Abstract
The crochetage sign—a notch near the R-wave peak in the inferior leads—in conjunction with right axis deviation, complete or incomplete right bundle branch block, and right ventricular hypertrophy (R/S ratio >1 in lead V1) on 12-lead electrocardiogram are highly suggestive of atrial septal defect. (Level of Difficulty: Intermediate.)
Key Words: atrial septal defect, electrocardiogram, imaging
Graphical abstract
Case
A 59-year-old female with a 5-year history of hypertension and hyperlipidemia presented with progressively worsening exertional dyspnea over the past 4 months.
What Is the Diagnosis?
Which clinical diagnosis is most closely represented in this electrocardiogram?
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A.
Atrial septal defect—ostium secundum
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B.
Cor pulmonale
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C.
Atrial septal defect—ostium primum
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D.
Ventricular septal defect
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E.
Pulmonic stenosis
The correct answer is A.
Explanation
The patient presented with progressive exertional dyspnea. Physical examination revealed a fixed split-second heart sound and right ventricular (RV) heave. The electrocardiogram (ECG) (Figure 1) showed the crochetage pattern. Subsequent transthoracic echocardiogram showed right-sided chamber enlargement with a secundum atrial septal defect (ASD) (length: 1cm, Qp/Qs: 1.7) (Video 1). Transesophageal echocardiogram was performed to guide transcatheter closure and to help exclude partial anomalous pulmonary venous return, which can also present clinically as isolated right heart failure.
Figure 1.
Initial ECG Showing Right Axis Deviation With Crochetage Pattern in Leads II, III, and aVF
ECG = electrocardiogram.
The crochetage pattern is represented by fragmented QRS complexes with a notch in the ascending part or at the apex of the R-wave, most commonly seen in the II limb lead followed by III, aVF leads (Figure 2). Crochetage sign may also be seen with ostium primum ASDs, ventricular septal defects, pulmonic stenosis, and cor pulmonale, but its occurrence is significantly less common compared to secundum ASDs (P < 0.001).1 The notching of the QRS complex reflects heterogenous RV contractions which occur with RV dilation and hypertrophy. Additional nonspecific ECG findings in a secundum ASD include complete or incomplete right bundle branch block (RBBB), right atrial enlargement, and RV hypertrophy. In comparison, primum ASD would most typically show left-axis deviation. A 15-lead ECG showing a dominant R’ in rV3 and rV4 indicative of right ventricular conduction delay is a highly sensitive ECG marker for a secundum ASD and is more specific than the finding of right ventricular conduction delay in lead V1.
Figure 2.
ECG With Highlighted QRS Complexes Depicting the Most Prominent Crochetage Signs
Red circles highlight inferior ECG leads where the crochetage sign is most common. Black arrows are pointing toward the notch. Abbreviation as in Figure 1.
The first published study describing crochetage found the pattern in 73% of patients with ASD.2 Its presence on ECG positively correlates with the severity of the left-to-right shunt and shunt size.1 The sensitivity and specificity of this sign for a secundum ASD progressively increase with the number of inferior leads involved. This sign has a specificity of 92% to 100% when the pattern is present in all 3 inferior leads.1 The associated presence of an incomplete RBBB further increases the specificity of the ECG for the diagnosis of ASD. The crochetage pattern is independent of the RBBB. The presence of a RBBB has a sensitivity of 36.1% and specificity of 80% for an ASD, indicating the crochetage sign could be a superior ECG marker for the detection of an ASD.3 In the crochetage pattern, notching of the R-wave usually occurs in the initial 80 ms of the QRS complex, whereas in a RBBB pattern, the conduction disturbance occurs in the latter part of the QRS complex.1
In our case, the crochetage pattern persisted on ECG post-ASD closure, however, early disappearance of the pattern has been reported in up to 35.1% of cases following ASD closure.1
In summary, the presence of the crochetage sign on ECG should serve as an important clinical clue prompting evaluation for a secundum ASD in the appropriate clinical scenario.
Funding Support and Author Disclosures
The funding for the article publishing charge has been provided by the Letts O'Brien Fund. The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Footnotes
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Appendix
For a supplemental video, please see the online version of this paper.
Appendix
ASD Shown on Bicaval View of Transesophageal Echocardiogram
References
- 1.Heller J., Hagège A., Besse B., et al. “Crochetage” (Notch) on R wave in inferior limb leads: a new independent electrocardiographic sign of atrial septal defect. J Am Coll Cardiol. 1996;27(4):877–882. doi: 10.1016/0735-1097(95)00554-4. [DOI] [PubMed] [Google Scholar]
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Associated Data
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Supplementary Materials
ASD Shown on Bicaval View of Transesophageal Echocardiogram