Mohd Farid

Mohd Farid

Sunday, July 30, 2017

Vein Of Marshall And Its Clinical Significant

Vein Of Marshall And Its Clinical Significant




The systemic veins may be arranged into three groups: (1) The veins of the heart. (2) The veins of the upper extremities, head, neck, and thorax, which end in the superior vena cava. (3) The veins of the lower extremities, abdomen, and pelvis, which end in the inferior vena cava.

The Veins of the Heart

Coronary Sinus (sinus coronarius)

Most of the veins of the heart open into the coronary sinus. This is a wide venous channel about 2.25 cm. in length situated in the posterior part of the coronary sulcus, and covered by muscular fibers from the left atrium. It ends in the right atrium between the opening of the inferior vena cava and the atrioventricular aperture, its orifice being guarded by a semilunar valve, the valve of the coronary sinus (valve of Thebesius).

Tributaries.—Its tributaries are the great, small, and middle cardiac veins, the posterior vein of the left ventricle, and the oblique vein of the left atrium, all of which, except the last, are provided with valves at their orifices.
1. The Great Cardiac Vein (v. cordis magna; left coronary vein) begins at the apex of the heart and ascends along the anterior longitudinal sulcus to the base of the ventricles. It then curves to the left in the coronary sulcus, and reaching the back of the heart, opens into the left extremity of the coronary sinus. It receives tributaries from the left atrium and from both ventricles: one, the left marginal vein, is of considerable size, and ascends along the left margin of the heart.
2. The Small Cardiac Vein (v. cordis parva; right coronary vein) runs in the coronary sulcus between the right atrium and ventricle, and opens into the right extremity of the coronary sinus. It receives blood from the back of the right atrium and ventricle; the right marginal vein ascends along the right margin of the heart and joins it in the coronary sulcus, or opens directly into the right atrium.
3. The Middle Cardiac Vein (v. cordis media) commences at the apex of the heart, ascends in the posterior longitudinal sulcus, and ends in the coronary sinus near its right extremity.
4. The Posterior Vein of the Left Ventricle (v. posterior ventriculi sinistri) runs on the diaphragmatic surface of the left ventricle to the coronary sinus, but may end in the great cardiac vein.
5. The Oblique Vein of the Left Atrium (v. obliqua atrii sinistri[Marshalli]; oblique vein of Marshall) is a small vessel which descends obliquely on the back of the left atrium and ends in the coronary sinus near its left extremity; it is continuous above with the ligament of the left vena cava (lig. venæ cavæ sinistræ vestigial fold of Marshall), and the two structures form the remnant of the left Cuvierian duct.

The following cardiac veins do not end in the coronary sinus:

The anterior cardiac veins, comprising three or four small vessels which collect blood from the front of the right ventricle and open into the right atrium; the right marginal vein frequently opens into the right atrium, and is therefore sometimes regarded as belonging to this group;

The smallest cardiac veins (veins of Thebesius), consisting of a number of minute veins which arise in the muscular wall of the heart; the majority open into the atria, but a few end in the ventricles.



Vein Of Interest
The Vein of Marshall, oblique vein of Marshall or the oblique vein of the left atrium is a small vein that descends on and drains the posterior wall of the left atrium. It drains directly into the coronary sinus at the same end as the great cardiac vein, marking the origin of the sinus. It represents the persistent left horn of the sinus venous (left SVC) and is important prenatally, but is of little importance postnatally. 

Source of Focal AF

In humans, the sinus node is not the only pacemaker. Boineau et al demonstrated widely distributed atrial pacemaker complexes in the human heart. In the isolated, perfused canine right atrium, ectopic pacemaker activity was most often found near the sinus node or the crista terminalis. These pacemakers may exhibit different responses to norepinephrine and acetylcholine. Scherlag et al reported that sympathetic stimulation could also induce left atrial ectopic activity. To study the source of these ectopic activities, we performed a computerized mapping study in the isolated-perfused canine left atrium. Isoproterenol can cause automatic rhythm with this preparation. On the basis of these findings, hypothesized that the Marshall bundle may serve as a source of focal AF in humans.

In the present study, they successfully cannulated the Vein of Marshall and recorded sharp potentials directly from the catheter within the Vein of Marshall. Because the Vein of Marshall is an epicardial structure and the recording site was not close to the pulmonary veins, it is unlikely that these sharp second potentials originated from the extension of the atrial musculature into the pulmonary veins. Rapid activation of the Marshall bundle might serve as a trigger of atrial arrhythmias, including AF. Finally, they were able to use the Vein of Marshall catheter as a guide for radiofrequency ablation. A radiofrequency lesion placed in the posterolateral left atrium between the Marshall bundle insertion and the ostium of the left inferior pulmonary vein resulted in successful treatment of the focal AF. This finding suggests that the trigger of the focal AF episodes resides not within the pulmonary veins, but in the Marshall bundle.
Vein of Marshall And Recurrent AF.

Atrial fibrillation (AF) or flutter can recur after pulmonary vein (PV) antral isolation (PVAI). The Vein of Marshall has been linked to the genesis of AF. The most accepted strategy for catheter ablation of atrial fibrillation (AF) is pulmonary vein (PV) antral isolation (PVAI), since the PVs or neighboring tissues are thought to provide the source of AF-initiating ectopic beats. The vein of Marshall and its associated myocardial fibers and nerves have been implicated in the genesis of AF by multiple mechanisms: as a source of ectopic beats initiating AF,as a connection pathway with neighboring myocardium and left PVs,and as a source of arrhythmogenic autonomic innervation. Given its location on the epicardial surface of the left atrial ridge, it is unclear whether a conventional PVAI reaches the Vein of Marshall sufficiently to ablate it. Therefore, we hypothesized that Vein of Marshall-dependent mechanisms may play a role in AF recurrences after PVAI.
Vein of Marshall as a Mechanism of AF Recurrence

Although a wealth of animal data supports the potential arrhythmogenic role of the Vein of Marshall, its role in human AF has been more elusive. Reports of paroxysmal AF initiating from Vein of Marshall-dependent triggers are abundant in the literature. Based on the potential role of the Vein of Marshall triggering AF; its well-documented sympathetic and parasympathetic innervation that can create a pro-AF physiological state in the atria; and the Vein of Marshall 's fibers connecting to the PVs, which could bypass endocardial ablation lesions and lead to PV reconnections, we had hypothesized that the Vein of Marshall could play a role in PVAI failures. However, aside from atrial ectopic beats and Vein of Marshall tachycardia in a minority of patients, we could not demonstrate AF initiation from Vein of Marshall triggers. This may reflect lack of arrhythmogenicity from the Vein of Marshall, but it also could be due to limitations in the stimulation techniques (isoproterenol, adenosine) used to unmask Vein of Marshall triggers.



Reference

1 comment:

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