Echocardiographic evaluation of pulmonary vascular resistance and reactivity in children with pulmonary hypertension

Introduction and Aim: Pulmonary vascular resistance and vasoreactivity are the most important prognostic factors in childhood pulmonary hypertension. Cardiac catheterization is the golden standard diagnostic procedure for pulmonary vascular resistance and vasoreactivity. Since cardiac catheterization is an invasive diagnostic method, it would be more beneficial and advantageous for children with pulmonary hypertension in case pulmonary vascular resistance and vasoreactivity is diagnosed by a non-invasive method. The present study aims to determine the power and effectivity of transthoracic Doppler echocardiography in diagnosis of pulmonary vascular resistance and vasoreactivity by performing transthoracic echocardiography and cardiac catheterization simultaneously.Materials and Methods: The present study reviews 40 healthy controls and 30 children with pulmonary hypertension as diagnosed by cardiac catheterization. For each subject, transthoracic Doppler echocardiography was performed at the distal region of the right ventricle outflow tract and Doppler determining indices including acceleration time (AcT), inflection time (InT), deceleration index (DI), deceleration time (DecT), right ventricle ejection time (RVET), AcT/RVET, TRPG/(RVOT VTI), TRv/(RVOT VTI), TRPG/(HRxRVOT VTI) and their values adjusted for heart beat rate were recorded. Vasoreactivity test by O2 was done in children with pulmonary hypertension so that any alteration in the parameters could be specified.Results: The mean age of the children with pulmonary hypertension was 77,6±93,2 months while the mean age of the healthy control subjects was 77,6±64,8 months. the AcT, AcTc, InT, InTc, DI, DIc, DecT, DecTc, AcT/RVET parameters of the children with pulmonary hypertension were statistically different from those of the healthy control subjects (p<0,001; p<0,001; p<0,001; p<0,001; p=0,02; p=0,01; p<0,001). Children with pulmonary hypertension were grouped into three according to their pulmonary vascular resistance (namely 0-3, 3-10 and >10 Wood Units). It was also found that AcTc, TRPG/(RVOT VTI), TRv/(RVOT VTI), and TRPG/(HRxRVOT VTI) were indicators of an increase in pulmonary vascular resistance (p=0,009; p=0,009; p=0,003; p=0,004). Moreover there was a statistically significant difference in the parameters of AcTc, DIc, DecT, TRPG/(RVOT VTI), TRv/(RVOT VTI), and TRPG/(HRxRVOT VTI) of the patients who responded to the vasoreactivity test (p=0,005; p=0,009; p=0,014; p=0,004; p=0,002; p<0,001).Discussion: Pulmonary vascular resistance and vasoreactivity can be evaluated by the examination of pulmonary artery flow-velocity curves with the help of transthoracic Doppler echocardiography. This evaluation would contribute to the determination of the requirement and optimal timing for catheterization and/ or cardiac surgery. Transthoracic Doppler echocardiography seems to be an effective test for screening increased pulmonary vascular resistance and vasoreactivity in children with pulmonary hypertension.