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.

Francesco Todaro (1839 – 1918)
Francesco Todaro

Francesco Todaro (1839 – 1918) Italian physician and anatomist born in Tripi, a village in the province of Messina, Sicily.

While still a medical student at the University of Messina, he joined the Garibaldini as a volunteer and fought at Corriolo and Milazzo during the campaign for Italian unification in 1860. After completing his medical degree, he pursued further anatomical training in Florence, studying under prominent figures including Moritz Schiff and Filippo Pacini (1812 – 1883) focusing his research myocardial and valve anatomy.

In his 1865 publication, "Novelle ricerche sopra la struttura delle orecchiette del cuore umano e sopra la valvola di Eustachio" Todaro described a fibrous extension of the valve of the inferior vena cava (Eustachian valve) starting at the point where the Eustachian valve and the valve of the coronary sinus (Thebesian valve) appear to merge. This structure later became known eponymically as the tendon of Todaro, component of the boundaries of the triangle of Koch, site for the atrioventricular node.

In page 33 of this publication Todaro states: “e perseguitatolo, con ogni accuratezza, in mezzo alle fibre muscolari del sotto, l'accompagnai fino al pilastro posteriore della fossa ovale, da ove mi accertai entrare pel corno posteriore, che qui ha origine, nella valvula di Eustachio, percorrendola in tutto il suo margine libero. Ho confermato dopo, questa osservazione, in molti altri casi ; ed ho trovato sempre costante, il tendine, anco quando la valvula d'Eustachio è quasi manchevole.” “I followed it to the posterior pillar of the oval fossa, from where I confirmed that it entered through the posterior horn, which originates here, into the Eustachian valve, following its entire free margin. I have subsequently confirmed this observation in many other cases, and have always found the tendon to be constant, even when the Eustachian valve is almost missing.”
 Tendon of Todaro

SVC: Superior vena cava, RPA: Right pulmonary artery, RSPV: Right superior pulmonary vein, RIPV: Right inferior pulmonary vein, IVC: Inferior vena cava, RAA: Right atrial appendage, FO: Foramen ovale, TV: Septal leaflet of the tricuspid valve. The yellow line shows the location of the "Tendon of Todaro".  

In 1867 he was appointed Professor of Human Anatomy at the University of Messina, and in 1871 he accepted the chair of anatomy at the University of Rome “La Sapienza”, where he remained until his death.

In 1874, Todaro became a member of the Accademia Nazionale dei Lincei, Italy’s foremost scientific academy. He also served as a Senator of the Kingdom of Italy.

Personal note: There are some publications that assert that the tendon of Todaro is rarely seen. That has not been my experience.

Sources:
1. Sopra la struttura delle orecchiette del cuore umano. Todaro F. Stabilimento Civelli Pub. Florence, Italy: 1865. (Italian)
2. TODARO, Francesco. Dorello P. Enciclopedia Italiana. 1937 (Italian)
3. Todaro, Francesco. Treccani Enciclopedia on line.(Italian) 

4. TODARO, Francesco. Ottaviani A. Dizionario Biografico degli Italiani. Vol. 95. (Italian)
5. Cardiac anatomy primer. McMullen, HL. Am Assoc Thorac Surg.