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Patrick Zakka, MD Profile picture
@PatrickZakka
May 5, 2022 • 7 tweets • 5 min read • Read on X
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🚧Calling all @CardioNerds! What is this sign on EKG called? #CNshowmeasign 🚧 Image
Crochetage sign is a notch on the apex of R waves in the inferior leads. It can be associated with ostium secundum ASDs. Image
It is a result of delayed depolarization of the right ventricle because of L to R shunt. This is why ostium secundum ASDs are also associated with:
🚦Right axis deviation
🚦Incomplete RBBB Image
⚡️ Sens/spec: 73.1%/92.6% (when in 1 inferior lead); 27.8%/100% (when in all inferior leads). Increased specificity when associated with incomplete RBBB.
⚡️ Correlated with greater anatomic defect or greater L to R shunt.
⚡️ Sens/spec for dx PFO in cryptogenic stroke: 36%/91%. Image
⏳ "Crochetage" = French for "notching"
⌛️ First described 1959 by Rodriguez-Alvarez et al in 11 patients with ostium secundum ASDs. Image
References:
pubmed.ncbi.nlm.nih.gov/8613618/
casereports.bmj.com/content/2016/b…
Thank you to my mentor @jcurrier17 for teaching me about EKGs seen in ASDs and inspiring this med ed project.
#CNshowmeasign brought to you by @PatrickZakka and @a_h_ghoneem.
Special thank you to @TDonisan (for the amazing graphics) and @AmitGoyalMD @Dr_DanMD for reviewing.
If there are any other signs you would like us to tackle, put them in the comments and let us know what to do next! Image

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More from @PatrickZakka

Patrick Zakka, MD Profile picture
Sep 20, 2021
Time for a #tweetorial!
In my medical training, I have seen several patients without cardiac history who have EKGs with prominent R waves in lead V1. Check out this 🧵for a differential diagnosis framework on categories and causes of large R waves in V1! #meded @CardioNerds
Let's start by reflecting on this statement: "I am confident that my list of differential diagnoses on large R waves in V1 is comprehensive."
We will begin by defining a tall R wave in V1. This occurs when the R to S ratio is greater than 1 (R:S > 1). Generally, R waves start small in V1, and progressively increase to a point where R waves become larger than S waves at the transition point (R>S) usually at V3-V4.
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