Yosef Karo

“ Rema: However if it's just found on the main Simpon of the heart [aorta] with its blunt end toward the outside, meaning toward the heart chamber - if the head of the needle is like a date pit it's kosher (his own opinion in his perush on BH"G) , as we ascribe it to having entered via the throat to the Simpon of the heart, and since its point is facing down it will not pierce it and the beast will spit it out by coughing and motion. ”

“ Aiyan, published Feb. 26 2021 and also Chullin 45b] 5 If the heart was removed, whether by some agent or by sickness, it's treif.
6 There's an opinion that if the heart fat is stuck to the heart very strong, we separate it with a knife and if either Boa'ei (pustules) on the heart (or) a smudge (Kort) of blood are found there then it's forbidden. And it's needless to say if these are found on the chamber [it's forbidden.]
Rema: If the blood is curdled in the thick of the muscle behold it's like a drop of blood and treif (A"W Ha-akrokh) . ”