More specifically, l wanna know how are the emotions ''medically'' related to the situations that can cause cardiac arrest.

Fred Sanford could probably be an expert on this.
l do not think strong emotions cause heart attacks unless their is a serious situation with your arteries that preexisted.

strong emotions result in the release of adrenaline into the blood stream, causing a great increase in heart rate and putting a heavy demand on the blood supply to the heart muscle. If the heart is already in the grasp of heart disease, this can cause a failure and result in an infarct. But, in a healthy heart, emotions do not and cannot cause heart attack, only in an already unhealthy heart.

Most emotions do not cause cardiac arrests. Chronic stress can lead to chronic inflammation of the vessels, increasing your risk of heart disease which then can lead to plaque build-up, then breaking off and leading to an occlusion which then can cause a heart attack and/or a cardiac arrest.

high intesity stress will cause ur blood pressure to shoot sky high. Its called fight or flight. It has everything to do with the sympathetic nervous system. It is the opposite of the parasympathetic nermous system which takes over when u r eating.. (or finished eating) & when u r sleeping & having sexual intercourse. Fight or flight causes a surge in norepinephrine causing all of the bodies mechanisms to start working as if u were being chase in the woods by a bear or had to lift a car from being on top of ur friend that was being crushed to death. A surge in epinephrine causes ur arteries to constrict, which increases ur blood pressure, it casuses ur pupils to dilate, ur heart rate will go up, & ur lungs will often expand (in order to give u more oxygen).
When the sympathetic nervous system is constantly working it is harmful to ur body. This can cause heart attacks & strokes which r basically parts of ur body that go without oxygenated blood for a certain period of time due to blockages & high blood pressures over time.