Myocardial Ischaemia Flashcards
What is ACS
Acute coronary syndrome
Unstable angina
NSTEMI
STEMI
Risk factors for ACS
Unmodifiable: age, male, family history
Modifiable: smoking, hypertension, hyperlipidaemia, obesity, diabetes, sedentary lifestyle
What is the underlying pathology for ACS
atherosclerotic plaque
plaque rupture
causes thrombosis
leading to ischaemia and necrosis of myocardium
Name 3 non-atherosclerotic causes of ACS
emboli
coronary artery vasospasm
vasculitis
NB these are rare
Typical changes on an ECG in MI in time order
hours: ST elevation, LBBB
days: T wave inversion, pathological Q waves
weeks: ST segment back to baseline
months-years: pathological Q waves, T waves revert to normal
Typical changes on an ECG in angina
ST depression
T wave inversion
MAY BE NORMAL ECG
What are the criteria for a diagnosis of acute MI
increased trop
and either:
symptoms of MI
ECG changes
how does ACS typically present
central crushing chest pain, may radiate down arm/to jaw nausea/vomiting SOB sweating palpitations
which groups of patients may not present with the typical symptoms of ACS
and how may they present instead?
elderly
diabetics
may present with syncope, pulmonary oedema, vomiting, acute confusion, hyperglaycaemia in diabetics
what investigations would you do if ACS was suspected
bloods - FBC, U&E, glucos, lipids, cardiac enzymes
ECG - ST elevation OR depression, LBBB
CXR - cardiomegaly, pulmonary oedema
what is the initial treatment for acute MI
GONAD
give:
oxygen - aim for 94-98% or 88-92% if COPD
GTN 2 puffs SL
Aspirin 300mg PO
Morphine 5-10 mg IV and antiemetic e.g. metoclopramide 10mg IV
what is the definitive treatment for ACS
primary PCI
thrombolysis
contraindications for thrombolysis
recent trauma/surgery severe hypertension (>200/120) previous allergic reaction recent haemorrhagic stroke cerebral neoplasm oesophageal varices severe liver disease
name 3 thrombolytic agents
streptokinase
alteplase followed by heparin
reteplase 2 IV boluses 2h apart
what is the best marker of myocardial necrosis
cardiac troponins T and I
describe how trop levels change during an MI
increase within 3-12h from the onset of chest pain
peak at 24-28h
decrease back to baseline over 5-14 days
if normal after 6 hours from onset and ECG is normal then MI very unlikely
what would you ask for in the history of someone with suspected ACS
SQITARS risk factors history of cardiac disease medications comorbidities
differentials for chest pain
cardiac - STEMI, NSTEMI, angina, pericarditis, myocarditis, aortic dissection
respiratory - pneumonia, PE, pneumothorax
GI - GORD, oesophageal spasm
MSK - rib#
what are the 3 subtypes of creatine kinase and where are they predominantly found
CK-MM - in skeletal muscle
CK-BB - in brain
CK-MB - heart
describe how levels of CK-MB change during an MI
increase within 3-12h after onset of chest pain
peak at 24h
back to baseline after 48-72h
what are the complications of MI
cardiac arrest cardiogenic shock heart block tachyarrythmias heart failure pericarditis
what lifestyle advice yould you give to a patients with angina?
stop smoking weight loss exercise control BP dietary advice
what pharmacological treatments can you give for angina?
aspirin statin beta blocker GTN for symptomatic relief calcium channel blocker
if lifestyle and medical management of angina fails, how would you treat a patient?
coronary angioplasty +/- stent
or CABG
