A 35-year-old woman is seen in the outpatient clinic due to palpitations. Over the past 6 months, she has noticed decreased exercise tolerance and episodes of her heart "racing in my chest." Temperature is 37.2 C (98.9 F) and blood pressure is 125/75 mm Hg. On examination, there is an early diastolic sound followed by a middiastolic murmur. The rest of the examination is unremarkable. ECG is shown in the exhibit.

Which of the following is the most likely finding on echocardiography?

Question

A 35-year-old woman is seen in the outpatient clinic due to palpitations. Over the past 6 months, she has noticed decreased exercise tolerance and episodes of her heart "racing in my chest." Temperature is 37.2 C (98.9 F) and blood pressure is 125/75 mm Hg. On examination, there is an early diastolic sound followed by a middiastolic murmur. The rest of the examination is unremarkable. ECG is shown in the exhibit.

Which of the following is the most likely finding on echocardiography?

Quizplus · Accepted Answer

11ec25c8_d0af_02ee_bc81_95699b83d3c6_MD0003_00 This patient's middiastolic murmur preceded by an early diastolic sound (ie, opening snap) is consistent with mitral stenosis (MS), which usually occurs in the setting of rheumatic heart disease. The irregularly irregular rhythm and absent P waves on ECG demonstrate atrial fibrillation, which is a common complication of MS that occurs due to left atrial dilation. Among patients with untreated MS, the prevalence of atrial fibrillation is up to 50%. MS impairs diastolic filling of the left ventricle and causes an increase in left atrial pressure, which leads to stretching of the left atrial walls. This atrial stretch can disrupt electrical conduction and trigger arrhythmogenic electrical foci; atrial fibrillation most commonly originates from arrhythmogenic foci in the pulmonary veins. Atrial fibrillation can induce acute decompensated heart failure in the setting of MS because many patients with MS require the additional left ventricular filling supplied by atrial contraction (ie, atrial kick at end-diastole) to remain compensated. Atrial fibrillation in the setting of MS also carries an even higher thrombogenic risk than nonvalvular atrial fibrillation, and routine anticoagulation with warfarin is indicated regardless of CHA₂DS₂-Vasc score. (Choice A) An atrial septal defect can cause increased blood flow in the right side of the heart. The defect itself does not generate a murmur, but right-sided flow murmurs (ie, low-grade systolic murmur of the pulmonic valve, low-grade diastolic murmur of the tricuspid valve) may be heard. An opening snap would not be present, and atrial fibrillation would be only a rare complication. (Choice C) A left atrial myxoma can obstruct the mitral valve and cause a presentation similar to MS; however, because the mitral valve is healthy, an opening snap would not be present. Thrombus may be seen in the left atrium in patients with MS, but it typically develops in the atrial appendage and would not be attached to the interatrial septum. (Choices D and E) Because in MS the obstruction to blood flow is upstream of the left ventricle, left ventricular structure remains normal (ie, no cavity dilation or wall hypertrophy). upstream Educational objective: Mitral stenosis (MS) is recognized by a middiastolic murmur preceded by an opening snap. Atrial fibrillation is common in MS and results from an increase in left atrial pressure with consequent left atrial stretching. In the setting of MS, atrial fibrillation can trigger decompensated heart failure and also carries a higher thrombogenic risk than nonvalvular atrial fibrillation. References: Management of atrial fibrillation in patients with rheumatic mitral stenosis. (http://www.ncbi.nlm.nih.gov/pubmed/29453328)

A 35-Year-Old Woman Is Seen in the Outpatient Clinic Due