Session 10 Flashcards
What are the common causes of chest pain and how do they present?
Cardiac - ischaemia (tightening pain), pericarditis (sharp pain) and aortic dissection (tearing pain)
Respiratory - lateral pleuritic pain (worse on inspiration and coughing). Causes include infection (pneumonia), pulmonary embolism and pneumothorax.
GI - e.g. Reflux oesophagitis - burning pain
MSK - trauma, muscle pain, none metastases. Worse on movement.
On what direction does coronary blood flow?
Epicardium to endocardium
What does myocardial oxygen supply and demand depend on?
Supply - coronary blood flow (depends on diastolic BP and coronary artery resistance) and O2 content of the blood
Demand - HR, wall tension (preload and afterload) and contractility
Describe the features of a stable and an unstable atheromatous plaque
Stable - small necrotic core and thick fibrous cap. Less likely to rupture/fissure.
Unstable - large necrotic core and thin fibrous cap. More likely to fissure, exposing blood to thrombogenic material in necrotic core.
What are the acute coronary syndromes?
Unstable angina -> non-ST segment elevation MI (NSTEMI) -> ST segment elevation MI (STEMI)
What is ischaemic chest pain typically described as?
Central, crushing and radiating (e.g. Left shoulder)
What is the difference in presentation between stable angina and acute coronary syndrome?
Stable angina shows no pain at rest, less severe pain, precipitated by stress/exercise and relieved by nitrates/rest.
Unstable angina results from a greater occlusion (between 70 and 90%).
How is stable angina diagnosed?
Mostly by history, but may also have examination signs for risk factors.
Resting ECG unusually normal. If diagnosis uncertain then an exercise stress ECG is carried out. Patient exercised until target reached, chest pain occurs or ECG changes occur (ST segment depression).
What are two surgical techniques for restoring coronary artery blood flow?
Percutaneous coronary intervention (PCI) - angioplasty and stenting.
Coronary artery bypass grafting from radial retry or saphenous vein.
What is the difference between NSTEMI and STEMI?
NSTEMI - infarct in not full thickness of myocardium. Shows ST depression and/or inverted T wave.
STEMI - infarct is full thickness of myocardium. ST elevation in leads facing area.
How is unstable angina distinguished from acute myocardial MI?
Levels of troponin I and T are elevated in acute MI nut not in unstable angina
Describe the release of different bio markers following an acute MI
Troponin I and T levels rise 3-4 hours after the first onset of pain, peak at 18-36 hours and decline slowly up to 10-14 days.
CK-MB (creative kinase isoenzyme specific to the myocardium) rises 3-8 hours after onset, peaks at 24 hours and declines up to 48-72 hours. Useful when new episodes of chest pain occur within 10 days.
Describe the management of a patient with acute coronary syndrome
An urgent ECG is done to differentiate between STEMI and NSTEMI/unstable angina.
STEMI is diagnosed if there is either ST elevation in 2 or more leads facing the same area or a new left bundle branch block.
For treatment of STEMI, if there is not emergency PCI available within 90-120 minutes fibrinolytic therapy is used. General treatments are pain relief, O2 if needed, organic nitrates and statins.
What are possible complications following acute MI?
Cardiac death, arrhythmias, heart block, ventricular tachycardia, ventricular/atrial fibrillation, heart failure and cardio genie shock.
What are causes of pericarditis?
Idiopathic
Infections (viral, TB)
Autoimmune
Cancer
