Clinical Utility of Transillumination on Transthoracic Imaging

• TI is a 3D rendering tool that applies a movable virtual light. • TI may improve anatomic definition and diagnostic yield of transthoracic imaging. • TI is particularly useful for optimal valve anatomy visualization. • New 3D techniques may help achieve TTE images with similar diagnostic yield to TEE.

Three-Dimensional Echocardiographic Deconstruction: Feasibility of Clinical Evaluation from Two-Dimensional Views Derived from a Three-Dimensional Data Set

BACKGROUND

Three-dimensional echocardiography (3DE) makes it possible to capture the entire heart in a single data set that theoretically could be used to extract any two-dimensional (2D) views and potentially replace the standard practice of serial 2D acquisitions. The aim of this study was to test the hypothesis that the quality of 3DE-derived 2D images is sufficient to allow the visualization of the left ventricular (LV), right ventricular (RV), and left atrial (LA) endocardium, on par with images from conventional two-dimensional echocardiography (2DE), and potentially more accurate quantification of chamber size and function.

METHODS

First, the investigators prospectively studied 36 patients who underwent 2DE in 14 standard views, and full-volume data sets from 3DE, from which the same views were extracted offline. The ability to visualize the LV endocardium, RV free wall, and LA endocardium was scored. LV linear dimensions, LV volumes, and LV ejection fraction (LVEF), LA volume, and RV basal dimension were measured and compared between both types of images. Thereafter, 40 patients who underwent 2DE, 3DE, and cardiac magnetic resonance (CMR) imaging on the same day were retrospectively studied. LV volumes and LVEF derived from 2DE and 3DE were compared side by side against the CMR reference.

RESULTS

Intertechnique agreement in visualization scores was 87% for LV segments, 86% for the RV free wall, and 83% for the LA endocardium. The correlations between 2DE- and 3DE-derived measurements were 0.95, 0.97, and 0.97 for LV volumes and LVEF, respectively, and 0.88 for RV basal dimension. Three-dimensional echocardiography-derived measurements of LV volumes and LVEF were more similar to those on CMR than those obtained on conventional 2DE.

CONCLUSIONS

The feasibility of segmental assessment of cardiac chambers using 3DE-derived 2D views is similar to that using conventional 2DE. This approach provides similar quantitative information, including more accurate LV volumes and LVEF measurements compared with CMR, and thus promises to significantly shorten the duration of the echocardiographic examination.

Postoperative tolvaptan use in left ventricular assist device patients: The TOLVAD randomized pilot study

PURPOSE

Tolvaptan, a selective vasopressin type-2 antagonist, has been shown to increase serum sodium (Na) and urine output in hyponatremic left ventricular assist device (LVAD) patients in retrospective studies. In this prospective randomized pilot study, we aimed to assess the efficacy of tolvaptan in this population.

METHODS

We conducted a prospective, randomized, non-blinded pilot study of LVAD recipients with post-operative hyponatremia (Na < 135 mEq/L) (NCT05408104). Eligible participants were randomized to receive tolvaptan 15 mg daily in addition to usual care versus usual care alone. The primary outcome was a change in Na level and estimated glomerular filtration rate (eGFR), from the first post-operative day of hyponatremia (the day of randomization) to discharge.

RESULTS

A total of 33 participants were enrolled, and 28 underwent randomization (median age 55 [IQR 50-62]), 21% women, 54% Black, 32% ischemic cardiomyopathy, median baseline Na 135 (IQR 134-138). Fifteen participants were randomized to tolvaptan (TLV) and 13 were randomized to usual care alone (No-TLV). Mean change in Na from randomization to discharge in the TLV group was 2.7 mEq/L (95%CI 0.7-4.7, p = 0.013) and 1.8 (95%CI 0.5-4.0, p = 0.11) in the No-TLV group, though baseline and final Na levels were similar between groups. The mean change in eGFR was 2.6 ml/min/1.73 m2 (95%CI 10.1-15.3, p = 0.59) in TLV versus 7.5 ml/min/1.73 m2 (95%CI 5.2-20.2, p = 0.15) in No-TLV. TLV participants had significantly more urine output than No-TLV patients during their first 24 h after randomization (3294 vs 2155 ml, p = 0.043).

CONCLUSION

TLV significantly increases urine output, with nominal improvement in Na level, in hyponatremic post-operative LVAD patients without adversely impacting renal function.

Three-Dimensional Transthoracic Static and Dynamic Normative Values of the Mitral Valve Apparatus: Results from the Multicenter World Alliance Societies of Echocardiography Study

BACKGROUND

Recent advances in mitral valve (MV) percutaneous interventions have escalated the need for a more quantitative and comprehensive assessment of the MV, which can be best achieved using three-dimensional echocardiography. Understanding normal valve size, structure, and function is essential for differentiation of healthy from disease states. The aims of this study were to establish normative values for MV apparatus size and morphology and to determine how they vary across age, sex, and race groups using data from the World Alliance Societies of Echocardiography Normal Values Study.

METHODS

Three-dimensional volumetric data sets obtained on transthoracic echocardiography in 748 normal subjects (51% men) were analyzed using commercial MV analysis software (TomTec Imaging Systems) to determine annular and leaflet dimensions and areas. The subjects were divided into groups by sex (378 men and 370 women) and age (18 to 40 years [n = 266], 41 to 65 years [n = 249], and >65 years [n = 233]) to identify sex- and age-related differences. In addition, differences among black, white, and Asian populations were studied. Inter- and intraobserver variability was assessed in a subset of 30 subjects and expressed as mean absolute difference between pairs of repeated measurements.

RESULTS

Compared with women, men had larger annular size measurements, larger tenting size parameters, and larger leaflet length and area. Compared with the black and white populations, the Asian population showed significantly smaller mitral annular size. Although many of the age, sex, and race differences in MV parameters were statistically significant, they were comparable with or smaller than the corresponding measurement variability. Indexing to body surface area and height did not eliminate these differences consistently, suggesting that parameters may need to be indexed according to their dimensionality.

CONCLUSIONS

This analysis of the World Alliance Societies of Echocardiography data provides normative values of mitral apparatus size and morphology. Although sex- and age-related differences were noted, they need to be interpreted with caution in view of the associated measurement variability.

Normal Values of Cardiac Output and Stroke Volume According to Measurement Technique, Age, Sex, and Ethnicity: Results of the World Alliance of Societies of Echocardiography Study

BACKGROUND

Assessment of cardiac output (CO) and stroke volume (SV) is essential to understand cardiac function and hemodynamics. These parameters can be examined using three echocardiographic techniques (pulsed-wave Doppler, two-dimensional [2D], and three-dimensional [3D]). Whether these methods can be used interchangeably is unclear. The influence of age, sex, and ethnicity on CO and SV has also not been examined in depth. In this report from the World Alliance of Societies of Echocardiography Normal Values Study, the authors compare CO and SV in healthy adults according to age, sex, ethnicity, and measurement techniques.

METHODS

A total of 1,450 adult subjects (53% men) free of heart, lung, and kidney disease were prospectively enrolled in 15 countries, with even distributions among age groups and sex. Subjects were divided into three age groups (young, 18-40 years; middle aged, 41-65 years; and old, >65 years) and three main racial groups (whites, blacks, and Asians). CO and SV were indexed (cardiac index [CI] and SV index [SVI], respectively) to body surface area and height and measured using three echocardiographic methods: Doppler, 2D, and 3D. Images were analyzed at two core laboratories (one each for 2D and 3D).

RESULTS

CI and SVI were significantly lower by 2D compared with both Doppler and 3D methods in both sexes. SVI was significantly lower in women than men by all three methods, while CI differed only by 2D. SVI decreased with aging by all three techniques, whereas CI declined only with 2D and 3D. CO and SV were smallest in Asians and largest in whites, and the differences persisted after normalization for body surface area.

CONCLUSIONS

The present results provide normal reference values for CO and SV, which differ by age, sex, and race. Furthermore, CI and SVI measurements by the different echocardiographic techniques are not interchangeable. All these factors need to be taken into account when evaluating cardiac function and hemodynamics in individual patients.

Electrochemical properties of columns in capillary electrochromatography

The most commonly used type of column in capillary electrochromatography (CEC) consists of a packed segment and an open (but buffer-filled) segment. The two segments differ importantly in two respects: firstly, their electrical resistivity; and secondly, their zeta potentials at a multitude of solid-liquid interfaces. Determination of the magnitude of these properties for each segment cannot be made using only results from the column as a whole. Instead, measurements of resistivity and zeta potentials of an entirely open, unpacked column can be used in conjunction with those of the CEC column to determine the electrochemical nature of both segments. This review of basic electrochemical properties will describe simple procedures that can be used to determine resistance, resistivity, conductivity, conductance, and field strength in each segment. In addition, it will be shown how the properties of each segment add together to give the same properties of the CEC column as a whole. The equations so derived will be applied to data from the literature and conclusions drawn from the results.

Rapid-rate thermophilic, single-stage and two-phase methane fermentation of synfuel-industry wastewaters

Thermophilic (55 degrees C) anaerobic digestion of wastewaters from wet carbonization of Minnesota peat was conducted in a simple, upflow digester at an HRT of one day to provide a methane yield of 0.20 SCM/kg VS added and a BOD5 reduction of 85%. Carbonization of Maine peat conducted for a much longer duration of thermal treatment produced recalcitrant and potentially toxic end products that reduced the biodegradability of wastewaters. Methane fermentation of the Maine-peat wet-carbonization waste was inhibited at an HRT of one day in the single-stage digester. However, two-phase digestion with separate acid-phase fermentation to promote hydrolytic degradation of toxic end products followed by separate methane fermentation at an HRT of 2 days exhibited a methane yield of 0.21 SCM/kg VS added and a BOD5 reduction of 76%. Volatile fatty acids profiles along the depths digesting cultures indicated that single-stage and two-phase digestion could be accomplished at one-half the reactor residence times (one day for single-stage and three days for two-phase) used in this research.

Characteristics of particle-loaded monolithic sol-gel columns for capillary electrochromatography. I. Structural, electrical and band-broadening properties

Particle-loaded (3 microm, C18) monolithic sol-gel columns have been prepared and selected characteristics measured. They have a surprisingly high permeability, allowing their operation in the microLC mode at pressures as low as 69 kPa where their efficiency is about 50000 plates per meter and the CEC mode where efficiency is at least 106000 plates per meter. These columns can withstand over 13.8 MPa pressure without compression or movement within the 75 microm capillary. Field strengths in the packed segments are approximately 50% greater than those in the open segments, due to the higher resistivity of the particle-laden regions. There is a relatively rapid loss of efficiency with increasing linear velocity in both the CEC and microLC modes, which may be due to a tortuosity effect in the inter- and intra-particulate voids. Chromatographic behavior is characteristic of conventional C18 particles, indicating that analytes have significant access to the surface within the pores of the immobilized bonded phase.

Pilot-scale gasification of municipal solid wastes by high-rate and two-phase anaerobic digestion (TPAD)

Bioconversion of municipal solid waste-sludge blend by conventional high-rate and two-phase anaerobic digestion was studied. RDF (refused-derived fuel)-quality feed produced in a Madison, Wisconsin, USA, MRF (materials-recovery facility) was used. High-rate digestion experiments were conducted with bench-scale digesters under target operating conditions developed from an economic feasibility study. The effects of digestion temperature, RDF content of digester feed, HRT, loading rate, RDF particle size, and RDF pretreatment with cellulase or dilute solutions of NaOH or lime on digester performance were studied. A pilot-scale two-phase digestion plant was operated with 80:20 (weight ratio) RDF-sludge blends to show that this process exhibited a higher methane yield, and produced a higher methane-content digester gas than those obtained by single-stage, high-rate anaerobic digestion.

Interaction of acids with halogenated aromatic compounds. I. Infrared spectrum of hydrogen chloride in fluorobenzene and related solvents

The complex infrared absorption band of HCl in fluorobenzene at c. 2800 cm-1 is due to the presence of three solute species; free molecules in cavities, which produce rotational side bands, molecules hydrogen- bonded to fluorine which give a sharp absorption band, and molecules bonded to the aromatic π-electron system which contribute a broader, overlapping band at lower frequency. Similar multiple absorptions are found for solutions of HCl and DCl in other fluorinated aromatics, and the asymmetry of the central absorptions for these solutes in chloro-, bromo-, and iodo-benzenes is attributed to an unresolved overlap of absorption bands due to halogen-bonded and T-bonded solute. The specific solvent-solute interaction theory of Bellamy for the infrared spectra of solutes in mixed solvents is thus extended to single solvents containing structures which give slightly different interaction energies with the solute.