A 34-year-old woman who recently emigrated from Russia comes to the physician due to weakness, exertional dyspnea, and orthopnea. On cardiac auscultation, a snap followed by a rumbling diastolic murmur is heard over the cardiac apex. The snap most likely occurs nearest to which of the following points on the cardiac pressure-volume loop?

Question

A 34-year-old woman who recently emigrated from Russia comes to the physician due to weakness, exertional dyspnea, and orthopnea.  On cardiac auscultation, a snap followed by a rumbling diastolic murmur is heard over the cardiac apex.  The snap most likely occurs nearest to which of the following points on the cardiac pressure-volume loop?

Quizplus · Accepted Answer

11ec160b_3c9a_0217_9249_7f1069f36356_MD0001_00 The left ventricular (LV) pressure-volume loop follows the cardiac cycle through left ventricular contraction, ejection, relaxation, and refilling, as follows: Isovolumetric contraction: The cardiac cycle begins with initiation of left ventricular contraction and closure of the mitral valve at point 1; an S1 is heard at this time, marking the end of diastole (Choice A). Although intraventricular pressure increases after point 1, initially, no blood leaves the ventricle because both the aortic and mitral valves are closed. At point 2, LV pressure overcomes systemic diastolic pressure and the aortic valve opens (Choice B). Ventricular ejection: LV volume decreases as blood is ejected into the aorta. The peak of the ejection curve denotes systolic blood pressure and represents the high point of LV afterload (Choice E). LV ejection ends at point 3 with aortic valve closure and an S2 is heard (Choice C). The horizontal distance between point 2 (or point 1) and point 3 represents the stroke volume. Isovolumetric relaxation: LV pressure rapidly falls from point 3 to point 4. No blood leaves or enters the left ventricle during this time because both the aortic and mitral valves are closed. Ventricular filling: The mitral valve opens at point 4 and diastolic filling of the left ventricle begins. LV volume and pressure gradually increase until mitral valve closure occurs again at point 1 and the cycle begins anew. Extra heart sounds (ie, an S3 or S4) may be heard during diastolic filling between point 4 and point 1 (Choice F). This patient with an audible snap followed by a rumbling diastolic murmur over the cardiac apex likely has mitral stenosis, which is most commonly seen due to underlying rheumatic heart disease in patients emigrating from Latin America, Africa, or Asia. The audible snap observed with mitral stenosis is created by the stenotic and calcified valve snapping open (ie, opening snap) and is heard during mitral valve opening at point 4. Educational objective: Mitral stenosis is characterized by an opening snap followed by a rumbling diastolic murmur that is best heard over the cardiac apex. On the left ventricular pressure-volume loop, the opening snap occurs during mitral valve opening at the end of isovolumetric relaxation, and it is followed by a diastolic rumble during diastolic filling.

A 34-Year-Old Woman Who Recently Emigrated from Russia Comes to the Physician