Detection of heart rate turbulence using an extended IPFM model

In this study, the IPFM model is extended to account for the presence of ectopic beats and heart rate turbulence (HRT). Based on the model extension, a new approach to characterize HRT is presented based on a set ofKarhunen- Loeve (KL) basis functions. The three most significant basis functions possess attractive physiological interpretations which reflect the difference in heart rate prior to the ventricular ectopic beat (VEB) compared to after HRT, an "average" HRT, and a delayed "average" HRT, respectively. HRT detection is based on the IPFM model extension, and involves a test statistic that results from a linear model. The HRT test statistic was studied on patients who underwent hemodialysis treatment. The goal was to distinguish between patients considered to be hypotension- resistant (HtR) and hypotension-prone (HtP). The results show that the test statistic of the two groups formed two non-overlapping clusters. The HtR-cluster exhibited much larger values than did the HtP-cluster (mean values 51 and 2, respectively), suggesting that HRT is mostly present in HtR patients.