# First Real-Time Imaging of Acute Effects of Arteriovenous Fistula on Regional Distribution of Pulmonary Perfusion in a Novel Porcine Model

## TL;DR

This study uses a new pig model to show how a large arteriovenous fistula changes blood flow in the lungs in real time.

## Contribution

First real-time imaging of acute AVF effects on pulmonary perfusion using a novel porcine model and electrical impedance tomography.

## Key findings

- Increased cardiac output and right ventricular work correlated with higher pulmonary artery pressure.
- Dorsal lung region received more blood flow after AVF creation.
- Pulmonary perfusion became more homogeneous after AVF opening.

## Abstract

The effects of a large arteriovenous fistula (AVF) on pulmonary perfusion remains to be elucidated. We aimed to study, for the first time, the real-time acute effects of a large AVF on regional distribution of pulmonary perfusion in a novel porcine model. Ten healthy swine under general anesthesia were studied. AVF was created by the connection of femoral artery and femoral vein using high-diameter perfusion cannulas. The AVF was closed and after 30 min of stabilization the first values were recorded. The fistula was then opened, and new data were collected after reaching stable state. Continuous hemodynamic monitoring was performed throughout the protocol. The following functional images were analyzed by electrical impedance tomography (EIT): perfusion and ventilation distributions. We found an increased cardiac output and right ventricular work, which was strongly correlated to an increased pulmonary artery mean pressure (r=0.878, P=0.001). The ventral/dorsal ratio of pulmonary perfusion decreased from 1.9±1.0 to 1.5±0.7 (P=0.025). The percentage of total pulmonary blood flow through the dorsal lung region increased from 38.6±11.7 to 42.2±10.4 (P=0.016). In conclusion, we have used EIT for the first time for studying the acute effects of a large AVF on regional distribution of pulmonary perfusion in a novel porcine model. In this new experimental model of hyperkinetic circulation caused by AVF, we documented an increased percentage of total pulmonary blood flow through the dorsal lung region and a more homogeneous perfusion distribution.