1. Arrhythmia discrimination using hemoglobin spectroscopy in humans
S.J. Compton, MD, FHRS, C.D. Swerdlow, MD, FHRS, R.C. Canby, MD, G.G. Strobel, MD, J.D. Zagrodzky, MD, C. Cinbis, PhD, J.K. Carney, PhD, S.K. Bhunia, PhD 
Heart Rhythm 
Volume 9, Issue 10, Pages (October 2012)
DOI: /j.hrthm
Copyright © 2012 Heart Rhythm Society Terms and Conditions

2. Figure 1
Implantable optical sensor. Encircled optical windows, at 10 mm separation, were used in the study.
Heart Rhythm 2012 9, DOI: ( /j.hrthm )
Copyright © 2012 Heart Rhythm Society Terms and Conditions

3. Figure 2
Typical responses of the nominal and the optimized O2 Indices during induced VF, along with the ECG (lead II) and arterial blood pressure. The point where the systemic arterial pressure dropped below the prior diastolic level (dashed line) for the first time, following the loss of pulsatile arterial pressure, was taken to be the start of cardiac arrest and the 0 on the time scale. Art. = arterial; ECG = electrocardiogram; Pr. = pressure; VF = ventricular fibrillation.
Heart Rhythm 2012 9, DOI: ( /j.hrthm )
Copyright © 2012 Heart Rhythm Society Terms and Conditions

4. Figure 3
The optimized O2 Index during NSR, AP, VP, and VF. Responses to VP are divided into 2 subgroups: ΔMAP <35 mm Hg and ΔMAP >35 mm Hg. Mean of all episodes and the standard error of mean are shown at 1-second intervals. Episodes of unequal durations were averaged. Number of VF episodes: 74 at 5 seconds, 56 at 10 seconds, and 20 at 15 seconds. AP = atrial pacing; MAP = mean arterial pressure; NSR = normal sinus rhythm; VF = ventricular fibrillation; VP = ventricular pacing.
Heart Rhythm 2012 9, DOI: ( /j.hrthm )
Copyright © 2012 Heart Rhythm Society Terms and Conditions

5. Figure 4
Distributions of the rate of change of the optimized O2 Index over the entire episode, during NSR and VF. Each bar spans ±0.5 around the center-point value on the horizontal axis. NSR = normal sinus rhythm; VF = ventricular fibrillation.
Heart Rhythm 2012 9, DOI: ( /j.hrthm )
Copyright © 2012 Heart Rhythm Society Terms and Conditions

6. Figure 5
Optical sensor operating characteristics for VF and NSR detection. NSR specificity reached 88% in 10 seconds and 97% in 15 seconds while maintaining 100% VF sensitivity. NSR = normal sinus rhythm; VF = ventricular fibrillation.
Heart Rhythm 2012 9, DOI: ( /j.hrthm )
Copyright © 2012 Heart Rhythm Society Terms and Conditions

7. Figure 6
Evolution of the sensitivity to VF and specificities to NSR and simulated SVT with the duration of detection at a constant detection threshold of NSR = normal sinus rhythm; SVT = supraventricular tachycardia; VF = ventricular fibrillation.
Heart Rhythm 2012 9, DOI: ( /j.hrthm )
Copyright © 2012 Heart Rhythm Society Terms and Conditions