Ventricular Fibrillation During Optical Coherence Tomography/Optical Frequency Domain Imaging　- A Large Single-Center Experience.

BACKGROUND: The risks of ventricular fibrillation (Vfib) associated with frequency-domain optical coherence tomography (OCT)/optical frequency domain imaging (OFDI) remain undetermined.Methods and Results:We retrospectively studied the occurrence of Vfib during OCT/OFDI for unselected indications. The frequency of Vfib and patient and procedural characteristics were investigated. A total of 4,467 OCT/OFDI pullback examinations were performed in 1,754 patients (median of 2.0 [2.0-3.0] pullbacks for 1.0 [1.0-1.3] vessels). OCT/OFDI was performed during PCI in 899 patients (51.3%). The contrast injection volume per pullback was 14.4 (11.7-17.2) mL with a flow rate of 3.4 (3.2-3.5) mL/s. Vfib occurred in 31 pullbacks (0.69%) in 30 patients (1.7%). No cases of Vfib occurred when using low-molecular-weight dextran. On multivariate analysis, contrast volume was the only independent factor for predicting Vfib (odds ratio, 1.080; 95% confidence interval, 1.008-1.158, P=0.029). The best cutoff value of contrast volume for predicting Vfib was 19.2 mL (area under the curve, 0.713, P<0.001; diagnostic accuracy, 87.1%). CONCLUSIONS: The present large, single-center registry study indicated that Vfib during OCT/OFDI was rare for unselected indications. Contrast injection volume used to displace blood should be limited to avoid Vfib.

Impact of Pressure Signal Drift on Fractional Flow Reserve-Based Decision-Making for Patients With Intermediate Coronary Artery Stenosis.

BACKGROUND: Fractional flow reserve (FFR) is an important physiological measure of intermediate coronary artery stenosis. Pressure signal drift (PD) is widely recognized but has largely been ignored in FFR measurements. We sought to determine the effect of PD on FFR-derived decision-making. METHODS AND RESULTS: We analyzed 1,218 FFR measurements for intermediate stenosis in 940 patients, in which the pullback maneuver confirmed PD ≤3 mmHg. The primary objectives were to determine the frequency and magnitude of PD and its effect on decision-making on the basis of an FFR cutoff of 0.80. In all, 479 (39.3%) measurements showed PD. PD was significantly associated with age, hypertension, reference diameter, left anterior descending artery lesion location, and read-out FFR values. Classification discordance between read-out and PD-corrected FFR values was detected in 44 (3.6%) measurements in total and in 9.2% of PD cases. The decision changed from FFR ≤0.80 to FFR >0.80 in 40 (3.3%) and vice versa in 4 (0.3%) measurements. PD showed no effect on decision-making when the FFR read-out value was ≤0.76 or ≥0.83. CONCLUSIONS: PD is not uncommon, and its effect on FFR-based decision-making was not negligible in the range between 0.77 and 0.82 where reclassification occurred in 18.7% of FFR measurements. (Circ J 2016; 80: 1812-1819).

Quasi-continuous transition from a Fermi liquid to a spin liquid in κ-(ET)2Cu2(CN)3.

The Mott metal-insulator transition-a manifestation of Coulomb interactions among electrons-is known as a discontinuous transition. Recent theoretical studies, however, suggest that the transition is continuous if the Mott insulator carries a spin liquid with a spinon Fermi surface. Here, we demonstrate the case of a quasi-continuous Mott transition from a Fermi liquid to a spin liquid in an organic triangular-lattice system κ-(ET)2Cu2(CN)3. Transport experiments performed under fine pressure tuning have found that as the Mott transition is approached, the Fermi liquid coherence temperature continuously falls to the scale of kelvins, with a divergent quasi-particle decay rate on the metal side, and the charge gap continuously closes on the insulator side. A Clausius-Clapeyron analysis provides thermodynamic evidence for the extremely weak first-order nature of the transition. These results provide additional support for the existence of a spinon Fermi surface, which becomes an electron Fermi surface when charges are delocalized.