A 58–year–old male with uncontrolled hypertension presented to the emergency department complaining of worsening dyspnea on exertion, orthopnea and bilateral lower extremity edema of several months duration. On physical exam he appeared flushed, and exhibited signs of hypervolemia, specifically jugular venous distention, diffuse bilateral crackles in all lung fields and warm lower extremities with bilateral pitting edema. Transthoracic echocardiogram revealed a severely dilated left ventricle with significantly reduced ejection fraction of 10%. Despite attempts to diurese and improve cardiac output with furosemide and milrinone, the patient’s renal function deteriorated. A Swan–Ganz catheter showed clear evidence of a paradoxical high output state with an elevated cardiac output of 15.8 L and a cardiac index of 6.55. Retroperitoneal ultrasound revealed a soft tissue density, further characterized by an MRI as a giant mass arising from the superior pole of the right kidney with a dilated right renal vein, concerning for renal cell carcinoma (RCC). Right renal angiogram confirmed the presence of a highly vascular mass with feeder vessels but no fistulas. Venous oxygen saturation measurements were significantly higher proximal to the renal vein rather than distal suggesting functional intrarenal arteriovenous (AV) shunting. Radical right nephrectomy was performed and histopathology confirmed the diagnosis of clear cell RCC. Postoperatively, his renal function stabilized and a repeat echocardiogram 7 days later showed significantly improved ejection fraction of 40% and a low–normal cardiac index of 2.6.
Patients with RCC rarely present with high output heart failure. Less than 30 cases have been described in the literature. Whether or not a particular subtype of RCC is associated with AV shunting is not known but at least four case reports have identified the clear cell variant as the culprit. In most instances, the diagnosis is established incidentally during angiography or surgery. In the absence of classical signs and symptoms of renal cell carcinoma, a high index of suspicion should be maintained in the presence of discrepant physical and laboratory findings; such as worsening renal function despite appropriate perfusion and treatment. In addition, the diagnostic workup of AV shunt in the setting of RCC has not been well defined. A dilated renal vein on MRI is highly suggestive of AV shunting in the appropriate clinical context. Venous oxygen saturation changes and angiography may be used to quantitate shunt flow. Heart failure symptoms typically improve after tumor resection.
Renal arteriovenous shunting is a rare complication of RCC but a reversible cause of high–output heart failure. A high index of suspicion can prevent a delay in diagnosis, and resection of the neoplasm is associated with improvement in cardiac function and heart failure symptoms.
Figure 1MRI– T2 weighted axial image of giant right renal mass with a dilated right renal vein, width (2 cm) suggestive of abnormally high blood flow.