Left Roof Research Articles

PO-03-068 CATHETER STABILITY AND LESION CHARACTERISTICS IN APNEA-ONLY RADIOFREQUENCY ABLATION LESIONS VS HIGH FREQUENCY, LOW TIDAL VOLUME - A SINGLE-CENTER ANALYSIS WITH CARTONET

Catheter stability plays a vital role in ensuring durable ablation lesions. The high frequency low tidal volume (HRV) has demonstrated improved catheter stability. Eliminating respiratory motion altogether could allow for further improvement in catheter stability. We compared catheter stability and lesion characteristics during intermittent apnea-only lesion protocol (IAP) vs. HRV A retrospective, single-center analysis of patients who underwent AF ablation utilizing Smart touch ST SF catheter under IAP and HRV respiratory protocols. All patients received ablations in both respiratory protocols. IAP was utilized for every ablation site. The repeat lesions using HRV protocol were performed at the left superior pulmonary vein (LSPV), left the roof, and septum. The ablation lesion data were collected from the Cartonet. The outcomes in two respiratory protocols – stability, surpoint value, impedance drop, and average contact force – were compared using a two-sided t-test. Of 21 patients with a mean age of 72.5 (SD ± 10.1), 38.1% were female, 14.3% had diabetes, 86% had hyperlipidemia, 81% had hypertension, and 52.4% had a smoking history. IAP demonstrated a trend towards improved catheter stability at the LSPV (0.87 vs. 0.91; p=0.28) and left roof (0.95 vs. 1.1; p=0.21). Surpoint values were higher with IAP at the LSPV (437.3 vs. 421.8; p= 0.006) and trended higher in the left roof (422.99 vs. 398.88; p=0.139), and septum (456.77 vs. 431.74; p=0.22). Average contact force trended lower with IAP at the LSPV (10.95 vs. 11.85; p=0.91), left roof (12.64 vs. 14.45; p=0.22), septum (12.37 vs. 13.48; p=0.12). The impedance drop was higher with IAP at the left roof (7.93 vs. 5.67; p=0.026) and trended lower with IAP at LSPV (6.48 vs. 7.4; p=0.28). Apnea-only ablation lesions demonstrated a trend towards improved catheter stability at LSPV and left roof. In addition, impedance drop during apnea-only lesions was higher in the left atrial roof. Larger multicenter studies are needed to validate our hypothesis. The Cartonet software is a beneficial tool for analyzing ablation lesion characteristics.

Time-dependent deformation and fracture evolution around underground excavations

A numerical time-dependent deformation model of rock by incorporating the stress corrosion model into a three-dimensional discrete element code was established to investigate time-dependent deformation and fracture evolution of surrounding rock around underground excavations with circular, inverted U-shaped and rectangular cross-sections. The mesoscale model input parameters were calibrated to replicate the mechanical behavior and failure patterns of the rock observed in laboratory. Numerical simulations on the time-independent and -dependent deformation and fracturing evolution of the rock around underground excavations with different shapes under hydrostatic stress were studied. The results show that the maximum time-independent displacements of circular, inverted U-shaped and rectangular openings are 11, 15, and 34 mm at left roof, right floor and left side, respectively. It shows that the surrounding rocks around the circular, inverted U-shaped openings are much more stable than that around the rectangular opening. The cracks within the surrounding rock around different shaped openings gradually increases as time goes by, and the tensile cracks are dominant. The progressive failure process of the circular openings under varying lateral pressures was further modeled. The results show the failure zone at the roof wall and floor wall becomes more evident with an increase in the lateral pressure coefficient.

Detection of subclinical riasopharyngeal carcinoma by fibreoptic endoscopy and multiple biopsy

Of 6054 people who had high titres of antibodies against the viral capsid antigen of Epstein-Barr virus but no symptoms or signs of nasopharyngeal carcinoma as assessed by conventional methods, 130 were randomly recruited and examined by fibreoptic endoscopy and biopsy of several sites of the nasopharynx. 7 cases of nasopharyngeal carcinoma were detected. The tumours were largely confined to the pharyngeal recess, which suggests that it is the area of the nasopharynx most prone to the development of the tumour. Tumour was found in both recesses in 1 subject, who also had evidence of transition from severe epithelial dysplasia to carcinoma in a sample from the left roof, which suggests that the disease was multifocal in origin. This study showed that endoscopy and biopsy of several sites of the nasopharynx are more effective than the conventional approach in the detection of subclinical nasopharyngeal carcinoma among seropositive individuals at high risk of the disorder.

Passive Avoidance Training Increases Fucokinase Activity in Right Forebrain Base of Day‐Old Chicks

Fucokinase (EC 2.7.1.52) activity was estimated in supernatants of homogenate from day-old chick forebrain. Enzyme kinetic studies gave a Km of 4.5 X 10(-6) M and Vmax of 3.72 nmol fucose converted into fucose-1-phosphate/mg prot/h. The pH optimum was 7.5. The enzyme is thus considerably more active than was reported for other species and tissues. There were no differences in enzyme activity between the four forebrain regions studied. One hour after chicks were trained on a one-trial passive avoidance learning paradigm, enzyme activity in the right forebrain base increased 14% over control values (p less than 0.02). The 11.3% increase in activity in the left forebrain base and 10.3% increase in the left roof were not statistically significant. The relationship of this change to the increased fucose incorporation into glycoproteins known to occur over a similar time period and the significance of the lateralization of the increase are discussed.