Incisura angularis

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A Moment in History

Jean George Bachmann
(1877 – 1959)

French physician–physiologist whose experimental work in the early twentieth century provided the first clear functional description of a preferential interatrial conduction pathway. This structure, eponymically named “Bachmann’s bundle”, plays a central role in normal atrial activation and in the pathophysiology of interatrial block and atrial arrhythmias.

As a young man, Bachmann served as a merchant sailor, crossing the Atlantic multiple times. He emigrated to the United States in 1902 and earned his medical degree at the top of his class from Jefferson Medical College in Philadelphia in 1907. He stayed at this Medical College as a demonstrator and physiologist. In 1910, he joined Emory University in Atlanta. Between 1917 -1918 he served as a medical officer in the US Army. He retired from Emory in 1947 and continued his private medical practice until his death in 1959.

On the personal side, Bachmann was a man of many talents: a polyglot, he was fluent in German, French, Spanish and English. He was a chef in his own right and occasionally worked as a chef in international hotels. In fact, he paid his tuition at Jefferson Medical College, working both as a chef and as a language tutor.

The intrinsic cardiac conduction system was a major focus of cardiovascular research in the late nineteenth and early twentieth centuries. The atrioventricular (AV) node was discovered and described by Sunao Tawara and Karl Albert Aschoff in 1906, and the sinoatrial node by Arthur Keith and Martin Flack in 1907.

While the connections that distribute the electrical impulse from the AV node to the ventricles were known through the works of Wilhelm His Jr, in 1893 and Jan Evangelista Purkinje in 1839, the mechanism by which electrical impulses spread between the atria remained uncertain.

In 1916 Bachmann published a paper titled “The Inter-Auricular Time Interval” in the American Journal of Physiology. Bachmann measured activation times between the right and left atria and demonstrated that interruption of a distinct anterior interatrial muscular band resulted in delayed left atrial activation. He concluded that this band constituted the principal route for rapid interatrial conduction.

Subsequent anatomical and electrophysiological studies confirmed the importance of the structure described by Bachmann, which came to bear his name. Bachmann’s bundle is now recognized as a key determinant of atrial activation patterns, and its dysfunction is associated with interatrial block, atrial fibrillation, and abnormal P-wave morphology. His work remains foundational in both basic cardiac anatomy and clinical electrophysiology.

Sources and references
1. Bachmann G. “The inter-auricular time interval”. Am J Physiol. 1916;41:309–320.
2. Hurst JW. “Profiles in Cardiology: Jean George Bachmann (1877–1959)”. Clin Cardiol. 1987;10:185–187.
3. Lemery R, Guiraudon G, Veinot JP. “Anatomic description of Bachmann’s bundle and its relation to the atrial septum”. Am J Cardiol. 2003;91:148–152.
4. "Remembering the canonical discoverers of the core components of the mammalian cardiac conduction system: Keith and Flack, Aschoff and Tawara, His, and Purkinje" Icilio Cavero and Henry Holzgrefe Advances in Physiology Education 2022 46:4, 549-579.
5. Knol WG, de Vos CB, Crijns HJGM, et al. “The Bachmann bundle and interatrial conduction” Heart Rhythm. 2019;16:127–133.
6. “Iatrogenic biatrial flutter. The role of the Bachmann’s bundle” Constán E.; García F., Linde, A.. Complejo Hospitalario de Jaén, Jaén. Spain
7. Keith A, Flack M. The form and nature of the muscular connections between the primary divisions of the vertebrate heart. J Anat Physiol 41: 172–189, 1907.

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Anterior view of the stomach

The term "incisura" is Latin, derived from the verb [incidere]* meaning "to cut" or [incisura]” meaning a "notch" or indentation in a structure, suggesting a distinctive incision, or cut. The second component, "angularis," is also Latin, derived from "angulus," which translates to "angle." The term "incisura angularis" can be translated as the "angular notch", a term that is also use for this gastric anatomical landmark.

The incisura angularis is a notch located along the lesser curvature of the stomach. Externally, it marks the transition between the body (corpus) and antrum of the stomach, an abdominal viscus. It is related to the gastrohepatic portion of the lesser omentum superolaterally. It should be mentioned that the lesser curvature vascular arcade runs within the lesser omentum, closely related to the gastric lesser curvature.

Found approximately midway between the esophagogastric junction and the pylorus, this external anatomical feature is easily identifiable internally during gastric endoscopy.

Structurally, the incisura angularis is formed by a fold of mucous membrane on the inner surface of the stomach, creating a small recess along the lesser curvature.

The stomach, although it has the same layers as the rest of the GI tract, presents an extra muscular layer in the area of the lesser curvature, which renders this area less distensible forming a muscular channel called the magenstrasse.

The mucosa layer is the deepest of the stomach layer. Within it, three areas of gastric mucosa are usually described: pyloric, transitional, and fundic. The incisura angularis corresponds mostly to the transitional zone. When there are mucosal changes that shown an invasion of another type of mucosa, it can mean preneoplastic changes. For this reason, the incisura angularis is an area that, when biopsied, can show early cancerous changes, as well as muscular atrophy, intestinal metaplasia, and dysplasia.

Preservation of the anatomy of the incisura angularis is critical during a sleeve gastrectomy, the most common bariatric procedure worldwide. The objective of a sleeve gastrectomy is to reduce the size of the stomach by placing a curved staple line along the left border of the magenstrasse, a lesser known gastric anatomy term.

Because of the location of the incisura angularis, improper placement of a straight gastric stapler could cause stenosis or stricture at this level. Another potential postoperative problem in this procedure is gastroesophageal reflux disease (GERD) where some authors have proposed an omentopexy as a way to modify the angle of the incisura angularis.

Sources:
1. "The Origin of Medical Terms" Skinner, HA 1970 Hafner Publishing Co.
2. "Medical Meanings - A Glossary of Word Origins" Haubrich, WD. ACP Philadelphia
3 "Tratado de Anatomia Humana" Testut et Latarjet 8 Ed. 1931 Salvat Editores, Spain
4. “The Rarely Sampled Incisura Angularis Is Useful for the Detection of Gastric Preneoplastic Lesions” Singhal, A. , Saboorian, H. , Turner, K. , Rugge, M. & Genta, R. (2023). The American Journal of Gastroenterology, 118 (10S), S1407-S1407.
5. “Incisura angularis belongs to fundic or transitional gland regions in Helicobacter pylori-naive normal stomach: Sub-analysis of the prospective multi-center study” Nakajima, S at al Digestive Endoscopy 2021; 33: 125–132
6. “Increasing the angle at the incisura angularis using omentopexy reduces/prevents GERD symptoms five years after laparoscopic sleeve gastrectomy?” Presidential Grand Rounds. Surgery for Obesity and Related Diseases, Volume 18, Issue 8, Supplement, 2022
7. “Gastric POEM to treat incisura angularis torsion after sleeve gastrectomy” Baptista, A; Davila, M; Guzman, M. Endoscopy 2019; 51(04)
8. “Obstruction after Sleeve Gastrectomy, Prevalence, and Interventions: a Cohort Study of 9,726 Patients with Data from the SOReg” Sillen, L; Andersson, E, Edholm, D. OBES SURG 31, 4701–4707 (2021)

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Incisura angularis

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