Software for Analysis of Heart Rate and Blood Pressure Time-series Data from the Valsalva Maneuver

The Valsalva Maneuver (VM) is a low-risk highly accessible test that measures the baroreflex-induced heart rate (HR) and blood pressure (BP) response to forced breathing against 40 mmHg intrathoracic pressure for 15 s. This study demonstrates the ValsalvaAnalyzer software, which combines modeling and data analysis to extract biomarkers from time-series BP and electrocardiogram (ECG) data. The software, programmed in MATLAB, incorporates a graphic user interface, making data analysis and mathematical modeling predictions accessible to clinicians. The software calibrated for PCs and Macs reads ECG and BP data measured during the VM. It automatically identifies R and S peaks in the ECG signal, with integrated user verification to ensure the accuracy of the captured signals. The RR intervals are used to predict HR, and the QRS complex magnitude changes are used to predict respiration. Systolic and diastolic BP are captured, and the user identifies the onset and VM duration from the SBP. The software automatically detects the four VM phases and the intrathoracic pressure. The latter is obtained by merging the respiratory signal at rest with the 40 mmHg pressure the subject breathes against during the VM. The most commonly reported clinical VM markers computed from the HR and BP data are reported along with estimates of patient-specific parameters obtained using a differential equations model, which predicts sympathetic and parasympathetic dynamics. The final output, over 35 metrics, includes BP and HR, maximum and minimum HR, the Valsalva ratio, and measures of baroreflex sensitivity, all saved to a spreadsheet. The software is intended to analyze the VM data, but the methodology can be extended to other autonomic tests. Its strength lies in combining quantities extracted from raw data with model outputs, augmenting clinical data with a mathematical model providing insight into autonomic immeasurable quantities.