1.
First draw the weird cross between a triangle and an oval.
2
Now add part of a circle behind it on the left.
3
Add a small tube behind that takes in blood from the body, and next to that draw the beginning of the Aorta. Draw a horizontal line on the right to start the Pulmonary Vein.
4
Finish of your Aorta and Pulmonary Vein, then add the Pulmonary artery sticking out on both sides.
5
Now you can shade it in so it looks more realistic. Enjoy your heart!