Low value of simple echocardiographic indices of ventricular dyssynchrony in predicting the response to cardiac resynchronization therapy.

AIMS: A recent study suggested that no single echocardiographic index of cardiac dyssynchrony can reliably identify candidates for cardiac resynchronization therapy (CRT). We examined the value of three simple echocardiographic indices for predicting the 6-month clinical and echocardiographic responses to CRT. METHODS AND RESULTS: We analysed data from 75 CRT-D system recipients. Standard echocardiography was used to measure aortic pre-ejection delay (APED), interventricular mechanical delay (IVMD), and delayed activation of the left ventricular (LV) infero-lateral wall (OVERLAP). Clinical responders were defined as patients who had an improved status, based on rehospitalization for heart failure, NYHA class, and peak oxygen consumption. Echocardiographic responders had a > or =10% decrease in LV end-systolic volume. During the study, one patient died and five were lost to follow-up. Of the remaining 69 analysable patients, 50 (72.5%) were classed as clinical responders and 41 (59.4%) as echocardiographic responders to CRT. Before CRT implantation, APED, IVMD, and OVERLAP were similar in responders and non-responders. The value of these indices of dyssynchrony as single or combined predictors of the clinical or echocardiographic response to CRT was low, with sensitivities ranging between 4 and 63%, and specificities between 37 and 100%. CONCLUSION: Simple echocardiographic indices of dyssynchrony were poor predictors of response to CRT.

Kinetics of microbial growth and biodegradation of methanol and toluene in biofilters and an analysis of the energetic indicators.

The kinetics of microbial growth and the biodegradation of methanol and toluene in (a) biofilters (BFs), and (b) biotrickling filters (BTFs), packed with inert materials, has been studied and analyzed. The specific growth rate, mu, for the treatment of methanol was 0.037h(-1) for a wide range of operating conditions. In the BF, mu was found to be a function of the methanol and toluene concentrations in the biofilm. In the BF used for treating methanol, mu was found to be affected by (1) the nitrogen concentration present in the nutrient solution, and (2) the kind of packing material employed. The kinetics of the methanol and toluene biodegradations were also analyzed using "mixed order" models. A Michaelis-Menten model type provided a good fit for the elimination capacity (EC) of the BTF treating methanol, while a Haldane model type provided a good fit to the EC of the BF treating methanol and toluene. The carbon dioxide production rate was related to the packed bed temperature and the content of the volatile solids within the biofilm. For the BF, the ratio of temperature/carbon dioxide production rate (PCO(2)) was 0.024 degrees C per unit of PCO(2), and for the BTF it was 0.15 degrees C per unit of PCO(2).