A 16-year-old boy is evaluated in the office due to leg cramps. He plays soccer but frequently stops in the middle of practice due to cramps in both legs. The patient is afebrile. Blood pressure is 170/90 mm Hg bilaterally in upper extremities. Point of maximal impulse is nondisplaced. S1 is normal, and S2 is physiologically split. An S4 is heard, as well as a continuous murmur best auscultated over the back at the left paravertebral area. Distal pulses in the radial arteries are prominent. Dorsalis pedis and posterior tibial pulses are difficult to palpate. The rest of the physical examination is unremarkable. Which of the following is the most likely cause of this patient's continuous murmur?

Question

A 16-year-old boy is evaluated in the office due to leg cramps.  He plays soccer but frequently stops in the middle of practice due to cramps in both legs.  The patient is afebrile.  Blood pressure is 170/90 mm Hg bilaterally in upper extremities.  Point of maximal impulse is nondisplaced.  S1 is normal, and S2 is physiologically split.  An S4 is heard, as well as a continuous murmur best auscultated over the back at the left paravertebral area.  Distal pulses in the radial arteries are prominent.  Dorsalis pedis and posterior tibial pulses are difficult to palpate.  The rest of the physical examination is unremarkable.  Which of the following is the most likely cause of this patient's continuous murmur?

Quizplus · Accepted Answer

11ec160b_38b4_15db_9249_41b9ada14bae_MD0001_00 This patient has upper extremity hypertension with diminished lower extremity pulses. These findings are consistent with coarctation of the aorta, a congenital heart defect characterized by narrowing of the aorta. Patients with severe aortic narrowing develop cardiogenic shock in the neonatal period; children and adults with more mild aortic narrowing may have asymptomatic hypertension and bounding pulses of the upper extremities with hypotension and diminished pulses in the lower extremities. Decreased distal perfusion can also lead to lower extremity claudication, as seen in this patient. To provide blood flow beyond the site of the coarctation, a compensatory network of collaterals often develops gradually. For instance, distal branches of the ascending aorta (eg, internal thoracic artery) can supply blood to intercostal arteries below the obstruction; blood can then flow retrograde through the intercostal arteries into the descending aorta to bypass the defect. Flow through collateral blood vessels accounts for the continuous murmur auscultated over the back in this patient. Left ventricular hypertrophy also can develop due to the aortic obstruction, resulting in an S4 gallop (as seen in this case). (Choices A and D) An atrial septal defect is characterized by a left-to-right intracardiac shunt and right-sided volume overload, causing increased blood flow through the tricuspid valve and pulmonary arteries. Cardiac examination reveals a fixed and widely split S2 and a systolic ejection murmur best heard over the second left intercostal space (ie, pulmonic flow murmur). (Choice C) Increased cardiac output due to low systemic vascular resistance can occur during septic shock. In contrast, aortic coarctation causes increased systemic vascular resistance due to obstructed aortic blood flow. (Choice E) Patent ductus arteriosus causes a continuous murmur best heard over the left infraclavicular area. However, differential hypotension and diminished pulses in the lower extremities would not be seen. Educational objective: Aortic coarctation classically leads to lower extremity claudication and increased blood pressure in the arms, as compared to the legs. Over time, unrepaired defects may lead to a compensatory collateral circulation that supplies blood to the descending aorta and creates a continuous murmur heard over the back. __________ References: Coarctation of the aorta. (http://www.ncbi.nlm.nih.gov/pubmed/28613663) Coarctation of the aorta and the nature of collateral circulation. (http://www.ncbi.nlm.nih.gov/pubmed/30761383)

A 16-Year-Old Boy Is Evaluated in the Office Due to Leg