Cardiovascular remodeling after AVF surgery in rats assessed by a clinical MRI scanner

Abstract

Purpose: To evaluate a cardiovascular magnetic resonance imaging (MRI) technique which allows the longitudinal analysis of cardiovascular remodeling in a rodent femoral arteriovenous fistula (AVF) model by means of a clinical scanner.

Materials and methods: Eight rats underwent femoral AVF surgery and four rats served as controls. Vascular and cardiac morphology as well as cardiac function was assessed from Week 3 to 12 using contrast-enhanced, time-resolved magnetic resonance angiography (MRA) and cardiac MRI (cine gradient-echo sequence) at 3 T in one imaging session.

Results: Arteriovenous surgery resulted in progressive venous dilation and a subsequent cardiac adaptation. This procedure led to downstream vasodilation of the iliac vein and inferior vena cava of 179% and 188%, respectively (3 weeks). To accommodate the increased returning blood volume, cardiac output (CO) increased significantly (P=.014; 6 weeks). This was caused by increased end-diastolic volume (EDV), stroke volume (SV) and heart rate (HR) consistent with an increased volume load. A continuous increase in heart weight peaked at 12 weeks. This increase combined with a distinct end-diastolic left ventricular dilation implied eccentric hypertrophy.

Conclusion: Small rodent MRI is feasible and clearly depicts fistula maturation and cardiac alterations. This technique proved to be a valuable tool for longitudinal in vivo monitoring in this model, which strongly resembles clinical findings in hemodialysis patients.