This is because the heart is enclosed by the lungs and breathing causes lungs to expand compressing on the infarcted heart increasing the pain
To protect your heart and lungs.
sea
An enclosed bathroom.
A portion of ocean that is enclosed or partly enclosed by land? ✓ sea
A tube to aid breathing may be inserted if the patient's airways or lungs have been damaged, as can happen during an explosion or a fire in a enclosed space.
Sound
'Inside enclosed' is within.
They are not always enclosed but most are. They are enclosed so you can enjoy the outside even in bad weather.
Thoracic Cavity is the second largest hollow space in the body that is enclosed by the ribs. This also contains two compartments which are the mediastinum and two pleural cavities.In a mammal, the Thoracic Cavity is a hollow cavity between the neck and the diaphragm protected by the rib cage, The cavity contains and protects the lungs and heart and is needed to make the lungs work.
Claustrophobia is a fear of enclosed spaces.
Enclosed, please find my final remittance.