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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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Medical suffix originating from the old Greek [πλήσσειν] (plessein) meaning “to strike” or the modern Greek [πληγείσες] meaning “stricken”. Its meaning in modern medical terminology is “paralysis”, the loss or impairment of bodily movement. This suffix can be seen in many medical terms:
- Quadriplegia: From the term [quad] meaning “four”. Loss of movement or paralysis in all four extremities
- Hemiplegia: From the prefix [hemi-] meaning “half”. Loss of movement or paralysis in one half of the body
- Paraplegia: The prefix [para-] means “alongside” or “parallel to”. Originally the word paraplegia was synonymous with [hemiplegia], but in modern times it is used to denote loss of movement or paralysis in the lower half of the body
- Cardioplegia: The root term [card] means “heart”. Stopping or paralyzing the heart. This is done as part of a heart operation where a solution is placed into the heart to stop it and allow for heart surgery. In the case of minimally invasive surgery retrograde cardioplegia is used by placing the cardioplegia solution through a catheter into the coronary sinus.
Note: The links to Google Translate include an icon that will allow you to hear the Greek or Latin pronunciation of the word.
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The septum pellucidum is a thin, transparent membrane that forms the medial wall of the lateral ventricles.
The term [septum] means “wall” or “partition” and [pellucidum] means “transparent”.
The septum pellucidum is found most of the time as a single, median structure that is shared by both lateral ventricles and is sometimes perforated, which has no pathological consequence.
In some cases this structure can be double, creating a separate medial wall for each lateral ventricle. When this happens the space between the lateral ventricles has been named the “cavum septi pellucidi”, the “fifth ventricle”, or is eponymically called the “ventricle of Vieussens”. This is shown in the accompanying image
Image modified from the original from “Surgical Anatomy” by John Deaver 1901. Public domain.
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The lateral ventricles of the brain are two separate cavities, each found within a cerebral hemisphere. The lateral ventricles are part of the ventricular system of the brain and contain cerebrospinal fluid which is produced within the ventricular system in the choroid plexuses, most of which are found in the lateral ventricles.
Each lateral ventricle communicates with the third ventricle by way of an interventricular foramen, also known as the foramen of Monro, allowing for circulation of the cerebrospinal fluid
Each lateral ventricle has four components:
1. The central component or “body”. This area is found superior to the thalamus and inferior to the corpus callosum
2. An anterior extension called the “frontal horn”. The boundary between the body and the frontal horn is the interventricular foramen of Monro
3. A posterior extension called the “occipital horn”
4. An anteroinferior extension called the “temporal horn”
The body of the lateral ventricle and the occipital and temporal horn meet at a common point called the “ventricular crossroad” or “isthmus”.
The accompanying animated image shows the lateral ventricles in red. Click on the image for a larger depiction
Sources:
1 "Tratado de Anatomia Humana" Testut et Latarjet 8 Ed. 1931 Salvat Editores, Spain
2. "Gray's Anatomy" 38th British Ed. Churchill Livingstone 1995.
3. Image credits: By Images are generated by Life Science Databases (LSDB). (License information))], public domain, via Wikimedia Commons
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The medical prefix [hemi-] means “half”. It is also the basis for the prefix [semi-] , also meaning “half”. We can see this term used in many medical terms such as:
- Hemisphere: literally “half a sphere”, as in the case of the cerebral hemispheres
- Hemiplegic: Paralized only on one half of the body
- Hemialgia: Pain on one half (of the body)
- Hemicephalalgia: Pain on one half of the head, a migraine
- Semilunar: Half a moon, name used for the aortic and pulmonary valves
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The eponym “ring of Vieussens” refers to a collateral circulation anastomotic communication between the right conal artery and the left conal artery. This communication, when present, is a potential life-saving pathway when there is stenosis or obstruction at the origin of either the right or the left coronary arteries, allowing blood to bypass the blockage.
This anastomosis is sometimes evident, although sometimes when the anastomosis is not seen on the surface of the heart, there is the possibility that the anastomosis is present subepicardially as demonstrated in the 2014 study by Loukas et al.
This ring is demonstrated in the accompanying image. For a three-dimensional volume–rendered CT demonstrating Vieussens’ collateral pathway please click here. For the full 2006 article by Hansen, click here.
Image property of CAA, Inc. Artist: Victoria Ratcliffe.
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Anterior view of the heart
The conal artery is the first anterior branch that arises from the right coronary artery. It can be double or multiple and it provides blood supply to the superior aspect of the conus arteriosus region (outflow tract) of the right ventricle. It is also known as the “conus artery”, and the “infundibular artery”. In about 50% of the cases the conal artery arises separately from the aorta, very close to the ostium of the right coronary artery. In this case the artery has been dubbed the “third coronary”.
In many cases, a secondary conal artery arises from the anterior interventricular (LAD) artery and is called the “left conal artery”. In some cases this left conal artery can be the only one present and there may be no “right” conal artery. When both conal arteries are present, in some cases and evident superficial anastomosis can be seen forming what is known as the “conal ring” or the “ring of Vieussens”, one of the few cases where there is actual collateral circulation between the right and the left coronary arteries.
Sources:
1. “The clinical anatomy of the conal artery” Loukas, M el al. J Clin Anat 2014 DOI: 10.1002/ca.22469
2. “The Clinical Anatomy of the Coronary Collateral Circulation: Loukas, M, et al J Clin Anat (2009) 22:146–160
3. “The Normal and Abnormal Anatomy of the Coronary Arteries” Loukas, M et al J Clin Anat (2009) 22:114–128
4 "Tratado de Anatomia Humana" Testut et Latarjet 8 Ed. 1931 Salvat Editores, Spain
5. "Anatomy of the Human Body" Henry Gray 1918. Philadelphia: Lea & Febiger
Image modified by CAA, Inc, Original image courtesy of bartleby.com