CPRS Case 5: MI Flashcards Preview

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Flashcards in CPRS Case 5: MI Deck (12)
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1

***Consent

- Consent: implied or express
- Oral consent is acceptable for minor invasive procedure, documentation offers protection for doctors
- Express and specific consent is required for major treatment with significant risks

Consent is valid only if:
- given voluntarily
- doctor has provided proper explanation of nature, effect and risks of treatment
- patient properly understands

1. Ways in which valid consent can be given
- non-verbally
- orally
- writing (written consent is evidence but not proof)

2. Written consent
- good practice:
—> procedure is complex / significant risk
—> involve general anaesthesia
—> significant consequence on patients’ life
- inability to sign can be documented in record

3. Need for witness
- witness is not mandatory
- good practice:
—> procedure is complex / significant risk
—> significant consequence on patients’ life
- witness should be involved in the whole process

4. Reconfirmation of consent
- when there is significant time lapse between signing and procedure
- material changes in patient’s condition

2

***Steps to obtain informed consent

1. Assess competence of patient
- capable of understanding the information
- capable of using and weighing
- capable of communicating a decision

2. Provide sufficient information
- explanation in person / with aid of information leaflet

3. Provide information particular to patient
- nature of medical condition
- available options include option not to treat + likely outcome
- consequence
- any uncertainty of doctor in his diagnosis

3. Provide information about procedure
- description
- common risks and complications
- uncommon risk with serious consequence
- what to expect before and after

4. Additional questions by patient

3

***20 categories in which doctor has to report death to coroner

Medical reasons:
- medical cause is uncertain
- septicaemia with unknown primary cause
- operation which occurred within 48 hours after major operation
- anaesthetic within 24 hours

Statutory reasons:
- official custody
- crime/ suspected crime
- suicide

Personal reasons:
- death of woman within 30 days after giving birth / abortion / miscarriage
- still birth
- occupational disease

Context:
- accident/injury
- death in private care premises
- occurred outside HK where body is brought into HK

4

Anatomy of coronary arterial system

See lecture

5

Relationship between radius and flow for any blood vessels, and outline the factors regulating coronary blood flow in health and ischaemic heart disease

See lecture regulation of blood flow

6

Diagnosis of MI by cardiac enzymes with reference to their specificity for cardiac damage and time course of their release

See chem patho + biochem practical

7

Rationales for administering antiplatelet drugs and anticoagulants following MI

Acute plaque changes may lead to thrombosis —> thromboembolism

Anti-platelet drugs and anticoagulants is to prevent thrombosis of arteries and hence thromboembolism from occurring

1. Aspirin: inhibits cyclooxygenase —> required for synthesis of thromboxane (for platelet activation)
2. Clopidogrel: inhibit ADP P2Y12 receptor —> inhibit platelet aggregation by preventing activation of glycoprotein IIb/IIIa
3. Low MW heparin: bind to antithrombin —> activate and accelerate antithrombin’s action to inhibit activated factor X

8

Pathological changes from MI

See lecture

9

Signs and symptoms of MI

Chest pain
- rapid, sudden
- provoked by activity, exercise, does not depend on resp / position
- squeezing, tightness, pressure, constriction, crushing, burning
- radiation to jaw, epigastrium, shoulders, arms
- diffuse pain
- prolonged and not relieved by rest / nitroglycerin
- weak S1, splitted S2, S3, S4
- Sympathetic activation: pallor, sweating, tachycardia
- Parasympathetic activation: diarrhoea, vomiting, bradycardia

10

Distinguish between ACS, STEMI, NSTEMI

***ACS
—> ECG
—> ST elevation: STEMI
—> no ST elevation: necrosis biomarker +ve —> NSTEMI
—> no ST elevation: necrosis biomarker -ve —> unstable angina

NSTEMI: temporary / partial occlusion of coronary arteries —> subendocardial infarction
STEMI: develop from complete occlusion of coronary arteries —> transmural infarction

Symptoms: no difference

ECG:
- NSTEMI: ST depression, T inversion, No ST elevation, ***No Q wave
- STEMI: ST elevation, T inversion, Q wave present

Cardiac markers:
- elevation of cardiac markers are milder in NSTEMI than STEMI

11

Principles of management of myocardial infarction

1. Correction of underlying risk factor
- antihypertensive
- lipid lowering drugs

2. Anti-anginal treatment

3. Antithrombotic treatment
- antiplatelet / anticoagulant

4. Reperfusion for STEMI
- Primary PCI
- thrombolytic therapy

5. Reperfusion for NSTEMI
- decide treatment according to risk
- early coronary angiography / revascularisation
- avoid thrombolytic therapy

12

Risk factors for Ischaemic heart disease

Non-modifiable
- advanced age
- male
- genetics

Modifiable
- high LDL, low HDL
- hypertension
- DM
- smoking