A 29-year-old woman, gravida 1 para 0, at 28 weeks gestation comes to the office to establish prenatal care after recently moving to a new city. She has had no complications in this pregnancy and had a normal anatomy ultrasound at 20 weeks gestation. On physical examination, the fundal height measures 28 cm. Cardiac auscultation reveals a 2/6 blowing systolic murmur best heard at the left sternal border. The murmur intensifies with inspiration, and there is no ejection click or palpable thrill at the sternal notch. The lungs are clear to auscultation. There is 1+ pitting edema to the midshins bilaterally. Which of the following is most likely responsible for this patient's murmur?

Question

A 29-year-old woman, gravida 1 para 0, at 28 weeks gestation comes to the office to establish prenatal care after recently moving to a new city.  She has had no complications in this pregnancy and had a normal anatomy ultrasound at 20 weeks gestation.  On physical examination, the fundal height measures 28 cm.  Cardiac auscultation reveals a 2/6 blowing systolic murmur best heard at the left sternal border.  The murmur intensifies with inspiration, and there is no ejection click or palpable thrill at the sternal notch.  The lungs are clear to auscultation.  There is 1+ pitting edema to the midshins bilaterally.  Which of the following is most likely responsible for this patient's murmur?

Quizplus · Accepted Answer

11ec160b_3b1f_493a_9249_3f139bca8266_MD0001_00 Beginning at 6 weeks gestation, maternal blood volume begins to increase to help accommodate the developing fetus; this increase can reach up to 50% from baseline toward the end of the third trimester. The cardiovascular system adapts accordingly with ventricular dilation and increased cardiac output. These changes can cause several auscultation findings during normal pregnancy: Pulmonic flow murmur: This is a low-grade systolic murmur best heard at the left upper or midsternal border. It is caused by high blood flow across the pulmonic valve. The anterior location of the pulmonic valve helps make the murmur relatively easily detectable. Like most right-sided murmurs, the intensity increases during inspiration as additional blood is pulled into the lungs and the right side of the heart. S3: This is caused by reverberation of sound during diastolic filling of an enlarged left ventricle. It is commonly associated with heart failure but is considered a normal finding in pregnancy. Venous hum: This is a continuous murmur likely caused by brisk blood flow through the jugular veins, and it is usually best heard in the right supraclavicular fossa. Overall, it is rare in adults but is commonly present in high-flow states such as pregnancy. (Choice A) Bacterial vegetation on the mitral valve can occur with infective endocarditis, typically leading to mitral regurgitation. The murmur of mitral regurgitation is a holosystolic murmur best heard at the cardiac apex, with decreased intensity during inspiration. (Choice B) Calcification of a congenital bicuspid aortic valve is a common cause of aortic stenosis. Affected patients are typically age >40 and have a crescendo-decrescendo systolic murmur best heard at the right upper sternal border. Like most left-sided murmurs, the murmur tends to decrease in intensity with inspiration. (Choice D) Inflammatory stiffening of the tricuspid valve can occur with rheumatic heart disease, leading to tricuspid stenosis. The murmur of tricuspid stenosis increases in intensity with inspiration, but it is diastolic rather than systolic. (Choice E) Myxomatous degeneration of the mitral valve can lead to mitral valve prolapse, which is recognized by a midsystolic click that may be followed by a murmur of mitral regurgitation. The timing (but not the intensity) of the click varies with changes in left ventricular blood volume. Educational objective: Normal pregnancy is associated with an increase in blood volume and cardiac output that frequently causes a pulmonic flow murmur and S3.

A 29-Year-Old Woman, Gravida 1 Para 0, at 28 Weeks