Clinical Summary and Initial Data on Vixiar Indicor™
The Vixiar Indicor has been utilized in several initial studies all conducted at Johns Hopkins examining key research questions related to using the technique and device prototypes to estimate left ventricular end diastolic pressure (LVEDP). This section presents brief summaries of the studies and conclusions.
Silber HA, Trost JC, Johnston PF, Maughan WL, Wang N-Y, Kasper EK, Aversano TA, Bush DE. Finger photoplethysmography during the Valsalva maneuver reflects left ventricular filling pressure. Am J Physiol Heart Circ Physiol; 2012;302:H2043-7
Device output reflects invasively measured LVEDP. 33 patients tested, pulse amplitude ratio (PAR) measured using finger photoplethysmography during the Valsalva maneuver vs. left ventricular end-diastolic pressure (LVEDP) measured invasively during cardiac catheterization. PAR > 0.4 has 85% sensitivity and 80% specificity for identifying LVEDP > 15 mmHg, a clinically meaningful threshold value.
Galiatsatos P, Parakh K, Monti J, Thavarajah S, Aneke-Ogbu H, Watson A, Kim D, Wang NY, Shafi T, Silber HA. A finger photoplethysmography waveform during the valsalva maneuver detects changes in left heart filling pressure after hemodialysis. BMC Nephrol. 2015;16:138.
PAR is sensitive enough to detect LVEDP reduction after one session of hemodialysis. PAR was measured in 27 dialysis patients before and after they underwent one session of hemodialysis. Weight decreased from 99.7 ± 36.9 kg to 97.0 ± 36.0 kg (p < 0.0003) with an average fluid removal of 3.07 ± 1.08 l. Correspondingly, PAR decreased from 0.74 ± 0.24 to 0.62 ± 0.23 (p = 0.003)
Gilotra et al. American Heart Association Scientific Sessions, 2015
PAR reflects PCWP by right heart catheterization in a group including heart failure patients. 60 patients were tested who were referred for right heart catheterization (RHC). PAR was significantly greater in patients with PCWP > 15 mmHg, a threshold value associated with differences in outcomes in heart failure patients.
Gilotra et al. Heart Failure Society Scientific Sessions, 2015
The device is sensitive enough to detect a very small increase in pulmonary capillary wedge pressure (PCWP) with leg raise. In 36 of the patients undergoing RHC, PAR was measured before and during a leg raise. The average increase in PCWP during leg raise was 2.7 mmHg (p<0.0001), and the average change in PAR was 0.03 (p=0.05). This is significant because the device is intended for detecting more substantial increases in filling pressure, which in heart failure patients might signal an approaching need for hospitalization.
Shafi et al. American Society of Nephrology Scientific Sessions, 2015
Calculated LVEDP using the device is associated with dyspnea and hypotension during hemodialysis. 32 patients undergoing hemodialysis were tested. Results showed that the device can detect levels of LVEDP that predict either hypotension during hemodialysis, or that correlate with patient-described symptoms of dyspnea.
Galiatsatos et al. American College of Cardiology Scientific Sessions, 2016
Calculated LVEDP using the device identifies elevated measured LVEDP by left heart catheterization. 82 patients undergoing left heart cath were tested. Calculated LVEDP correlated with measured LVEDP with a high degree of significance, encompassing all ejection fractions. Calculated LVEDP had 70% sensitivity and 86% specificity in identifying LVEDP > 20 mmHg.
Gilotra et al. American College of Cardiology Scientific Sessions, 2016
Day-of-Discharge PAR predicts 30-day HF outcomes with high specificity. 46 heart failure inpatients were tested on the day of discharge. Outcome events within 30 days of discharge were tracked, defined as readmission for heart failure, death, or need for IV diuresis. Discharge PAR was significantly higher for the 12/46 patients who had a 30-day outcome event compared to the 34 who did not have an event (0.64 vs. 0.48, p=0.02). A discharge PAR ≥ 0.76 had 94% specificity and 42% sensitivity for predicting a 30-day outcome event (AUC = 0.66; OR 7.38, 95% CI 1.41-38.42).