NBME 18 Cor pulmonale (NBME Answers)

Retired NBME 18 Answers

nbme18/Block 2/Question#28 (reveal difficulty score)
A 68-year-old man comes to the physician ...
Cor pulmonale 🔍 / 📺 / 🌳 / 📖
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+11 upvote downvote
submitted by ∗drdoom(1206)

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Responding to @azibird’s comment:

Backfilling of blood from the lungs into the R ventricle is stretching out the R side (dilation) and also remodeling the heart via hypertrophy (the heart has to pack on mass to eject the ever greater amount of blood piling up from lungs). Dilation of the R ventricle “pulls apart” the leaves of the tricuspid valve=lower left sternal border; when the heart is in systole, the tricuspid valves don’t make good contact and blood rushes from high pressure compartment (RV) to the low pressure (RA) == pansystolic murmur

The tricuspid murmur gets worse with inspiration because when you ask someone to take a good, deep breath, the diaphraghm (a very strong muscle, indeed) pulls the entire thoracic cage down and outward (expansion) — including the heart! Because the heart “gets pulled from all directions”, the tricuspid leaflets make even less contact == bigger hole == more pronounced murmur during systole.

The point of maximal impulse (the heart apex) is way below the xiphoid because this guy’s heart is so big from the years of dilation and hypertrophy — that’s also why S2 sounds are distant: the great vessels (and their valves) are buried even deeper than usual, so you can’t hear them snapping shut (aortic & pulmonic valves; S2=“dub”).

heart sound areas => https://images.app.goo.gl/2F1wUeppSd9vL2os9

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+4 upvote downvote
submitted by ∗thisshouldbefree(51)

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2 pack cig for 50 years = 100 pack years HTN edema LE = LHF hepatomegally = RHF now for the important finding; "murmur that increases on inspiration" -> this is indicative of right sided murmers.

cor pulmonale = my definition is HF as a result of a lung disease

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+2 upvote downvote
submitted by medstudent123425(2)

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Given his history of being a chronic smoker his lungs are messed up (the wheezes that are heard kind of point to it too), probably leading to pulmonary HTN/lung problems. And that can lead to right sided heart failure which can present with a tricuspid regurgitation which is the pan-systolic murmur that they're talking about. That along with the pitting edema and the hepatomegaly (cardiac cirrhosis) kind of point you in the direction of cor pulmonale.

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+1 upvote downvote
submitted by ∗azibird(279)

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Can someone explain the physical findings?

"Cardiac examination shows a grade 2/6 pansystolic murmur heard best at the lower left sternal border, which increaes on inspiration. The point of maximal impulse is palpated in the sub-xiphoid area S1 and S2 sounds are distant"

I don't understand how any of these would correspond to cor pulmonale.

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drdoom Backfilling of blood from the lungs into the R ventricle is stretching out the R side (dilation) and also remodeling the heart via hypertrophy (the heart has to pack on mass to eject the ever greater amount of blood piling up from lungs). Dilation of the R ventricle “pulls apart” the leaves of the tricuspid valve=``lower left sternal border``; when the heart is in systole, the tricuspid valves don’t make good contact and blood rushes from high pressure compartment (RV) to the low pressure (RA) == ``pansystolic murmur`` +1

drdoom The tricuspid murmur gets worse with inspiration because when you ask someone to take a good, deep breath, the diaphragm (a very strong muscle, indeed) pulls the entire thoracic cage down and out (expansion) — including the heart! Because the heart “gets pulled from all directions”, the tricuspid leaflets make even less contact == bigger hole == more pronounced murmur during systole. +4

drdoom The point of maximal impulse (the heart apex) is way below the xiphoid because this guy’s heart is so big from the years of dilation and hypertrophy — that’s also why the S2 sounds are distant: the great vessels (and their valves) are buried even deeper than usual, so you can’t hear them snapping shut (aortic & pulmonic valves; S2=“dub”). +1

cancelstep Similar to what's been said, but here's how I answered: Agree that a pancystolic murmur at LL Sternal Border is tricuspid regurgitation, increases with inspiration because increased right ventricle preload would increase amount of regurgitation. PMI in sub-xiphoid area means that the strongest contraction is happening sub-xiphoid which has to be due to right ventricular hypertrophy (left ventricular hypertrophy would push PMI towards axilla). Diffuse, scattered wheezes bilaterally are probably indicative of COPD from history of smoking which would cause a secondary pulmonary hypertension due to hypoxemia and vasoconstriction in the lungs (primary is idiopathic, most commonly occurs in younger/middle-aged females). So this explains why you have RVH. Pulmonary edema would be crackles on lung auscultation and would point to Left HF, but not the case here. Also, BP 150/80 in a 68-year old without any medication is definitely high, but not causing AS. Peripheral/liver edema = RHF +6

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