Anatomical Basis for the Cardiac Interventional Electrophysiologist

Figure 5

(a) The region of the cavotricuspid isthmus in simulated right anterior oblique (RAO) view and the paraseptal, inferior, and inferolateral isthmuses are marked 1, 2, and 3, respectively. (b) Opened right atrium in simulated RAO view showing the position of the ablation catheter at the site of inferior or central isthmus (marked with number 2) of application of radiofrequency. (c) This atrial view shows the cavotricuspid isthmus with transillumination. The lines mark (1) the paraseptal isthmus, (2) the inferior isthmus, and (3) the inferolateral isthmus. Note the smooth vestibule immediately proximal to the tricuspid valve and the pectinate muscles in the posterior regions. (d, e) This series of histological sections through inferolateral (d) and inferior (e) isthmuses from a heart with dominance of right coronary artery. Note in (d) the prominent and fibromuscular Eustachian valve in the posterior sector or P, thin myocardium in middle sector or M, and thicker myocardium in the anterior sector (vestibule) or A. In (e), histologic section shows a pouch of the sub-Eustachian recess. Note the lesser transmural thickness in this area. The right coronary artery is in the epicardial fat related to the smooth vestibule. (f, g, h) These hearts show variations in morphology of the Thebesian valve guarding the coronary sinus orifice, the sub-Eustachian pouch, and Eustachian ridge. Ao = aorta, CSO = coronary sinus orifice, EV = Eustachian valve, ER = Eustachian ridge, ICV = inferior cava vein, MCV = minor coronary vein, OF = oval fossa, PT = pulmonary trunk, RAA = right atrial appendage, RCA = right coronary artery, RVOT = right ventricle outflow tract, SCV = superior cava vein, TC = terminal crest, and TV = tricuspid valve.

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