A 45-year-old man comes to the office due to exertional dyspnea and fatigue. The patient spends most of his time indoors because of his symptoms. He has end-stage renal disease due to glomerulonephritis, and 6 months ago he began hemodialysis via an arteriovenous fistula. The patient has stayed close to his "dry" weight, and his hemoglobin has been maintained in the desired range with iron and erythropoietin supplementation. He is afebrile. Blood pressure is 160/60 mm Hg and pulse is 100/min and regular. Oxygen saturation is 96% on room air. The right arm arteriovenous fistula is distended with very strong pulse augmentation. Carotid upstroke is brisk. The point of maximal impulse is displaced to the left, and a soft systolic murmur is heard over the cardiac apex that does not change with the Valsalva maneuver. Scattered rales are heard at the lung bases. The extremities are warm, and there is trace peripheral edema. Which of the following is the most likely cause of this patient's symptoms?

Question

A 45-year-old man comes to the office due to exertional dyspnea and fatigue.  The patient spends most of his time indoors because of his symptoms.  He has end-stage renal disease due to glomerulonephritis, and 6 months ago he began hemodialysis via an arteriovenous fistula.  The patient has stayed close to his "dry" weight, and his hemoglobin has been maintained in the desired range with iron and erythropoietin supplementation.  He is afebrile.  Blood pressure is 160/60 mm Hg and pulse is 100/min and regular.  Oxygen saturation is 96% on room air.  The right arm arteriovenous fistula is distended with very strong pulse augmentation.  Carotid upstroke is brisk.  The point of maximal impulse is displaced to the left, and a soft systolic murmur is heard over the cardiac apex that does not change with the Valsalva maneuver.  Scattered rales are heard at the lung bases.  The extremities are warm, and there is trace peripheral edema.  Which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d33f_7201_bc81_13befde16825_MD0003_00 This patient with an arteriovenous fistula has multiple findings suggestive of high-output heart failure. High-output heart failure usually involves increased cardiac output (CO) in response to a disturbance that causes reduced systemic vascular resistance (SVR). Such disturbances include: disturbances Peripheral vasodilation due to unmet metabolic demand (eg, hyperthyroidism, severe anemia) Increased quantity of peripheral vessels (eg, Paget disease, morbid obesity) Bypass of systemic arteriolar resistance due to an enlarged arteriovenous fistula (as in this patient) In response to low SVR, the left ventricle increases contractility and stroke volume to maintain adequate CO for tissue perfusion. This increase in stroke volume leads to high-amplitude pulsation and hyperdynamic circulation, evidenced by widened pulse pressure (eg, >60 mm Hg difference between systolic and diastolic blood pressure), brisk carotid upstroke, and warm extremities. Heart rate is also increased to aid CO. low SVR The reduced SVR and increased CO also lead to increased venous return to the heart (increased cardiac preload). Despite high output, the left ventricle is unable to keep up with the increased venous return and venous hydrostatic pressure increases, causing peripheral swelling and pulmonary edema. Eccentric left ventricular hypertrophy may develop (eg, laterally displaced point of maximal impulse), and the high blood flow can create a systolic flow murmur. (Choice A) In contrast to most cases of heart failure, in which cardiac function is impaired and reduced CO is the primary disturbance, high-output heart failure involves mostly intact cardiac function and reduced SVR is the primary disturbance (with CO increased). primary disturbance (Choice B) Flail mitral leaflet leads to acute mitral valve regurgitation and subsequent heart failure. Because CO is reduced, evidence of hyperdynamic circulation (eg, widened pulse pressure, brisk carotid upstroke, warm extremities) is not expected. (Choice C) Hypertrophic cardiomyopathy is recognized by a systolic ejection murmur that increases in intensity with maneuvers that decrease left ventricular blood volume (eg, Valsalva). This patient's systolic murmur that does not change is more consistent with the persistent high blood flow that occurs with high-output heart failure. (Choice D) Idiopathic pulmonary arterial hypertension (group 1 pulmonary hypertension) results from a primary increase in pulmonary vascular resistance. It presents with dyspnea, fatigue, and lower extremity swelling but should not cause pulmonary edema or evidence of hyperdynamic circulation. pulmonary vascular resistance Educational objective: High-output heart failure usually results from increased cardiac output in response to a reduction in systemic vascular resistance (eg, arteriovenous fistula). It involves hyperdynamic circulation (evidenced by widened pulse pressure and brisk carotid upstroke) and increased cardiac venous return, leading to peripheral and pulmonary edema. References: High-output heart failure: a 15-year experience. (http://www.ncbi.nlm.nih.gov/pubmed/27470455)

A 45-Year-Old Man Comes to the Office Due to Exertional