Which vein collects venous drainage from the apex and the left aspect of the heart?

Coronary Sinus

Great cardiac vein

Left anterior descending artery

Left ventricular tributary to great cardiac vein

Left ventricle

Left circumflex artery

Coronary sinus

Three different volume-rendered images in a patient undergoing coronary CTA show the coronary sinus venous system. The left lateral view shows the great cardiac vein as it accompanies the LAD in the anterior interventricular groove, then as it curves in the left coronary sinus to accompany the LCX. The confluence of the great cardiac vein with the oblique vein of the left atrium (not seen) marks the start of the coronary sinus. Multiple left ventricular veins drain into the great cardiac vein.

Chamber Remodeling

As discussed above, the variable relationship of the coronary sinus and great cardiac vein to the mitral annulus creates significant challenges. Anchors, in either the atrium or ventricle, have been developed to directly remodel these chambers to decrease chamber diameters and to decrease the diameter of the mitral annulus (Figure 47-13). The opportunity to use an anchor in the coronary sinus, combined with a second anchor system in the right atrium, has been evaluated as a means of applying more traction on the mitral annulus.

The St. Jude Medical (Minneapolis, MN) system is composed of four helical anchors, two loading spacers, a tether rope, and a locking mechanism. The distal pair of anchors is delivered via the coronary sinus into the LV myocardium near the posterior leaflet scallop; the proximal pair of anchors is delivered via the right atrium into the posteromedial trigone. The double anchors are connected by a cable to enable reduction of the posteromedial MA and are locked via a self-retracting nitinol structure. Proof of concept has been demonstrated in animal models.83

Epicardial and Perivascular Sites

Approximately 9% of idiopathic VTs originate epicardially, most often near coronary venous sites: the great cardiac vein (GCV), the anterior interventricular vein (AIV), and the middle cardiac vein (MCV).10 Immediately distal (in the retrograde direction to blood flow) to the coronary sinus ostium, the coronary sinus gives rise to the MCV, which courses in the posterior interventricular sulcus. The coronary sinus courses in the inferior aspect of the atrioventricular groove parallel to the mitral valve annulus and ends at the valve of Vieussens in the region of obtuse marginal arteries. Beyond the valve of Vieussens, the vein continues as the GCV, coursing epicardially directly overlying the lateral mitral annulus. The junction of the AIV and the GCV is immediately lateral to the LCC. Proximal to distal, the AIV is adjacent to the posterolateral subvalvar RVOT, or the epicardial lateral RVOT, and to the anterior epicardial space. Transpericardial mapping of the origin of epicardial idiopathic VTs has confirmed their propensity for origin near these perivascular structures.10

Atrial Appendage-to-Ventricular Accessory Pathways

Most reported epicardial APs occur adjacent to a CS diverticulum, the MCV, or the great cardiac vein.45 The atrial appendage-to-ventricular pathway is a recognized variant of AP connections that is characterized by an epicardial course connecting the atrial appendage and the ventricular base, most frequently on the right side. RF energy at endocardial sites may be ineffective, resulting in failure of ablation or recurrence of pathway conduction.

The first histologic documentation of this pathway type was at autopsy after the sudden death of a pediatric patient with known Wolff-Parkinson-White syndrome.46 A bandlike muscular structure extending from the underside of the right atrial appendage to the right ventricle was identified during dissection of the right AV groove (Fig. 25-6). Internally, this structure corresponded to a pouch with a muscular wall that coursed through the epicardial fat and ultimately continued into the ventricular myocardium about 5 mm from the annular insertion of the tricuspid valve.

Features suggestive of this pathway variant include (1) a preexcitation pattern indicative of a right anterior or right anterolateral pathway; (2) retrograde atrial activation recorded earlier in the right atrial appendage than at the tricuspid annulus; (3) a relatively long ventriculoatrial (VA) conduction time during tachycardia, consistent with a long epicardial AP course and earliest ventricular activation recorded more than 1 cm apical to the tricuspid annulus; (4) failed or transient loss of pathway conduction with RF delivery at the tricuspid annulus; and (5) the need for high-energy delivery within the appendage to achieve permanent pathway elimination.

Arruda and colleagues47 reported three bidirectional APs, each with an atrial insertion at the atrial appendage, representing fewer than 0.5% of cases in their series of 646 patients undergoing catheter ablation for the Wolff-Parkinson-White syndrome. After unsuccessful RF catheter ablation, pathway conduction was eliminated in two patients by surgical separation of the atrial appendage from the ventricle at a site distant to the annulus, on the left side in one patient and on the right in the other. RF current eliminated conduction in the third patient when delivered to the tip of the right atrial appendage. Similarly, Milstein and associates48 observed a bridge of tissue crossing from the base of the right atrial appendage into the fat pad overlying the base of the right ventricle at least 10 mm distal to the tricuspid annulus at surgery. Transection of this tissue resulted in loss of preexcitation.

Successful RF catheter ablation was also reported by Soejima and associates49; however, application of RF current within the appendage was limited by frequent impedance rises when a 4-mm-tip electrode ablation catheter was used. High-energy delivery and elimination of impedance rise was achieved by substitution of an 8-mm large-tip ablation catheter. Similar advantages are afforded by saline-irrigated catheters.

Nonfluoroscopic three-dimensional mapping has also facilitated catheter ablation.50 In our laboratory, this approach was used in a patient with three prior unsuccessful ablation attempts. The baseline 12-lead ECG was suggestive of a right-sided AP (Fig. 25-7). At electrophysiology study, earliest atrial activation occurred within the right atrial appendage during orthodromic reentrant tachycardia and ventricular pacing (Fig. 25-8). Initial ablation attempts were made using a 4-mm-tip electrode ablation catheter, but successful pathway elimination within the right atrial appendage was achieved with a saline-irrigated catheter. Adding complexity to a technically challenging case was the presence of a broad pathway insertion or muscle “band” that acted like multiple discrete APs. This feature had undeniably contributed to the failure of previous attempts. Electroanatomic mapping proved invaluable by allowing remapping of earliest retrograde atrial activation after ablation of successive pathway “strands.”

Epicardial elimination of an atrial appendage–to-ventricular pathway was reported in a patient who had undergone multiple unsuccessful endocardial attempts.51 Transcutaneous instrumentation through a subxiphoid puncture permitted insertion of a 7-French (7F) deflectable catheter into the epicardial space. Epicardial mapping using a three-dimensional electroanatomic mapping system assisted localization of the earliest atrial activation and an AP potential at the anterior aspect of the heart. Delivery of low-power RF current at 20 W permanently eliminated pathway conduction without recurrence.

Fibrous Trigone (Aorto-Mitral Continuity Ablation)

Despite the fibrous nature of aorto-mitral continuity and fibrous trigone, a number of focal tachycardias and APs have been mapped and successfully ablated in this region, suggesting that muscular fibers may cross what is otherwise thought to be a predominantly fibrous structure. APs that cross the fibrous trigone are rare but form a particular challenge for mapping and ablation. It is important to consider such an AP when traditional mapping of the right and left AV rings fail to provide early sites of activation, or multiple early sites are found, inconsistent with a single insertion, especially when the diagnostic study is most compatible with a left or right anteroseptal AP.92 Careful mapping of the outflow tracts or the sinuses of Valsalva demonstrates the ventricular insertion commonly, rather than the traditional AV ring. On the left side, this may guide ablation to the aorto-mitral continuity.93 Ablation of these pathways can be challenging because of the proximity of the atrial insertion to the AV node, and the anatomically unusual site of the ventricular insertion. Access to these pathways can be uniquely obtained from the right or left coronary cusp or at the aorto-mitral continuity, depending on the ventricular insertion. The usual care must be taken while mapping and delivering RF, or while performing cryoablation within the sinuses of Valsalva (see Chapter 28).

CARDIAC SULCI OR GROOVES

Cardiac veins

Vessels that remove metabolic wastes and deoxygenated blood away from the heart and usually do not collect occlusive material blocking blood flow.

The great cardiac vein: main tributary of the coronary sinus. Moves blood away from the anterior aspect of the heart and runs with the LAD.

The middle cardiac vein: accompanies the posterior interventricular vein. Moves blood from the posterior interventricular septum, the posterior wall of the left and right ventricles.

The small cardiac vein: accompanies the AM. Removes blood from the right ventricle into the right atrium.

The left posterior vein: one of the main tributaries of the coronary sinus. Moves blood away from the inferior wall of the left ventricle.

The oblique vein: main tributary of the coronary sinus. Removes blood from the posterior wall of the left atrium.

Cardiac Veins

The cardiac veins, in general, follow the distribution of the coronary artery system, running parallel and superficial to the coronary arteries and their branches. The great cardiac vein runs parallel but in opposite direction to the LAD in the anterior interventricular groove (see Fig. 50.3A). The great cardiac vein continues its course in the left anterior AV groove along with the LCx artery (see Fig. 50.3A). Throughout its course, the great cardiac vein receives its tributaries from the left ventricle and atrium. In the left posterior AV groove, the great cardiac vein becomes a larger venous structure known as the coronary sinus (see Fig. 50.3B). The coronary sinus is about 3 to 5 mm in diameter and 2 to 5 cm in length and receives blood from most cardiac veins before it empties into the right atrium. One of its major tributaries is the middle cardiac vein, which runs superiorly in the posterior interventricular groove along the PDA (see Fig. 50.3B). It empties into the coronary sinus at the crux of the heart. The lateral, posterolateral, and posterior cardiac veins of the left ventricle receive blood from their respective aspects of the left ventricle before emptying into the coronary sinus along the left AV groove. There are multiple anterior cardiac veins that receive blood from the right ventricle and drain into the small cardiac vein. The small cardiac vein runs along the right AV groove downward toward the crux, where it subsequently empties into the coronary sinus. Some of the anterior cardiac veins drain directly into the right atrium.

Identification of the coronary sinus and its tributaries are important in the electrophysiological study of the cardiac conduction system. The coronary sinus is a frequent site for placing a pacing catheter or electrode in an electrophysiologic study. In patients with heart failure and dyssynchrony between the right and left ventricles, cardiac resynchronization therapy with biventricular pacing can help to resynchronize the right and left ventricles, hence improving cardiac output, heart failure symptoms, and survival.15,16 Biventricular pacing involves placement of a pacing electrode into one of the anterolateral tributaries of the great cardiac vein or posterior vein of the left ventricle via the coronary sinus.

Ventricular Tachycardia

A few case series on cryoablation for ventricular tachycardia have been published.165,166 Obel and coworkers reported three cases of left ventricular outflow tract tachycardia successfully ablated from the distal great cardiac vein.167 In a larger series, cryoablation with an 8-mm-tip catheter was attempted in 14 patients with highly symptomatic frequent monomorphic ventricular premature beats or nonsustained ventricular tachycardia originating within the right ventricular outflow tract.168 Cryoablation resulted in complete success in all but one patient. Three patients reported slight pain arising from local pressure of the catheter on the right ventricular outflow tract with no pain related to delivery of cryothermal energy. All patients with acutely successful procedures remained arrhythmia free at 3 months of follow-up.