WBR0428
| Author | [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D. and Alison Leibowitz [1])]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathology |
| Sub Category | SubCategory::Cardiology |
| Prompt | [[Prompt::A 57-year-old man is brought to the emergency department with acute-onset, severe chest pain. The patient's wife reports he had a upper respiratory infection 6 days prior to presentation. In the ED, his temperature is 37 °C (98.6 °F), heart rate is 112/min, and blood pressure is 80/50 mmHg. Physical examination is remarkable for jugular venous distension (JVD) and weakness of peripheral radial pulse upon inspiration. What is the most important factor in determining the severity of 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 clinical presentation of cardiac tamponade. |
| Answer B | AnswerB::Plaque rupture and location of thrombus formation within the coronary artery |
| Answer B Explanation | [[AnswerBExp::A plaque rupture and the location of thrombus formation play an important role in the clinical presentation among patients who present with a myocardial infarction (MI).]] |
| Answer C | AnswerC::Patient’s past medical history |
| Answer C Explanation | AnswerCExp::The patient's pericarditis is caused by the patient's recent upper respiratory infection. However, the patient's past medical history is not associated with the severity of his presentation. |
| Answer D | AnswerD::Amount of fluid accumulation within the pericardial sac |
| Answer D Explanation | AnswerDExp::Although the amount of fluid accumulation is important, even larger volumes of accumulated fluid may be associated with no symptoms had the fluid accumulated over a prolonged period of time. |
| Answer E | AnswerE::Weakness of peripheral radial pulse upon inspiration |
| Answer E Explanation | [[AnswerEExp::Pulsus paradoxus is a clinical feature of cardiac tamponade but it is not characteristic. It may also be present in other cardiac diseases (cardiogenic shock), pulmonary diseases (COPD, asthma, interstitial lung disease, pulmonary hypertension, PE), and non-cardiac non-pulmonary diseases (e.g. superior vena cava obstruction). Pulsus paradoxus occurs when arterial pressure falls significantly with inspiration due to increased right ventricular filling with decreased left ventricular filling.]] |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::Cardiac tamponade is a potentially fatal compression of the heart due to pericardial accumulation with fluid, pus, blood, clots, or even gas. Cardiac tamponade may be a complication of a ruptured myocardial infarction, a recent cardiothoracic procedure, tuberculous infection, neoplasia, uremia, or pericarditis. The primary abnormality of cardiac tamponade is the compression of the heart chambers that results in an elevated intrapericardial pressure. As the pericardial fluid expands, the pericardium stretches to accomodate the gradually increasing volume. As the amount of fluid further increases, however, the pericardium then becomes inextensible, and the heart chambers are then affected by the increasing pericardial pressure. The heart chambers will progressively become smaller and mean diastolic pericardial and chamber pressures will ultimately equalize. The most important determinant of the severity of clinical presentation of cardiac tamponade is the rate of fluid accumulation. In the case of slow and chronic fluid accumulation, compensatory cardiac stretch mechanisms are adequate, and patients may remain asymptomatic for a prolonged period of time. In contrast, clinical presentations are much more severe when fluid accumulates rapidly and cardiac stretch mechanisms are not granted sufficient time for compensation. 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. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::cardiac, WBRKeyword::tamponade, WBRKeyword::pericardium, WBRKeyword::fluid accumulation, WBRKeyword::chest pain, WBRKeyword::chamber, WBRKeyword::cardiology, WBRKeyword::cardiovascular |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |