Normal Values of Pulmonary Artery Acceleration Time (PAAT) and Right Ventricular Ejection Time (RVET) in Children and Adolescents, and the Impact of PAAT/RVET Index in Assessment of Pulmonary Hypertension

Aims: New echocardiographic modalities including pulmonary artery acceleration time (PAAT) and right ventricular ejection time (RVET) are evolving to facilitate an early noninvasive diagnosis for pulmonary hypertension (PH) in adults. In children, PAAT depends on age, body surface area (BSA), and heart rate (HR) and is used to predict PH. Normal values of RVET and their role to predict PH in children are still missing. PAAT/RVET index correlates negatively with PH. We hypothesized that this index is a good predictor for PH in children and adolescents independent of age, BSA, and HR and RVET is significantly reduced in PH.

Methods and Results: PAAT and RVET of 401 healthy children and 31 PH-patients were measured using pulsed-wave Doppler. PAAT/RVET index for both groups was calculated. Sensitivity and specificity in prediction of PH of PAAT, PAAT z-score, and PAAT/RVET-index were compared.

We demonstrated normal values of RVET in children. In the healthy group, PAAT and RVET correlated significant positive to age (p < 0.001) and BSA (p < 0.001), and negative to HR (p < 0.001). PAAT/RVET index correlated weakly to age, BSA, and HR (p < 0.001). In predicting PH, RVET is significantly reduced (p < 0.001). Comparing area under the curve (AUC), the difference between sensitivity and specificity of PAAT/RVET index < 0.29 and calculated PAAT cutoff point (87 milliseconds) was significant (p < 0.001). Equally, AUC comparison between PAAT/RVET index < 0.29 and PAAT z-score of −1.33 was significant (p = 0.008).

Conclusion: PAAT/RVET index < 0.29 represents a good predictor of PH with a 100% sensitivity and a 95.8% specificity. PAAT/RVET index is a simple tool and facilitates prediction of PH independent from z-scores.