Conformal atomic layer deposition of TA-based diffusion barrier film using a novel mono-guanidinate precursor.

In this work, we present elaboration of Ta-based thin films by ALD from a novel tantalum precursor, the eta2-N,N'-isopropylethylguanidinato-tetra-diethylamino tantalum ([eta2-(i)PrNC(NEt2)NEt]Ta(NEt2)4, IEGTDEAT). Ammonia was used as reducing agents. The experimental conditions were optimized by quartz microgravimetry, studying the influence of duration of precursors and purge pulses and the substrate temperature. An optimal deposition temperature of 260 degrees C was showed. Ta-based thin films deposited on planar and patterned substrates showed a perfect conformality and continuity, even at low number of cycles.

Canadian consensus recommendations for the measurement and reporting of diastolic dysfunction by echocardiography: from the Investigators of Consensus on Diastolic Dysfunction by Echocardiography.

Abnormalities of diastolic filling are increasingly recognized as a cause of symptoms and predictors of outcome in patients with most forms of heart disease. Noninvasive assessment of diastolic filling is possible in almost all patients, but accurate evaluation must relate echocardiographic Doppler measurements to the complex physiologic and hemodynamic factors responsible for normal and abnormal filling. This evaluation has been facilitated by recent correlation of Doppler measurement of mitral and pulmonary venous inflow with hemodynamic studies. These studies have confirmed that when a careful, integrated approach is taken, Doppler flow patterns can document a progressive pattern of abnormality in many conditions. Impaired left ventricular (LV) relaxation is seen early and is recognized by a decrease in early transmitral LV filling and an increased proportion of filling during atrial contraction. As abnormalities progress, increasing LV chamber stiffness and elevated left atrial pressure lead to a "pseudonormal" filling pattern that previously has caused considerable confusion. This can be unmasked by careful evaluation of pulmonary venous inflow and the use of the Valsalva maneuver. When marked diastolic abnormalities are present, LV filling has restrictive features characterized by rapid early filling, a very stiff left ventricle with high filling pressures, and a poor prognosis. Routine measurement of indexes of diastolic filling have been hampered by uncertainty as to what should be measured, what techniques should be used, definition of normal values, and a clear method of reporting findings. This report represents the efforts of a Canadian consensus group to define a national standard for the performance and reporting of echocardiographic Doppler studies of diastolic filling.

Aortic regurgitation: a common complication after surgery for hypertrophic obstructive cardiomyopathy.

Surgical ventriculomyectomy and ventriculomyotomy by the aortic approach are safe and effective methods of relieving symptoms and obstruction to left ventricular outflow in patients with hypertrophic obstructive cardiomyopathy. With the addition of Doppler ultrasound to the routine follow-up assessment of these patients an unexpectedly high occurrence of aortic regurgitation was found in the postoperative patients. Because aortic regurgitation has been reported to rarely accompany this condition, 67 patients with hypertrophic obstructive cardiomyopathy were studied clinically and with Doppler echocardiography for the presence and severity of aortic regurgitation. Severity of the regurgitation was quantitated by pulsed or color Doppler echocardiography according to the length and width of the regurgitant jet in at least two views. In 37 patients with hypertrophic obstructive cardiomyopathy who did not undergo surgery, aortic regurgitation was detected in only 1 (3%) by Doppler ultrasound and in none clinically. In 52 patients who did undergo surgery and were studied a mean of 7.8 years postoperatively, aortic regurgitation of trivial to moderate degree was common, being detected in 28 (54%) by Doppler ultrasound and in 6 (12%) clinically. In a subgroup of 22 patients who were studied preoperatively and again early postoperatively (mean 6 weeks), new aortic regurgitation was found in 8 (36%) and was graded as trivial in all. Aortic regurgitation is a common complication related to ventriculomyectomy and ventriculomyotomy in patients with hypertrophic obstructive cardiomyopathy. Although initially trivial, the regurgitation may progress in severity over time. The regurgitation has been well tolerated in all patients studied to date.

Optimized count-based scintigraphic left ventricular volume measurement.

Count-based scintigraphic left ventricular end-diastolic (LVED) volume measurement was optimized using a reproducible method for determining left ventricular counts and an independently measured average apparent tissue attenuation coefficient (0.16 cm-1). Tissue depth was calculated by triangulation. Results were compared to single-plane contrast ventriculographic volumes by an area-length method, performed within one hour, in 18 patients. The overall correlation of measurements of LVED volume by the 2 methods was 0.96 with standard error of the scintigraphic estimate of 15.8 ml. For 6 patients with angiographically normal wall motion, the correlation of volume measurements was 0.99 with standard error of the estimate of 5.1 ml. The mean absolute difference in LVED volume by the 2 methods was 3.8 ml in the group with normal wall motion compared to 19.2 ml in the 12 patients with angiographically abnormal wall motion. Area-length LVED volume calculation assumes that the left ventricle conforms to a standard shape. Discrepancies in volume estimates with abnormal ventricular wall motion suggest that the area-length method is less accurate. Optimized count-based LVED left ventricular volume measurement is accurate and might be preferable to single-plane contrast angiographic volume measurement of abnormal ventricles.