Case Analysis of a Unique RIII‐C Single Coronary Artery with Type IV Dual LAD and Right‐Dominant Triple PDA
Authors: Lanik Wyatt , Sayyed Samer , Hovseth Chad , McCumber Travis , Snow Ethan 
Published: May 2022

INTRODUCTION

Coronary artery anomalies (CAAs) are rare congenital variations of normal coronary artery anatomy. Examples of CAAs include a single coronary artery (SCA) (instead of separate, left and right vessels) arising from the aortic trunk to supply the entire myocardium (prevalence = 0.024% to 0.066%), two left anterior descending arteries (LAD) (instead of one) occupying the anterior interventricular sulcus (prevalence = 0.02% to 1%), and three posterior descending arteries (PDA) (instead of one) occupying the posterior interventricular sulcus (prevalence uncertain). Reports of rare CAAs, especially those previously undocumented to occur simultaneously, serve as valuable references for medical education and clinical practice. The present study describes an especially unique CAA discovered in a human cadaveric heart where a SCA gives rise to distinct dual LAD and triple PDA. The study aims to characterize the involved CAAs and investigate the anatomy, histology, and clinical considerations of this unique coronary anatomy.

METHODS

The SCA, dual LAD, and triple PDA CAAs were discovered during routine cadaveric dissection in a medical education curriculum. The heart was eviscerated, and the CAAs were carefully cleaned of extraneous tissue, photographed, and measured. The SCA was characterized using Lipton’s classifications, and the dual LAD was classified according to the thirteen variations (“Types”) of dual LAD described in the literature. Masson’s Trichrome histological staining was performed to examine CAA tissue integrity via light microscopy. Courses of the CAAs were superimposed on volume rendered computerized tomographic angiography (CTA) images depicting normal coronary anatomy for comparison.

RESULTS

The SCA arose from a solitary coronary ostium in the right coronary sinus and traveled 0.57 cm from the aortic trunk before quadfurcating into the right coronary artery (RCA), long LAD, left main coronary artery (LMCA), and descending septal artery (DSA). The RCA maintained normal anatomic course before terminating in a right‐dominant triple PDA. The long LAD coursed pre‐pulmonic along the anterior interventricular sulcus for 13.89 cm before terminating near the apex of the heart. The LMCA tracked retro‐aortic, between the aorta and the atrial wall, for 5.67 cm before bifurcating into the left circumflex artery (LCX) and short LAD. The short LAD paralleled long LAD within the anterior interventricular sulcus for 10.8 cm before anastomosing with the second PDA near the apex. Additional anastomoses were noted near the apex of the heart between the long LAD, short LAD, second PDA, third PDA, diagonal branches of the short LAD, and left marginal artery. The DSA coursed between the aorta and pulmonary trunk before entering the interventricular septum.

CONCLUSIONS

The heart presented in this study was supplied by a unique (Lipton’s) RIII‐C SCA with Type IV dual LAD and right‐dominant triple PDA. Unexpected complications can arise from cardiac procedures involving patients with unknown CAAs such as these. This report may serve as a key reference for cardiothoracic surgeons, interventional cardiologists, coronary angiographers, and medical educators when considering simultaneous occurrence of these rare CAAs.