# Microscope-assisted, rodent whole heart perfusion fixation for histological characterization of myocardium remodeling

## TL;DR

This paper introduces a new method for preserving rodent hearts for histological study, using a microscope-assisted technique that avoids damaging the heart tissue.

## Contribution

A novel, non-invasive, microscope-assisted method for whole rodent heart perfusion fixation that preserves tissue integrity.

## Key findings

- The method enables thorough perfusion of fixative through both sides of the rodent heart.
- The technique is atraumatic to the ventricles and surrounding structures.
- It uses accessible microsurgical tools and a dissecting light microscope.

## Abstract

Investigating mechanisms of heart disease, its progression, and developing therapeutics that target cardiac remodeling often requires translational model organisms. In vivo, rodent models have been well established as a means to explore heart pathologies for their physiologic similarities, low cost, reproducibility, and breeding efficiency. Chemical fixation and harvest of cardiovascular structures is an essential preliminary step to histological assessment that enables the characterization of macro and subtle tissue changes. Our method establishes a novel and reproducible strategy for optimal cardiac perfusion, cardiectomy, and chemical fixation of the whole rodent heart. Our non-survival, microscope-assisted surgical technique allows for robust and efficient fixation of the rodent myocardium, heart valves, and vasculature preserving precious features in preparatory steps for histological staining.•Optimized method to sample blood, exsanguinate and thoroughly perfuse fixative through the left and right side of the whole rodent heart.•Protocol is atraumatic to the ventricles and surrounding structures; Injections are into the inferior vena cava (IVC) and left atrium.•Performed using accessible microsurgical tools and aided by a dissecting light microscope.

Optimized method to sample blood, exsanguinate and thoroughly perfuse fixative through the left and right side of the whole rodent heart.

Protocol is atraumatic to the ventricles and surrounding structures; Injections are into the inferior vena cava (IVC) and left atrium.

Performed using accessible microsurgical tools and aided by a dissecting light microscope.

This novel method optimizes the preservation of rodent myocardium for histological study without the drawbacks of the current standard technique, which punctures the myocardium and inadequately evacuates blood products from the heart and vessels.

Image, graphical abstract