Coumadin ridge

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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: March 11, 2020; Hits: 10484

Coumadin ridge
Click on the image for a larger version

UPDATED: The [Coumadin ridge], also known as the [Warfarin ridge], or a [left atrial pseudotumor]. is an excessive elevation or protrusion of a normal ridge found between the left superior pulmonary vein and the internal ostium of the left atrial appendage. Usually this ridge will extend inferiorly towards and anterior to the ostium of the left inferior pulmonary vein. The Coumadin ridge is considered an anatomical variation of the otherwise small ridge, known as the left lateral ridge.

Because of its location and morphology, some cardiologists and radiologists have mistaken this elevation or fold of the internal anatomy of the left atrium for a thrombus and prescribed anticoagulant therapy (Coumadin or Warfarin) when none was needed, hence its name.

To understand the generation of the Coumadin ridge we must understand the embryology of this area of the heart. The left atrial appendage is the original left atrium in the embryo, which is displaced anteriorly and superolaterally when the veins that enter the atrium start to dilate at their distal end creating the left sinus venarum. After the left atrium proper has formed, the left atrial appendage is left as nothing more than an embryological remnant that can cause problems if the patient has atrial fibrillation (AFib). The ridge forms at the point where the left atrial appendage and the sinus venarum meet.

The Coumadin ridge can vary in morphology, from presenting as an elevated ridge, to a bulbous, pedunculated mass that seems to float within the left atrial appendage and undulate, following the cardiac motion, forcing the cardiologist into believing they are in the presence of a thrombus or a tumor within the heart.

This fold of tissue may contain the ligament of Marshall, autonomic nerves, and a small artery. In rare cases there may be an actual tumor arising from the location of the Coumadin ridge, but this is just a coincidence.

Now that the Coumadin ridge is a better known anatomical variation, cardiologist sometimes refer to their finding as a pseudotumor, a description that may scare the patient, but is only but a fold of tissue inside the heart.

Finding a Coumadin ridge in a patient with atrial fibrillation can be an interesting situation requiring differential diagnosis, as a patient with AFib can present with thrombi in the left atrial appendage. What to do? Is it or is it not a thrombus? Also, a differential diagnosis is needed in the case where the image is actually that of a left atrial tumor or an atrial myxoma.

The accompanying image is own work based on Sra (2004) and McKay (2008), and is a graphite on paper sketch. The image shown an internal view of the left atrium showing the left superior and inferior pulmonary vein, the ostium of the left atrial appendage and a segment of the area of the mitral valve.

We would like to thank Dr. Randall K Wolf, a contributor to Medical Terminology Daily for suggesting this article.

Sources:
1. “Coumadin ridge: An incidental finding of a left atrial pseudotumor on transthoracic echocardiography” Lohdi,AM, et al. World J Clin Cases. 2015 Sep 16; 3(9): 831–834
2. “Coumadin ridge” Tasco, V. https://radiopaedia.org/articles/coumadin-ridge
3. “Papillary fibroelastoma arising from the coumadin ridge” Malik, M, Shilo, K, Kilic,A. J Cardiovasc Thorac Res. 2017;9(2):118-120.
4. “‘Coumadin ridge’ in the left atrium demonstrated on three dimensional transthoracic echocardiography” McKay,T., Thomas, L. Europ J Echocard (2008) 9, 298–300
5. “Endocardial imaging of the left atrium in patients with atrial fibrillation” Sra J; Krum D; Okerlund D; Thompson H. J Cardiovasc Electrophysiol 2004 Feb; Vol. 15 (2), pp. 247

Coumadin ridge

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