A 32-year-old man is evaluated in the emergency department due to fever, night sweats, and chills over the last several days. The patient has been using intravenous drugs recently as he is "stressed out." He has otherwise been in good health with no medical problems. Temperature is 38.3 C (101 F), blood pressure is 120/80 mm Hg, and pulse is 105/min and regular. Further evaluation reveals aortic valve endocarditis with an intracardiac abscess and small fistula formation between the aortic root and right ventricle. Doppler ultrasound interrogation of the fistula will most likely reveal which of the following blood flow patterns?

Question

A 32-year-old man is evaluated in the emergency department due to fever, night sweats, and chills over the last several days.  The patient has been using intravenous drugs recently as he is "stressed out."  He has otherwise been in good health with no medical problems.  Temperature is 38.3 C (101 F), blood pressure is 120/80 mm Hg, and pulse is 105/min and regular.  Further evaluation reveals aortic valve endocarditis with an intracardiac abscess and small fistula formation between the aortic root and right ventricle.  Doppler ultrasound interrogation of the fistula will most likely reveal which of the following blood flow patterns?

Quizplus · Accepted Answer

11ec160b_3c94_0e9a_9249_b37846c17f3e_MD0001_00 This patient with aortic valve endocarditis has developed an intracardiac fistula between the aortic root and right ventricle. Aortocavitary fistulas are an uncommon complication of bacterial endocarditis caused by extension of the infection from the valve to the adjacent myocardium. Echocardiography with Doppler analysis can be used to detect and quantify shunts in patients with intracardiac fistulas. During the normal cardiac cycle, central aortic pressure (eg, 120/80 mm Hg) is higher than right ventricular pressure (eg, 25/5 mm Hg) during systole and diastole. Consequently, in patients with aortocavitary fistula, Doppler interrogation will most likely demonstrate continuous blood flow from the higher-pressure aortic root to the lower-pressure right ventricle (left-to-right cardiac shunt) (Choices B and C). This can lead to a continuous murmur heard on cardiac auscultation. (Choices D, E, and F) Pressure in the aortic root is always greater than in the right ventricle throughout systole and diastole; therefore, blood flow from the right ventricle to the aortic root would not be expected in this patient. Educational objective: During the normal cardiac cycle, central aortic pressure is higher than right ventricular pressure during systole and diastole. Consequently, an intracardiac fistula between the aortic root and right ventricle will most likely demonstrate a left-to-right cardiac shunt as blood continuously flows from the aortic root (high pressure) to the right ventricle (low pressure). __________ References: Aorto-cavitary fistulous tract formation in infective endocarditis: clinical and echocardiographic features of 76 cases and risk factors for mortality. (http://www.ncbi.nlm.nih.gov/pubmed/15618052)

A 32-Year-Old Man Is Evaluated in the Emergency Department Due