What is a possible complication of an untreated arteriovenous fistula?

An untreated arteriovenous fistula can lead to heart failure due to volume overload because this condition allows blood to flow directly from arterial circulation to venous circulation without passing through the capillaries, which normally regulate blood flow resistance. This increased volume returning to the heart can cause the heart to work harder to pump this excessive blood volume, leading to eventual myocardial stress and heart failure.

Additionally, the continuous high blood flow can cause a significant increase in cardiac output. Over time, if this volume overload is not addressed, it results in the dilation of the heart chambers, decreased efficiency of heart function, and the development of heart failure symptoms. This complication highlights the importance of monitoring patients with arteriovenous fistulas, particularly in those requiring hemodialysis, to prevent such significant cardiovascular complications.