17. Acute Coronary Syndromes Flashcards
What causes a STEMI?
Acute complete obstruction of a coronary artery
What is an aborted STEMI?
Rapid early reperfusion of a thrombotic occlusion of an epicardial coronary artery
- no increase in troponin plasma levels to suggest necrosis
What are the criteria for diagnosis of a MI?
Detection of increase/decrease in cardiac biomarkers (i.e. troponin) + at least 1 of the following:
- Symptoms of ischaemia.
- New or presumed new significant ST-T wave changes or left bundle branch block on 12-lead ECG.
- Development of pathological Q waves on ECG.
- Imaging evidence of new or presumed new loss of viable myocardium or regional wall motion abnormality.
- Intracoronary thrombus detected on angiography or autopsy
What is type 1 MI?
Atherosclerotic plaque rupture, ulceration, fissure, erosion or dissection with resulting intraluminal thrombus in one or more coronary arteries leading to decreased myocardial blood flow and/or distal embolization and subsequent myocardial necrosis.
What is type 2 MI?
Condition other than coronary plaque instability contributes to an imbalance between myocardial oxygen supply and demand
What are some mechanisms of type 2 MI?
- Coronary artery spasm
- Coronary endothelial dysfunction
- Tachyarrhythmias, bradyarrhythmias
- Anaemia
- Respiratory failure
- Hypotension
- Severe hypertension
- Heart failure
What are the common complications after an MI?
- acute pulmonary oedema
- complete heart block or dangerous tachyarrhythmia
- post MI ventricular septal defect developed
- mitral regurgitation due to papillary muscle rupture or dysfunction
- Effect on LV function
- Left ventricular mural thrombus
What needs to be considered in the history of someone with possible acute coronary syndrome?
Cardiac sounding? Radiation? Relieved with GTN? How long? Is it getting worse? Pleuritic?
Risk Factors
Smoker, FH, high cholesterol, HTN, thrombophilia
When examining a patient what haemodynamics do you need to consider
BP (if systolic <90mmHg –Cardiogenic shock)
Tachycardia or Bradycardia (2:1 Heart block, Complete heart block)
JVP
Lungs - clear or wet?
Heart sounds – this could be life saving – missing a murmur could be costly!
Cool peripheries?
Which ECG leads are inferior, lateral and anteroseptal?
Inferior: II, III, aVF
Lateral: I, aVL, V5, V6
Anterospetal: v1-v4
On an ECG what do the following mean:
ST elevation, St depression, T wave inversion, Heart block, Ventricular dysrhythmia
ST elevation: sudden occulsion, also persists long term as a mark of Left ventricle aneurysm
ST depression: implies under supply of blood to myocardial but not sudden coronary occulsion.
T wave inversion: implies under supply of blood to myocardium but not sudden coronary occulsion, there can be other non ischaemia related causes
Heart block: various grades
Ventricular dysrhythmia: Vt, VF and ECTOPICS
What 4 ECG presentations does an ST elevation evolve with and what should be done when an ST elevation is present
- Hyper acute T waves
- St segment elevation
- T wave inversion
- Pathological Q waves
• Need to go directly to the cath lab for emergency percutaneous coronary intervention
With a Non ST elevation MI(NSTEMI), what is present on the ECG and what blood tests should you consider
ECG: can be normal, ST depression and T inversion may be present
BLOOD TESTS:
• Haemoglobin (anaemia) – will need to consider antiplatelets
• Renal function (angiograms – contrast, may develop AKI).
• Cholesterol
• HBA1C
• Troponin
What is an echocardiogram?
an ultrasound of the heart; noninvasive method for monitoring cardiac performance
Can look at: LV function, wall motion, valvular disease, complication from MI
What questions should be asked in investigation of ACS?
- What happened? (occlusion, narrowing?)
- When did it happen?
- Where did it happen? (right, left coronary?)
- How bad is it? (complications of MI)
- Why did it happen? (plaque rupture, dissection? risk factors?)