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DOI: 10.1055/s-2008-1037876
A novel experimental model on chronic right ventricular volume overload
Aims: Chronic pulmonary regurgitation is a well-known complication after correction of Tetralogy of Fallot (TOF). However, the phenomenon lacks a valid experimental model.
Methods: Under general anaesthesia and mechanical ventilation, 4–5-month-old sheep (n=16) weighing 35–45kg were operated through left anterior thoracotomy. Baseline right ventricular function was obtained by inserting conductance catheters through the pulmonary artery. Thereafter, a transannular patch was sutured to the RVOT. The ring of the pulmonary valve was transsected through an incision over the patch without cardiopulmonary bypass. Pulmonary regurgitation and right ventricular function were assessed again. Data were statistically analysed with paired samples t-test.
Results: All animals survived the procedure. Pressure-volume-loop analysis presented significantly elevated pressure and volume loading of the right ventricle. Maximum developed pressure augmented from 26.14±4.10mmHg to 30.46±3.73mmHg (p<0.01). RVEDP [10.5±2.8 to 13.9±3.6mmHg (p<0.01)] and RVESP [19.3±3.0 to 21.7±3.1mmHg, (p<0.05)] were elevated. Dp/dt max, dp/dt min and heart rate rose from 418.9±88.8 to 492.6±98.9 (p<0.01), 306.9±61.2 to 327.9±60.5 (n.s.), 88.1±13.3 to 92.9±13.2 (p<0.05), respectively. Ejection fraction decreased from 72.9±11.3% to 56.6±11,9% (p<0.01).
Conclusion: Surgical valvulotomy after transannular patch implantation may constitute a suitable experimental design to investigate chronic pulmonary regurgitation after surgical correction of TOF.
Fig. 1: RVOT before the procedure
Fig. 2: PV-Loop measurement before transannular patch
Fig. 3: PV-Loops
Fig. 4: PV-Loop measurement after transannular patch