WBR0428

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Cardiology
Prompt	[[Prompt::A 57 year old male patient presents to the emergency deparment with severe acute-onset chest pain. The patient is previously healthy with a history of respiratoy illness 6 days prior to presentation. On physical examination, the patient’s vital signs show a temperature of 37 degrees C (98.6 degrees F), heart rate of 112 beats per minute, and blood pressure measuring 80/50 mmHg. On physical examination, the physician notes that there is marked jugular venous distension (JVD), and weakness of peripheral radial pulse upon inspiration. 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::Rate of fluid accumulation relative to pericardial compensatory stretch mechanisms plays a significant role in determining the patient’s clinical presentation.
Answer B	AnswerB::Plaque rupture and and location of thrombus formation in coronary artery
Answer B Explanation	AnswerBExp::Plaque rupture and location of thrombus formation plays an important role in the clinical presentation of a patient presenting with a myocardial infarction (MI).
Answer C	AnswerC::Patient’s past medical history
Answer C Explanation	[[AnswerCExp::Patients with different past medical histories and precipitating factors can all lead to cardiac tamponade. The cause of the disease and the past medical history is not as important as the rate of fluid accumulation in the clinical presentation 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, some patients require much more amount to start having symptoms. This in fact is due to whether the accumulation occurred rapidly or over a delayed time and whether the pericardium was allowed to stretch or not. Acute cardiac tamponades require a much lesser amount of fluid to accumulate for symptoms to start than in cases of slow accumulation.]]
Answer E	AnswerE::Presence of pulsus paradoxus
Answer E Explanation	[[AnswerEExp::Pulsus paradoxus can be present in cardiac tamponade, but it is not always present. Pulsus paradoxus occurs in other condition as well. Pulsus paradoxus occurs when arterial pressure falls significantly with inspiration due to increased right ventricular filling and decreased left left ventricular filling. Absent pulsus paradoxus occurs when inspiratory underfilling of the left ventricle relative to filling of the right ventricle is prevented.]]
Right Answer	RightAnswer::A
Explanation	[[Explanation::Cardiac tamponade is a potentially fatal compression of the heart due to accumulation of pericardial fluid, pus, blood, clots, or even gas. Cardiac tamponade can be a complication of a ruptured myocardial infarction, a recent cardiothoracic procedure, tuberculous infection, neoplasia, uremia, or pericarditis. The accumulation can be due to effusion, trauma, or cardiac muscle rupture. Tamponade is characterized by several physiological changes that alter diagnosis and treatment. The primary abnormality of cardiac tamponade is the compression of heart chambers due to the elevated intrapericardial pressure. At first, the pericardium stretches normally with time. However, the pericardium then becomes inextensible, and the heart chambers will then become affected by the increasing pericardial pressure and heart chambers will progressively become smaller and mean diastolic pericardial and chamber pressures will ultimately equalize. The rate of fluid accumulation and the compensatory cardiac mechanisms are two important factors that determine clinical presentations 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 are two important factors that determine clinical presentations of cardiac tamponade. Reference: Spodick D. Acute Cardiac Tamponade. N Eng J Med. 2003;349:684-690. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::cardiac, WBRKeyword::tamponade, WBRKeyword::pericardium, WBRKeyword::fluid, WBRKeyword::chest, WBRKeyword::pain, WBRKeyword::chamber, WBRKeyword::rate
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::