An 18-year-old woman comes to the office for a physical prior to beginning a community college program. She recently moved into a fourth-floor apartment and reports some mild dyspnea with climbing stairs. The patient has no chest pain, lightheadedness, or syncope. She has a history of heavy menstrual bleeding for which she takes oral contraceptive pills. She does not use tobacco and consumes a few drinks at parties. The patient reports that one of her younger sisters was born with "a hole" in the heart that closed spontaneously in infancy. Temperature is 36.7 C (98 F), blood pressure is 100/60 mm Hg, pulse is 92/min, and respirations are 14/min. Pulse oximetry shows 98% on room air. Weight is 75 kg (165.3 lb) and height is 160 cm (5 ft 3 in) tall. BMI is 29 kg/m². Her conjunctivae are pink and mucous membranes are moist. There is no jugular venous distension. Lungs are clear on auscultation. During expiration, there is an extra high-pitched sound heard after the S1. There is a grade 3/6 systolic crescendo-decrescendo murmur that is loudest at the left upper sternal border. The S2 is split throughout the respiratory cycle and splitting increases with inspiration. The murmur does not increase with standing. Her dorsalis pedis pulses are 2+ bilaterally. Which of the following is the most likely mechanism of this patient's murmur?

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11ec25c8_d2db_cdb5_bc81_c37e7a0f4497_MD0003_00 This patient most likely has pulmonic valve stenosis (PS), which most commonly occurs as an isolated congenital defect and rarely occurs as an acquired defect (eg, rheumatic fever, carcinoid syndrome). Severe PS is typically diagnosed early in life due to presentation of right-sided heart failure, but patients with relatively mild PS often remain asymptomatic throughout childhood and develop symptoms (eg, dyspnea with exertion) in early adulthood. Cardiac auscultation reveals a pulmonic ejection click (high-pitch sound after S1 best heard during expiration) followed by a crescendo-decrescendo systolic murmur over the left second intercostal space. The murmur intensifies with inspiration when there is increased blood volume in the right side of the heart. The stenosis also causes the pulmonic valve to close later than usual, resulting in widened splitting of the aortic and pulmonic components of S2; the splitting is further increased during inspiration. left second intercostal space splitting (Choice A) Atrial septal defect is a common congenital defect that leads to increased blood flow in the right side of the heart. Patients can have a mid-systolic murmur due to increased flow across the pulmonic valve; however, the S2 is widely split without variation during respiration (wide and fixed splitting). (Choice B) A bicuspid aortic valve is the most common congenital defect seen in adults. Premature valvular calcification can lead to aortic stenosis (AS) in patients in their 40s and 50s, but AS would be unlikely in this 18-year-old woman. AS typically causes a systolic murmur in the right second intercostal space; it also leads to narrowed or paradoxical splitting of S2 due to delayed closure of the aortic valve. (Choice C) A functional (benign) flow murmur can occur in patients with anemia (eg, due to menorrhagia) due to increased flow across the aortic and pulmonic valves; however, an ejection click or abnormal splitting of S2 is not present. (Choice D) Cardiac auscultation in patients with hypertrophic cardiomyopathy reveals a harsh systolic murmur at the left mid-sternal border; the murmur increases in intensity with maneuvers that decrease left ventricular blood volume (eg, Valsalva, standing). (Choice F) Patients with tricuspid regurgitation have a holosystolic murmur over the left lower sternal border that is intensified by an increase in venous return (eg, leg raising, deep inspiration, hepatic compression). An ejection click or wide splitting of S2 is not present. Educational objective: Pulmonic valve stenosis usually occurs as a congenital defect and can often remain asymptomatic until adulthood. Cardiac auscultation reveals an ejection click, followed by a crescendo-decrescendo systolic murmur over the left second intercostal space and widened splitting of S2. References: Long-term outcomes of balloon valvuloplasty for isolated pulmonary valve stenosis. (http://www.ncbi.nlm.nih.gov/pubmed/27826708)

An 18-Year-Old Woman Comes to the Office for a Physical