Correlation Between Lesion Location and Timing of Lesion Appearance During the Cardiac Cycle in the Right Coronary Artery on Angiography

Background: Mechanisms driving lesion formation at specific sites in the right coronary artery (RCA) remain unclear. However, novel acoustic mapping for RCA blood flow suggests four possible lesion sites: 1R (mid-segment, proximal), 2R (mid-segment, distal), 3R (distal) and 4R (proximal). This study investigated whether the transition from diastole-to-systole influences lesion location in the RCA. The hypothesis is that “Water‑hammer” pressure surge during the diastole‑to‑systole transition causes the strongest, most frequent lesions at site 1R, weaker ones at distal site 3R, and milder, less common lesions at 4R (diastole) and 2R (systole‑to‑diastole).

Methods: Thirty patients with unstable angina underwent a new dynamic coronary angiography technique. Initially, the coronary artery was fully injected with contrast. After the injection stopped, blood (white) began to replace the contrast (black). All lesions, flow movement, direction, and characteristics were recorded. The timing of lesion visibility on coronary angiography was then analyzed using the Fisher’s exact test to determine its relationship with the cardiac cycle.

Results: A significant association was found between RCA lesion severity and timing during the cardiac cycle (Fisher’s exact test, p <0.05). Lesions at site 1R appeared predominantly during the transition from diastole-to-systole (68.8%), with some visible only during diastole. Lesions at site 4R were exclusively diastole, while those at site 2R appeared during the transition from diastole-to-systole.

Conclusion: The transition of flow at the end of diastole and systole creates a collision between antegrade and retrograde flow, causing coronary lesions, especially at 1R . This result unmasks the mechanism triggering plaque formation in coronary arteries.