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Background-Atrial fibrillation (AF) is associated with significant abnormalities of left atrial (LA) systolic and diastolic function. This study describes a novel measure, LA stiffness index, that estimates LA diastolic function and its association with clinical outcomes of catheter ablation. Methods and Results-A total of 219 AF patients referred for ablation (59% paroxysmal, mean CHA 2 DS 2 VASc score 1.7±1.4) were enrolled. Atrial pressure and volume loops were prepared from invasive pressure measures and cardiac magnetic resonance imaging volumetric data during sinus rhythm for all patients. An LA stiffness index was created, defined by the ratio of change in LA pressure to volume during passive filling of LA (ΔP/ΔV). Patients were followed prospectively. Mean LA stiffness index for AF patients was 0.6±0.5 mm Hg/mL (paroxysmal AF 0.51±0.4 and persistent AF 0.73±0.6; P<0.001). Linear regression analysis showed a rise in the stiffness index with age, increasing at a rate of 0.02 mm Hg/mL per year (P<0.001). The LA stiffness index was higher in patients with previous LA ablation(s) for AF (0.51±0.35 versus 0.83±0.70; P<0.001). Forty of 160 patients had recurrence after AF ablation with a mean follow-up of 10.4±7.6 months. Patients with recurrence had higher stiffness index than those without recurrence (0.83±0.46 versus 0.40±0.22; P<0.001). Conclusions-LA stiffness index, a novel measure to assess LA diastolic function, increases with age and is higher in persistent AF and in the setting of repeat AF ablation. Greater LA stiffness index was independently associated with recurrence of AF after LA ablation. (Circ Arrhythm Electrophysiol. 2016;9:e003163.

Early induction of therapeutic hypothermia (TH) is recommended in out-of-hospital cardiac arrest (CA); however, currently no reliable methods exist to initiate cooling. We investigated the effect of high flow transnasal dry air on brain and body temperatures in adult porcine animals. Adult porcine animals (n = 23) under general anesthesia were subject to high flow of transnasal dry air. Mouth was kept open to create a unidirectional airflow, in through the nostrils and out through the mouth. Brain, internal jugular, and aortic temperatures were recorded. The effect of varying airflow rate and the air humidity (0% or 100%) on the temperature profiles were recorded. The degree of brain cooling was measured as the differential temperature from baseline. A 10-minute exposure of high flow dry air caused rapid cooling of brain and gradual cooling of the jugular and the aortic temperatures in all animals. The degree of brain cooling was flow dependent and significantly higher at higher airflow rates (0.8°C -0.3°C, 1.03°C -0.6°C, and 1.3°C -0.7°C for 20, 40, and 80 L, respectively, p < 0.05 for all comparisons). Air temperature had minimal effect on the brain cooling over 10 minutes with similar decrease in temperature at 4°C and 30°C. At a constant flow rate (40 LPM) and temperature, the degree of cooling over 10 minutes during dry air exposure was significantly higher compared to humid air (100% saturation) (1.22°C -0.35°C vs. 0.21°C -0.12°C, p < 0.001). High flow transnasal dry air causes flow dependent cooling of the brain and the core temperatures in intubated porcine animals. The mechanism of cooling appears to be evaporation of nasal mucus as cooling is mitigated by humidifying the air. This mechanism may be exploited to initiate TH in CA.

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Necrotizing soft tissue infections (NSTIs) are severe, life-threatening forms of infection. Tissues from the epidermis to the deep musculature may be affected. This includes necrotizing forms of cellulitis, myositis, and fasciitis. Delayed diagnosis can lead to widespread tissue loss, limb loss, and mortality, representing a group of infectious surgical emergencies requiring time-sensitive aggressive debridement. This article presents a unique case with a particularly ambiguous and vague presentation of type 2, group A streptococcal NSTI in an intravenous drug abuser. This rapidly spreading infection subjected her to profound morbidity, with loss of all four extremities. Type 2 NSTIs are particularly challenging to diagnose as they often present without classic signs of skin changes, subcutaneous air, and crepitus. They also spread more rapidly and, as such, have a higher morbidity and mortality rate than type 1 NSTIs. We are striving to increase physician awareness of such cases, with the aim of earlier recognition and earlier limb and life-saving interventions.