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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Heart, anterior view
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The right coronary artery (RCA) is one of the two branches that arises from the ascending aorta and provide blood supply to the heart. The RCA begins at the coronary ostium, situated usually within the right sinus of Valsalva found in the aortic valve, one of the semilunar valves of the heart.

The RCA gives off in its initial course two arteries: the conus artery, which gives blood to the conus arteriosus, the outflow tract of the right ventricle, and the artery to the sinoatrial (SA) node, a component of the conduction system of the heart.

The RCA descends in the atrioventricular sulcus, giving off a series of small right ventricular branches and a couple of small right atrial branches, it then bends around the acute margin (margo acutus) and passes to the posterior surface of the heart. Just before the RCA bends posteriorly, it will give off the acute marginal artery, usually a thin, longer branch that extends towards the cardiac apex.

In its posterior trajectory the RCA gives off a couple of small posterior right ventricular arteries and then ends at the crux cordis, where the RCA gives off the posterior interventricular artery, commonly known as the posterior descending artery (PDA). The RCA will also give off the posterolateral artery, which, situated in the atrioventricular sulcus, extends the vascular territory of the RCA into the region of the left ventricle. This origin of the PDA from the RCA is subject to anatomical variation, which gives origin to the concept of coronary dominance.

Arising from the terminal portion of the RCA (sometimes from the posterolateral artery) is the artery to the atrioventricular (AV) node, another component of the conduction system of the heart. It is easily understood that stricture or stenosis of the RCA (depending on location) can then lead to damage of the conduction system of the heart.

Human heart and coronary artery anatomy and pathology are some of the many lecture topics developed and presented by Clinical Anatomy Associates, Inc.

Image property of: CAA.Inc.Artist: Victoria G. Ratcliffe