Acute coronary syndromes Flashcards
What is the role of fibrin involved in clot formation?
Fibrin forms a mesh over wounds - this is the beginning of a clot
Name the two acute coronary syndromes
Unstable angina and acute myocardial infarction
What results in myocardial ischaemia?
Inbalance between myocardial blood supply and demand
What is the definition of angina pectoris?
Acute pain, usually in the chest, resulting from an increased oxygen and glucose demand but a decreased ability to provide it, usually due to a partially occluded coronary artery or vasospasm.
What is the typical presentation of angina pectoris?
- Squeezing/crushing/heavy/tight chest pain
- Fist to chest (Levine’s sign)
- Pain/discomfort may radiate to shoulders/arms/
neck/back/jaw/epigastrium - Usually lasts 3-5 min and rarely exceeds 15 min
- Not changed by swallowing, coughing, deep breathing or positional changes
- Anxiety
- Diaphoresis or clammy skin
- Nausea, vomiting
- Shortness of breath
- Weakness
- Palpitations
- Syncope
Is angina pectoris an acute or ischaemic coronary syndrome?
Ichaemic
What usually provokes angina pectoris?
- Exercise
- Eating
- Emotion/Stress
What usually relieves angina pectoris?
- Rest/removal of provoking factor
- Nitrates
- Aspirin
What is stable angina pectoris?
- Reasonably predictable frequency, onset, and duration
- Relief predictable with rest/nitrates
What are the treatment goals for stable angina pectoris?
- Reduce myocardial oxygen/glucose demand
- Improve myocardial blood supply
Describe the treatment of stable angina pectoris
- Physical and psychological rest
- Position of comfort (sitting or supine)
- O2 only if indicated
- Cardiac monitoring
- GTN, aspirin, morphine/fentanyl, ondansetron
What are the indications for treating stable angina pectoris as AMI?
- First time angina
- Unstable angina
- Angina requiring more than 3 GTN sprays (lasting longer than 15 minutes)
What is variant angina?
Angina that occurs at rest, is the result of coronary vasospasms, and is treated long term with calcium channel blockers
True or false: variant angina may result in abnormal 12 lead ECG changes that resolve with minimal treatment
True
What is the definition of unstable angina?
Prolonged chest pain/ischaemic symptoms or an atypical presentation of angina without evidence of AMI, usually associated with significant or progressing occusion of a coronary artery or severe vasospasm. It is considered ‘pre-infarction angina’.
Describe atypical presentation of unstable angina
- Increased frequency or duration of episodes
- Onset with less exertion than normal
- Increased severity of symptos
- Requires more GTN than usual to relieve symptoms
Describe the treatment of unstable angina
Same as stable angina, with addition of:
- IV access
- 12 lead monitoring
- Pain management as necessary
- Other standard management by indication (ondansetron etc)
What is acute myocardial injury?
Presentation of unstable angina or acute ischaemia with potential for myocardium salvage
What is the definition of acute myocardial infarction?
Necrosis of myocardial tissue caused by a lack of oxygenation and blood flow resulting from an occluded coronary artery
AMI is also often used to describe acute injury when extent of necrosis is unknown but imminent
What are the precipitating factors of AMI?
- Coronary thrombosis (most common)
- Coronary vasospasm
- Microemboli
- Severe hypotension/shock
- Acute hypoxia
- Acute volume overload
What is the initiating event in most ischaemic coronary events?
Rupture of vulnerable plaque’s soft lipid core
What does rupture of atheromatous plaque result in?
Thrombus formation
A persistent thrombotic occlusion (2-4+ hours) may result in what?
Acute myocardial infarction
Repeated thrombus formations may have what effect?
Further decrease lumen size
What does intermittent non-occlusive thrombus formation result in?
Unstable angina
What is the presentation of acute myocardial infarction?
- Similar to angina but lasts longer and is not easily relieved with rest or GTN
- Symptoms may be more severe (feeling of impending doom)
- Pain often radiates to arms/neck/jaw/back/epigastrium
- Some present atypically (complaints of only weakness or shortness of breath)
- Dysrhythmias
- Sudden cardiac death
What are the Rx goals for AMI?
- Rapid identification and dx
- Decrease myocardial oxygen demand (remove stressors, relieve pain, reduce cardiac workload)
- Inhibit further clot formation
- Transport for reperfusion therapy
Describe the management of AMI
Same as angina, plus:
- IV fluids when indicated
- 12 lead monitoring
All pts with inferior elevation should be checked with what additional ECG view?
V4R
How is a V4R ECG reading obtained?
Move V4 over to the R side and take another 12 lead; elevation indicates RV involvement, meaning the pt is preload dependent (which is a contraindication for GTN)
What may increase the risk of misdiagnosis?
- Elderly with atypical symptoms
- Young pts with unsuspected AMI
- LBBB
- ALOC
- Diabetics
- Mental disorders
STEMI dx requires confirmation of two of three criteria; name them
- Hx
- ECG changes
- Elevation of serum levels of cardiac markers
What is the definition of sudden cardiac death?
Sudden unexpected biologic death, presumably resulting from CVD (most commonly VF).
