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Flashcards in Acute Coronary Syndrome Deck (12)
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1
Q

Define acute coronary syndrome (ACS), what it encompasses and its common pathology

A

ACS encompasses a spectrum of unstable coronary artery disease.

Includes; Unstable angina, STEMI & NSTEMI

Common pathology; ruptured plaque, thrombus formation & inflammation (with vasoconstriction due to platelets releasing serotonin & thromboxane-A2)

2
Q

Define unstable angina

A

A type of angina pectoris caused by disruption of an atherosclerotic plaque with partial thrombosis & possible embolisation.

Severe pain at rest in crescendo fashion.

3
Q

What are the ECG findings in unstable angina?

A
  • ST depression
4
Q

Define STEMI and explain ECG findings

A

ST-elevated myocardial infarction

  • Transmural necrosis occurs to myocardium due to prolonged ischaemia
  • ECG, on leads facing MI;
    • ST elevation (transmural infarct causes current flow towards injury (towards +ve electrode..))
    • Hyperacute (tall) T wave which then depress and then return to normal (due to potassium channel changes?)
    • Later Q waves (ECG sees through infarcted tissue to other side of heart, where current in going the opposite way, causing increased negative Q wave)
    • First T waves go up, then ST seg follows, then T waves depress, then ST seg goes normal, then T wave goes normal, then Q wave is born
5
Q

Define NSTEMI and explain ECG findings

A

Non ST-elevated myocardial infarction

  • Subendocardial necrosis occurs to myocardium due to prolonged ischaemia
  • ECG, on leads facing MI;
    • ST normal/ depressed (subendocardial infarct causes current flow towards injury (away from +ve electrode..))
    • Hyperacute (tall) T wave which then depress and then return to normal (due to potassium channel changes?)
    • No Q waves
6
Q

Outline the risk factors for ACS

A
  • Sex: male
  • Age : older
  • Diabetes mellitus
  • BP high
  • Elevated cholesterol (hyperlipidaemia)
  • Tobacco
  • Sedentary
  • Family history
  • Obesity

Others include;

  • Stress
  • Type A personality
  • High apoprotein A, fibrinogen, insulinaemia, homocysteine
  • Cocaine use
7
Q

What are the symptoms & signs of MI?

A

Symptoms

  • Acute central chest pain lasting >20mins
    • Also; nausea, sweatiness, dyspnoea, palpitations
    • OR no pain (silent infarct (elderly, diabetics)
    • May radiate to arms/ neck/ jaw/ teeth

Signs

  • Distress, anxiety, pallor, sweatiness
  • Inc or dec pulse/ BP
  • 4th heart sound (sound of atrium contracting with extra effort [to push blood into ventricles which are stiff due to infarct])
  • Heart failure signs;
    • Inc JVP
    • 3rd heart sound (due to dilated ventricles which rapidly fill..)
    • Basal crepitations
  • Pansystolic murmur
  • Low grade fever
  • Later;
    • Pericardial friction rub
    • Peripheral oedema
8
Q

What are the investigations of and how do you diagnose an MI?

A

Acute MI;

  • Cardiac biomarkers; tropnonin T & I, creatine kinase, myoglobin
  • ECG;
    • Hyperacute (/inverted) T waves
    • ST elevation (/depression)
    • Q waves
    • New LBBB
  • CXR;
    • Cardiomegaly
    • Pulmonary oedema
    • Widened mediastnum (aortic rupture)
  • Cholesterol (within 12h of onset of symptoms)
  • Glucose & HbA1C - Hyperglycaemia common with ACS, indicator of poor survival/ inc. complications
  • FBC - anaemia & baseline
  • INR, APTT
9
Q

Explain what & why cardiac enzymes are used in investigations

A

Cardiac troponin (T & I) [gold standard]

  • Inc within 3-12hrs after chest pain onset
  • Peak 24-48hr
  • Baselin 5-14days

Creatinine Kinase

  • CK-MM (skeletal muscle); inc after trauma, activity, myositis, afrocaribs, hypothyroidism
  • CK-BB (brain)
  • CK-MB (heart); THE ONE TO LOOK FOR.

Myoglobin

  • Highly sensitive but not specific
  • Rice within 1-4hr of chest pain onset
10
Q

Outline differentials for ACS!

A
  • Angina
  • Pericarditis
  • Myocarditis
  • Aortic dissection
  • PE
  • Oesophageal reflux/ spasm
11
Q

Outline the immediate treatment & management of an Non-/STEMI

A

Immediate treatment

  • Aspirin 300mg
  • Atenolol (B-blocker)
  • Diamorphine (pain)
  • Metoclopramide (antiemetic due to morphine side effect)
  • Oxygen

STEMI

  • Clopidogrel/ prasugrel (anti platelet’s)
  • PCI!!

NSTEMI

  • Fondaparinux (similar to LMWH)
  • Clopidogrel (anti platelet)
  • PCI/ CABG!!
12
Q

Outline the complications of MI

A
  • Cardiac arrest
  • Cardiogenic shock
  • Unstable angina
  • Bradycardias/ heart block
    • Sinus bradycardia
    • 1stº - PR > 0.2s (inf MI)
    • 2ndº Type 1 - progressive prolongation of PR until 1 drops
    • 2ndº Type 2 - P wave blocked all or nothing (high risk of complete block, pace them)
    • 3rdº - ALL P waves blocked, atria/ ventricles beating seperatly (usually resolved within days, pace them)
    • Bundle branch block
  • Tachyarrhythmias [caused by calcium influx in reperfusion into ischaemic cells (damaged membrane) raising resting membrane potential, also low K+, hypoxia & acidosis)
  • Pericarditis [acute MI pericarditis, chemical mediators diffuse to pericardium]
  • Dressler’s syndrome [post MI pericarditis, antigens from MI released into circulation, antibodies react with pericardium [[cause pleural effusions, fever, anaemia & inc ESR]]
  • Cardiac temponade [rupture & rapid effusion into pericardium (no time to stretch) putting pressure on heart, pulsus paradoxus, inc JVP, muffled heart sounds]
  • DVT & PE [prophylactically heparinized]
  • Systemic embolism [mural thrombus]
  • Mitril regurgitation [papillary muscles]
  • Ventricular;
    • Septal defect [MI & rupture, pansystolic murmur, inc JVP, cardiac failure]
    • Right ventricular failure [low CO & inc JVP]
    • Left aneurysm [occurs late due to weak wall bulging out, LVF, angina, recurrent VT, systemic embolism]