Force-Interval Relationships of the Heart Measured With Photoplethysmography During Atrial Fibrillation

Abstract

Force-interval relationships (FIRs) of the heart represent the relationships between inter-beat intervals (IBIs) and strength of the ventricular contractions. These relationships are typically measured invasively and are altered from normal in heart failure (HF). An unobtrusive and continuous measurement of FIRs could be beneficial when HF and atrial fibrillation (AF) coexist in order to understand if AF causes progression of HF. We hypothesize that FIRs could be assessed during AF with IBIs and hemodynamic changes captured unobtrusively by photoplethysmography (PPG) at the wrist. FIRs were assessed by using Spearman's rank correlation between the pulse onset change in the PPG waveform and either the preceding or pre-preceding IBIs (r pre and r pre−pre) in 5-minute segments. 32 patients (14 continuous AF, 18 no AF) were measured during the night with PPG and electrocardiography as a reference. The mean and standard deviation of r pre were-0.25 ± 0.08 and 0.05 ± 0.12 (p < 0.0001), and of r pre−pre 0.60 ± 0.09 and 0.16 ± 0.14 (p < 0.0001), during AF and sinus rhythm, respectively. Areas under the Receiver Operating Characteristics curve were 0.987 and 0.998, respectively. Thus, during AF the IBIs correlate with the beat-to-beat changes of blood volume measured with PPG, likely to indicate that FIRs can be measured unobtrusively with the PPG signal.

Detecting Atrial Fibrillation and Atrial Flutter in Daily Life Using Photoplethysmography Data

“…Moreover, some of the features derived from the PPG waveform have been used to discriminate ventricular arrhythmias [23]. The PPG waveform characteristics have been also studied in the context of force-interval relationship during AF [46] and mechanical alternans [47]. This could indicate that the PPG waveform itself contains information about different rhythms and cardiac function.…”

Methods of Extracting Feature from Photoplethysmogram Waveform for Non-Invasive Diagnostic Applications

“…The reference beat labels were aligned based on the IBI sequence from PPG and ECG reference beat times. Force-interval relationship can be assessed during atrial fibrillation with the IBIs captured by PPG [23]. Banerjee [7] and Li [24] used the Gaussian technique to extract features from PPG pulses.…”

“…This technique is practical and inexpensive, but many aspects, such as the balanced of the specificity and sensitivity of the test, treatment changes for patient, and validation of work, must be considered. IBI is an unobtrusive parameter in diagnosis study [23]. MA must be reduced while the subject is going to bed to continuously monitor the IBI from PPG.…”