If you feel a sharp, grasping pain that goes up into your jaw and into your arm (often the left one), and it feels like there is a vice around your chest, the chances are you might be having a heart attack.
If you are alone, you have a short time - about 10 seconds - to get help.... But what if you can't?
The answer is to COUGH! Breathe very deeply and cough heavily as if you are trying to clear a blocked throat. Keep breathing deeply and coughing HARD!
The deep breaths pull in more oxygen and the coughing squeezes your heart and can help get it going again.
Obviously as soon as you can call for medical help.
I have a neat PowerPoint about this..... email me on firstname.lastname@example.org and I'll email a copy.