What diagnosis might you strongly suspect from the ECG in this patient with chronic progressive shortness of breath?

Written by Magnus Nossen

ECG interpretation is largely based on pattern recognition. Today's case provides another example of an ECG pattern that you can put in your memory bank. There are numerous different patterns one needs to learn in order to master the art of ECG interpretation. 

The recording was obtained from a 20 something female complaining of chronic progressive shortness of breath. 

Can you make the diagnosis of the patient in today's case off of the ECG? 

What is on your list of differential diagnoses? 

The ECG in todays post shows normal sinus rhythm. The HR is about 80bpm. There is normal AV conduction. There is an incomplete RBBB with and rSr’ QRS morphology in the right precordial leads V1-V2. Borderline right axis deviation. The QRS duration is less 100ms. Incomplete RBBB can be a normal finding. There are T wave inversions extending to V3. There is fragmentation/notching of all three R waves in the inferior leads. 

The above constellation of findings, notching of the QRS in all three inferior leads accompanied by an incomplete or complete RBBB is quite specific for hemodynamically significant ASD.  

Above you can see the inferior leads beneath each other. One QRS complex has been magnified from each lead. The QRS notching is apparent. This is the Crochetage sign.

The patient in today's case was found to have both a large secundum type ASD as well as partial anomalous pulmonary venous return in which one of the pulmonary veins drained to the right atrium. Both the ASD and the anomalous pulmonary venous return will give volume overload of the right heart causing the ECG findings in today's case. 

The chief complaint in today's case was SOB. The symptoms had progressed over time. Had there been acute onset of symptoms a pulmonary embolus would have had to been ruled out. It is important to identify patients with large ASDs as these patients are at risk of paradoxical embolism and large ASD are also associated with right heart failure. Timely intervention is needed to prevent irreversible damage to the pulmonary vasculature and the right heart. The patient in todays case underwent surgical correction of her congenital heart defect. 

Learning points:

Crochetage sign is strongly associated with hemodynamically significant left to right shunts at the atrial level. 

(Most commonly caused by large ASD) 

Acute and chronic RV strain can have some similar ECG findings, but acute right heart strain is usually not associated with QRS fragmentation in the inferior leads. 

Crochetage sign is associated paradoxical embolism and can be a clue to the cause of cryptogenic stroke

A young woman with epigastric pain. ECG Crochetage sign? What is the significance?

Crochetage sign

Crochetage sign LITFL

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MY Comment, by KEN GRAUER, MD (7/28/2024):

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Nice case by Dr. Nossen that reviews the Crochetage Sign (which I discussed in My Comment from the January 8, 2020 post in Dr. Smith's ECG Blog). Depending on the clinical setting in which you practice — this may (or may not) be an ECG sign that you have encountered.

• That said — the combination of ECG findings described by Dr. Nossen in today's case, in association with the clinical history of a young woman complaining of progressive shortness of breath — should prompt immediate consideration of a potential hemodynamically significant ASD (Atrial Septal Defect).

ECG Findings in Today's Case:

As per Dr. Nossen — the ECG signs of a significant ASD in today's case include the following: i) Incomplete RBBB pattern (rSr' in lead V1 — with narrow terminal S waves in lateral leads I and V6); — ii) Vertical (nearly rightward) frontal plane axis (suggested by the nearly more-negative-than-positive S wave in lead I); iii) RV "strain" — suggested by deep and symmetric anterior T wave inversion; — and, iv) The Crochetage Sign.

• For clarity in Figure-1 — I've reproduced Dr. Nossen's magnified illustration of the crochetage sign in today's case.

Figure-1: I've added WHITE arrows to highlight the crochetage sign in each of the inferior leads.

Regarding the Crochetage Sign:

As I reviewed in the January 8, 2020 post — the term “crochetage” is French. The infinitive of the verb that means “to crochet” ( = crocheter in French) — and the initial literature on this subject came out of Paris in 1996 by Heller et al in JACC. 

• The study by Heller et al is noteworthy, because their conclusions hold true today, more than 20 years later. Their study was based on evaluation of 1,560 older children and adults — in which they searched for a Crochetage Pattern ( = a notch on the upstroke of the R wave in one or more of the inferior leads). Five different types of valvular heart disease were present among subjects in their study (about 1/3 had secundum atrial septal defect) — and about 1/3 of the patients were normal subjects.
• There was a high (but far-from-perfect) correlation between the presence of crochetage in the patients with ASD (Atrial Septal Defect). Specificity for ASD greatly increased (ie, ≥92% in their study) when crochetage was seen in all 3 of the inferior leads — and/or — when incomplete RBBB (IRBBB) was also present.
• I don’t believe the mechanism for the crochetage “notch” on ECG with ASD is known. What has been observed — is that presence of crochetage showed good correlation to shunt severity. Of interest — early disappearance of crochetage was observed in ~1/3 of patients following surgical correction (though the IRBBB pattern persisted).

NOTE: Although descriptions vary in the literature that I've seen — true crochetage is said to occur on the upstroke of the R wave in inferior leads, occurring within the first 80 msec. of the QRS. So in today's ECG — the notching (WHITE arrows in Figure-1) — simulates the triphasic pattern of rbbb conduction in lead III — occurs on the upstroke in lead aVF — but on the downstroke (instead of the upstroke) of the R wave in lead II. That said — many of the examples that I've seen posted on-line are not necessarily on the "upstroke" of the R wave. 

• Clinical Question: — What we should make of notching that we occasionally see in one or more of the inferior leads as a result of any of the following: i) Artifact; ii) A "rbbb equivalent" pattern (in which a triphasic complex may be seen in lead III and/or lead aVF — with similar implication as an incomplete RBBB pattern); — or — iii) As a result of scarring (fragmentation) in a patient with prior infarction and/or cardiomyopathy. That is — How to distinguish occasional inferior lead notching from crochetage that is likely to be a "true" marker of a significant ASD?
• Application of Bayes' Theorem may help in answering this clinical question (See My Comment in the April 19, 2024 post in Dr. Smith's ECG Blog) — in that the prevalence of an ASD in the population being looked at should prove insightful (ie, Notching in 1 or 2, but not 3 inferior leads — in an otherwise asymptomatic patient without IRBBB or RV "strain" — is unlikely to be a marker for ASD).
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• Final Clinical Point: Listen carefully for signs of ASD (ie, fixed split S2) when inferior lead notching is seen — especially if incomplete RBBB or RV "strain" is seen — and have a low threshold for getting an Echo if ASD is a consideration.