Coronary sinus venogram. Catheter passed via internal jugular vein into right atrium and into coronary sinus.
The coronary sinus travels in the left atrioventricular groove and receives the great, middle and small cardiac veins. It empties into the right atrium near the inferior venacaval orifice. Its orifice is guarded by a rudimentary “Thebesian” valve. The small cardiac vein runs in the right atrioventricular orifice. The middle cardiac vein runs in the posterior interventricular groove. The great cardiac vein runs in the anterior interventricular groove and continues as the coronary sinus. The venous valve of Vieussens is located at the junction of the great cardiac vein and the coronary sinus. The oblique left atrial vein of Marshall and the posterior left ventricular vein also drains at this junction. 85% of cardiac venous drainage occurs via the coronary sinus. The anterior cardiac veins (2 to 4) drain the right ventricle and directly enter the right atrium. The smallest cardiac veins or Thebesian veins drain directly into the cardiac chambers they overlie.
The coronary sinus is important in electrophysiological studies, especially for ablation of WPW syndrome accessory pathways. It may be used to infuse cardioplegic solutions during cardiac surgery.