Chest pain and Ischemic heart disease Flashcards
Explain the site, radiation and feeling of typical ischemic chest pain
Site: central, left-sided
Radiation: left/right/both arms, neck, jaw, back, epigastric, also pain may be isolated to these sites with no chest pain
Feeling: Heavy, ‘crushing’
Which area of the heart is most vulnerable to ischemia, why?
Sub endocardial area, as it’s closest to the LV cavity so myocardial wall pressure is greatest, blood vessels in this region are smaller and become extra vaso-constricted
How much must a lumen be occluded to experience angina?
How much is the lumen typically occluded to experience angina at rest?
about 70% normally, 90% occluded to experience angina at rest
Why is increased HR or occlusion detrimental to the perfusion of myocardium?
This shortens the time of diastole, and diastole is when heart muscle is relaxed, therefore coronary arteries are able to vasodilate and blood flow is at its max. A shortened diastole means there is less time for adequate blood to reach the myocardium
What are collateral vessels and where are they?
Why do they develop/expand?
Vessels that form perfusion links between smaller arteries and arterioles, but not between large arteries and the epicardium. They can develop/expand when the myocardium is ischemic and needs extra blood routes
What are the 2 components of a plaque
Fibrous cap and necrotic centre
Explain how the lumen of an artery would appear in someone with a stable angina
An intact plaque has formed above lipids, occluding the artery about 70%
What happens if a plaque inside a vessel breaks?
The fibrous cap undergoes erosion or fissuring, exposing the blood to thrombogenic substances in the necrotic centre
A platelet clot is formed and eventually a fibrin thrombus that occludes most of the lumen and can form a thromboemboli
Name 3 non-modifiable and 4 modifiable risk factors for ischemic heart disease
Also, name 6 lifestyle factors that can contribute to attaining IHD
Non-modifiable: age, male, family history
Modifiable: cigarette smoking, hypertension, diabetes, hyperlipidaemia
Lifestyle factors: stress, obesity, lack of exercise, unhealthy diet, depression, excessive alcohol
What is the key difference between a stable angina and an Acute coronary syndrome?
If the pain is reproducible in a stable angina: brought on typically by the same amount of exertion
Name the 3 types of Acute coronary syndromes and list them in order of increasing severity:
- Unstable Angina
- NSTEMI
- STEMI
What 2 things typically relieve stable angina pain, how long does it typically take?
Rest and/or nitrates in 5 minutes
What would you mainly use to diagnose a stable angina
The History
If you were to examine a patient with stable angina, name 4 things you might find
- Higher BP
- LV dysfunction
- Evidence of atheromas elsewhere, ie peripheral vascular disease
- corneal arcus
What is involved in an invasive CT coronary angiography?
A catheter is inserted into the radial or femoral artery and threaded to the aorta. A dye is then released that indicates the location of the blockage
Name 2 tests that can be performed on a patient with a stable MI involving the effects of exercise
- Exercise ECG stress test: have patient do exercise until target HR is reached, until ischemia begins; symptoms start or ECG changes
- Stress echocardiography; if the patient cannot do exercise give patient dobutamine to mimic the stress of exercise and see where the damaged tissue is
What drugs can you give for the following…
a) Venodilation
b) decrease HR and contractility
c) Decrease afterload
d) Decrease platelet aggregation
e) decrease LDLs and cholesterol, lowers progression of atherosclerosis and increases plaque stability
a) nitrates
b) B-blockers, Ca2+ channel inhibitors
c) ACE inhibitors lower blood pressure
d) aspirin
e) statins
Name 3 arteries and 1 vein that can be used for performing a coronary artery bypass
Bypass the stenosis:
Arteries: Left and R internal mammary artery, radial artery
Veins: Saphenous vein
What does a PCI stand for, what is it used for?
Percutaneous Coronary Intervention: angioplasty and stents, consists of inflating a ‘balloon-like’ device in an artery with a stent until the artery has been re-opened and the stent is rigidly holding it open. The balloon is then deflated and removed, and the stent remains.
Describe the presentation of acute coronary syndromes
Presence of risk factors.
Pain that is more frequent, severe and longer in duration that can be brought on with little-no exertion and typically lasts longer than 15 minutes.
Name as many symptoms as you can that might be experienced by a patient close to having an MI
- Patient distress: a feeling of impending doom
- cold, clammy, sweaty, pale
- Breathlessness: possible due to pulmonary edema from LV systolic dysfunction or mechanical complication
- Nausea, vomiting, bowel + bladder urgency
- Presyncope (lightheaded) or syncope (fainting)
What might you find on an examination of a patient close to having an MI?
- patient is anxious, distressed, sweaty, clammy, etc
- tachycardia/arrhythmia
- Low BP
- Signs of heart failure: S3 and S4
- Crackles in lung bases: indicates L Ventricular Failure
What differentiates a STEMI from an Unstable Angina or NSTEMI on an ECG?
STEMI: ST elevation
NSTEMI or Unstable Angina: ST depression, can have T wave inversion (but this can also happen before an MI), or no ECG changes
What is troponin, what can measuring the levels of troponin in the blood be useful for?
Troponin is an important protein in actin/myosin interaction and is released in myocyte death, so its levels indicate how long ago and how much myocyte death is occurring
Rises 3-4 hours after onset of pain
Peaks at 18-36 hours
Declines slowly, but remains present for up to 10-14 days
What is the difference in troponin levels between an Unstable angina and NSTEMI?
Unstable Angina: NO troponin, no myocyte death (yet)
NSTEMI: + Troponin, there has been tissue death
What do most coronary artery lumens look like in patients with a STEMI?
Would you find certain biomarkers?
90% have total occlusion
You would find troponin, as a STEMI is extensive ischemic injury involving the full myocardium and tissue death has undoubtedly occurred
How would you manage a patient presenting with chest pain or symptoms suggestive of an MI?
- ECG within 10 minutes
- If there’s persistent ST elevation activate the PPCI (primary PCI) pathway (and if unable to get them to a location able to perform this within 2 hours give thrombolytic drugs)
- If there is NOT persistent ST elevation repeat an ECG in 20 minutes to make sure
What immediate treatment would you provide for an NSTEMI?
Anti-thrombotic therapy: anticoagulants; heparin
Anti-platelet agents: aspirin and clopidogrel
Anti-ischemic therapy: B-blockers, IV nitrates
General measures: pain control, oxygen if needed
What are pathological reasons someone might have a sinus tachycardia or sinus bradycardia?
Sinus Tachycardia: (pain, anxiety) and heart failure
Sinus Bradycardia: SA node ischemia
Name 5 complications of an MI
- Arrhythmias
- First, second or third-degree heart block
- Atrial fibrillation
- Heart failure: Myocardial contractility decreases
- Cardiogenic Shock
- Death
Why does ST-depression/ST elevation occur?
Ischemia triggers K+ to leak out from the injured sub-endocardial cells which causes depolarisation: creating the ST depression in leads facing the injured area
What surgical treatment could you provide for a pericardial effusion?
Pericardiocentesis: aspirating fluid out of the pericardial sac
Name 3 clinical features you could use to diagnose an aortic dissection?
- Immediate onset of pain with a tearing character radiating to back and between shoulder lades
- Variation in pulse and/or BP between R and L arm
- Mediastinal and/or aortic widening on chest radiograph
When should creatine kinase be detectable in the blood?
3-5 hours after an MI
Name 4 causes for recurrent chest pain other than angina
- Peptic ulcer disease
- Biliary colic
- Chest wall: ribs and muscle overexertion/trauma
- Psychogenic
