EndoPAT® assesses digital flow mediated dilation during reactive hyperemia using measurements from both arms – occluded side and control side.
EndoPAT® provides an index of endothelial function
in two forms:
RHI and LnRHI
RHI (Reactive Hyperemia Index) is the post-to-pre occlusion PAT signal ratio in the occluded side, normalized to the control side and further corrected for baseline vascular tone.
Normal: RHI > 1.67 Abnormal: RHI ≤ 1.67
LnRHI is a similar index after natural log transformation with a matched cutoff:
Normal: LnRHI > 0.51 Abnormal: LnRHI ≤ 0.51
Natural log is a monotonic transformation therefore it does not change the dichotomous diagnosis for any individual test.
LnRHI provides a better double sided distribution than RHI that is closer to normal distribution. It offers better separation between disease states.
Risk Score Calculator
The EndoPAT® Risk Score Calculator provides the 3 most commonly used cardiovascular risk assessment methods
Framingham Risk Score Estimates 10 year risk of Coronary Heart Disease, MI or cardiac death (Adults treatment panel III, JAMA 2001). Applies to subjects without known heart disease or diabetes. Utilities different models for men and women using the following oredictors: age, total cholesterol, HDL, systolic blood pressure, treatment for hypertension and smoking.
SCORE is the European estimate of a 10 year risk of fatal CVD (EHJ, 2003). Charts are divided to low risk regions (Belgium, France, Greece, Italy, Luxemburg, Spain, Portugal) and high risk regions (all other European countries) using the following predictors: gender, age, total cholesterol, systolic blood pressure and smoking.
Reynolds Risk Score provides 10 years risk of MI, stroke, revascularization or cardiac death (JAMA 2007, Circ 2008). Reynoldsrisk score uses the following predictors: gender, age, total cholesterol, HDL, systolic blood pressure, hsCRP and parent MI before age 60.
Lower AI values (including negative results) reflect better arterial elasticity.Augmentation Index (AI)*
Measures arterial stiffness, calculated via pulse waveform analysis of the PAT signal and is considered an independent risk factor for CVD not necessarily correlated to endothelial function.
AI is calculated from PAT pulses recorded at the base-line period.
EndoPAT® averages multiple pulses, identifies the systolic peak (P1) and the reflected wave’s peak (P2) then incorporates them into the formula: (P2-P1)/P1.
The result is further normalized to heart rate of 75bpm (AI@75).
The AI result is provided relative to gender matched, non-selective populations.
Heart rate variability (HRV)*
A measure of heart beat-to-beat variability in either time
or frequency domain.
HRV reflects the status of the autonomic nervous system (ANS) and is associated with the balance between sympathetic and parasympathetic activities that may reflect various pathological conditions.
EndoPAT® HRV is calculated from the baseline period, based on the ESC and North American Society of Pacing Electrophysiology task force standard.
Results are available in various time
and frequency domain formats