Analysis of heart rate variability in a rabbit model of heart failure using Karhunen-Loeve expansion

A long-term experiment was conducted by the use of a doxorubicin rabbit model of heart failure. Heart failure was progressively induced in two groups of animals by weekly administrating doxorubicin in amount of 2 mg/kg and 4 mg/kg, respectively. Control animals were injected saline. The ECG was continuously recorded for three weeks prior to treatment and up to ten weeks post-treatment. In analysis, eleven time-domain and frequency-domain heart rate variability (HRV) parameters were computed for every usable 5-minute segment for the entire period of recordings. Karhunen-Loeve expansion was utilized to track the changes of HRV as heart failure develops. The concept is extracting basis components of pretreatment HRV by using singular value decomposition and determining change of these basis components in posttreatment HRV by observing its coefficients. The results show changes in coefficient values in treatment animals, while it remains unchanged in control animals.