Update on echocardiography of coronary sinus anatomy and physiology.

The coronary sinus (CS) can be imaged echocardiographically as a small tubular sonolucency in the posterior atrioventricular groove. To date, its importance to echocardiographers has been that CS dilatation usually signifies a persistent left superior vena cava. Recently, we developed a technique to image CS caliber over the duration of the cardiac cycle. CS contraction accompanies the P wave on the electrocardiogram, in sinus rhythm or in various arrhythmias. CS contraction is always absent in atrial fibrillation. In sinus rhythm, CS contraction may be attenuated or absent if congestive heart failure, with marked venous congestion, is present. Thus, this attenuation is a potentially valuable echocardiographic sign of elevated central venous pressure. We demonstrate the echo visualization of CS-related structures, such as tributary veins and the Thebesian valve. The potentially useful concept of the CS as a "miniventricle" is discussed. CS blood flow can be recorded by interrogation in the right heart inflow view. The pattern of CS antegrade flow and the exceptional situation of retrograde systolic CS flow from a posteriorly directed tricuspid regurgitant jet are demonstrated.