RESUMO
Objective:To explore the changes of right ventricular myocardial perfusion in pulmonary arterial hypertension (PAH) pig models with a quantitative analysis technique based on dynamic SPECT myocardial perfusion imaging, and analyze the relationship between myocardial blood flow, hemodynamics and right ventricular function.Methods:Eleven Chinese miniature pigs (all males, 6-8 months old) weighing 25-30 kg were selected. The PAH models were established by ligating the main pulmonary artery and embolizing the right lower pulmonary artery. After the models were established, dynamic myocardial perfusion imaging with one-day resting/adenosine stress 99Tc m-methoxyisobutylisonitrile (MIBI) SPECT was performed, and the quantitative parameters of left and right ventricles were obtained, including stress myocardial blood flow (SMBF), rest myocardial blood flow (RMBF) and myocardial flow reserve (MFR: the ratio of stress to rest myocardial blood flow). Right heart catheterization was performed to evaluate the mean pulmonary arterial pressure (mPAP), and the right heart function index tricuspid annular plane systolic excursion (TAPSE) was measured by transthoracic echocardiography. According to TAPSE, animals were divided into right heart function preserved group ( n=5, TAPSE≥17 mm) and right heart dysfunction group ( n=4, TAPSE<17 mm). Pearson correlation analysis and the independent-sample t test were used for data analysis. Results:Nine experimental pig models were established with increased mPAP of (38.1 ± 11.6 ) mmHg (1 mmHg=0.133 kPa). Myocardial perfusion imaging showed clear radiotracer uptake in the right heart and myocardial hypertrophy. There was a significant positive correlation between right ventricular myocardial RMBF ((0.71±0.13) ml·min -1·g -1) and mPAP ( r=0.94, P< 0.001). The SMBF in the decreased right ventricular function group was significantly lower than that in the preserved right ventricular function group ((1.66±0.35) vs (2.24±0.30) ml·min -1·g -1;t=2.68, P=0.032). Conclusion:SPECT myocardial blood flow quantification can be used to evaluate the right ventricular myocardial blood flow in pig models of PAH.