Cardiogenic shock due to coronary artery perforation or stent thrombosis: This is a likely cause given the recent PTCA and stent placement. High cortisol and high PCT (procalcitonin) levels suggest a significant stress response and possible infection or inflammation, but in the context of a recent cardiac procedure, cardiogenic shock is a primary concern.

Hemorrhagic shock due to bleeding complications: Although the carotid artery Doppler is normal, bleeding can occur at the access site or internally, leading to shock. The high cortisol level could be a response to blood loss and hypotension.
Anaphylactic shock: This could be a reaction to the contrast dye used during PTCA or to medications administered during the procedure. High cortisol levels could be seen in anaphylaxis as part of the body's stress response.
Septic shock: Given the elevated PCT, which is a marker of bacterial infection, septic shock is a possibility, especially if the patient has an underlying infection or if the procedure introduced bacteria into the bloodstream.

Tamponade due to cardiac rupture: Although less common, cardiac rupture leading to tamponade is a life-threatening condition that can occur post-PTCA. It requires immediate recognition and intervention.
Pulmonary embolism: This could be a cause of shock, especially if there was a complication during the procedure that led to clot formation. It's less directly related to the PTCA but is a critical diagnosis not to miss.
Aortic dissection: This is a rare but potentially fatal condition that could occur, especially if the patient has underlying vascular disease. The normal carotid Doppler does not rule out a dissection, as it might not be visualized in this test.

Contrast-induced nephropathy leading to shock: While not directly causing shock, severe renal impairment could contribute to a complex clinical picture, including fluid overload and electrolyte imbalances that might precipitate shock.
Air embolism: This is a rare complication of vascular procedures and could lead to shock if significant. It would be more likely if there were issues with the procedure or equipment that allowed air to enter the vascular system.