Medical Terminology Daily - Est. 2012

Medical Terminology Daily (MTD) is a blog sponsored by Clinical Anatomy Associates, Inc. as a service to the medical community. We post anatomical, medical or surgical terms, their meaning and usage, as well as biographical notes on anatomists, surgeons, and researchers through the ages. Be warned that some of the images used depict human anatomical specimens.

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A Moment in History

Jean George Bachman

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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This article is part of the series "A Moment in History" where we honor those who have contributed to the growth of medical knowledge in the areas of anatomy, medicine, surgery, and medical research.

Dr. Jean-Francois Calot
Jean-Francois Calot (1861 – 1944)

Jean-Francois Calot (1861 – 1944). French physician and anatomist, Jean-Francois Calot was born in Arrens-Marsous, a small farming community of the Hautes-Pyrénées. He received his bachelor degree in 1880 at Saint-Pe de Bigorre,  and then continued to study Medicine at the University of Paris, where he worked as an anatomy prosector. His doctoral thesis “De La Cholecystectomie” (On Cholecystectomy) was published in 1890 and republished in 1891.

Although his main interest laid in orthopedics and tuberculosis, Calot’s name is eponymically tied to an anatomical landmark described in his thesis, the “Triangle of Calot”, a triangular area that includes the biliary ducts associated with the gallbladder and the vascular supply to the gallbladder. This is an important region because of the high number of anatomical variations found in the area.

There is a discrepancy between the original description of this triangular region by Calot and what is used today. For more information, click on this link to read more on the “Triangle of Calot”, also known as the “cystohepatic triangle”.

During his medical career Calot worked at several French hospitals including the Rothschild hospital where he became Chief of Surgery. He was also the Chief of Surgery for the Cazin-Perrochaud Hospital, and the Orthopedic Institute of Berck-sur-Mer

Dr. Jean-Francois Calot and the treatment of Pott's disease
Dr. Jean-Francois Calot and
the treatment of Pott's disease

During his orthopedic career Calot published many books “Chirurgie et orthopédie de guerre”, “Les maladies qu'on soigne á Berck”, “Berck et ses traitements : les raisons de sa supériorit?”, but his opus magnus is the book “« L'orthopédie indispensable aux praticiens” (Indispensable orthopedics for practitioners).

Calot is also known for his treatment of tuberculotic abscesses, and a conservative approach to musculoskeletal tuberculosis. The surgical approach of the times was to surgically open and clean the tuberculotic bone. Calot is known to have said “Ouvrir la tuberculose, c'est ouvrir la porte d' la mort” (To open the tuberculosis is to open the door to death).

Continuing his studies and treatment of tuberculosis, on December 22nd, 1896 Calot presents the the French Academy of Medicine a study of the treatment of 37 patients with hyperkyphosis due to Pott’s disease, a tuberculotic spinal deformity, named after Sir Percival Pott. This method included traction and a brace. The second image shows this treatment. Dr. Calot is standing at the center, looking at the patient.

In 1900 Calot founded the “Orthopedic Institute of Berck” which today is known as “Calot’s Institute of Berck-sur-Mer”.

Sources:
1. “Calot's triangle” Abdalla S, Pierre S, Ellis H. Clin Anat. 2013 May;26 (4):493-501
2. “La Vie et l'OEuvre de Francois Calot, chirurgien orthopédiste de Berck” Loisel, P. (in French). Report presented at Société Francaise d'Histoire de la Médecine on 18 March 1987

Image 1: Original image courtesy of the National Library of Medicine
Image 2: Original image public domain courtesy of the Universite Paris-Descartes Histoire de la Santé