Application of phonocardiography on preterm infants with patent ductus arteriosus

The patent ductus arteriosus (PDA) is a prevalent disease in case of preterm newborns. The assessment of some parameters of the PDA with simple and noninvasive measurement equipment, such as phonocardiography (PCG), could be of great significance. In this paper two features of the heart sound have been investigated. The first one is the sensitive identification of murmur related to PDA. This was achieved by calculating the average maximal late systolic envelope value (LSEVmax), which was significantly greater in case of preterms with PDA (p < 0.05). The second feature was the investigation of the splitting interval (SI) of the second heart sound (S2). For this a S2 sound model valid for preterms was developed. By estimating the SI using a heuristic method it was found, that the estimated splitting time increased by 30% around the time of the closure of the PDA in case of pharmacologically treated preterm newborns. In case of both analysis a characteristic heart sound calculation method was applied for improved reliability of the extracted features.