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MSPA- Cardiology > Acute Coronary Syndrome > Flashcards

Acute Coronary Syndrome Flashcards

1
Q

What is the definition of ACS ?

A

It is a spectrum of syndromes ranging from unstable angina- NSTEMI- STEMI.

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2
Q

What is the pathophysiology of ACS?

A

Coronary artery occlusion due to atherosclerotic or thrombotic emboli causing ischaemia which if not reversed leads to myocardial infarct and necrosis.

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3
Q

What is the pathophysiology of stable angina ?

A

stable angina occurs when the coronary vessels fail to meet the myocardial O2 demand during exercise or stress. It occurs mainly due to the stenosis of the coronary vessels and vasospasm.

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4
Q

what are the four main factors that contribute to increased O2 demand?

A

Heart rate, systolic blood pressure, myocardial wall tension, and myocardial contractility.

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5
Q

What are the four factors that determine the myocardial blood flow?

A

Coronary artery diameter and tone, collateral blood flow, perfusion pressure, and heart rate

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6
Q

what is the pathophysiology of chest pain ?

A

Myocardial ischemia stimulates chemosensitive and mechanoreceptive receptors within the cardiac muscle fibers and the surrounding coronary vessels. This triggers impulses through the sympathetic afferent pathways from the heart to the cervical and thoracic spine. Each spinal level has a corresponding dermatome; the discomfort described by the patient will often follow the specific dermatomal pattern.

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7
Q

What is the pathophysiology of unstable angina ?

A

The pathophysiology of unstable angina is a combination of intraluminal plaque formation, intraluminal thrombosis, vasospasm, and elevated blood pressure causing obstruction of the blood flow to the myocardium.

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8
Q

What is the pathophysiology of NSTEMI ?

A

Subtotal occlusion of the coronary vessel causing subendocardial ischaemia.

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9
Q

What is the pathophysiology of STEMI ?

A

It occurs due to complete occlusion of the epicardial artery causing extensive transmural ischaemia and myocardial infarction.

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10
Q

What are the classical symptoms of heart attack ?

A
  • Anxiety, diaphorosis, pallor, crushing substernal chest pain, and dyspnoea.
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11
Q

What is the atypical presentation of heart attack ?

A

The most common atypical symptoms of heart attack are gastrointestinal discomfort, chest pain without having typical characteristics of angina pectoris, syncope, and cough and breathlessness. It can be silent attack also in patients who are diabetic, woman, elderly, and post-operative patients.

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12
Q

When is 3rd heart sound typically heard ?

A

The third heart sound (S3), also known as the “ventricular gallop,” occurs just after S2 when the mitral valve opens, allowing passive filling of the left ventricle. The S3 sound is actually produced by the large amount of blood striking a very compliant left ventricle. It can be heard in the context of fluid overload.

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13
Q

When is S4 or 4th heart sound typically heard?

A

The fourth heart sound, S4, also known as ‘atrial gallop’ results from the contraction of the atria pushing blood into a stiff or hypertrophic ventricle, indicating failure of the left ventricle, diastolic dysfunction due to left ventricular stiffness.

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14
Q

What are the systemic and vital sign changes seen in heart attack ?

A
  • Distress
  • pallor
  • Diaphorosis
  • Tachycardia
  • Supraventricular or
    ventricular arrhythmia
  • Hypotension due to acute LVF
    *
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15
Q

What are the respiratory and cardiovascular signs of heart attack ?

A

*Respiratory: lower zone crackles and pulmonary edema.
* cardiac: New murmur due to mitral regurgitation secondary to papillary muscle necrosis, S3 and or S4 gallops, JVPE due to acute CCF, Carotid bruit and loss of peripheral pulses due to cardiogenic shock.

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16
Q

What is the diagnostic approach to chest pain ?

A
  • Persistant ST elevation- STEMI
  • ST/ T wave abnormalities with raise and fall of troponin - NSTEMI.
  • Normal or undetermined ECG with chest pain and normal troponin - unstable angina.
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17
Q

What is the sequence of serial ECG in chest pain ?

A

on arrival - 3 hrs- 6hrs looking for ST Elevation / Depression / dynamic T wave inversion / Q waves / new LBBB

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18
Q

What is the sequence of Serial cardiac biomarkers in patients admitted with chest pain ?

A

*Normal sensitivity Troponin T or I – on arrival, 6hrs, 12hrs
*High Sensitivity Troponin T or I – On arrival, 3hrs, 6hrs.
+ coronary angiography to detect obstructing plaque.

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19
Q

What is the arterial territory of anterio-septal lead V1 and V4 ?

A

LAD

20
Q

What is the arterial territory of antero-lateral leads I, aVL, V3-V6

A

LAD + LCx

21
Q

What is the arterial territory of inferior leads II, III, aVF?

A

RCA

22
Q

What is the arterial territory of lateral leads aVL, lead I, V5 and V6 ?

A

LCX

23
Q

What is the troponin I & T dynamics in AMI ?

A

They raise within 2 to 3 hrs after the insult and the elevation can persist for <10 days. It is elevated in 80% of cases with in 3 hrs.

24
Q

What are the non AMI causes of troponin elevation ?

A

– Severe tachycardia or
bradycardia
– Myocarditis
– Dissecting aneurysm
– PE
– Chronic or acute renal
dysfunction
– CVA or SAH
– Any critically ill pt, esp
sepsis

25
Q

what is the gold standard investigation in ACS ?

A

Coronary angiography with percutaneous coronary
intervention (PCI)

26
Q

What are the other screening tests in AMI ?

A
  • FBC - to rule out anaemia or infection percipitated MI.
  • Fasting lipids & glucose
  • Renal function: To rule out CKD induced arteriopathy, K+ disorder induced arrhythmia causing MI.
  • CXR to rule out aortic dissection.
  • Toxicology screening to look for cocaine causing MI.
27
Q

What to look for in CXR in the context of AMI ?

A
  • Alveolar oedema in a bat-wing distribution.
    *Kerley Blines,
    *Cardiomegaly, pleural effusions, *prominent upper lobe pulm vessels (pulm venous HTN)
    *Abnormal cardiac contours w/LV aneurysms.
28
Q

What is the utility of NT-proBNP / BNP in AMI ?

A

Elevates in response to increasing volume stretching myocardial tissue. Therefore, used as a marker for decompensated HF.

29
Q

When is telemetry indicated in AMI ?

A

When there is Very high risk of a ventricular arrhythmia acutely after
sustaining an MI.

30
Q

What constitutes Dual anti-plt therapy (DAPT)?

A

Aspirin (300mg loading dose) + 2nd agent such clopidogrel.

31
Q

What are the temporal aspects of PCI and Thrombolysis ?

A
  • PCI within 90 min is the gold standard.
  • Thrombolysis: If PCI is not possible within 120 min.
32
Q

When is O2 therapy indicated in AMI ?

A

If saturation <90

33
Q

What are the indications of GTN in AMI ?

A

*Useful for relief of chest pain as it decreases pre-load.
* It is contraindicated in inferior MI.

34
Q

what is the indication of beta blocker in MI ?

A
  • It works as anti-ischaemic as it reduces myocardial load.
  • It is contraindicated in HF, bradycardia, heart block, cardiogenic shock, etc.
35
Q

What is the role of Aspirin in anti-platelet therapy ?

A

300mg loading dose, then 75mg OD for life.

36
Q

What is the role of P2Y12 inhibitor Clopidogrel in anti-platelet therapy ?

A

Clopidogrel 300mg loading dose, then 75mg OD maintenance for 12 month.

37
Q

What is the role of P2Y12 inhibitor Ticagrelor in anti-platelet therapy ?

A

Ticagrelor 180mg loading dose, then 90mg BD maintenance for 12 months.

38
Q

What is the role of P2Y12 inhibitor Prasugrel in anti-platelet therapy ?

A

Prasugrel 60mg loading dose, then 10mg OD maintenance for 12 month.

39
Q

what is the indication for GPIIb/IIIa inhibitors in anti-platelet therapy ?

A

Usually only administered during PCI in high risk patients.

40
Q

When should non-dihydropyridine CCB should be added in anti-ischaemic therapy ?

A

It should be added with BB if the patients continues to be symptomatic .

41
Q

What is the indication for morphine in AMI ?

A

2-4mg + 2mg increments for analgesia and improving dyspnoea.

42
Q

What are the indications for thrombolysis ?

A
  • NO access to PCI (<120mins)
    *ST elevation >1mm in 2 contiguous limb leads or >2mm in 2 contiguous chest leads.
  • New LBBB
  • Sx onset < 12 hrs prior to presentation.
43
Q

what is the time window for greatest benefit from thrombolysis ?

A

Within 4 hours of the onset of AMI

44
Q

What is the most common drug for thrombolysis?

A

Alteplase which converts plasminogen to the proteolytic enzyme plasmin, which lyses fibrin as well as fibrinogen

45
Q

What are the contraindications for thrombolysis ?

A
  • Intracranial pathology and Hx of SAH
  • Severe HTN
  • Hx of abdominal or urinary tract surgery within 3 weeks.
  • Hx of major surgery within 2 weeks.
  • LP or arterial puncture at non-comprasible sites within 1 week.
    *Known bleeding tendency
  • CPR >10mins
  • Suspected aortic dissection
  • If streptokinase is the thrombolitic agent prior exposure and allergic reactions.
46
Q

What are the relative contraindications for thrombolysis ?

A
  • Investigations show:
    – Plts <100
    – INR > 1.7
  • Clinical exam findings:
    – Evidence of bleeding
    – Sustained BP >180/>110
47
Q

What is the long term management of AMI patients ?

A
  • Aspirin, 75mg OD for life and statins for all with an Aim of LDL <1.8 mmol/L.
  • ACE for all to prevent HTN mediated LTV remodelling.
  • B-blockers to all w/LtVEF <40%.
  • Cardiac rehabilitation and psychological support.

MSPA- Cardiology (8 decks)

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