RESUMEN
BACKGROUND: High-output heart failure is a rare condition that occurs when the heart is unable to respond to a sustained increase in blood demand. On echocardiography, a cardiac index of > 4 L/min/m2 (or 6 L/min) is a clear indicator of this disorder. The causes of high-output heart failure vary, but they all involve peripheral vasodilation or arteriovenous shunting. Renal cell carcinoma is well known for producing high levels of angiogenic growth factors that induce arteriovenous shunts. The decrease in peripheral arterial resistance and the increase in venous return result in a permanent high cardiac output, followed by congestive heart failure. Single bone metastases of renal clear cell carcinoma tumours causing high cardiac output and heart failure symptoms have been reported less than ten times in the medical literature. CASE PRESENTATION: Before a right-shoulder painful lump with a murmur when auscultated, magnetic resonance imaging revealed a large scapular mass, which was biopsied and found to be a bone metastasis of renal cell carcinoma. Two months later, the patient developed heart failure for the first time. There was no evidence of cardiac disease on echocardiography. The cardiac output was 9.8 L/min and the cardiac index was 5.1 L/min/m2. Doppler ultrasound revealed numerous arteriovenous shunts in the large scapular metastasis and a right axillary artery flow of 24% of cardiac output. Sustained lower cardiac output was obtained following lesion-focused radiotherapy and systemic antiangiogenic treatment with axitinib and pembrolizumab. CONCLUSIONS: Herein, we present a unique case of high-output heart failure in a 70-year-old man diagnosed by echocardiography and upper-limb Doppler ultrasound in the context of metastatic renal cell carcinoma without pre-existing cardiac disease. We stress the potentially life-threatening hemodynamic consequences of hypervascularity associated with arteriovenous shunts within a single metastatic renal cell carcinoma implant, the importance of auscultating any progressing bone mass, and the utility of non-invasive Doppler ultrasound assessment in this setting.
