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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 sinuses of Valsalva are dilations related to both the aortic root of the ascending aorta and the root of the pulmonary trunk. These sinuses form part of the functional aspect of the corresponding aortic valve and pulmonary valve. Each one of these semilunar valves presents normally with three sinuses of Valsalva, although the sinuses of the pulmonary valve are smaller than those of the aortic valve.
One of the problems encountered when describing each sinus of Valsalva is the fact that the sinus itself is not a structure, but a space. This space is found between the corresponding valve leaflet (or cusp) and the arterial wall which presents with a concavity, thus creating the sinus. This concavity is important functionally as it allows the leaflet to “flutter” in the arterial stream without getting stuck to the arterial wall. Physiological studies on the presence of the sinuses of Valsalva indicate that they play an important role decreasing of minimizing the stress of the valve leaflets.
The dilation of the sinuses of Valsalva also creates a bulbous region at the origin of both the ascending aorta and the pulmonary trunk, the “root” of these arteries. For a better view of this bulbous region, click here. The boundary between the bulbous sinusal segment and the tubular segment of the arteries is known as the sinotubular junction (STJ).
The accompanying image shows a human ascending aorta that has been cut open to show the sinuses of Valsalva (yellow arrows), and the three cusps (leaflets) of the aortic valve. These are the non-coronary cusp (NCC), right coronary cusp (RCC), and the left coronary cusp (LCC). The ostia of the coronary arteries are visible inferior to the STJ.
The sinuses of Valsalva are named after Antonio Maria Valsalva (1666 - 1723), an Italian physician and anatomist.
Sources:
1. “Anatomy of the aortic root: implications for valve sparing surgery” Charitos EI, Sieveres, HH Ann Cardiothorac Surg 2013;2(1):53-56
2. “Clinical Anatomy of the Aortic Root” Anderson, RH Heart 200; 84: 670–673
3. “The Anatomy of the Aortic Root” Loukas, E et al. Clin Anat 2014; 27:748-756
4: "Stress Analysis of the Aortic Valve With and Without the Sinuses of Valsalva" Beck, A et al J Heart Dis 2001; 10 (1) 1-11
Image property of: CAA.Inc.>. Photographer: D.M. Klein
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The word [sinus] is Latin and refers to a "pocket" or a "curved surface or structure". In medical terms the word [sinus] is used more in the meaning of "pocket" and refers to a cavity that has only one entrance (or exit) both in anatomy and surgery.
The term is used properly when referring to pocket-like structures such as the "sinuses of Valsalva" or the "prostatic sinus", as well as the sinuses found in the cranium such as the frontal sinus, the ethmoidal sinus, the sphenoid sinus, etc.
The word is incorrectly used to denote structures that have more than one entrance (or exit) such as the coronary sinus or the venous sinuses found in the cranial dura mater.
The corresponding root term is [-sin-] which then can be used in words such as [sinotubular junction]
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![Coronary Arteries. The [*] indicates the left coronary artery](/images/MTD/LargeImages/coronaryarterieslabels_lg.jpg "Coronary Arteries. The [*] indicates the left coronary artery")
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UPDATED: The [anterior interventricular artery] is one of the two branches of the left coronary artery, the other one being the circumflex artery (CFX). Although the name "anterior interventricular artery" is the anatomical name, this artery is most commonly known by its clinical name, the [left anterior descending artery], or LAD.
The LAD lies deep to the epicardium in the subepicardial fatty layer. It gives off several important branches, including one or two (sometimes three) large diagonal arteries that provide blood supply to the anterior aspect of the left ventricle. Also of importance, the LAD provides several septal perforator arteries that provide blood supply to the anterior 2/3rds of the interventricular septum.
Because of the extensive arterial territory of the LAD, and its involvement with the left ventricle and the interventricular septum, the LAD is sometimes called by a non-clinical term: "the widow-maker".
There can be interesting anatomical variations in the coronary arteries of the heart. For a detail on these anatomical variations, click here. Heart and coronary artery anatomy is one of the many lecture topics presented by CAA, Inc
Image property of:CAA.Inc.. Artist:Victoria G. Ratcliffe
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UPDATED: The prefix [inter-] means "between". The root term [ventricul-] refers to a ventricle, from the Latin [ventriculus], meaning "little sac" or "little belly". The word [septum] is Latin, and means "wall", "division", or "partition". The plural form for [septum] is [septa].
There are two septa in the heart. The interatrial septum (see superior image, item "E") is found between the atria, and the interventricular septum (see superior image, item "D"). The interventricular septum has two components, the muscular interventricular septum, and a small, superiorly situated membranous septum. The interventricular septum is quite muscular as seen in both images. Click on each image for a larger picture.
The cardiac interventricular septum receives blood supply from branches of both the right and left coronary arteries. The anterior 2/3rds of the interventricular septum receive blood supply through anterior septal perforators that arise from the left anterior descending artery (LAD), a branch of the left coronary artery.
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The posterior 1/3rd of the interventricular septum receives blood supply by way of posterior septal perforators that arise from the posterior descending artery (PDA), a branch of the right coronary artery.
For a detail of the blood supply to the interventricular septum, click on the inferior image.
Superior image property of: CAA.Inc. Photographer: D.M. Klein.
Inferior image modified from "Slide Atlas of Cardiac Anatomy" (out of print): Library catalog.
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From Latin, meaning “opposite to”. This term has been used since the late 1700’s in English literature to denote “the lowest point”.
This term will be of interest as we study the anatomy of the aortic valve and aortic root.
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UPDATED: This word has a Greek origin from the term [ανεύρυσμα], composed of [ana] meaning "complete or throughout", and [eurus] meaning "wide", a "complete widening or dilation". It is used to refer to the dilation of an artery. Aneurysms can be formed in any artery, although they have some preferred sites. The most common aneurysms are found in the aorta, arterial circle of Willis, the root of the cerebral arteries, and internal carotid arteries.
Biomechanical studies suggest that once an aneurysm forms it will generally progress in its dilation until aneurysmal rupture. Because of turbulent flow within the aneurysm large clots are usually formed, which in turn can cause emboli.
The image shows an excised infrarenal abdominal aortic aneurysm (AAA). The two common iliac arteries can be seen. If you click on the image you will be able to see the same aneurysm opened through its posterior wall and the clot that was contained inside.
Since the definition of [aneurysm] is "a dilation of an artery", it is wrong to refer to the dilation of a vein as a "venous aneurysm. The proper term to refer to the dilation of a vein is [varix].
Image property of: CAA.Inc. Photographer: David M. Klein