The CS is responsible for most of the venous drainage of the heart, receiving coronary venous blood from a number of tributaries including the small, middle, great, and oblique cardiac veins as well as the left marginal vein and the left posterior vein. It travels along the posterior atrioventricular groove of the heart and empties into the right atrium between the inferior vena cava inlet and the septal leaflet of the TV.
Retrograde cardioplegia alone or as an adjunct to antegrade cardioplegia is commonly used in cardiac surgery. Administration of retrograde cardioplegia in patients with coronary artery disease improves cooling of the myocardium distal to the coronary obstructions and may confer long-term benefits for LV systolic function11. In patients with aortic insufficiency, retrograde cardioplegia is important to provide adequate myocardial protection without causing LV distention12. Cannulation of the CS for retrograde cardioplegia delivery is also critical in minimally invasive cardiac surgery, where the CS cannula is placed percutaneously by the anesthesiologist using TEE guidance1–7.
Although insertion of a CS cannula can be facilitated and confirmed using fluoroscopic guidance and pressure waveform analysis, perioperative real-time TEE has the benefit of providing continuous visualization of both the CS and CS cannula without the need for contrast or radiation exposure7 and can both reduce the risk of CS injury13 and detect complications related to cannulation14,15. Prior to instrumentation of the CS, imaging allows for the identification of anatomic variants that may preclude the use of retrograde cardioplegia such as a persistent left superior vena cava, Thebesian valve16,17, atrial septal defect or sinus venosus defect18, Chiari network2, or anomalous great cardiac venous drainage19,20.
The ME modified bicaval view is the preferred initial window for CS cannulation because it permits complete visualization of cannula insertion and advancement4–6,9,10. Inclusion of additional windows, in particular the ME4C view, improves CS imaging and success of cannulation2,4−7. Although the length of the CS is not assessed and its ostium is not visualized from the ME2C view, visualization of the CS cannula in this view confirms that the cannula has been advanced to the mid-to distal CS along the posterior and inferior left atrium4.
Inclusion of the TG-CS view in the authors’ standard comprehensive TEE exam of the CS was prompted by its successful use in a minimally invasive case requiring percutaneous CS cannulation in which none of the ME views successfully imaged the CS. The TG window has previously been described as an option to to image the CS9. However, details regarding acquisition and utility of these views are not available. To obtain the TG-CS view, the probe is turned towards the right from the TG LV LAX view with the omniplane angle rotated to 80–100 degrees. Additional advancement of the omniplane angle would enable further visualization of the right heart and vena cavae.
In this study, we found that the CS was visualized in the TG-CS view in 98% of patients. It was visualized in all patients from at least one TEE view, and all four views in 90% of patients. After placement, the CS cannula could be seen in all patients from at least one view.
Based on the results reported in this study, the TG-CS view provides an additional modality to image the CS and CS cannula and offers an effective alternative if ME views are limited. In this study, the ME views were able to image the CS 100% of the time. However, this retrospective study was limited by its relatively small number of patients and may not have captured the subset of patients with variable anatomy and potentially challenging ME coronary sinus imaging. In these patients, the TG-CS view may be helpful and introduces a potentially helpful new way of imaging the CS.