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Chest pain with a slow pulse
A 61-year-old man has had crushing chest pain for an hour. His ECG shows ST elevation in leads II, III and aVF. His heart rate is 44/min.
Step 1 of 4
Which artery is most likely occluded?
Correct answer: D
ST elevation in II, III and aVF is an inferior MI, usually from the right coronary artery in a right-dominant heart (the circumflex in a left-dominant one).
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D
ST elevation in II, III and aVF is an inferior MI, usually from the right coronary artery in a right-dominant heart (the circumflex in a left-dominant one).
Step 2 of 4
Why is he bradycardic?
Correct answer: A
The RCA usually gives the SA nodal and AV nodal arteries, so inferior MI causes bradycardia and AV block (see cardiac conduction system).
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A
The RCA usually gives the SA nodal and AV nodal arteries, so inferior MI causes bradycardia and AV block (see cardiac conduction system).
Step 3 of 4
His blood pressure falls to 82/50 mm Hg. His lungs are clear and his JVP is raised.
What is the most appropriate next step?
Correct answer: D
Hypotension with clear lungs and a raised JVP suggests a right ventricular infarct from a proximal RCA occlusion. The RV is preload-dependent, so give fluids and avoid nitrates and other preload reducers.
Show answer
D
Hypotension with clear lungs and a raised JVP suggests a right ventricular infarct from a proximal RCA occlusion. The RV is preload-dependent, so give fluids and avoid nitrates and other preload reducers.
Step 4 of 4
On day 4 he becomes suddenly breathless with pulmonary edema and a new holosystolic murmur.
What is the most likely cause?
Correct answer: A
Papillary muscle rupture typically occurs about 2–7 days after an MI and causes acute mitral regurgitation. The posteromedial papillary muscle has a single blood supply (from the posterior interventricular artery), so it ruptures after inferior MI (see mitral valve).
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A
Papillary muscle rupture typically occurs about 2–7 days after an MI and causes acute mitral regurgitation. The posteromedial papillary muscle has a single blood supply (from the posterior interventricular artery), so it ruptures after inferior MI (see mitral valve).
Key points
- Inferior MI (II, III, aVF) → RCA → bradycardia and AV block.
- Hypotension + clear lungs + raised JVP → RV infarct: fluids, no nitrates.
- New holosystolic murmur days after inferior MI → posteromedial papillary muscle rupture.
Study: Right coronary artery, Cardiac conduction system, Mitral valve, Heart