Thread by @nickmmark

Non-COVID teaching: Can you identify this unusual cause of chronic cough? (Hint: always carefully look at tubes and lines on #CXR and axis on #EKG) #medtwitter #FOAMed #FOAMrad

So let’s jump into this #FOAMed case. On the CXR we’ve got a couple interesting things:
* the PICC line appears to terminate on the wrong (e.g. left) side (white arrow)
* the aortic knob is on the wrong (e.g. right) side (grey arrow)
* it’s hard to identify the cardiac silhouette

Some of these findings are easy to miss. To avoid missing things, it’s really important to have a systematic approach to reading a CXR. Here’s a good one:
➡️mededportal.org/doi/10.15766/m…

The EKG also has a couple abnormalities
* a rightward axis (263 degrees)
* negative P’s & T’s in I and aVL
* upward QRS in aVR
* abnormal R wave progression (open arrows)
(some of these are subtle too; once again a systematic approach is very helpful)

The best explanation for the CXR and EKG findings is dextrocardia. (This is easier to see on the CT scan below.) But there’s more going on than just isolated dextrocardia. In order to understand the unifying diagnosis we need to understand what cilia are and what they do.

Cilia are tiny cellular motors connected to slender protuberances on the cell surface. They are made up of microtubules and dynein arms to move them. Here’s a picture of cilia on the lung and a video of them in action

These cilia are important for many things:
* clearing debris out of the lungs and upper airways
* enabling sperm to move
* establishing a gradient of signaling molecules to determine laterality in embryogensis

Cilia are really important for clearing bacteria and other debris out of the airway and lungs. Patients with ciliary dysfunction are predisposed to sinusitis, otitis media, and pneumonia.

To summarize, cilia are important. When they don’t work:
* airway cilia —> broncheictasis, infections
* sperm cilia —> infertility
* cilia in embryogenesis —> abnormalities in organ laterality —> dextrocardia/situs inversus

Kartagener’s syndrome is a rare type of a ciliopathy - a disorder of cilia. In Kartagener’s the motors (the arms that pull on adjacent tubules) are absent, so the cilia can’t move. This leads to the triad of bronchiectasis, infertility, and situs inversus.

To summarize what we've learned:
* use a systematic approach to read CXRs & always look at tubes/lines
* remember the signs of situs inversus on EKG
* cilia are important for clearing secretions
* Kartagener’s is a rare cause of bronchiectasis, situs inversus, and sinusitis