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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

This protocol presents a model of long-term ventricular fibrillation in rat hearts induced by continuous stimulation with low-voltage alternating current. This model has a high success rate, is stable, reliable, and reproducible, has a low impact on cardiac function, and causes only mild myocardial injury.

Abstract

Ventricular fibrillation (VF) is a fatal arrhythmia with a high incidence in cardiac patients, but VF arrest under perfusion is a neglected method of intraoperative arrest in the field of cardiac surgery. With recent advances in cardiac surgery, the demand for prolonged VF studies under perfusion has increased. However, the field lacks simple, reliable, and reproducible animal models of chronic ventricular fibrillation. This protocol induces long-term VF through alternating current (AC) electrical stimulation of the epicardium. Different conditions were used to induce VF, including continuous stimulation with a low or high voltage to induce long-term VF and stimulation for 5 min with a low or high voltage to induce spontaneous long-term VF. The success rates of the different conditions, as well as the rates of myocardial injury and recovery of cardiac function, were compared. The results showed that continuous low-voltage stimulation induced long-term VF and that 5 min of low-voltage stimulation induced spontaneous long-term VF with mild myocardial injury and a high rate of recovery of cardiac function. However, the low-voltage, continuously stimulated long-term VF model had a higher success rate. High-voltage stimulation provided a higher rate of VF induction but showed a low defibrillation success rate, poor recovery of cardiac function, and severe myocardial injury. On the basis of these results, continuous low-voltage epicardial AC stimulation is recommended for its high success rate, stability, reliability, reproducibility, low impact on cardiac function, and mild myocardial injury.

Introduction

Cardiac surgery is usually performed via thoracotomy, with blocking of the aorta and perfusion with a cardioplegic solution to arrest the heart. Repeat cardiac surgery can be more challenging than the initial surgery, with higher complication and mortality rates1,2,3. Furthermore, the conventional median sternotomy approach may cause damage to the bridge vessels behind the sternum, the ascending aorta, the right ventricle, and other important structures. Extensive bleeding due to the separation of connective tissue, sternal wound infection, and sternal osteomyelitis ....

Protocol

All the experimental procedures and protocols used in this investigation were reviewed and approved by the Animal Care and Use Committee of PLA General Hospital.

1. Preparing the Langendorff apparatus

  1. Prepare the Krebs-Henseleit (K-H) buffer. To prepare the K-H buffer, add the following to distilled water: 118.0 mM NaCl, 4.7 mM KCl, 1.2 mM MgSO4, 1.2 mM NaH2PO4, 1.8 mM CaCl2, 25.0 mM NaHCO3, 11.1 mM glucose, an.......

Representative Results

A total of 57 rats were used in the experiments, of which 30 fulfilled the inclusion criteria. The included animals were divided into five groups, with six animals in each group: the control group (Group C), the low-voltage continuously stimulated long-term VF group (Group LC), the high-voltage continuously stimulated long-term VF group (Group HC), the low voltage-induced spontaneous long-term VF group (Group LI), and the high voltage-induced spontaneous long-term VF group (Group HI). The experimental process for each gr.......

Discussion

This protocol establishes an animal model of long-term VF in isolated rat hearts that has not been previously reported. Additionally, different electrical stimulation conditions were compared in this study. This study provides a model for studies related to ventricular fibrillation arrest during cardiac surgery.

The success rate of the model is a very important indicator that is related to personnel, time, and economic costs. In VF models, the success rate includes whether VF can be induced in.......

Acknowledgements

This work was carried out with the support of Cardiovascular Surgery, First Medical Center, Chinese PLA General Hospital and the Laboratory Animal Center, Chinese PLA General Hospital.

....

Materials

NameCompanyCatalog NumberComments
0 Non-absorbable sutureEthicon, Inc.Preparation of the isolated heart
95% O2 + 5% CO2Beijing BeiYang United Gas Co., Ltd. K-H buffer
AcqKnowledge softwareBIOPAC Systems Inc.Version 4.2.1Software
Automatic biochemistry analyzerRayto Life and Analytical Sciences Co., Ltd.Chemray 800CK-MB assay
BIOPAC research systemsBIOPAC Systems Inc.MP150Hardware
Blunt needle (20 G, TWLB)Tianjin Hanaco MEDICAL Co., Ltd.H-113AP-SModified Langendorff perfusion system
Calcium chlorideSinopharm Chemical Reagent Co.,Ltd10005861K-H buffer
CK-MB assay kits Changchun Huili Biotech Co., Ltd.C060CK-MB assay
Curved forcepShanghai Medical Instrument (Group) Co., Ltd.Preparation of the isolated heart
EDTASinopharm Chemical Reagent Co.,Ltd10009717K-H buffer
Electrical stimulatorBIOPAC Systems Inc.STEMISOCHardware
FilterTianjin Hanaco MEDICAL Co., Ltd.H-113AP-S
GlucoseSinopharm Chemical Reagent Co.,Ltd63005518K-H buffer
Heparin sodiumTianjin Biochem Pharmaceutical Co., Ltd.H120200505Preparation of the isolated heart
IsofluraneRWD Life Science Co.,LTD21082201Preparation of the isolated heart
Magnesium sulfateSinopharm Chemical Reagent Co.,Ltd20025118K-H buffer
Needle electrodesBIOPAC Systems Inc.EL452Hardware
Ophthalmic clampShanghai Medical Instrument (Group) Co., Ltd.Preparation of the isolated heart
Ophthalmic forcepsShanghai Medical Instrument (Group) Co., Ltd.Preparation of the isolated heart
Ophthalmic scissorsShanghai Medical Instrument (Group) Co., Ltd.Preparation of the isolated heart
Perfusion tubeTianjin Hanaco MEDICAL Co., Ltd.H-113AP-SModified Langendorff perfusion system
Potassium chlorideSinopharm Chemical Reagent Co.,Ltd10016318K-H buffer
Sodium bicarbonateSinopharm Chemical Reagent Co.,Ltd10018960K-H buffer
Sodium chlorideSinopharm Chemical Reagent Co.,Ltd10019318K-H buffer
Sodium dihydrogen phosphate dihydrateSinopharm Chemical Reagent Co.,Ltd20040718K-H buffer
Sprague-Dawley (SD) ratsSPF (Beijing) biotechnology Co., Ltd.Male, 300-350gPreparation of the isolated heart
ThermometerJiangsu Jingchuang Electronics Co., Ltd.GSP-6Modified Langendorff perfusion system
TissueforcepsShanghai Medical Instrument (Group) Co., Ltd.Preparation of the isolated heart
Tissue scissorsShanghai Medical Instrument (Group) Co., Ltd.Preparation of the isolated heart
Toothed forcepsShanghai Medical Instrument (Group) Co., Ltd.Preparation of the isolated heart
VentilatorChengdu Instrument FactoryDKX-150Preparation of the isolated heart
Water bath1Ningbo Scientz Biotechnology Co.,Ltd.SC-15Modified Langendorff perfusion system
Water bath2Shanghai Yiheng Technology Instrument Co., Ltd.DK-8DModified Langendorff perfusion system

References

  1. Kilic, A., et al. Clinical outcomes of mitral valve reoperations in the United States: An analysis of the society of thoracic surgeons national database. The Annals of Thoracic Surgery. 107 (3), 754-759 (2019).
  2. Akins, C. W., et al.

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Ventricular FibrillationRat ModelLangendorff ApparatusKrebs Henseleit BufferPerfusionECGElectrical StimulationAnesthesiaDissectionCardiac Surgery

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