Walter Eduard Carl Koch (1880

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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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Details: Written by: Efrain A. Miranda, Ph.D.; Published: February 23, 2026; Hits: 1519

Walter Eduard Carl Koch (1880–1962), German physician, anatomist, and pathologist. Born in Dortmund, Germany, studied medicine at the University of Freiburg and the Kaiser Wilhelm Academy in Berlin, attaining his doctorate in 1907.

He served as a military physician, and later at the Kaiser Wilhelm Academy and in Berlin. Koch specialized in pathology and pathological anatomy and was appointed professor in 1922. Later he became head of the Pathology Department at the Westend Hospital in Berlin and held academic positions after World War II, including a professorship at the newly reconstituted Free University of Berlin. He died in 1962.

He is remembered by the eponymous “triangle of Koch, “site for the atrioventricular node. Although he never referred to this area as a triangle, or used his name to refer to this area, he described it as we know it today in his 1922 publication “Der Funktionelle Bau des Menschlichen Herzens” (The functional structure of the human heart).

Plate X.1 by Walter EC Koch (1922)

In Plate 10.1 Koch shows a photograph of the right atrium where he has drawn the “Tawara’schen Knotten”- an early name for the atrioventricular node (knot of Tawara) – and he describes it as follows: “Vorhofsfeld im rechten Vorhof, vom Sinusstreifen als Fortsetzung der Valvula Eustachii, von der Coronarvenenmündung und dem Ansatz der Tricuspidalisiklappe umsäumt, in weichem der Anfangstait des Reizleitungssystems (schematisch eingezeichnet) gelegen ist: Sinusstreifen und Tricuspidalis treffen sich an der Pars membranacea dort, wo der Stamm den Knoten verläßt” (The atrial region in the right atrium, bordered by the sinoatrial band, a continuation of the Eustachian valve, by the coronary vein (sinus) orifice and the insertion of the tricuspid valve, in which the initial stage of the conduction system (schematically shown) is located: the sinoatrial sinus and the tricuspid valve meet at the pars membranacea where the trunk leaves the node.) The handwriting on the image is by Koch himself.

Note that Koch does not mention the tendon of Todaro as a landmark in this description (although Todaro’s tendon is mentioned in this publication), and Koch calls it the “sinoatrial band").

The term "triangle of Koch" refers to a triangular area in the right atrium with defined anatomical boundaries:

• Medial border: the tendon of Todaro
• Inferior border: the tricuspid valve leaflet
• Posterior border: the orifice of the coronary sinus.

The apex of this triangle corresponds to the location of the atrioventricular node.

Note: In spite of my efforts, I could not find a photograph or a portrait of Walter E.C. Koch. Dr. Miranda.

Sources:
1. "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.
2. "Tratado de Anatomia Humana" Testut et Latarjet 8th Ed. 1931 Salvat Editores, Spain
3. Anderson RH, Sánchez-Quintana D, Nevado-Medina J, Spicer DE, Tretter JT, Lamers WH, Hu Z, Cook AC, Sternick EB, Katritsis DG. . The Anatomy of the Atrioventricular Node. J of Cardiovasc Development and Disease. 2025; 12(7):245.
4. Koch, Walter “Der Funktionelle Bau des Menschlichen Herzens” Urban & Schwarzenberg. 1922. Berlin

Walter Eduard Carl Koch (1880–1962)

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