A 60-year-old female is undergoing P.C.I after a coronary narrowing was found on a previous diagnostic angiography. She is known to have coronary vessels which are prone to spasm, therefore, the cardiologist administers 2 puffs of sublingual GTN prior to the procedure and a fuher 400 mg of GTN during the procedure. During the procedure, the patient's systolic blood pressure suddenly drops to 70mmHg. At this point, the patient is pale, clammy and complaining of light-headedness. The patient's pulse rate is noted to be 70bpm and regular. What is the most appropriate management plan at this stage?