If tachycardias can be induced during the EP study, then by studying the electrical signals recorded from the electrode catheters, the precise cause of the tachycardia can usually be identified. Once this is accomplished, the appropriate therapy for the tachycardia usually becomes clear.
A dilute acid is one that is not very concentrated. You can make an acid solution more dilute by adding water. Note that you have to be careful with the terms strong and weak; very strong acids can also be very dilute.
The acid illustrated is hydrochloric acid. Pure hydrochloric acid is a gas, but it dissolves easily in water to produce a solution of hydrogen ion and chloride ion. Since nearly all of it is dissociated in water, it is called a strong acid. Acids that do not dissociate completely are called weak acids.