Atrial Septal Defect

ASD's commonly cause no EKG findings unless significant enough to produce right atrial dilation, which ultimately will cause P wave changes (P pulmonale). If this eventually leads to right ventricular hypertrophy, patients can develop signs of RVH or right heart strain (ie incomplete or complete RBBB). However, the crochetage sign is what has been noted to be a classic EKG finding of ASD's. It is classically described as notching near the apex of the R wave in the inferior leads. The mechanism for this EKG change is not known. If it is present, the patient may not have an ASD but should be referred for an Echo for evaluation. If the Crochetage sign is seen throughout all of the inferior leads, the specificity is very high for an ASD. This is important for evaluation of pediatric EKG's (for congenital heart disease), and may also be important for stroke patients (for PFO's).

Examples:

Further Reading:

http://hqmeded-ecg.blogspot.com/search/label/Crochetage%20sign

https://www.onlinejacc.org/content/27/4/877#tab1

https://casereports.bmj.com/content/2016/bcr-2016-217817

https://dl.uswr.ac.ir/bitstream/Hannan/87332/1/2018%20PediatricCardiology%20Volume%2039%20Issue%205%20June%20%2827%29.pdf

https://www.sciencedirect.com/science/article/abs/pii/S002207360600149X

https://www.ahajournals.org/doi/full/10.1161/01.str.29.7.1393