WBR1014

Author	[[PageAuthor::Rim Halaby, M.D. [1] (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Physiology
Sub Category	SubCategory::Cardiology
Prompt	[[Prompt::A 76-year-old woman presents with complaints of dyspnea and generalized fatigue. She states that she becomes short of breath when she when she either lies down or walks 2 flights of stairs. Laboratory work-up is remarkable for markedly elevated NT-proBNP. Echocardiography demonstrates abnormal filling dynamics of the left ventricle with preserved contractility and elevated left atrial filling pressures with left atrial enlargement. Which of the following most likely corresponds to this patient's left ventricular end-diastolic and end-systolic volumes, respectively?]]
Answer A	AnswerA::200 and 60 mL
Answer A Explanation	[[AnswerAExp::The ejection fraction calculated from the given end-systolic and end-diastolic volume is 70% [(200-60)/200 x 100]. An ejection fraction of 70% is considered normal or within the upper limit of normal. Diastolic heart failure is characterized by a normal ejection fraction.]]
Answer B	AnswerB::200 and 100 mL
Answer B Explanation	[[AnswerBExp::The ejection fraction calculated from the given end-systolic and end-diastolic volume is 50% [(200-100)/200 x 100]. An ejection fraction of 50% is considered mildly low.]]
Answer C	AnswerC::180 and 100 mL
Answer C Explanation	[[AnswerCExp::The ejection fraction calculated from the given end-systolic and end-diastolic volume is 44% [(180-100)/180 x 100]. An ejection fraction of 44% is considered low.]]
Answer D	AnswerD::150 and 75 mL
Answer D Explanation	[[AnswerDExp::The ejection fraction calculated from the given end-systolic and end-diastolic volume is 50% [(150-75)/150 x 100]. An ejection fraction of 50% is considered mildly low.]]
Answer E	AnswerE::110 and 70 mL
Answer E Explanation	[[AnswerEExp::The ejection fraction calculated from the given end-systolic and end-diastolic volume is 36% [(110-70)/110 x 100]. An ejection fraction of 36% is considered low.]]
Right Answer	RightAnswer::A
Explanation	[[Explanation::This patient presents with symptoms of heart failure with echocardiographic findings suggestive of diastolic dysfunction. Diastolic heart failure is characterized by abnormal relaxation and/or filling of the ventricles. It may be associated with left atrial enlargement due to the elevated pressures in the left heart chambers. While NT-proBNP is elevated in both systolic and diastolic heart failure (cut-off values depend on patient age, comorbidities, and renal insufficiency), the ejection fraction differentiates systolic heart failure from diastolic heart failure. Systolic heart failure is characterized by a decreased ejection fraction while diastolic heart failure is characterized by a preserved/normal (or occasionally elevated) ejection fraction. A normal ejection fraction ranges from 55% to 75%. The ejection fraction can be calculated as follows: Ejection fraction= (end diastolic volume - end systolic volume)/ end diastolic volume. Educational Objective: Systolic heart failure is characterized by a decreased ejection fraction while diastolic heart failure is characterized by a preserved/normal (or occasionally elevated) ejection fraction. A normal ejection fraction ranges from 55% to 75%. The ejection fraction can be calculated as follows: Ejection fraction= (end diastolic volume - end systolic volume)/ end diastolic volume. References: First Aid 2015 page 273]]
Approved	Approved::Yes
Keyword	WBRKeyword::Ejection fraction, WBRKeyword::Diastolic heart failure, WBRKeyword::Heart failure, WBRKeyword::Cardiology, WBRKeyword::Heart, WBRKeyword::Contractility, WBRKeyword::Diastolic dysfunction, WBRKeyword::BNP, WBRKeyword::NT-proBNP
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::