Introduction:
Pulse amplitude ratio (PAR) (ratio of pulse pressure at end of Valsalva maneuver (VM) to before onset) correlates with filling pressure. We developed a noninvasive device to measure PAR using finger photoplethysmography (PPG).
Hypothesis:
PAR reflects PCWP in heart failure (HF) patients and can detect a change in volume status.
Methods:
Patients referred for right heart catheterization (RHC) or admitted for HF performed three 10-second trials of a standardized VM (at 20 mmH measured via a pressure transducer) while PPG waveforms were recorded.
Results:
Amongst 60 patients undergoing RHC (Table 1), PAR correlated with PCWP (Pearson correlation coefficient = 0.53, p<0.0001; Fig 1A), particularly in the 25 patients with systolic HF (Pearson correlation coefficient = 0.60, p=0.002; Fig 1B). A multivariable linear model for PCWP including PAR, age, BMI, blood pressure and heart rate improved ability to predict PCWP (r2=0.54). Difference in mean PAR for patients with a PCWP < 15 mmHg versus ≥ 15 mmHg was statistically significant (p=0.0001; Fig 1C). PAR ≥ 0.515 predicted PCWP ≥ 15 mmHg with 83% sensitivity and 80% specificity (85% PPV). Presence of a positive Kussmaul’s sign did not alter the correlation between PAR and PCWP (p=0.897 for interaction). In 8 patients admitted with HF, PAR decreased by a mean of 0.10 from admission to discharge (p=0.023, effect size=0.85).
Conclusions:
We demonstrate that the response of a finger PPG waveform to a standardized VM in HF patients can estimate PCWP and also detect changes after diuresis. The ability to detect elevated filling pressures noninvasively prior to development of symptomatic congestion could reduce HF hospitalizations.
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