Thread by @VivekKulkarniMD

One of the best examples I’ve seen of Kussmaul’s sign: inspiratory increase in JVP.

Why does this happen?

My first #tweetorial 🧵, a la @AvrahamCooperMD @tony_breu @AndreMansoor

#meded #cardioed #cardiotwitter @CooperCVFellows @CooperIMRes @BrighamMedRes @PennCVFellows

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2/ Normally, with inspiration, the negative intrathoracic pressure is transmitted to the heart chambers (❤️ is in the thorax, after all), which makes JVP decrease. Here is an example of normal: neck veins collapsing with inspiration, then filling again with expiration.

3/ Inspiration also causes increased RV filling, but it is easily accommodated by the RV. RA pressure doesn’t change much from the increased filling itself; more predominant is drop in thoracic pressure. Very satisfyingly seen with invasive CVP/RAP measurement, as shown.

4/ Kussmaul’s sign happens for 2 broad physiologic reasons:
1. Increased RV filling cannot be accommodated.
2. Negative intrathoracic pressure is not transmitted to the cardiac chambers.

Let’s deal with each one.

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1a. Any RV problem that prevents the RV from handling a sudden influx of blood will lead to an increased RA pressure with inspiration. Causes in this bucket include RV infarction, acute PE, tricuspid stenosis, and also restrictive cardiomyopathy.

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1b. And even with a normal RV, extreme negative inspiratory pressure can cause so much increased filling that the RV can’t accommodate. This can happen with severe exacerbation of asthma or COPD.

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2. With pericardial constriction, the thickened/calcified pericardium shields the cardiac chambers from the changes in intrathoracic pressure, so RAP doesn’t have the normal inspiratory drop. But why doesn’t the RA pressure just stay the same?

8/ In constriction, when intrathoracic pressure drops, pulmonary venous pressure drops, but the LA pressure is shielded by pericardium. This reduces the LV filling gradient, causes septal shift into the LV, and increases RV filling…ultimately leading to increased RA pressure.

9/ What about tamponade?

Classic teaching is that Kussmaul’s sign is NOT present—negative intrathoracic pressure can still be transmitted to cardiac chambers. But more accurate is that it probably depends on the cause, and sometimes pts can have effusive-constriction.

10/ In truth, Kussmaul’s sign is probably not a specific or specific marker of any particular diagnosis. But it should make you think about what might be going on, and to go hunting for causes!

11/ To sum up:
- Kussmaul’s sign is when JVP rises with inspiration.
- Think of causes in two broad categories: RV cannot accommodate, or pericardium is shielding the heart.
- #JVP exam is so much more than just a number!

12/ Check out this article by @AndreMansoor for some further reading: ncbi.nlm.nih.gov/pmc/articles/P…

And any feedback for me would be appreciated!