The catheterization revealed a congenital heart defect — a corkscrew twist in my circumflex artery (the artery that curls around the left side of the heart to carry blood to the rear of the heart) — and this twist has a ridge inside that eventually caused a 99% blockage of the artery. Imagine twisting a hose until it kinks. So I now have a 15mm x 3mm stent holding my artery open — perfectly correcting the defect.