Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry.

Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI-APi-TOF (Chemical Ionization-Atmospheric Pressure interface-Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI-APi-TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4-H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self-contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit.

New particle formation in the free troposphere: A question of chemistry and timing.

New particle formation (NPF) is the source of over half of the atmosphere's cloud condensation nuclei, thus influencing cloud properties and Earth's energy balance. Unlike in the planetary boundary layer, few observations of NPF in the free troposphere exist. We provide observational evidence that at high altitudes, NPF occurs mainly through condensation of highly oxygenated molecules (HOMs), in addition to taking place through sulfuric acid-ammonia nucleation. Neutral nucleation is more than 10 times faster than ion-induced nucleation, and growth rates are size-dependent. NPF is restricted to a time window of 1 to 2 days after contact of the air masses with the planetary boundary layer; this is related to the time needed for oxidation of organic compounds to form HOMs. These findings require improved NPF parameterization in atmospheric models.

Size matters more than chemistry for cloud-nucleating ability of aerosol particles.

Size-resolved cloud condensation nuclei (CCN) spectra measured for various aerosol types at a non-urban site in Germany showed that CCN concentrations are mainly determined by the aerosol number size distribution. Distinct variations of CCN activation with particle chemical composition were observed but played a secondary role. When the temporal variation of chemical effects on CCN activation is neglected, variation in the size distribution alone explains 84 to 96% of the variation in CCN concentrations. Understanding that particles' ability to act as CCN is largely controlled by aerosol size rather than composition greatly facilitates the treatment of aerosol effects on cloud physics in regional and global models.

[Comparison of ergometer and dipyridamole echocardiography in patients with suspected coronary heart disease]. / Vergleich von Ergometer- und Dipyridamol-Echokardiographie bei Patienten mit vermuteter koronarer Herzkrankheit.

To compare exercise echocardiography (EE) and dipyridamole echocardiography (DE), echocardiographically assessable wall motion abnormalities were examined in 80 patients with suspected coronary artery disease. Issues of the study were the evaluation of feasibility, sensitivity, specificity, and the necessity of recordings under dynamic maximal stress (peak exercise) on a bicycle. DE had a better feasibility than EE (95% vs. 84%, p < 0.05). Eleven percent of patients had no interpretable echocardiograms during peak exercise. However, after peak exercise all patients had adequate images. In order to calculate sensitivity of the methods, coronary stenoses of at least 70% on coronary angiograms were considered. Sensitivity of DE (73%) was similar to that of EE (75%). In patients with single-vessel disease both methods were less sensitive (63% and 67%) than in patients with multi-vessel disease (86% each). However, compared with stress ECG both methods proved to be superior (p < 0.05). In 31% of patients with coronary artery disease only recordings during peak exercise led to pathological findings. By not applying the EE during peak exercise the results of these patients would have been falsely negative i.e. regarded as normal. The specificity of DE (87%) was similar to that of EE (80%). In conclusion, there are no significant differences between DE and EE except feasibility and side-effects. Both methods are superior to stress ECG in terms of sensitivity regarding detection of ischemic myocardium. However, their precision needs to be evaluated differentially: Sensitivity was higher among patients with multi-vessel disease compared with those with single-vessel disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular geometry and function before and after mitral valve replacement.

Left ventricular geometry and function were assessed in 20 patients with mitral stenosis (MS) and in another 20 patients with mitral insufficiency (MI) five days before and 12 days after mitral valve replacement by transthoracic (TTE) and transesophageal (TEE) echocardiography, as well as late postoperatively (mean: 194 days) by TTE. The continuity of the subvalvular apparatus could not be preserved in any of these patients. In mitral stenosis the area ejection fraction (AEF) in the short axis of the left ventricle (LV) did not change significantly early or late postoperatively. There was a significant lengthening of the left ventricular longitudinal axis in the apical four chamber view whereas the transverse axis remained unchanged. This was likely the result of the discontinuity between the mitral valve and the papillary muscles. AEF and ejection fraction (EF) determined in the four chamber view showed a slight tendency to decrease in the postoperative phase. Patients with mitral insufficiency likewise showed a significant increase of the LV longitudinal diameter postoperatively. In the short axis of the left ventricle and in the apical four chamber view a significant reduction of the AEF was observed. Furthermore, left ventricular EF dropped significantly postoperatively. This decrease was caused by the extension of the LV longitudinal axis accompanied by an enlargement of the transverse diameter as well as by an afterload increase, and a masked impairment of left ventricular function preoperatively. Wall motion analysis of the LV in both groups documented new postoperative hypokinesis especially in the septal segments. At late postoperative examination the hypokinesis disappeared in about 50% of the patients.(ABSTRACT TRUNCATED AT 250 WORDS)

[In vitro diagnosis of coronary plaque morphology with intravascular ultrasound: comparison with histopathologic findings]. / In-vitro-Diagnose der koronaren Plaquemorphologie mit intravaskulärem Ultraschall: Vergleich mit histopathologischen Befunden.

The aim of this study was to validate the accuracy of a commercially available intravascular ultrasound system in diagnosing plaque composition in human coronary arteries. Thirty-five coronary arteries of 18 human autopsy hearts were perfused with NaCl under a pressure of 100 mmHg and examined using a Diasonics ultrasound system and 4.8 F 20 MHz catheters. An ultrasound diagnosis was made of 139 coronary sections using previously published standard criteria and compared with histologic findings. In addition, the influence of the histologic pattern of lipid and calcific deposits on the accuracy of the ultrasound diagnosis was evaluated. Of the 25 sections with a histologically normal intima, 14 (56%) were correctly identified by ultrasound, whereas fibrotic thickening was diagnosed in the remaining 11 sections. There were 114 plaques by histology which were correctly visualized by ultrasound as plaques in all instances. Plaque calcification was correctly diagnosed in 54 of 63 (86%) sections, but massive calcifications were more reliably identified by ultrasound than small speckled calcifications (43/44 = 98% vs 11/19 = 58%, p < 0.001). Fibrosis was present in all 114 plaques and was correctly visualized by ultrasound in all instances. When lipid was diagnosed by ultrasound as a homogeneous zone of low signal intensity within a fibrous plaque as suggested in the literature, lipid accumulations were identified with a sensitivity of 26% (16/62) and a specificity of 92% (71/77). When lipids were diagnosed if more than a quarter of the plaque area showed lower signal intensity than the tissue surrounding the vessel, the sensitivity of ultrasound was improved to 73% (45/62) but specificity fell to 30% (23/77). The entire histologic composition of a section was correctly diagnosed by ultrasound in only 42% of the 139 sections. Further technical improvements are therefore mandatory before intracoronary ultrasound will be able to provide a reliable analysis of plaque composition, especially of the lipid content.

Diagnosis of heart tumours by transoesophageal echocardiography: a multicentre study in 154 patients. European Cooperative Study Group.

In a retrospective multicentre study, the diagnostic potential of transoesophageal 2D-echocardiography (TEE) as compared to precordial 2D-echocardiography (TTE) was determined in 154 patients with primary or secondary tumours of the heart. Additionally, the value of standard diagnostic parameters, such as symptoms, X-ray of the chest and electrocardiogram were evaluated. In 84 patients (24 male, 60 female; age 20-85, mean 56.6 years) intracardial tumours were present, and 70 patients (37 male, 33 female; age 18-79, mean 44.3 years) presented with peri- or paracardial tumours. The main symptoms of patients with intracardial tumours were dyspnoea (60.7%), vena cava syndrome (22.2%) and chest pain (20.2%). Embolization was found in 11.9%. Left or right atrial enlargement was observed on chest X-ray in 23 patients, and echocardiographic abnormalities in 17 cases. The patients with peri- or paracardial tumours presented with dyspnoea in 51.4% of cases, loss in body weight in 20.0% and with vena cava syndrome and chest pain in 17.1%. The chest X-ray was abnormal in 56 patients. Unspecific ST segment changes in the electrocardiogram were observed in five, and arrhythmias in seven cases. Diagnosis of atrial myxomas was achieved by TTE in 95.2%, by TEE in 100%, by angiography in 78.4%, by computed tomography (CT) or magnetic resonance tomography (NMR) in 70%. Identification of the attachment point was made by angiography in 8.1%, by TTE in 64.5% and by TEE in 95.2%. In 22 patients with intracardial tumours (myxomas excepted) diagnosis was achieved by TTE in 90.9%, by TEE in 100%, by CT or NMR in 88.9% and by angiography in 50%.(ABSTRACT TRUNCATED AT 250 WORDS)

Reproducibility of assessment of left-ventricular function using intraoperative transesophageal echocardiography.

Reproducibility of results is an important point in assessing the utility of intraoperative transesophageal echocardiography for evaluating changes in left-ventricular function. The purpose of the present study was to define the intra- and interobserver reproducibility of the qualitative assessment of left-ventricular regional wall motion and the quantitative assessment of global left-ventricular function. In addition, the interstudy reproducibility of two examinations was tested when the probe was displaced and replaced in the esophagus. A transesophageal short-axis view at the level of the papillary muscles was obtained in 86 patients undergoing cardiac surgery. In the 80 patients with adequate images, regional wall motion was visually graded and area ejection fraction was calculated by two observers and assessment was repeated by the same observer one day later. The same observer graded wall motion differently in only 5% (24/480) of segments. Grading by two observers differed in 9% (43/480) of segments. Assessment differed by one grade at the most and in not more than 2 out of 6 segments per patient. Repeated measurements of area ejection fraction (AEF) by the same observer correlated well (r = 0.97 before and r = 0.97 after cardiopulmonary bypass) with a mean percent difference of 6%. A similarly close correlation was found for measurements of two observers (r = 0.90 and r = 0.93, respectively) with a mean percent difference of 10% for area ejection fraction. The correlation for the first and second examination in the same patient by one observer was acceptable (r = 0.78 and r = 0.80, respectively) with a mean percent difference of 15% for area ejection fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac involvement during and after malaria.

In 22 patients without a previous history of cardiac disease, we prospectively evaluated cardiac involvement during acute malaria and 9 +/- 5 months after recovery using non-invasive methods including resting electrocardiogram (ECG) and two-dimensional (2D) echocardiography. During the acute phase ECG abnormalities were common (5/22); pericardial effusion was found in 2 patients and global left ventricular hypokinesia in 1 patient infected with Plasmodium falciparum. At a follow-up of 19 patients, the resting ECG and echocardiography were normal or had normalized in all patients. The results of our study suggest that persistent cardiac damage following malarial infection seems to be rare; however, further trials in a larger patient population are needed to confirm our findings.

Regurgitant flow in cardiac valve prostheses: diagnostic value of gradient echo nuclear magnetic resonance imaging in reference to transesophageal two-dimensional color Doppler echocardiography.

Gradient echo nuclear magnetic resonance (NMR) imaging and transesophageal two-dimensional color Doppler echocardiography are flow-sensitive techniques that have been used in the diagnosis and grading of valvular regurgitation. To define the diagnostic value of gradient echo NMR imaging in the detection of regurgitant flow in cardiac valve prostheses and the differentiation of physiologic leakage flow from pathologic transvalvular or paravalvular leakage flow, 47 patients with 55 valve prostheses were examined. Color Doppler transesophageal echocardiography was used for comparison. Surgical confirmation of findings was obtained in 11 patients with 13 valve prostheses. Gradient echo NMR imaging showed regurgitant flow in 37 of 43 valves with a jet seen on transesophageal echocardiography and it detected physiologic leakage flow in 4 additional valves. There was 96% agreement between the two methods in distinguishing between physiologic and pathologic leakage flow. The methods differed on jet origin of pathologic leakage flow in six prostheses. The degree of regurgitation was graded by both NMR imaging and transesophageal echocardiography, according to the area of the regurgitant jet visualized; gradings were identical for 75% of valve prostheses. Quantification of jet length and area showed a good correlation between the two methods (r = 0.85 and r = 0.91, respectively). Gradient echo NMR imaging is a useful noninvasive technique for the detection, localization and estimation of regurgitant flow in cardiac valve prostheses. However, because transesophageal echocardiography is less time-consuming and less expensive, gradient echo NMR imaging is unlikely to displace transesophageal echocardiography and should be used only in the occasional patient who cannot be adequately imaged by echocardiography.

[Transesophageal echography in staging of bronchial cancers]. / Transösophageale Echographie im Staging von Bronchialkarzinomen.

The kind of relation of central lung cancer (c) to the walls of the central pulmonary arteries (PA) and the aorta is an important information prior to operative or interventional (laser/afterloading) therapy. As computed tomography (CT) and angiography are often inaccurate in the assessment of PA-infiltration, we assessed the diagnostic value of transesophageal echography (TEE) in the staging of LC. 16 patients (pts.) were investigated using TEE in addition to CT or magnetic resonance imaging (MRI). Eleven pts. had central LC, 3 peripheral LC, 1 anterior mediastinal mass and 1 central pneumonia (cancer excluded). 2 pts. with central LC were unable to swallow the probe. In 9/9 pts. with central LC, 1/3 pts. with peripheral LC and 1 pt. with enlarged anterior mediastinum the tumour mass could be visualized. In the pt. with a centrally located infiltrate on chest radiogram TEE demonstrated enlarged hilar lymph nodes, but excluded a central tumour. Main PA branches could be identified in all 14/14 pts. Central left or right PA were compressed slightly in 3 pts. and severely in 2 pts., with a near total occlusion in one (confirmed by MRI/CT). TEE revealed PA-infiltration in 2 pts. and aortic wall infiltration in 2 other pts. Despite adjacent tumour mass aortic wall infiltration was excluded in 2 pts. Enlarged hilar lymph nodes could be demonstrated in 2/9 pts. with central LC, whereas CT/MRI showed enlarged mediastinal lymph nodes in 7/9 pts. In conclusion, TEE is able to visualize central lung cancer and gives useful additional informations about the kind of relation to central PA and the aorta.(ABSTRACT TRUNCATED AT 250 WORDS)

Failure of radiotherapy to resolve fatal lung damage due to paraquat poisoning.

The most effective treatment of severe paraquat poisoning in man is uncertain. In order to prevent pulmonary fibrosis, we employed radiotherapy of both lungs in a 23-year-old patient with severe paraquat poisoning; however, it failed to prevent the fatal outcome.

Diagnostic value of transesophageal echocardiography in cardiac surgery.

The aim of this study was to assess the diagnostic value of intraoperative 2-D color Doppler transesophageal echocardiography (ITEE) for the surgeon and anesthesiologist in patients undergoing coronary bypass surgery or heart valve replacement. Information given by ITEE in 100 cardiac operations was documented. We judged the ITEE information, considering to what extent it was not to be obtained by other methods and to what extent it influenced the operation itself. The value was classified as dispensable (0), informative (1), valuable (2), or essential (3). In 50 consecutive patients with heart-valve replacement (25 aortic valve prostheses, 25 mitral valve prostheses) ITEE was 38 x (0), 8 x (1), 4 x (2). In 50 consecutive patients undergoing coronary artery bypass graft surgery it was 33 x (0), 11 x (1), 4 x (2), 2 x (3). The two essential diagnoses referred to undetected vein graft occlusions. Information classified as valuable mainly referred to left and right ventricular function or valvular and prosthetic valve function when difficulties occurred during and after extracorporeal circulation. In conclusion, information given by ITEE, although generally regarded as dispensable in the procedures considered, was valuable in 10% of cases and in 2% even essential.

[Advantages of biplane transesophageal echocardiography]. / Vorteile der biplanen transösophagealen Echokardiographie.

Biplane transesophageal echocardiography (BTEE) was intraoperatively performed on 27 patients; ten patients with coronary artery bypass graft surgery, ten with aortic valve replacement, five with mitral valve replacement, one with reconstruction of complete AV-canal, and one with surgical repair of dissecting aortic aneurysm. Compared with the transverse views of the monoplane TEE, BTEE permits the following additional images of the heart: 1) Longitudinal "two-chamber-view" for assessment of left ventricular (LV) anterior, apical, and posterior wall motion, and for assessment of mitral valve anatomy and function (e.g., grading of color flow regurgitation). 2) Imaging of the right-ventricular outflow tract (RVOT) for evaluation of RVOT obstruction, including a crosswise imaging of aortic valve. 3) Proximal two-thirds of the aorta ascendens for the diagnosis of dissecting aortic aneurysm (de Bakey Types I and II). 4) Imaging of the superior vena cava, helpful for detecting transposition of pulmonary veins. 5) Apex of left ventricle, advantageous for detecting thrombus. 6) Longitudinal view of the descending aorta: from the origin of the left subclavian artery down to the origin of the coeliac artery (origins of both vessels, inclusively). We prepared post mortem sections of the heart corresponding to the longitudinal echocardiographic views and documented them by photography. In conclusion, the second plane provides an important improvement in semi-invasive imaging of the heart.

[A new Doppler echocardiography parameter of diastolic ventricular function]. / Ein neuer dopplerechokardiographischer Parameter der diastolischen Ventrikelfunktion.

The evaluation of flow velocities in left ventricular inflow tract (LVIT) by Doppler echocardiography gives information about the diastolic ventricular function. In late diastole, shortly after the flow velocity of atrial contraction V(A), we notice in the left ventricular outflow tract (LVOT) a laminar flow velocity directed to the aortic valve. The purpose of this study was to compare this flow velocity V(A*) in the LVOT with the flow velocity of the atrial contraction V(A), and the flow velocity of early diastole V(E) in LVIT, to determine whether such comparison would provide information concerning diastolic function. We studied three groups: 39 patients with left ventricular hypertrophy (HY) (mean age 56 +/- 12 y, 77% male), 41 patients with coronary heart disease (KHK) (mean age 53 +/- 10 y, 85% male) and 41 healthy subjects (N) (mean age 50 +/- 16 y, 51% male); all three groups were studied by pulsed Doppler from apical 4 chamber view in LVOT for maximal velocity (Vmax-A*) and time velocity integral of A* (TVI-A*), and in LVIT for maximal velocity of early diastole (Vmax-E), maximal velocity of atrial contraction (Vmax-A), ratio Vmax-E/Vmax-A, and the time velocity integrals (TVI-E, TVI-A). A slight correlation between Vmax-A* and Vmax-A was found (r = .60), being nearly the same as for TVI-A* and TVI-A (r = .64).(ABSTRACT TRUNCATED AT 250 WORDS)

Changes of the degree of hypertrophy in hypertrophic obstructive cardiomyopathy under medical and surgical treatment.

The aim of our study was to establish the extent to which therapy of hypertrophic obstructive cardiomyopathy (HOCM) can influence the degree of hypertrophy. By means of two-dimensionally guided M-mode echocardiography, 120 patients with HOCM (age range 4-72 years, mean age 41 years) were observed over an average period of 49 +/- 41 months. Depending on the respective therapy, we formed four patient groups: group 1: 13 patients without any therapy (follow-up period 31 +/- 30 months); group 2: 27 patients receiving propranolol (follow-up period 47 +/- 34 months); group 3: 50 patients receiving verapamil (follow-up period 39 +/- 27 months), and group 4: 30 patients with myectomy (follow-up period 34 +/- 32 months). In group 4, as expected, the thickness of the interventricular septum (IVS) decreased postoperatively (from 24.2 +/- 4.5 to 19.8 +/- 6.7 mm, p less than 0.05), and the left ventricular posterior wall (LVPW) thickness also decreased later postoperatively (from 13.0 +/- 2.6 to 11.9 +/- 2.3 mm, p less than 0.05). The left ventricular diameters increased. In groups 2 and 3 treated with pharmacotherapy as in the untreated patients of group 1, on average there was no change in IVS and LVPW thickness nor in the left ventricular diameters (with the exception of increasing left ventricular end-diastolic diameter in the propranolol-treated group). In contrast to group 1, in occasional cases there were substantial decreases of IVS thickness (11% of the patients in group 2, 13% in group 3) or LVPW thickness (13% of the patients in group 2, 12% in group 3).(ABSTRACT TRUNCATED AT 250 WORDS)

[Possibilities and limits of quantitative analyses using Doppler echocardiography]. / Möglichkeiten und Grenzen quantitativer Analysen mittels der Doppler-Echokardiographie.

Blood flow velocities can be quantified using Doppler echocardiography if the angle is known. Systolic ventricular function can be evaluated by stroke-volume measurement (product of blood flow velocity over time), but individual data may depart significantly from invasive measurements. Information on the diastolic ventricular function is based on measurements in the ventricular inflow tract. These parameters are very sensitive, but not specific at all. The quantification of valvular stenosis is the domain of Doppler echocardiography. Pressure gradients can be obtained from the degree of the blood flow acceleration. The calculated valve area in aortic stenosis using the continuity equation and in AV-valvular stenosis using pressure half-time measurements renders reliable, valuable, and clinically relevant information which is quite independent of cardiac output and additional valvular regurgitations. However, a detailed knowledge about the potential impact on the acquired data due to the specific methodology, the investigator, and the individual patient is mandatory. Out of the Doppler-derived intraventricular pressure indices, the determination of the systolic right ventricular and pulmonary artery pressures in patients with tricuspid regurgitation is widely accepted and has clinical implications. Several semiquantitative procedures to evaluate regurgitant volumes have been developed, at present, however, a definite and reliable quantification is not possible.