Patterns and timing of Doppler-detected intracavitary and aortic flow in hypertrophic cardiomyopathy

This study describes the velocity characteristics of left ventricular and aortic outflow in 25 patients with hypertrophic “obstructive” cardiomyopathy. Systematic pulsed and continuous wave Doppler analysis combined with phonocardiography and M-mode echocardiography was used to establish the pattern and timing of outflow in the basal and provoked states. This analysis suggests that 1) the high velocity left ventricular outflow jet can be reliably discriminated from both aortic flow and the jet of mitral regurgitation using Doppler ultrasound; 2) the Doppler velocity contour responds in a characteristic fashion to provocative influences including extrasystole and Valsalva maneuver; 3) the onset of mitral regurgitation occurs well before detectable systolic anterior motion of the mitral valve; 4) left ventricular flow velocities are elevated at the onset of systolic anterior motion of the mitral valve, suggesting a significant contribution of the Venturi effect in displacing the leaflets and chordae; 5) the high velocities of the outflow jets are largely dissipated by the time flow reaches the aortic valve; and 6) late systolic flow in the ascending aorta is nonuniform, with formation of distinct eddies that may contribute to “preclosure” of the aortic valve

Filling patterns in left ventricular hypertrophy: A combined acoustic quantification and Doppler study

AbstractObjectives. The purpose of this study was to evaluate the potential of acoustic quantification compared with Doppler echocardiography for assessment of left ventricular diastolic dysfunction.Background. Diastolic dysfunction usually accompanies left ventricular hypertrophy. Although Doppler echocardiography is widely used, it has known limitations in the diagnosis of diastolic abnormalities. The ventricular area-change waveform obtained with acoustic quantification technology may provide an alternative to assess diastolic dysfunction.Methods. Potential acoustic quantification variables (peak rate of area change and mean slope of area change rate during rapid filling, amount of relative area change during rapid filling and atrial contraction) were obtained and compared with widely used Doppler indexes of ventricular filling (isovolumetric relaxation time, pressure half-time, peak early diastolic velocity/peak late diastolic velocity ratio, rapid filling, atrial contribution to filling) ia 16 healthy volunteers and 30 patients with left ventricular hypertrophy.Results. Criteria for abnormal relaxation were present in 68% of patients by acoustic quantification and in 64% of patients by Doppler echocardiography. However, abnormal relaxation was identified in 89% of patients by one or both methods. Acoustic quantification indicated abnormal relaxation in the presence of completely normalized Doppler patterns and in patients with mitral regurgitation or abnormal rhythm with unreliable Doppler patterns.Conclusions. Acoustic quantification potentially presents a new way to assess diastolic dysfunction. This technique may be regarded as complementary to Doppler echocardiography. The combined use of the methods may improve the diagnosis of left ventricular relaxation abnormalities

784-3 Prognostic Significance of Intimal Thickening Detected by Intracoronary Ultrasound in Heart Transplant Recipients

Intracoronary ultrasound (ICUS) is a sensitive tool for the detection of intimal thickening in coronary arteries of heart transplants recipients. However, the prognostic significance of this intimal thickening has not been proven.During a one year period, 90 transplant recipients had ICUS examination at the time of their annual angiogram. For each ICUS study an intimal index (II), defined as the ratio of the plaque area to the area within the media, was measured for the most diseased segment imaged. The angiogram at the time of ICUS was reviewed for the presence of visually apparent coronary artery disease (V-CADI· Those patients (n=19) with V-CAD present at the time of ICUS were excluded from the study. The time since transplantation for the 71 pts without V-CAD ranged from 1 to 15 yrs, with a mean of 4.2 yrs and median of 3.9 yrs. The subsequent annual follow-up angiograms of the 71 patients without V-CAD at the time of ICUS were reviewed for the development of V-CAD. Mean duration of angiographic follow-up was 2.0 yrs (range 1–3 yrs).V-CAD developed on follow-up angiograms in 13 of the 71 pts. Mean time to development of V-CAD was 1.5 yrs. Forty-six patients had II<0.3, 4 (9%) of whom subsequently developed V-CAD. Twenty-five patients had II ≥0.3, 9 (36%) of whom developed V-CAD. Odds ratio for future V-CAD between pts with II<0.3 and II 2: 0.3 was 5.9 (95% CI 1.8 to 19.0, difference significant at p<0.01 by Fisher's Exact test).In a subgroup of 22 patients more than 5 years post transplantation at the time of ICUS, 12 had II<0.3 and 10 had II 2≥0.3. In this subgroup none of the 12 pts with II<0.3 developed V-CAD and only 1 of the 10 with II >0.3 developed V-CAD (difference not significant).Conclusion — Among patients more than 1 year and less than 5 years post-transplantation without visually apparent angiographic coronary artery disease, the presence of moderate to severe intimal thickening by ICUS is predictive of the future development of angiographically apparent CAD. Intimal thickening as detected by ICUS is of prognostic significance in patients with angiographically silent transplant coronary artery disease

The observation of nitric acid-containing particles in the tropical lower stratosphere

Airborne in situ measurements over the eastern Pacific Ocean in January 2004 have revealed a new category of nitric acid (HNO₃)-containing particles in the tropical lower stratosphere. These particles are most likely composed of nitric acid trihydrate (NAT). They were intermittently observed in a narrow layer above the tropopause (18&plusmn;0.1 km) and over a broad geographic extent (>1100 km). In contrast to the background liquid sulfate aerosol, these particles are solid, much larger (1.7-4.7 &micro;m vs.&nbsp;0.1&micro;m in diameter), and significantly less abundant (<10^-4 cm^-3 vs.&nbsp;10 cm^-3). Microphysical trajectory models suggest that the NAT particles grow over a 6-14 day period in supersaturated air that remains close to the tropical tropopause and might be a common feature in the tropics. The small number density of these particles implies a highly selective or slow nucleation process. Understanding the formation of solid NAT particles in the tropics could improve our understanding of stratospheric nucleation processes and, therefore, dehydration and denitrification

Dynamics of Immune System Gene Expression upon Bacterial Challenge and Wounding in a Social Insect (Bombus terrestris)

The innate immune system which helps individuals to combat pathogens comprises a set of genes representing four immune system pathways (Toll, Imd, JNK and JAK/STAT). There is a lack of immune genes in social insects (e.g. honeybees) when compared to Diptera. Potentially, this might be compensated by an advanced system of social immunity (synergistic action of several individuals). The bumble bee, Bombus terrestris, is a primitively eusocial species with an annual life cycle and colonies headed by a single queen. We used this key pollinator to study the temporal dynamics of immune system gene expression in response to wounding and bacterial challenge

A multiple proxy and model study of Cretaceous upper ocean temperatures and atmospheric CO2 concentrations

Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 21 (2206): PA2002, doi:10.1029/2005PA001203.We estimate tropical Atlantic upper ocean temperatures using oxygen isotope and Mg/Ca ratios in well-preserved planktonic foraminifera extracted from Albian through Santonian black shales recovered during Ocean Drilling Program Leg 207 (North Atlantic Demerara Rise). On the basis of a range of plausible assumptions regarding seawater composition at the time the data support temperatures between 33° and 42°C. In our low-resolution data set spanning ~84–100 Ma a local temperature maximum occurs in the late Turonian, and a possible minimum occurs in the mid to early late Cenomanian. The relation between single species foraminiferal δ18O and Mg/Ca suggests that the ratio of magnesium to calcium in the Turonian-Coniacian ocean may have been lower than in the Albian-Cenomanian ocean, perhaps coincident with an ocean 87Sr/86Sr minimum. The carbon isotopic compositions of distinct marine algal biomarkers were measured in the same sediment samples. The δ13C values of phytane, combined with foraminiferal δ13C and inferred temperatures, were used to estimate atmospheric carbon dioxide concentrations through this interval. Estimates of atmospheric CO2 concentrations range between 600 and 2400 ppmv. Within the uncertainty in the various proxies, there is only a weak overall correspondence between higher (lower) tropical temperatures and more (less) atmospheric CO2. The GENESIS climate model underpredicts tropical Atlantic temperatures inferred from ODP Leg 207 foraminiferal δ18O and Mg/Ca when we specify approximate CO2 concentrations estimated from the biomarker isotopes in the same samples. Possible errors in the temperature and CO2 estimates and possible deficiencies in the model are discussed. The potential for and effects of substantially higher atmospheric methane during Cretaceous anoxic events, perhaps derived from high fluxes from the oxygen minimum zone, are considered in light of recent work that shows a quadratic relation between increased methane flux and atmospheric CH4 concentrations. With 50 ppm CH4, GENESIS sea surface temperatures approximate the minimum upper ocean temperatures inferred from proxy data when CO2 concentrations specified to the model are near those inferred using the phytane δ13C proxy. However, atmospheric CO2 concentrations of 3500 ppm or more are still required in the model in order to reproduce inferred maximum temperatures.Funding for this research was provided by the U.S. Science Support Program of the JOI, the Andrew W. Mellon Foundation Endowed Fund for Innovative Research, and Deutsche Forschungsgemeinschaft through the DFG-Research Center Ocean Margins