Myocardial infarctions
risk factors for coronary artery disease
INTERHEART is an international multi-center case-control study which delineated the following modifiable risk factors for coronary artery disease
Smoking
Abnormal lipid profile/blood apolipoprotein
Hypertension
Diabetes mellitus
Abdominal obesity
Lack of daily consumption of fruits or vegetables
Lack of physical activity
Alcohol consumption
The acute occlusion of one or multiple large epicardial coronary arteries for more than 20 to 40 minutes can lead to acute myocardial infarction.
The occlusion is usually thrombotic and due to the rupture of a plaque formed in the coronary arteries.
The occlusion leads to a lack of oxygen in the myocardium, which results in sarcolemmal disruption and myofibril relaxation
These changes are one of the first ultrastructural changes in the process of MI, which are followed by mitochondrial alterations.
The prolonged ischemia ultimately results in liquefactive necrosis of myocardial tissue.
The necrosis spreads from sub-endocardium to sub-epicardium. The subepicardium is believed to have increased collateral circulation, which delays its death.
The infarcted area heals by scar formation, and often, the heart is remodeled characterized by dilation, segmental hypertrophy of remaining viable tissue, and cardiac dysfunction.
Evaluation
The three components in the evaluation of the MI are clinical features, ECG findings, and cardiac biomarkers.
ECG It should be obtained within 10 minutes of the patient’s arrival in the emergency department.
Acute MI is often associated with dynamic changes in the ECG waveform.
Serial ECG monitoring can provide important clues to the diagnosis if the initial EKG is non-diagnostic at initial presentation.
Serial or continuous ECG recordings may help determine reperfusion or re-occlusion status.
A large and prompt reduction in ST-segment elevation is usually seen in reperfusion.
What does a heart attack feel like?
Many people feel pain in their chest during a heart attack.
It can feel like discomfort, squeezing or heaviness, or it can feel like crushing pain.
People often think they’re having indigestion or heartburn when they’re actually having a heart attack.
Some people only experience shortness of breath
What are the symptoms of a heart attack?
Heart attack symptoms that people describe most often include:
Chest pain
Shortness of breath or trouble breathing.
Trouble sleeping
Nausea or stomach discomfort.
Heart palpitations.
Anxiety or a feeling of “impending doom.”
Feeling lightheaded, dizzy or passing out.
complications of a heart attack
Complications associated with heart attacks include:
Arrhythmias
Heart failure.
Heart valve problems.
Stroke.
Sudden cardiac arrest.
Depression and anxiety.
Cardiogenic shock.
Mechanical complications of a heart attack, such as a ventricular septal defect or free wall rupture. These are more likely to happen
tests done to diagnose a heart attack?
Blood tests: One of the most reliable ways to diagnose a heart attack is to check for cardiac troponin
in blood.
The rising and/or falling pattern of cardiac troponins values with at least one value above the 99 percentile of upper reference limit
associated with symptoms of myocardial ischemia would indicate an acute MI.
During a heart attack, the damage to heart muscle cell always causes this chemical marker to appear in bloodstream.
#Myocardial infarctions, its Causes and Management, Lectures by Dr Alamzeb#
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