Acute Coronary Syndrome / MI Flashcards
what is the definition of ACS
a clinical syndrome of acute ischaemia chest pain either at rest or with a crescendo pattern of pain on minimal exertion, associated with ECG change of ischaemia.
what does ACS include (3)
STEMI
NSTEMI
unstable angina
how is STEMI distinguished
presence of persistant ST elevation
what is different in NSTEMI compared to angina
rise in troponin or creatinine kinase (serum markers of myocardial injury)
(negative serum troponin at 6-12 hours after onset of chest pain suggests unstable angina rather than NSTEMI).
what is the difference between stable angina and unstable angina?
occurs at lower level of exertion. if occurs at rest its more severe.
what is ACS caused by?
atherescloertoic narrowing of the coronary arteries.
what is mechanism of all ACS?
rupture or erosin of fibrous cap of a coronary artery plaque
with subsequent formation of a platelet rich clot and vasoconstriction produced by platelet release of seratonin and thromboxane A2.
what is a myocardial infarction due to?
rupture of an atheresclerotic plaque, followedy by thromobosis and inflammation.
what are the two types of acute MI?
1) Transmural (Q waves) area of ischaemia necrosis extends throughout the whole thickness of the heart muscle from endocardium -> myocardium -> epicardium. leaves permanent Q waves on ECG.
usually result of complete occlusion of area’s blood supply. associated with atheresclerosis involving major coronary artery and can be subdivided into anterior, posterior and inferior
2) non transmural ( non Q waves) - area of ischemic necrosis that does not extend through the full thickness of myocardial wall segment. it is the endocardial and subendocardial zoens of hte myocaridal wall segment that are the least perfused regions of the heart and most vulnerable to condiition of ischameia.
occurs as the occluded artery is a relatively small branch or becuase there is good collatoeral flow around the occluded vessel
what do you see on an ECG for NSTEMI?
T wave invresion
ST depression
no new pathalogical Q waves
symtpoms of acute MI (8)
- acute central chest pain (more severe than angina and lasts for hours and occurs at rest)
- pain which radiates to arms, neck, jaw, back and epigastrium
3, dysopnea - nausea / vomiting
- sweating (diaphoresis)
- restlessness
- palpitations
- 20% have no pain (silent infarctions) e.g. elderly, diabetic or post tranpsnat pateints. may present with hypotension, syncope, arrhythmias, pulmonary oedema, epigastric pain, acute confusion state or stroke.
sigsn of acute STEMI
may present with no physical signs unless ocmplciations
- anxious,
- pale
- grey
- increased BP
- Signs of heart fialure.
what blood investigaitons would you do?
FBC
U&E
Glucose
Lipids
what doy ou see in an ECG for STEMI?
ST segment elevation (1mm in limb leads and 2mm in 2 contingous chest leads
New LBBB is also and indicator of acute MI
T wave flattening or inversion
Pathological Q waves (broad > 1mm) and deep (> 2mm or >25% of r wave) which are aseen once full-thickness infarction has occured.
where is the infarct if ECG changes are seen in leads II, III or AvF?
inferior MI
RCA
where is the infarct if ECG cahgnes are seen in V2 - V4?
anterior septal MI
LAD
where is the infarct if ECG changes are seen in v5 - v6?
lateral wall MI
LCX
where is the infarct if R waves in V1 and V2, ST depression in V1- V3
posterior MI
RCA