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CORONARY SINUS REVIEW CORONARY SINUS REVIEW

Imaging of the coronary venous system has traditionally been overshadowed by that of the coronary arteries.

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Knowledge of the anatomy of the coronary sinus (CS) and cardiac venous drainage is important because of its relevance in electrophysiologic procedures and cardiac surgeries..

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Several procedures make use of the CS, such as left ventricular pacing, mapping and ablation of arrhythmias, retrograde cardioplegia and stem cell therapy.

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Coronary Venous Anatomy of Coronary Venous Anatomy of the Heartthe Heart

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The cardiac veins can be grouped into the following categories, according to the region being drained:

the CS and its tributaries , the anterior cardiac veins, and the thebesian veins.

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Normal coronary venous anatomy on volume-rendered images from contrast material–enhanced coronary CT angiography. (a) Anterolateral view of the heart shows the anterior interventricular vein (AIV) coursing through the anterior interventricular sulcus parallel to the left anterior descending artery (LAD). It continues as the great cardiac vein (GCV) in the left atrioventicular groove along with the left circumflex artery (LCX).

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Posteroinferior view of the heart shows the GCV continuing as the CS, which finally drains into the right atrium (RA). Also shown are the posterior interventricular vein (PIV) accompanying the posterior descending artery (PDA), the posterior vein of the left ventricle (PVLV), and the left marginal vein (LMV) accompanying the obtuse marginal artery (OMA). 8

The anterior cardiac veins are the primary venous return for the anterior wall of the right ventricle.

There are three or four small veins total, which ultimately drain into the right atrium, although the pattern of drainage is diverse. Each vein may open directly into the right atrium, or the veins may coalesce to form a common venous trunk before emptying into the right atrium

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The thebesian veins (venae cordis minimae) are a number of small veins that drain the subendocardium. They are composed of endothelial cells and are continuous with the endothelial lining of the cardiac chambers.

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CS and Its Tributaries The major tributaries of the CS include

(a) the anterior interventricular vein, (b) the GCV, (c) the left marginal vein and posterior vein, and (d) the middle cardiac vein or posterior interventricular vein

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Anterior Interventricular Vein.—The anterior interventricular vein ascends in the anterior interventricular sulcus parallel to the left anterior descending coronary artery, then continues as the GCV

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Great Cardiac Vein.—The GCV is a continuation of the anterior interventricular vein and runs along the left atrioventricular groove parallel to the left circumflex coronary artery, ultimately terminating in the CS. The transition from the GCV to the CS is defined by the left atrial oblique vein of Marshall externally and the valve of Vieussens internally

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Left Marginal Vein and Posterior Vein of the Left Ventricle.—The left marginal vein usually courses adjacent to the obtuse marginal artery along the lateral aspect of the left ventricle and drains into the GCV or directly into the CS. The posterior vein drains the diaphragmatic and lateral wall of the left ventricle and in most cases drains into the CS; infrequently, it can also drain into the GCV. The posterior vein of the left ventricle may be a single large vessel or consist of several smaller veins.

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Middle Cardiac Vein or Posterior Interventricular Vein.—The middle cardiac vein runs in the posterior interventricular groove, parallel to the posterior descending coronary artery, and drains into the inferior aspect of the CS just proximal to its termination in the right atrium Given its location, it is also referred to as the posterior interventricular vein.

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Small Cardiac Vein.—When present, the small cardiac vein runs in the right atrioventricular groove. It drains into the CS or directly into the right atrium.

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Embryology of Coronary sinusEmbryology of Coronary sinus

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The left horn of the sinus venosus and adjacent left common cardinal vein (LCC) remain in adult life as the CS.

The right horn of the sinus venosus persists as the venous portion of the right atrium.

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The length of the CS varies from 3 to 5.5 cm and is dependent on the site of the drainage of the posterolateral vein. The diameterof the CS is also variable and is dependent on the loading conditions, presence and extent of atrial myocardium with the coronary vein, and the presence of underlying cardiac disease or priorcardiac surgery.

The CS lies in the sulcus between the left atrium and ventricle and is a continuation of the great cardiac vein from the valve of the great cardiac vein to the ostium of the CS as it terminates in the right atrium.

The CS begins proximally at the right atrial orifice and ends distally at the valve of Vieussen’s. The CS receives blood from the ventricular veins during ventricular systole and empties into the right atrium

during atrial systole.

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The wall of the CS is made up of striated myocardium that is continuous with the atria, forming a myocardial sleeve around the venous system

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The CS, like the rest of the cardiac venous system, contains various valves. The most common valve is the Thebesian valve at the ostium of the CS.

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The Thebesian valve is a crescent shaped structure often found guarding the mouth of the CS as it opens to the right atrium. The Thebesian valve is highly variable and occasionally may present an obstruction during cannulation of the CS.

The CS also contains the valve of Vieussen’s that often marks the end of the vein. These venous valves are also frequently found at the entrance of the ventricular veins into the great cardiac vein.

The right ventricular venous system drains directly into the right ventricle through the Thebesian venous network

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The CS ostium is 5–15 mm in diameter and is located on the posterior interatrial septum anterior to the Eustachian ridge and valve and posterior to the tricuspid annulus.

The ostium is often covered, to a variable extent, by the Thebesian valve. The valve usually covers the superior and posterior surfaces of the ostium, but may be covered completely with formation of fenestrations. 34

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Cardiac-Veins-Coronary-Sinus-Ostium-startimage.mp4

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Coronary Sinus Anatomy: Ajmer Working Group Classification:

Author(s): R.K. Gokhroo, MD, DM, Devendra Singh Bisht,

MD, DM, Deepak Padmanabhan, MD, DM, Sajal Gupta, MD, DM

Issue Number: Volume 26 - Issue 2 - February 2014

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Methods and results: The CS-angiographic features and incidence of structural anomalies were prospectively studied in 56 patients undergoing AP radiofrequency ablation.

Retrograde CS angiography was successfully performed in 46/56 pt (82%), (33 males/13 females). The CS angiographic findings of the 46 patients were compared to the AP localization established by electrophysiological mapping and to the successful ablation sites.

CS anomalies were identified in 17 (37%) patients and included the following: CS diverticulum (seven patients), funnel shaped ostium (three patients), CS aneurysm (two patients), subthebasian pouch (one patient), sharp angulation (one patient), and bulbous malformation (one patient). 43

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Perhaps more importantly accurate radiographic anatomy is needed with standardized fluoroscopic views [right and left anterior oblique (LAO) projections] to guide placement of leads and sheath of catheter cannulation of the main body of this vein.

In the LAO projection, when cannulating the CS, the lead catheter will be seen to move leftward after entry.

In the RAO projection, catheter or lead movement towards the sternum (anterior) signifies cannulation of ventricular vein where as posterior deflection or orientation suggests that an atrial vein has been entered.

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Barcelo et al. pointed out that the coronary sinus is not a simple vein. Their finding confirms that observation by showing the dynamic variation of the coronary sinus lumen, probably as part of a physiologic phase: the draining and conducting of blood.

An exaggerated response to this mechanism could potentially modify cyclic coronary circulation and perfusion, causing slow flow phenomena or other pathophysiologic changes in patients with normal coronary arteries or with other pathology, such as abnormal relaxation of the ventricular wall.

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Preshaped coronary sinus guiding catheter.

6 F steerable electrophysiology catheter with a fixed D-curve

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If corkscrew tortuosities and acute take-off angles of the only acceptable posterolateral target veins make intubation fail, a coronary wire can be used to place a Multifunctional Probing catheter (manufactured by Boston Scientific) into the proximal vein segment

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The modified bicaval view is the preferred “working view” for engaging the CS ostium. A standard bicaval view displays the SVC and IVC; a modified bicaval view displays the SVC and CS. A narrow range of depth, multiplane angle, and left/right turning may be required to produce satisfactory images, making this view potentially difficult to acquire. Practice in a variety of patients is recommended prior to the time when the view will be needed to guide placement. Conditions that distort anatomy, including aortic root dilation and cardiac remodeling, add to the difficulty in acquiring this view.

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Message Message CS showing the dynamic variation of the lumen,

probably as part of a physiologic phase: the draining and conducting of blood.

CS anomalies are common.

It can be important to identify some anatomic variations, even though they are clinically occult, to ensure appropriate preprocedural planning. Both CT and magnetic resonance imaging provide excellent noninvasive depiction of the anatomy and anomalies of the CS.

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