A 42-year-old patient applied to an oral surgeon for the purpose of oral cavity sanitation. After anesthetization the patient felt sudden attack of nausea, weakness, he got the sense of compression behind his breastbone, heart pain; he began vomiting. The patient lost consciousness, there appeared convulsions. Objectively: the patient’s skin is pale, covered with cold clammy sweat, pupils don’t react to the light. The pulse is thready, arterial pressure cannot be detected. What is the most probable diagnosis?