The heart lies in the mediastinum with its own long axis tilted relative to the long axis of the body. Appreciation of this discrepancy is important in the setting of cross-sectional echocardiography.
Answer: A. Superior Vena Cava B. Right Atrium C. Coronary Sinus D. Inferior Vena Cava E. Pulmonary Veins F. Left Atrium G. Left Ventricle H. Right Ventricle
A cross-section of the ventricular mass is shown as viewed in left anterior oblique orientation. The right ventricle is anterior to the circular left ventricle, to the left hand as viewed in the section. Note the fibrous continuity of the valvar leaflets in the roof of the left ventricle (dotted line), in contrast to the situation in the right ventricle where the supraventricular crest (SVC) separates the leaflets of the tricuspid and pulmonary valves.
It is important to remember that electrical activation always precedes mechanical activation, just by milliseconds. Electrical Activation to Mechanical Contraction Heartbeats occur as electrical impulses move through the heart. The electrical side of the heart and its contractions are at the core of how the heart operates. This is what constitutes a heartbeat.
The pericardium is a thin, membranous, fibroserous sac that surrounds and protects the heart. The pericardial sac confines and stabilizes the position of the heart in the thoracic cavity. The pericardial cavity is located between the pericardium and outermost layer of the heart, called the epicardium. It contains a small amount of pericardial fluid that acts as a lubricant to allow the heart to fill and empty in a frictionless environment.
Continuity between the reflections along the pulmonary veins and caval veins forms a large posterior recess within the pericardial cavity. This is the oblique sinus lying behind the left atrium. In addition, there are smaller pulmonary recesses. Variations in the reflections on individual pulmonary veins and caval veins have an impact on access for pulmonary venous isolation from the pericardial space. Anterior to the left atrium, posterior to the great arteries, lies the transverse sinus. Its inferior margin is usually at a level above the aortic sinuses.
The phrenic nerve is made up of motor nerve fibers that produce contractions of the diaphragm, and sensory innervation for the mediastinum, pericardium, pleura, diaphragm, upper abdomen, liver, and gallbladder. On the surface of the pericardial sac descends the phrenic nerves together with the pericardiophrenic arteries that are branches from the internal mammary artery. The right phrenic nerve descends vertically along the right lateral surface of the superior caval vein to be related to the rightposterior aspect of the right atrial wall, and in front of the root of the lung in close proximity to the anterior wall of the right superior pulmonary vein. The left phrenic nerve descends on the left side close to the aortic arch and onto the pericardium over the left atrial appendage and the left ventricle. The bifurcation of the pulmonary trunk, the right and left pulmonary arteries, are related to the dome and separated only by the fibrous pericardium. The aortic arch passes over the pulmonary bifurcation. Left vocal cord paralysis is a known complication of left atrial enlargement consequent to mitral stenosis. It is thought to be caused by the enlarged atrium pushing the bifurcation superiorly against the arch, compressing the left recurrent laryngeal nerve that lies in between. Similarly, pushing the dome superiorly during ablation procedures may cause transient nerve palsy.
The left atrium is the most posteriorly situated of the cardiac chambers. Owing to the obliquity of the atrial septum, the left atrium is situated mainly posteriorly and to the left of the right atrium. In front of the left atrium lies the transverse pericardial sinus and anterior to that is the aorta. Posteriorly, behind the pericardium overlying the left atrium, is the tracheal bifurcation and the esophagus.
A, Thoracic organs viewed from the back after removal of the descending thoracic aorta to show the course of the esophagus (Es) in situ and its relationship to the vagus nerves and lymph nodes. B, The course of the esophagus as viewed from the front after removal of the heart and posterior pericardium. The LA wall between the PVs (v) is in front of the esophagus, which is covered by a plexus of branches from the vagus nerve (green) and esophageal arteries arising from the descending aorta (DAo). Ao indicates aorta; CS, coronary sinus; ICV, inferior caval vein; and PT, pulmonary trunk.
Figure 3. A, B, Sagittal sections through the heart and esophagus (Es) showing a middle section between the left and right PVs and a section close to the left PVs (LS and LI), respectively. Transverse sections through the LA and esophagus show the esophagus related to the middle of the posterior atrial wall (C), the esophagus passing close to the right inferior PV (D), and the esophagus close to the left inferior PV (E).
Related to the posterior wall is the esophagus that lies behind the fibrous pericardium, separated by fibro-fatty tissues containing lymph nodes and branches of the left vagus nerve. The esophagus, surrounded by esophageal arteries and the periesophageal plexus from branches of the vagus nerve, occupies a variable position between the right and left pulmonary veins. Thus, not only is the esophagus and its arterial supply, but also the nerve plexuses and lymph nodes may be put at risk when ablating the posterior atrial wall
A sagittal section close to the left VA junction showing the nonuniform thickness of the atrial wall and 3 levels (red lines) at which measurements were made. S indicates superior; M, middle; I, inferior; LI, left inferior; and LS, left superior PV. The left atrium has muscular walls. It possesses a venous component that receives the pulmonary veins, a vestibule, an appendage, and it shares the septum with the right atrium.
The major part of the left atrium, includingthe septal component, is smooth-walled. The smoothest parts are the superior and posterior walls that make up the atrial body, the pulmonary venous component, and the vestibule. The anterior wall that is immediately inferior to the muscular interatrial bundle (Bachmann’s bundle) can be very thin, andmeasures approximately 1–2mm in thickness transmurally. The superior wall, or dome, is thickest compared with the posterior and postero-inferior walls, measuring 3.5–6.5 mm in formalin-fixed normal specimens.
Running along the postero-inferior wall of the left atrium is the coronary sinus, which is the continuation of the great cardiac vein. It occupies the left atrioventricular groove but in the majority of hearts it is not at the same level as the mitral annulus nor does it always run parallel to the mitral orifice. The oblique vein of Marshall, located between the left atrial appendage and the left upper and lower pulmonary veins, runs inferiorly along the postero-inferior atrial wall to join the coronary sinus (Fig. 3B). In the majority of individuals this vein is obliterated for the most part. It remains patent as an isolated malformation in 0.3% of the normal population as the persistent left superior caval vein draining into the coronary sinus.
that are potential sites for deposition of thrombus Owing to its tubular shape, its junction with the left atrium is narrow, often defined by a waist (Fig. 4A). On the endocardial aspect, the superior and posterior borders of the os (orifice) of the appendage are well demarcated by a “ridge” separating the os from the orifice of the left superior pulmonary vein. The os is not perfectly round. it is oval in shape with mean long diameter of 17.4 ± 4 mm and short diameter of 10.9 ±4.2 mm whorl-like network of pectinate muscles line the endocardial surface of the appendage. In between the muscle bundles, the wall is paperthin.
A sleeve of atrial myocardium continuous with left wall surrounds the proximal portion of the pulmonary veins. The longest sleeves are on the superior pulmonary veins, whereas some inferior veins may be devoid of sleeves (Fig. 4D). The sleeves are not uniform in thickness although they tend to be thicker and more circumferential at the veno-atrial junction and fade, becoming discontinuous toward the lung hilum. (A) This longitudinal section through the four cardiac chambers profiles the atrial septum and the ventricular septum. The valve of the oval fossa (open arrow) is thin, whereas the rim of the fossa is infolded atrial wall (black arrow). The attachments of the tricuspid and mitral valves (circles) are not at the same level. The asterisk denotes the location of the compact atrioventricular node.
Interatrial muscular bridges in the subepicardium. (A) shows thin bridges crossing the posterior interatrial groove. There are several thin bridges (arrows) between the interpulmonary bundle and the intercaval bundle. Other small bridges (v) connect the circular fibres of the inferior wall with the entrance of the inferior caval vein. (B) shows the posterior view of a heart with a broad band (double-headed arrow) in the subepicardium connecting the inferior wall of the left atrium to the inferior cavo-atrial junction in the right atrium. (C) is a view from the left showing small muscular bridges (small arrows) between the inferior wall of the left atrium and the coronary sinus (CS). Abbreviations as in Fig. 1.
Congenital abnormal of the heart 會使得 transseptal procedure and catheter ablation 造成很大的困難 , Generalized, in the ordinary procedure of catheter ablation of AF, coronary sinus was from the coronary sinus, and the tansseptal procedure was performed with long-sheath via the right or left femoral vein, with single or double transeptal procedure to go the left atrium
Echocardiographic guided transseptal puncture. (A) fluoroscopic image of the transseptal needle abutting the intra-atrial septum in the left anterior oblique (LAO) projection. A phased array transducer for intracardiac echocardiography (ICE) is positioned in the right atrium and is turned to face the intra-atrial septum. An additional quadripolar catheter is seen. (B) A corresponding ICE image with the left (LA) and right atrium (RA) marked. The white arrow indicates the transseptal needle which is tenting the fossa ovalis and prolapsing it into the LA. (C) A fluoroscopic image again in the LAO projection in which the transseptal needle is against the septum and the transoesophageal (TOE) probe is in the oesophagus. An additional quadripolar catheter is seen. (D) A corresponding TOE image with the transducer angled at 110u to give the bicaval view. The white arrow shows the needle tenting the fossa and prolapsing it into the LA. SVC, superior vena cava.
(A) is a simulated right anterior oblique view of the inside of the right atrium displayed by incising the lateral atrial wall and reflecting it back. The corresponding diagram shows the atrial components. The terminal crest separates the smooth wall of the venous sinus from the rough wall of the appendage. This en face view of the septal surface gives a false impression of an extensive atrial septum. (B) shows the broad triangular-shaped appendage forming the major portion of the right atrium. The dotted oval marks the sinus node which is located in the terminal groove (indicated by broken line on the diagram). The solid line indicates the plane of the histological section shown on panel (C). Cut in cross-section, the sinus node (within broken line on C) and its arterial supply occupies the subepicardial region in relation to the musculature of the terminal crest (Masson's trichrome stain). CS, coronary sinus. Other abbreviations as in Fig. 1.
(A) is a simulated right anterior oblique view showing the triangle of Koch demarcated by the tendon of Todaro posteriorly, the tricuspid valve anteriorly, the coronary sinus inferiorly and the central fibrous body (O) at the apex. The ‘septal’ isthmus (}) is part of the smooth vestibule (↔). The inferior isthmus (---) lies between the orifice of the inferior caval vein and the tricuspid valve. The eustachian valve guarding the inferior caval vein is large in this heart. Note the pouch (★), or sinus of Keith, inferior to the coronary sinus and the muscular rim around the oval fossa. (B) is a dissection displaying the inferior pyramidal space. The corresponding diagram shows the atrial walls (stippled) and their cut edges (hatching) overlying ventricular myocardium. (C and D), in similar orientation as A, display the internal aspects of the isthmic region with the lateral wall retracted inferiorly. The endocardium has been removed to display the myoarchitecture. (p, m and a) indicate the posterior, middle and anterior zones of the inferior isthmus. Note the parallel alignment of the fibres in the body of the terminal crest (open arrow) and the divisions distally in the approach to the inferior isthmus. C shows a major fascicle continuing into the middle zone while D shows fine multiple branches. AV, atrioventricular; CS, coronary sinus; ICV, inferior caval vein; SCV, superior caval vein.
Schematic representations to show the relationship of the atrial structures in standard fluoroscopic views. The triangle of Koch is marked by diagonal hatching and the eustachian valve by cross hatching. The putative fast and slow pathways are represented by filled and open notched arrows respectively. The sinus node (shaded oval) is located in the terminal groove (dotted line). AV, atrioventricular.
A 12 lead ECG in a case of typical type I atrial flutter. The atrial rate is 300 bpm and the ventricular rate is 150 bpm; 2:1 AV block is present. Note that the atrial activity is best seen in leads II, III, and aVF and is barely perceptible in lead I. Reproduced with permission from Waldo AL, Kastor JA: Atrial flutter. In: Kastor JA, ed. Arrhythmias. Philadelphia: WB Saunders Co, 1994:105–15.
(a) Right anterior oblique view of internal structures of RA and (b) right anterior oblique endocardial views (right image is magnified to show detail) of right atrioventricular junction show boundaries of Koch triangle (☆) and RA CTI. The CTI lies between the orifice of the IVC and the attachment of the septal TV (STV, yellow arrows). Three levels (green arrows) of the CTI are shown: the inferolateral isthmus (ILI), the central isthmus (CI), and the paraseptal isthmus (PSI). The central and paraseptal isthmi are common targets for ablation of atrial flutter. The anterior part of the paraseptal isthmus between the coronary sinus (CS) ostium margin and the attachment of the septal TV is called the septal isthmus (SI). In other words, the septal isthmus is part of the RA vestibule (white double-headed arrow) at the level of the paraseptal isthmus. The septal isthmus is often the target for ablation of the slow pathway in atrioventricular node (AVN) reentrant tachycardia. The Koch triangle is bordered posteriorly by a fibrous extension from the eustachian valve and/or ridge (ER) called the tendon of Todaro (TT, white dotted line in b) and anteriorly by the attachment of the septal TV. The paraseptal isthmus forms the base of the Koch triangle, consisting of the ostium of the coronary sinus and the septal isthmus. The apex of the triangle is the anatomic location of the central fibrous body. The AVN resides in the Koch triangle near the apex and continues distally with the penetrating bundle of His. The bundle of His starts being surrounded by the connective tissue of the central fibrous body immediately subjacent to the membranous septum (M). In the magnified view of the CTI (right image in b), the projected anatomic course of the AVN artery (AVNa) in relation to the septal isthmus is shown. The AVN artery arises from the penetrating U-turn of the right coronary artery (RCA) near the start of the posterior descending artery (PDA). AAo = ascending aorta, CT = crista terminalis, EV = eustachian valve, OF = oval fossa, RAA = RA appendage, RV = right ventricle, SVC = superior vena cava, ThV = thebesian valve, TR = tricuspid valve level (bordered by yellow and white arrows in b).
Left: atrial activation in typical atrial flutter (AFL). Right: activation in reverse typical AFL. The atria are represented schematically in a left anterior oblique view, from the tricuspid (left) and mitral rings. The endocardium is shaded and the openings of the superior (SVC) and inferior vena cava (IVC), coronary sinus (CS), and pulmonary veins (PV) are shown. The direction of activation is shown by arrows. Dashed areas mark approximate location of zones of slow conduction and block. Lettering on the right hand panel marks the low (LPS), mid (MPS), and high (HPS) posteroseptal wall, respectively. Modified after Cosío FG et al. J Cardiovasc Electrophysiol 1996;7:60–70.
Schematic of the right atrium, as viewed in the right anterior oblique projection, illustrates the hypothesized reentrant circuit in typical atrial flutter (arrows) and the role of the eustachian valve and ridge in forming a line of conduction block between the inferior vena cava (IVC) and the coronary sinus ostium (CS). The eustachian valve/ridge and the tricuspid annulus (TA) form boundaries of a protected channel within the reentrant circuit, beginning with the posterior isthmus (between the TA and the IVC, site A) and ending with the septal isthmus (between the TA and the CS, site C). Dashed lines represent the anterior end of the tendon of Todaro, which has overlying right atrial myocardium. SVC indicates superior vena cava.
Targets for typical or reverse typical atrial flutter ablation. The schematic drawing shows the atria in an anterior view. The endocardium, inside the tricuspid (left) and mitral (right) rings, is shaded. The openings of the inferior vena cava (IVC), coronary sinus (CS), and left pulmonary veins (PV) are shown in black. Long arrows show activation sequence in common atrial flutter. The striped areas (large open arrows) mark ablation targets: 1, IVC–tricuspid valve isthmus; 2, CS–tricuspid valve isthmus; 3, CS–IVC isthmus. SVC, superior vena cava. Reproduced with permission from Cosío et al.19
Photographs of the right atrial septum taken in the right anterior oblique projection in two autopsy hearts to illustrate the anatomic relationship of the eustachian valve (EV) and eustachian ridge (ER) to the inferior vena cava (IVC), coronary sinus ostium (CS), and thebesian valve (ThV) in A and D. Note the continuity between the EV and the ThV in D, which might produce a continuous line of conduction block, compared with the more muscular region between the ER and the CS in A, which might allow conduction between the ER and the CS. B shows the location of the orthogonal electrode catheter extending along the EV and ER, between the IVC and the CS. C illustrates the lines of ablation across the septal isthmus (SI) and the posterior isthmus (PI). Note the shorter length and smoother surface across the SI than the PI. FO indicates fossa ovalis; TA, tricuspid annulus.
Orthogonal fluoroscopic views showing the positions of the 20 pole Halo catheter and the two pacing electrodes at the low lateral right atrium (LLRA) and coronary sinus ostium (CSO). On the left is the 60° left anterior oblique (LAO) view, and on the right is the 30° right anterior oblique (RAO) view. As shown, the Halo 1 to Halo 5 bipoles are to map the anterolateral free wall of right atrium, while Halo 6 to Halo 10 bipoles map the septum. Another coronary sinus catheter is in the position for guiding the location of the coronary sinus ostium and for mapping the interatrial conduction. The isthmus length (the dotted line between the tips of the two deflectable catheters at the LLRA and CSO) in the IVCO–TA–CSO region was 28 mm in the 60° LAO view.
Radiographs in the right anterior oblique projection (A) and left anterior oblique projection (B) show the positions of the multielectrode catheters in the right atrial appendage (RAA), His bundle region (HB), around the tricuspid annulus (TA), along the eustachian valve/ridge between the inferior vena cava and the coronary sinus (IVC-CS), and the mapping catheter (MAP) positioned at the septal isthmus. Arrows around the TA catheter identify the locations of bipolar electrode pairs. Electrograms are shown in Figs 10 and 11.
Radiographs in the right anterior oblique projection show the ablation catheter (ABL) positions during ablation along the septal isthmus, beginning at the tricuspid annulus at the level of the posterior margin of the coronary sinus ostium (A) and extending to the posteroapical margin of the coronary sinus ostium (B), completing ablation approach A. Extension of the ablation line to the eustachian ridge (C) completes ablation approach A and B. RV indicates right ventricle; other abbreviations as in previous figures.
Short pouch-like recess isthmus; shows a flat vestibular structure against the tricuspid annulus and a pouch-like recess long near the IVC.
(A) Opened right atrium in simulated right anterior oblique view to show the horseshoe shaped terminal crest (double dotted line). The crest arches anterior to the orifice of the superior vena cava (SCV) and extends to the area of the anterior interatrial groove. Inferiorly, the crest turns in beneath the orifice of the inferior vena cava (ICV), breaking up into a series of trabeculations in the area of the atrial wall known as the inferior isthmus (brace). Numbers 1 to 4 mark the points at which the thickness and width were measured. (B) The right atrium opened along the incisions marked by blue asterisks and the lateral wall deflected so as to display the crest (TC) on the endocardial surface separating the smooth walled venous component from the trabeculated appendage (RAA). The white asterisks are the cut surfaces of the crest. Note the ramifications in the inferior isthmus (brace). (C) Anterior aspect between the superior vena cava (SCV) and right appendage. The “septum spurium” (SS) is the most prominent anterior pectinate muscle arising from the crest (white asterisk). OF, oval fossa; TV, tricuspid valve; CS, coronary sinus.
(A–C) Endocardial aspects of the lateral wall of the right atrium opened and displayed in the same orientation as fig 1B. Transillumination shows the variability (70%, 22%, and 8%) in branching of the terminal crest in the inferior isthmus. (D) Endocardial surface of the lateral wall has a criss-crossing trabecular architecture within the tip of the appendage whereas in the remaining wall the pectinate muscles have a uniform parallel alignment almost without crossovers between them. In contrast, the pectinate muscles in (E) have a non-uniform arrangement with abundant interlacing trabeculations between them. (F) Scanning electron micrograph of non-macerated specimen confirmed the irregular alignment (arrows) of the muscular myofibrils within the pectinate muscles. Original magnification (F) ×75. CS, coronary sinus; OF, oval fossa; PM, pectinate muscle; SS, septum spurium; TC, terminal crest; V, Vestibule of the right atrium.
Cardiac AnatomyCardiac Anatomy
From view ofFrom view of
Taiwan Heart Rhythm Society~ Allied Professional Education Program
心臟 科內心臟 科內
A cross-section of the ventricular mass is shown as viewed
in left anterior oblique orientation.
Anderson R H et al. Heart 2001;85:716-720
Normal Heart ConductionNormal Heart Conduction
Electrical activation alwaysElectrical activation always
precedes mechanical activation,precedes mechanical activation,
just by milliseconds.just by milliseconds.
Heartbeats occur as electricalHeartbeats occur as electrical
impulses move through the heart.impulses move through the heart.
The electrical side of the heart andThe electrical side of the heart and
its contractions are at the core ofits contractions are at the core of
how the heart operates. This ishow the heart operates. This is
what constitutes a heartbeat.what constitutes a heartbeat.
Supraventricular tachycardiaSupraventricular tachycardia
N Engl J Med 2006;354:1039-51
Spontaneous Initiation of Atrial Fibrillation bySpontaneous Initiation of Atrial Fibrillation by
Ectopic Beats Originating in the Pulmonary VeinsEctopic Beats Originating in the Pulmonary Veins
HAISSAGUERRE; N Engl J Med 1998; 339:659-HAISSAGUERRE; N Engl J Med 1998; 339:659-
Thin membranous,Thin membranous,
fibroserous sac Surroundsfibroserous sac Surrounds
and protects heart Confinesand protects heart Confines
and stabilizes position ofand stabilizes position of
Pericardial CavityPericardial Cavity
Located betweenLocated between
pericardium and epicardiumpericardium and epicardium
Contains pericardial fluidContains pericardial fluid
that acts as lubricantthat acts as lubricant
Pericardial sacPericardial sac
Part of the ascending aorta, the pulmonary trunk, the superior
caval vein, and portions of the pulmonary veins are
Phrenic NervePhrenic Nerve
Made up of motor nerve fibers that produce contractions of the diaphragm, and
sensory innervation for the mediastinum, pericardium, pleura, diaphragm, upper
abdomen, liver, and gallbladder.
Left Phrenic Nerve
descends on the
left side close to the
aortic arch and onto
over the left atrial
appendage and the
Right PhrenicRight Phrenic
descends verticallydescends vertically
along the right lateralalong the right lateral
surface of the superiorsurface of the superior
caval vein to be relatedcaval vein to be related
to the right posteriorto the right posterior
aspect of the RA wall,aspect of the RA wall,
and in close proximity toand in close proximity to
the anterior wall of thethe anterior wall of the
right superior pulmonaryright superior pulmonary
arterial ligamentarterial ligament
(dactus arteriosus)(dactus arteriosus)
Relationship to Neighboring
Structures of the Left Atrium
The right phrenic nerve running along the fibrous pericardium
is close to the atrial insertion of the right superior pulmonary
The left phrenic nerve passes over the left atrial appendage.
Posteriorly, the esophagus descends adjacent to the fibrous
pericardium covering the posterior and postero-inferior walls
of the left atrium.
Interatrial muscular connections exist at the septum, along
Bachmann’s bundle and also at the muscular sleeves of the
coronary sinus and pulmonary veins.
Thoracic organs viewed from the back after removal of the descending
thoracic aorta to show the course of the esophagus (Es)
Sánchez-Quintana D et al. Circulation 2005;112:1400-1405
A, B, Sagittal sections through the heart and esophagus (Es) showing a
middle section between the left and right PVs and a section close to the left
PVs (LS and LI), respectively.
Sánchez-Quintana D et al. Circulation 2005;112:1400-1405
Close relationship of the
left atrium to the esophagus
Sagittal section close to the left VA junction showing the nonuniform
thickness of the atrial wall and 3 levels (red lines) at which
measurements were made.
Sánchez-Quintana D et al. Circulation 2005;112:1400-1405
Thickness of LA wallThickness of LA wall
Bachmann’s bundlepatent foramen ovalepatent foramen ovale
Vein of MarshellVein of Marshell
Persistent left superior venaPersistent left superior vena
Ho S Y et al. Cardiovasc Res 2002;54:325-336
Orientation of Pulmonary veins
Anatomic landmark of atrialAnatomic landmark of atrial
transseptal puncturetransseptal puncture
Atrial Structure andAtrial Structure and
Pulmonary VeinsPulmonary Veins
Transseptal Procedure in
Ordinary AF Patients
RAO 30 LAO 60
Transeptal procedure from IVC
Catheter in the Left PV
RAO for anterior and posterior LAO for inside and outside PV
Catheter in the Right PV
Anterior line, more
away from spine
RS anterior RS posterior
In chronic cases
Catheter in RS
RAO for inside and outside LAO for anterior and posterior of PV
(A) is a simulated right anterior oblique view of the inside of the right atrium displayed
by incising the lateral atrial wall and reflecting it back.
Ho S Y et al. Cardiovasc Res 2002;54:325-336
Eustachian valveEustachian valve
The eustachian valve, guarding the entrance of theThe eustachian valve, guarding the entrance of the
inferior caval vein, is variably developed.inferior caval vein, is variably developed.
Usually it is a triangular flap of fibrous or fibro-Usually it is a triangular flap of fibrous or fibro-
muscular tissue that inserts medially to themuscular tissue that inserts medially to the
eustachian ridge, or sinus septum, which is theeustachian ridge, or sinus septum, which is the
border between the oval fossa and the coronaryborder between the oval fossa and the coronary
In some cases, the valve is particularly large andIn some cases, the valve is particularly large and
muscular, posing an obstacle to catheters passedmuscular, posing an obstacle to catheters passed
from the inferior caval vein to the inferior part of thefrom the inferior caval vein to the inferior part of the
right atrium.right atrium.
Triangle of Koch: demarcated by the tendon of Todaro posteriorly,
the tricuspid valve anteriorly, the coronary sinus inferiorly and the
central fibrous body (O) at the apex.
Ho S Y et al. Cardiovasc Res 2002;54:325-336
slow pathwayslow pathway
Triangle of KochTriangle of Koch
Ho S Y et al. Cardiovasc Res 2002;54:325-336
sinus nodesinus node
Thebesian valveThebesian valve
A small crescentic flap, usually guardsA small crescentic flap, usually guards
the orifice of the coronary sinus.the orifice of the coronary sinus.
Frequently, the valve is fenestrated.Frequently, the valve is fenestrated.
An imperforate valve completelyAn imperforate valve completely
covering the orifice is very rare.covering the orifice is very rare.
Photographs of the right atrial septum taken in the right anterior oblique projection in two
autopsy hearts to illustrate the anatomic relationship of the eustachian valve (EV) and
eustachian ridge (ER) to the inferior vena cava (IVC), coronary sinus ostium...
Nakagawa H et al. Circulation 1996;94:407-424
Sinus of KeithSinus of Keith
The atrial wall inferior to the orifice of theThe atrial wall inferior to the orifice of the
coronary sinus is usually pouch-like.coronary sinus is usually pouch-like.
It is often described as the sinus of Keith, orIt is often described as the sinus of Keith, or
the sub-eustachian sinus.the sub-eustachian sinus.
It forms the posterior part of the so-calledIt forms the posterior part of the so-called
‘flutter’ or ‘lateral’ isthmus, between the‘flutter’ or ‘lateral’ isthmus, between the
inferior caval vein and the tricuspid valve inferior caval vein and the tricuspid valve
Right or LeftRight or Left
J Am Coll Cardiol. 2002;39(3):500-508.
Anatomic location of the origin of the
arrhythmia, with corresponding 12-
Note the different morphology in
leads V1 and V2 with respect to the
L = left coronary aortic sinus;
N = noncoronary aortic sinus;
R = right coronary aortic sinus;
RVOT = right ventricular outflow
J Am Coll Cardiol. 2002;39(3):500-508.
Radiographic views of the mapping catheter (Map) at the successful
ablation site in the left coronary sinus cusp. The mapping catheter
was located below the ostium of the left main coronary artery).
Successful ablation fromSuccessful ablation from
aortic sinus cuspaortic sinus cusp