MI Flashcards
What is myocardial infarction?
Necrosis of cardiac tissue (myocyte death) due to prolonged myocardial ischaemia due to COMPLETE occlusion of artery by thrombus.
What are the two types of MI?
NSTEMI and STEMI
Briefly describe the pathophysiology of MI?
- Rupture or erosion of vulnerable fibrous cap of coronary artery atheromatous plaque
- Platelet aggregation, adhesion, local thrombosis, vasoconstriction and distal thrombosis embolism
- Prolonged complete arterial occlusion resulting in myocardial necrosis.
In relation to vascular occlusion what is the difference between STEMI and NSTEMI?
- STEMI - Complete occlusion of a MAJOR coronary artery previously affected by atherosclerosis, causing a full thickness damage of heart muscle
- NSTEMI - A complete occlusion of a MINOR or a partial occlusion of a major coronary artery previously affected by atherosclerosis. This causes partial thickness damage of heart muscle
What is transmural ischemia?
When the infarction extends through the sub-endocardium to the sub-epicardial myocardium.
What two types can ischemia be split into?
Type 1 - due to plaque rupture
Type 2 - due to increase in 02 demand
Give three risk factors for MI?
- Age
- Male
- History of premature coronary heart disease
- Premature menopause
- Diabetes mellitus
- Smoking
- Hypertension
- Hyperlipidaemia
- Obesity and sedentary lifestyle
- Diabetes mellitus
- Family history of Ischaemic Heart Disease (IHD) - MI in first degree relative below 55
What are the signs of MI?
- Pale, clammy, sweaty
- Distress, anxiety
- BP high or low
- HR high or low
- 4th heart sound
- May be signs of heart failure (Raised JVP, 3rd heart sound, basal crepitations)
- Pansystolic murmur
- Pericardial rub or peripheral oedema may develop
What are the symptoms of MI?
- Central crushing chest pain, lasting more than 20 mins
- Pain may radiate to jaw, neck or left arm
- Nausea
- Dyspnea
- Palpitations
What would you see on an ECG trace in the case of a STEMI?
- ST elevation
- Tall T waves
- Left bundle branch block (LBBB)
- T wave inversion
- Pathological Q waves follow
Tall T waves at the start and then they will invert after a few hours.
After a few days, the ST segment returns to normal - After weeks or months, the T wave may return to upright but the Q WAVE REMAINS
What would you see on an ECG trace in the case of an NSTEMI?
- ST depression
- T wave inversion
- May show no change
Other than an ECG what two tests would you do if you suspected myocardial infarction?
Troponin levels and transthoracic echocardiography.
What is the treatment for a myocardial infarction (MONA)?
M - Morphine
O - Oxygen
N - Nitrates
A - Aspirin
What is the surgical treatment for MI?
PCI
What are the risk factor modifications that you can make to prevent MI?
- Stop smoking
- Lose weight and exercise daily
- Healthy diet
- Treat hypertension & diabetes
- Low fat diet with statins
