WBR0675

Author	[[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathophysiology
Sub Category	SubCategory::Cardiology
Prompt	[[Prompt::An 82-year-old man is brought to the emergency department with severe shortness of breath, sweating, and altered state of consciousness. Past medical history is significant for prior myocardial infarction with ischemic heart failure. Physical examination is remarkable for cold extremities. After initial assessment, the patient is diagnosed with cardiogenic shock. Which of the following additional findings is consistent with the patient's condition?]]
Answer A	AnswerA::Decreased total peripheral resistance
Answer A Explanation	[[AnswerAExp::Total peripheral resistance increases in cardiogenic shock. Recall that blood pressure = cardiac output x total peripheral resistance. When the cardiac output decreases, the vasculature increases its tone to increase the blood pressure. This increase in vascular tone increases the peripheral resistance.]]
Answer B	AnswerB::High-output heart failure
Answer B Explanation	AnswerBExp::Cardiogenic shock is defined as low-output failure.
Answer C	AnswerC::Tachycardia
Answer C Explanation	AnswerCExp::Patients with cardiogenic shock often have tachycardia to compensate for the low cardiac output.
Answer D	AnswerD::Strong radial pulse
Answer D Explanation	AnswerDExp::Patients with cardiogenic shock usually have a non-palpable or decreased pulse due to the development of tachyarrhythmias.
Answer E	AnswerE::Polyuria
Answer E Explanation	AnswerEExp::Patients with cardiogenic shock often have oliguria due to decreased perfusion to the kidneys.
Right Answer	RightAnswer::C
Explanation	[[Explanation::The patient in this scenario is presenting with cardiogenic shock most likely due to a low-output heart failure. The patient has symptoms and a past medical history consistent with this diagnosis. Cardiogenic shock is a state of systemic hypoperfusion due to a decrease in cardiac output. It is characterized by increased total peripheral resistance, which explains the patient's cold extremities. Additionally, patients often has very weak and sometimes absent radial pulses due to the combination of low-output circulation and tachyarrhythmias. Given the decreased renal perfusion, patients with cardiogenic shock often have oliguria or anuria secondary to acute kidney injury. Although considered a state of shock, it is always important to note that cardiogenic shock is associated with tachycardia and tachyarrhythmias, not bradycardia, in attempt to compensate for the low output. Educational Objective: Patients with cardiogenic shock usually have associated tachycardia to compensate for the low cardiac output. References: Felker GM, Adams KF, Konstam MA, O'connor CM, Gheorghiade M. The problem of decompensated heart failure: nomenclature, classification, and risk stratification. Am Heart J. 2003;145(2 Suppl):S18-25.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Cardiogenic shock, WBRKeyword::Tachycardia, WBRKeyword::Bradycardia, WBRKeyword::Low-output heart failure, WBRKeyword::High-output heart failure, WBRKeyword::Heart failure
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::