Anatomical paradox: When ventricular outflows crisscross , left main becomes closer to RVOT , than even the LVOT !


If you think coronary artery ostia are exclusively related to LVOT, and they nowhere come closer to RVOT, we are seriously wrong for some hidden anatomical reasons. Though, Its a well recognised anatomical reality , we had to learn it from EP labs during the ablation of RVOT VT. The left main ostium is at equal (If not more ) at risk as we ablate across RVOT.The reason being the complex twist God conferred on the outflow tracts of heart.

The LVOT goes beneath and posteriorly travels from left to right, while the opposite happens for RVOT. This results in the net anatomical conundrum of RVOT and LVOT sharing common wall at some part.

Here is an excellent article that specifically looked into this issue of the relationship between RVOT and the coronary artery.

(VASEGHI, M., CESARIO, D.A., MAHAJAN, A., WIENER, I., BOYLE, N.G., FISHBEIN, M.C., HOROWITZ, B.N. and SHIVKUMAR, K. (2006), Catheter Ablation of Right Ventricular Outflow Tract Tachycardia: Value of Defining Coronary Anatomy. Journal of Cardiovascular Electrophysiology, 17: 632-637. doi:10.1111/j.1540-8167.2006.00483.x)

The following illustration from this paper reinforces this . The left main is just 4mm away from RVOT.(While, the distance from LVOT to left main ostium is much wider)

Final message

Never underestimate the risk of injuring the left coronary ostia when you manipulate catheters and devices across RVOT. This is especially true with RVOT ablations. There has been so many instances of injuring coronary arteries and precipitating ACS. Working within the right heart tends to give a false sense of safety, as if you are away from systemic coronary circulation. After all, both outflow tracts originate from the same embryological source (bulbus cordis) still, intertwined in adult life, not willing to leave its innate anatomical Intimacy that began and ended between 4 th and 8th week of fetal life.

  1. D. Biermann, J. Schonebeck, M. Rebel et al., “Left coronary artery occlusion after percutaneous pulmonary valve implantation,” The Annals of Thoracic Surgery, vol. 94, pp. e7–e9, 2012.View at: Google Scholar