View source for WBR0357

{{WBRQuestion
|QuestionAuthor=Neeraja danda M.B.B.S
|ExamType=USMLE Step 2 CK
|MainCategory=Internal medicine
|SubCategory=Cardiovascular
|MainCategory=Internal medicine
|SubCategory=Cardiovascular
|MainCategory=Internal medicine
|SubCategory=Cardiovascular
|MainCategory=Internal medicine
|MainCategory=Internal medicine
|SubCategory=Cardiovascular
|MainCategory=Internal medicine
|SubCategory=Cardiovascular
|MainCategory=Internal medicine
|SubCategory=Cardiovascular
|MainCategory=Internal medicine
|SubCategory=Cardiovascular
|MainCategory=Internal medicine
|MainCategory=Internal medicine
|SubCategory=Cardiovascular
|Prompt=A 55 year old female presented to urgent care with acute chest pain associated with nausea, and vomiting, which radiated to her left arm for the last 45  minutes. Electrocardiogram reveals ST segment elevation in II, III, aVF. Aspirin was administered. A medical center with a catheterization laboratory was within 60  minutes distance. What is the most appropriate step in the management of this patient?
|Explanation=Management of myocardial infarction depends on the time between the onset of symptoms and arrival in the ER. Typical “door to needle time” (for thrombolysis) is said to be 30 minutes but the mortality benefit extends until 12 hours after the onset of pain. Thombolysis is considered the best option only when angioplasty is not feasible. Otherwise angioplasty is the best treatment and typical door to balloon time is less than 90 minutes. In this case, the onset of pain was 45 minutes ago and time of travel to the medical center with a catheterization lab is 60 minutes, so the patient could not undergo catheterization with less than a 90 minute door to balloon time.  Thus, the best choice here is to initiate tPA therapy.

'''Educational Objective:''' Door to needle time for thrombolysis ought to be under 30 minutes but its mortality benefit extends until 12 hours after the onset of pain. Door to balloon time for angioplasty should be less than 90 minutes. The decision of whether to perform thrombolysis or angioplasty depends on whether or not a sufficiently low door to balloon time can be achieved. 

'''References:''' Page 68, 69  Master the boards Step 2 CK second edition
|AnswerA=Transport her to the medical center
	

|AnswerAExp='''Incorrect''' Taking her to the medical center for angioplasty is not the best choice as it exceeds the door to balloon time of 90 minutes
|AnswerB=Start tPA
|AnswerBExp=Door to needle time for thrombolysis ought to be under 30 minutes but its mortality benefit extends until 12 hours after the onset of pain.The decision of whether to perform thrombolysis or angioplasty depends on whether or not a sufficiently low door to balloon time can be achieved
|AnswerC=Start calcium channel blockers
|AnswerCExp='''Incorrect''' Calcium channel blockers are mainly used in managing Prinzmetal’s angina and Cocaine related  myocardial infarction.
|AnswerD=Start Glycoprotein IIb, IIIa Inhibitors
|AnswerDExp='''Incorrect''' Glycoprotein IIb, IIIa inhibitors offer mortality benefits in ST depression myocardial infarction.

|AnswerE=Measure Cardiac enzymes
|AnswerEExp='''Incorrect''' Cardiac enzymes start to rise one hour after pain onset. They should be measured but starting tPA is the best next step here
|RightAnswer=B
|Approved=Yes
}}