A 24-year-old man is evaluated for fatigue and palpitations. He reports good exercise tolerance with only mild dyspnea on exertion. Electrocardiogram shows normal sinus rhythm with a right bundle branch block. Right and left cardiac catheterization is obtained and the following blood oxygen saturation values are reported: Which of the following is the most likely physical examination finding in this patient?
A)Brachial-to-femoral pulse delay
B)Continuous murmur at the left sternal border
C)Digital clubbing
D)Fixed splitting of S2
E)Holosystolic murmur at the left sternal border

Question

A 24-year-old man is evaluated for fatigue and palpitations.  He reports good exercise tolerance with only mild dyspnea on exertion.  Electrocardiogram shows normal sinus rhythm with a right bundle branch block.  Right and left cardiac catheterization is obtained and the following blood oxygen saturation values are reported: Which of the following is the most likely physical examination finding in this patient?
A)Brachial-to-femoral pulse delay
B)Continuous murmur at the left sternal border
C)Digital clubbing
D)Fixed splitting of S2
E)Holosystolic murmur at the left sternal border

Quizplus · Accepted Answer

Explanation: 11ec2b69_c121_c954_8f63_c129dab91c89_MD0005_00 This patient's oxygen saturation values show a significant step up in oxygen saturation - from 57% to 74% - between the right atrium and right ventricle. This is most likely due to a ventricular septal defect (VSD) with left-to-right shunt. The left-to-right shunting allows the mixing of oxygenated blood from the left ventricle with the deoxygenated blood in the right ventricle. Patients with a VSD typically have a harsh holosystolic murmur with maximal intensity over the left third and fourth intercostal spaces, often accompanied by a palpable thrill. (Choice A) Brachial-to-femoral pulse delay is typically seen in patients with coarctation of the aorta. Patients with coarctation have no intra-cardiac shunting of blood and would not be expected to have any abnormal patterns of oxygen saturation. (Choice B) Patent ductus arteriosus (PDA) causes a characteristic continuous murmur heard best in the left infraclavicular area. PDA causes left-to-right shunting of blood from the aorta to the main pulmonary artery and would be expected to cause a step-up in oxygen saturation from the right ventricle to the pulmonary artery. (Choice C) Digital clubbing is seen in a variety of pulmonary or cardiovascular disorders, including bronchiectasis, pulmonary neoplasms, and certain cyanotic congenital heart disorders (eg, tetralogy of Fallot [TOF]). TOF is the most common cyanotic congenital heart defect and has 4 characteristic anatomic features: Right ventricular outflow tract obstruction Overriding aorta Right ventricular hypertrophy VSD VSD in the context of TOF is typically identified in childhood and is associated with significant intermittent or continuous cyanosis. This adult patient has good exercise tolerance and is unlikely to have undetected TOF as the cause of these findings. (Choice D) Patients with atrial septal defect and large left-to-right shunts have a characteristic wide and fixed splitting of the second heart sound. Blood oxygen saturation measurements in such patients show a significant step-up in oxygen saturation from the superior/inferior vena cava to the right atrium. Educational objective: Blood oxygen saturation measurements at different levels during right heart catheterization can be used to determine the location and differentiate between causes of left-to-right shunt (eg, atrial septal defect, ventricular defect, patent ductus arteriosus). References: Ventricular septal defects. (http://www.ncbi.nlm.nih.gov/pubmed/17101870)

A 24-Year-Old Man Is Evaluated for Fatigue and Palpitations