rupture
 BBB or RBBB
 Ventricular arrhytmias:
Fibrilation
Bradhyarrhytmia
 Cardiogenic shock
 Hypovolemia
Pharmacologic treatment
• An MI requires immediate medical attention.
Treatment attempts to save as much viable
heart muscle as possible and to prevent
further complications, hence the phrase
"time is muscle". Oxygen, aspirin, and
nitroglycerin may be administered.
Morphine was classically used if nitroglycerin
was not effective; however, it may increase
mortality in the setting of NSTEMI.
Pharmacologic treatment
• Reviews of high flow oxygen in myocardial
infarction found increased mortality and
infarct size, calling into question the
recommendation about its routine
use. Other analgesics such as nitrous
oxide are of unknown benefit. An MI requires
immediate medical attention. Treatment
attempts to save as much viable heart muscle
as possible and to prevent further
complications, hence the phrase "time is
muscle".
Pharmacologic treatment
• Oxygen, aspirin, and nitroglycerin may be
administered. Morphine was classically used if
nitroglycerin was not effective; however, it
may increase mortality in the setting of
NSTEMI. Reviews of high flow oxygen in
myocardial infarction found increased
mortality and infarct size, calling into question
the recommendation about its routine use.
Other analgesics such as nitrous oxide are of
unknown benefit.
Other Lifestyle Changes and
Other Therapies
•Smoking should always be discouraged.
•Pneumococcal and influenza immunization
may reduce the incidence of respiratory
infections that may worsen HF.
Other Lifestyle Changes and
Other Therapies
•Continuous positive airway pressure (CPAP) to
improve daily functional capacity and quality of
life may be used in patients with HF and
obstructive sleep apnea.
•Non-pharmacologic techniques for stress
reduction may be considered as a useful adjunct
for reducing anxiety in patients with HF.
Nursing
Diagnosis
1. Decreased Cardiac Output related to: changes in
the frequency of heart rhythm.
2. Impaired Tissue Perfusion related to: decrease in
cardiac output.
3. Ineffective Airway Clearance related to:
accumulation of secretions.
Nursing
Diagnosis
4. Ineffective Breathing Pattern related to: lung
development is not optimal.
5. Impaired Gas Exchange related to: pulmonary
edema.
6. Acute Pain relate to: increase in lactic acid.
7. Fluid Volume Excess related to: retention of
sodium and water.
Nursing
Diagnosis
8. Imbalanced Nutrition, Less Than Body
Requirements related to:
Inadequate intake.
9. Activity Intolerance relate to: imbalance between
myocardial oxygen supply and needs.
10. Self-Care Deficit related to: physical weakness.
Nursing
Intervention
• Administer analgesics as ordered.
• Organize patient care and activities to allow
periods of uninterrupted rest.
• Provide a clear liquid diet until nausea
subsides.
• Provide stool softener to prevent straining
during defecation.
Nursing
Intervention
• Assist with range of motion exercises.
• Provide emotional support, and help reduce
stress and anxiety.
• Assess and record the patient’s severity,
location, type, and duration of pain.
• Check his blood pressure after giving
nitroglycerin, especially during first dose.
Nursing
Intervention
• Thoroughly explain the medication and
treatment regimen.
• Review dietary restriction with the patient.
• Advise the patient about appropriate
responses to new or recurrent symptoms.
• Stress the need to stop smoking.
Nursing
Intervention
Psychological and social support
• Patients should be offered basic stress
management advice and may not need more
complex treatment such as cognitive
behavioural therapy.
Nursing
Intervention
• Psychological and social support
However, one study found that six
components of psychological intervention usual care, educational, behavioural, cognitive,
relaxation and support - offered positive
benefits in terms of clinical outcomes
Nursing
Intervention
Psychological and social support
• Partners and carers should be involved if this
is in accordance with the patient's wishes.
• Patients with anxiety or depression should be
managed according to the appropriate NICE
guidance.
Discharge planning
Medicines management plan
• Consider starting guideline-recommended medicines in
hospital before discharge.
• Provide all patients with a written medicines management
plan which includes:
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a list of all medicines
the dose and plan for any required dose titration
intended duration of therapy
the purpose and potential benefits of therapy
potential adverse effects of each medicines
schedule for follow-up and monitoring
access to consumer medicine information.
Discharge planning
• provide smoking-cessation advice and support to
all patients who smoke
• Smoking is one of the most significant risk factors
• for cardiovascular disease, including myocardial
infarction (MI).
• Stopping smoking is associated with a substantial
reduction in risk of all-cause mortality among
patients with coronary heart disease.