Chest Pain & Acute Coronary Syndrome Flashcards
What are the different common causes of chest pain
Musculoskeletal: Costochondritis, bone
Respiratory: Pleuritis
GI: GORD (gastro-oesophageal reflux disease), peptic ulcer
Vascular: Aortic dissection
Cardiac: Ischaemia
Skin: Shingles
Describe the risk factors for coronary atheroma
High cholesterol
High BP
Diet (e.g.saturated fats)
Obesity
Diabetes
Smoking
Describe the pathophysiology of stable angina
- Buildup of atherosclerotic plaques in the coronary arteries
- Reduction in blood flow leading to shortage of O2&Nutrients, which can cause it to become ischemic
Clinical features & treatment of stable angina
Clinical features:
-dull, central cardiac chest pain on exertion, relieved by rest
-Pain may radiate to shoulder, jaw, left arm
-no associated autonomic features
Treatment:
-GTN (Glyceryl trinitrate) causes vasodilation of veins to 🔽 the workload of the heart by 🔽 cardiac returna
Clinical features & treatment of unstable angina
Clinical features:
-dull, central cardiac chest pain on exertion at rest
-no autonomic features
ECG:
-ST depression, T inversion
Treatment:
Describe the pathophysiology of unstable angina
- Rupture of an atherosclerotic plaque in the coronary arteries
- Triggers formation of a blood clot that can completely block the affected artery
What conditions are included in Acute Coronary Syndrome
-Unstable angina
-Myocardial infarction (STEMI, NSTEMI)
Describe the pathophysiology of Myocardial Infarction
- Plaque rupture & thrombus formation
- Occlusion of coronary artery leading to infarction
Clinical features of myocardial infarction
Clinical features:
-intense, dull, central pain
-pain may radiate to shoulder, left arm, jaw
-Sympathetic nervous system: nausea, generalised pallor, sweating, dyspnoea
ECG:
STEMI- complete coronary artery occlusion causing a transmural (full-thickness) injury to a region of the myocardium
-ST elevation, Pathological Q wave
NSTEMI- partial occlusion of a coronary artery causing a sub-endocardial injury
-ST depression, T wave inversion
Blood test: Troponin (I, T) (+ve)
How is a Q wave formed on ECG in MI
In MI the dead muscle tissue doesn’t produce action potential
-picks up a signal from the opposite side of the heart
-this is directed away from the electrode causing a Q wave
Q wave = muscle necrosis.
For a Q wave to be determined as pathological it must:
- > 1 small square wide
- > 2 small squares deep
-Depth must be more than ¼ the height of the subsequent R wave
Management of Myocardial Infarction
MONA:
Morphine - pain relief
Oxygen - the cardiac output may be reduced so oxygen is important to maintain oxygen saturations
Nitrates - vasodilation of veins to 🔽cardiac return and ease strain on the heart, and to 🔼 blood flow through the coronary arteries
Aspirin - anti-platelet
Others:
-statin
-bisoprolol
-ace inhibitor
Troponin rise is only seen in which conditions?
STEMI & NSTEMI
Investigations used in coronary artery disease
Invasive coronary angiogram: Identify the affected coronary artery and for its occlusion
Stent: To maintain blood flow through the artery
Others:
-Chest X-Ray (pulmonary oedema)
-Urea&electrolytes (kidney function,cardiogenic shock)
-Echocardiogram (valve damage, rate of flow, LV impairment)
Identify region of the heart affected from the particular groups of leads which show changes in MI
Septal: V1&V2
Anterior: V1-V6
Lateral: V5&V6
Anteroseptal: V1-V4
Anterolateral: V3-V6
Inferior: II, III, aVF
High lateral: I, aVL
