Koch's triangle

Not to be confused with Koch snowflake.

Dissection in right anterior oblique view of the right atrium shows the borders of the triangle of Koch. In this view, the putative fast and slow pathways toward the AV node (dotted shape in yellow) are depicted. Asterisk (*): central fibrous body, CSO: coronary sinus ostium, ER: Eustachian ridge, ICV: inferior cava vein, OF: oval fossa, STV: septal leaflet of the tricuspid valve, and TT: tendon of Todaro.

Koch's triangle, also known as the triangle of Koch, is named after the German pathologist Walter Koch. ^[1] It is an anatomical area located at the base of the right atrium, and its boundaries are the coronary sinus orifice, tendon of Todaro, and the septal leaflet of the right atrioventricular valve (also known as the tricuspid valve). ^[2] It is anatomically significant because the atrioventricular node is located at the apex of the triangle. The base is formed by the coronary sinus orifice and the vestibule of the right atrium, and the hypotenuse is formed by the tendon of Todaro, which is often a continuation off the Eustachian valve. Other structures near to it are the membranous septum and the Eustachian ridge. Variations in the size of Koch's triangle are common.

The triangle of Koch is an important landmark for atrioventricular catheter ablation procedures for the localization of the atrioventricular node. ^[3]

Tendon of Todaro

The tendon of Todaro delimits the antero-superior boundary of the triangle of Koch. The apex of Koch's triangle is the location of the atrioventricular node. ^[4] It is part of the fibrous skeleton of the heart, located in the right atrium. It was described^{[ citation needed ]} by Italian anatomist Francesco Todaro. It is a continuation of the Eustachian valve of the inferior vena cava and the Thebesian valve of the coronary sinus.

The tendon is near-impossible to locate in a living heart, so clinicians use other features to determine the boundaries of the Koch's triangle. ^[5] Some cardiologists even go as far as rejecting the usefulness of the tendom as an anatomical landmark altogether. ^[6]

References

1. Conti, Andrea A. (2011). "Calling the Heart by Name: Distinguished Eponyms in the History of Cardiac Anatomy" (PDF). The Heart Surgery Forum. 14 (3): E183-7. doi:10.1532/HSF98.20101047. PMID   21676685. S2CID   28989761. Archived from the original (PDF) on 2018-08-02.
2. Catheter ablation of cardiac arrhythmias. Huang, Shoei K.,, Miller, John M. (John Michael), 1954- (Third ed.). Philadelphia, PA. 2015. pp. Figure 6-6. ISBN   9780323244299. OCLC   892338420.
3. Feger, Joachim. "Triangle of Koch | Radiology Reference Article | Radiopaedia.org". Radiopaedia. Retrieved 2024-01-19.
4. McGuire, Mark A.; Johnson, David C.; Robotin, Monica; Richards, David A.; Uther, John B.; Ross, David L. (1992-09-15). "Dimensions of the triangle of Koch in humans" . The American Journal of Cardiology. 70 (7): 829–830. doi:10.1016/0002-9149(92)90574-I. ISSN   0002-9149. PMID   1519544.
5. Yen Ho & Anderson 2000.
6. James 1999.

Further reading

• Sumitomo, Naokata; Tateno, Shigeru; Nakamura, Yoshihide; Ushinohama, Hiroya; Taniguchi, Kazuo; Ichikawa, Rie; Fukuhara, Junji; Abe, Osamu; Miyashita, Michio; Kanamaru, Hiroshi; Ayusawa, Mamoru; Harada, Kensuke; Mugishima, Hideo (2007). "Clinical Importance of Koch's Triangle Size in Children". Circulation Journal. 71 (12): 1918–21. doi: 10.1253/circj.71.1918 . PMID   18037746.
• Francalanci, Paola; Drago, Fabrizio; Agostino, Domenico Antonio; Liso, Gaetano; Giommo, Vincenzo; Boldrini, Renata; Ragonese, Pietro; Bosman, Cesare (1998). "Koch's Triangle in Pediatric Age: Correlation with Extra- and Intracardiac Parameters". Pacing and Clinical Electrophysiology. 21 (8): 1576–9. doi:10.1111/j.1540-8159.1998.tb00245.x. PMID   9725156.
• Inoue, Shin; Becker, Anton E. (1998). "Koch's Triangle Sized Up: Anatomical Landmarks in Perspective of Catheter Ablation Procedures". Pacing and Clinical Electrophysiology. 21 (8): 1553–8. doi:10.1111/j.1540-8159.1998.tb00242.x. PMID   9725153.
• Sánchez-Quintana, Damián; Picazo-Angelín, Beatriz; Cabrera, Alberto; Murillo, Margarita; Cabrera, José Ángel (2010). "Koch's Triangle and the Atrioventricular Node in Ebstein's Anomaly: Implications for Catheter Ablation". Revista Española de Cardiología. 63 (6): 660–7. doi:10.1016/S1885-5857(10)70140-7. PMID   20515623.
• Anderson, R. H.; Cook, A. C. (2007). "The structure and components of the atrial chambers". Europace. 9 (Suppl 6): vi3–9. doi: 10.1093/europace/eum200 . PMID   17959691.
• James, Thomas N. (1999). "The Tendons of Todaro and the "Triangle of Koch":: Lessons from Eponymous Hagiolatry" . Journal of Cardiovascular Electrophysiology. 10 (11): 1478–1496. doi:10.1111/j.1540-8167.1999.tb00207.x. ISSN   1045-3873. PMID   10571368 . Retrieved 2025-05-13. Todaro tendons are too often absent (or multiple) to warrant use as anatomic landmarks
• Yen Ho, Siew; Anderson, Robert H. (2000). "How Constant Anatomically is the Tendon of Todaro as a Marker for the Triangle of Koch?" . Journal of Cardiovascular Electrophysiology. 11 (1): 83–89. doi:10.1111/j.1540-8167.2000.tb00741.x. ISSN   1045-3873. PMID   10695467 . Retrieved 2025-05-13. the tendon of Todaro is not visible in the operating room or in the catheterization laboratory. Instead, clinicians use as surrogate a projected line between the eustachian valve and the central fibrous body

External links

• "Triangle of Koch". University of Minnesota.
• "Illustration". health-pictures.com.^{[ dead link ]}