WBR0428

Author	[[PageAuthor::Rim Halaby, M.D. [1], (Reviewed by Alison Leibowitz)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Cardiology
Prompt	[[Prompt::A 57-year-old male presents to the ER with severe acute-onset chest pain. The patient had a respiratory illness 6 days prior to presentation. Upon physical examination, you note marked jugular venous distension (JVD), weakness of peripheral radial pulse upon inspiration, a temperature of 37 °C, heart rate of 112 beats per minute, and blood pressure measuring 80/50 mmHg. Which of the following is the most important factor in determining the clinical presentation of this patient’s condition?]]
Answer A	AnswerA::Rate of fluid accumulation relative to pericardial stretch
Answer A Explanation	AnswerAExp::The rate of fluid accumulation, relative to pericardial compensatory stretch mechanisms, plays a significant role in the patient’s clinical presentation.
Answer B	AnswerB::Plaque rupture and and location of thrombus formation in coronary artery
Answer B Explanation	[[AnswerBExp::A plaque rupture and the location of thrombus formation play an important role in the clinical presentation of a patient presenting with a myocardial infarction (MI).]]
Answer C	AnswerC::Patient’s medical history
Answer C Explanation	[[AnswerCExp::The cause of the disease and the patient's medical history are secondary to the rate of fluid accumulation in the clinical manifestation of cardiac tamponade.]]
Answer D	AnswerD::Amount of fluid accumulation within pericardial sac
Answer D Explanation	AnswerDExp::Although the amount of fluid accumulation is important, patients symptoms manifest with different volumes based upon the rate of accumulation.
Answer E	AnswerE::Presence of pulsus paradoxus
Answer E Explanation	[[AnswerEExp::Pulsus paradoxus may manifest in cardiac tamponade, but it is not characteristic. Pulsus paradoxus occurs when arterial pressure falls significantly with inspiration, due to an increased right ventricular filling and decreased left ventricular filling.]]
Right Answer	RightAnswer::A
Explanation	[[Explanation::Cardiac tamponade, a potentially fatal compression of the heart, results from an accumulation of pericardial fluid, pus, blood, clots, or gas. Cardiac tamponade can be a complication of a ruptured myocardial infarction, a recent cardiothoracic procedure, tuberculous infection, neoplasia, uremia, or pericarditis. The accumulation may be due to effusion, trauma, or cardiac muscle rupture. The primary abnormality of cardiac tamponade is the compression of heart chambers resulting from the elevated intrapericardial pressure. The pericardium stretches normally with time, but then becomes inextensible. With the increasing pericardial pressure, the heart chambers progressively become smaller until the mean diastolic pericardial and chamber pressures equalize. The rate of fluid accumulation and the compensatory cardiac mechanisms determine the clinical manifestations of cardiac tamponade. Educational Objective: Cardiac tamponade is the compression of the heart chambers by pericardial fluid. The rate of fluid accumulation and the compensatory cardiac mechanisms determine the clinical manifestations of cardiac tamponade. References: Spodick D. Acute Cardiac Tamponade. N Eng J Med. 2003;349:684-690.]]
Approved	Approved::Yes
Keyword	WBRKeyword::cardiac, WBRKeyword::tamponade, WBRKeyword::pericardium, WBRKeyword::fluid accumulation, WBRKeyword::chest pain, WBRKeyword::chamber, WBRKeyword::cardiology, WBRKeyword::cardiovascular
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