Define the Angina pectoris and Myocardial infarction.

Patient was admitted in the hospital and put on cardiac monitor. The following day an exercise tolerance test was performed to test the function of heart under stress. This test gave an ischemic ECG response during exercise, characterized by a downward-sloping S-T segment. Exercise resulted in chest pain, which was relieved by sublingual nitroglycerin. Coronary angiography was done, which showed coronary artery obstruction >70% in two major arteries.After visualization of obstruction, cardiologist performed the angioplasty and inserted stent to dilate his obstructed vessels.
Patient was discharged with medications medical advices and regular follow ups.

Answer the following questions
1. Name the four chambers and four valves present in human heart.
2. Based on above scenario what is the likely diagnosis, and why you made this diagnosis?
3. Compare the normal EKG with the patient’s EKG, note down the differences.
4. Define the Angina pectoris and Myocardial infarction.
5. Write four healthy habits one should adopt to prevent coronary heart disease.
6. Nitroglycerin increases the diameter of the blood vessels (vasodilator). How does it reduce the pain in this patient?