Associations of Left Ventricular Hypertrophy and Geometry with Adverse Outcomes in Patients with CKD and Hypertension.

BACKGROUND AND OBJECTIVES: Left ventricular hypertrophy (LVH) and abnormal left ventricular (LV) geometry predict adverse outcomes in the general and hypertensive populations, but findings in CKD are still inconclusive. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We enrolled 445 patients with hypertension and CKD stages 2-5 in two academic nephrology clinics in 1999-2003 who underwent both echocardiography and ambulatory BP monitoring. LVH (LV mass >100 g/m(2) [women] and >131 g/m(2) [men]) and relative wall thickness (RWT) were used to define LV geometry: no LVH and RWT≤0.45 (normal), no LVH and RWT>0.45 (remodeling), LVH and RWT≤0.45 (eccentric), and LVH and RWT>0.45 (concentric). We evaluated the prognostic role of LVH and LV geometry on cardiovascular (CV; composite of fatal and nonfatal events) and renal outcomes (composite of ESRD and all-cause death). RESULTS: Age was 64.1±13.8 years old; 19% had diabetes, and 22% had CV disease. eGFR was 39.9±20.2 ml/min per 1.73 m(2). LVH was detected in 249 patients (56.0%); of these, 125 had concentric LVH, and 124 had eccentric pattern, whereas 71 patients had concentric remodeling. Age, women, anemia, and nocturnal hypertension were independently associated with both concentric and eccentric LVH, whereas diabetes and history of CV disease associated with eccentric LVH only, and CKD stages 4 and 5 associated with concentric LVH only. During follow-up (median, 5.9 years; range, 0.04-15.3), 188 renal deaths (112 ESRD) and 103 CV events (61 fatal) occurred. Using multivariable Cox analysis, concentric and eccentric LVH was associated with higher risk of CV outcomes (hazard ratio [HR], 2.59; 95% confidence interval [95% CI], 1.39 to 4.84 and HR, 2.79; 95% CI, 1.47 to 5.26, respectively). Similarly, greater risk of renal end point was detected in concentric (HR, 2.33; 95% CI, 1.44 to 3.80) and eccentric (HR, 2.30; 95% CI, 1.42 to 3.74) LVH. Sensitivity analysis using LVH and RWT separately showed that LVH but not RWT was associated with higher cardiorenal risk. CONCLUSIONS: In patients with CKD, LVH is a strong predictor of the risk of poor CV and renal outcomes independent from LV geometry.

Modeling of submicrometer aerosol penetration through sintered granular membrane filters.

We present a deep-bed aerosol filtration model that can be used to estimate the efficiency of sintered granular membrane filters in the region of the most penetrating particle size. In this region the capture of submicrometer aerosols, much smaller than the filter pore size, takes place mainly via Brownian diffusion and direct interception acting in synergy. By modeling the disordered sintered grain packing of such filters as a simple cubic lattice, and mapping the corresponding 3D connected pore volume onto a discrete cylindrical pore network, the efficiency of a granular filter can be estimated, using new analytical results for the efficiency of cylindrical pores. This model for aerosol penetration in sintered granular filters includes flow slip and the kinetics of particle capture by the pore surface. With a unique choice for two parameters, namely the structural tortuosity and effective kinetic coefficient of particle adsorption, this semiempirical model can account for the experimental efficiency of a new class of "high-efficiency particulate air" ceramic membrane filters as a function of particle size over a wide range of filter thickness and texture (pore size and porosity) and operating conditions (face velocity).

Theoretical Study of Aerosol Filtration by Nucleopore Filters: The Intermediate Crossover Regime of Brownian Diffusion and Direct Interception.

We study the problem of aerosol filtration by formulating a unified approach that incorporates the dominant mechanisms of particle capture in cylindrical pores. The theoretical approach presented here takes into account the effects of flow slip at the pore wall and predicts an enhanced efficiency in the intermediate crossover regime between Brownian diffusion and direct interception. We also suggest how the results obtained for cylindrical pores can be used to estimate the efficiency of granular ceramic filters in the region of the most penetrating particle size, where the enhanced efficiency effects are strongly amplified by the large number of pores, or more generally unit bed elements, acting in series. Copyright 2001 Academic Press.