Volume overload heart failure model.

Rats underwent surgery to produce an arteriovenous (A-V) fistula using the needle technique as previously described (2, 7, 39). Briefly, under anesthesia (Isoflurane: 5% for induction; 1.5% for maintenance balanced with O₂), the inferior vena cava and the abdominal aorta were exposed using a midline incision. Both vessels were clamped caudal to the renal artery and the aortic bifurcation, respectively. The aorta was punctured using an 18-gauge needle and advanced until it perforated the adjacent vena cava. Immediately afterward, a drop of histoacryl glue (BBraun, Germany) was used to seal the aorta at the puncture point. The A-V fistula was confirmed by visualization of bright red arterial blood entering the vena cava through the anastomosis. The peritoneal cavity was closed with absorbable suture (Novosyn 4/0, BBraun, Germany), and the skin was closed with absorbable suture (Novosyn 3/0, BBraun, Germany) and metallic clips (Kent Scientific, Torrington, CT). Postoperative management consisted of administration of 5 mg sc enrofloxacin, 1 mg sc ketoprofen, 5 mL ip saline solution, and 2% topical lidocaine hydrochloride jelly. Sham-operated rats underwent the same anesthesia and surgical procedures without the anastomosis.