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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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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
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Anterior view of the heart
The conus arteriosus is a conical region of the right ventricle as seen from the anterior aspect. This conical region is found between the atrioventricular sulcus on the right side and the left anterior descending artery (LAD), also known as the anterior interventricular artery. At the apex of the conus arteriosus are the pulmonary valve and the pulmonary trunk.
A short fibrous band has been described originating from the superior aspect of the conus arteriosus and the fibrous region of the atrioventricular sulcus and the base of the aorta. It is called the “conus arteriosus tendon”.
Internally the conus arteriosus is smooth-walled and is called by clinicians the “outflow tract” of the right ventricle. Because of the funnel-shape of the outflow tract and its continuation with the pulmonary trunk this area is also called the “infundibulum” of the right ventricle.
Blood supply to the conus arteriosus is by way of the conal artery. This is usually the first anterior branch of the right coronary artery
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
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The limbus of the fossa ovalis (limbus fossae ovalis) is a muscular ridge that borders the fossa ovalis, an oval-shaped depression found in the interatrial septum, on the right atrium side.
The limbus fossae ovalis is best developed superiorly and to the sides of the fossa ovalis. It is deficient and not as evident in the inferior aspect, as seen in the accompanying image.
Several authors have described the limbus fossa ovalis as a part of the conduction system of the heart facilitating the distribution of the electrical stimulus from the sinoatrial (SA) node to the atrioventricular (AV) node and as part of Bachman’s bundle.
The limbus fossae ovalis is known by the eponym “the ring or anulus of Vieussens”
Sources:
1. “The development of the limbus fossae ovalis in the human heart—a new septum” Christie, GA. J Anat. Jan 1963; 97: 45–54
2. “The Limbic Ledge: A Landmark for Transseptal Left Heart Catheterization” Bloomfield, DA and Sinclair-Smith BC. Circulation. 1965;31:103-107
3. “Cardiac Arrhythmia: Mechanisms, Diagnosis, and Management” Podrid, PJ; Kowey, PR Lippincott Williams & Wilkins, 2001
4. “Electrical Connections: The Precise Location and Preferential Conduction” Sakamoto, SI et al. J Cardiovasc Electrophysiol. 2005;16(10):1077-1086
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UPDATED: The word [limbus] is Latin and means "edge", "fringe", or "border". In Medieval Latin the limbus was considered to be an area on the edge of hell where souls waited for their final judgment.
In human anatomy the term is used to mean an "edge", a "border", or a "boundary", such as the limbus of the eye, the border between the iris and the cornea. For an image of the corneal limbus click here.
Another example is the "limbus fossa ovalis", or the "ring or anulus of Vieussens" a muscular border to the fossa ovalis of the heart.
By extension, the term also applies to the limbic system, a group of nuclei, sulci and gyri of the brain found bordering the corpus callosum. The limbic system is involved in emotions, depression, motivation, learning, and memory.
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Medical terminology suffixes are sometimes formed by several components. The suffix component [-y] means "process" and can be used in many different ways.
A "process" can be an actual bony outcropping, a structure, or it can be an action or a series of actions.
Let's dissect a few suffixes to analyze their construction:
• [-(o)tomy]: This suffix is composed by [-tom-], derived from the Greek word [τομή] meaning "to incise" or "to cut". By adding the suffix component [-y] we obtain the meaning of "process of cutting".
• [-ectomy]: This suffix is more complicated. It originates from two Greek root terms εκτός meaning "out or outside" and "[tomos], which means "to cut" or "to open". By adding the suffix component [-y] we obtain the meaning of "process of cutting out". Other synonyms are: extirpation, excision, and removal.
• [-(o)logy]: The accepted meaning of this suffix is "study of", although a better meaning would be "process or action of studying". This suffix has an interesting evolution that you can read here.
The suffix [-y] can also be used alone, as in the case of the anatomical term mesentery. This term is of Greek origin. The prefix [mes(o)-] means "middle", the root term [-enter-] means "small intestine" or "intestine", and the suffix [-y] means "process" or "structure". Thus, the mesentery is "a structure in the middle".