Atrial natiuretic peptide release at rest and with exercise after cardiac transplantation with bicaval anastomoses

AbstractBicaval anastomoses in orthotopic cardiac transplantation offer the advantage of preserving the right atrial geometry. To elucidate the impact of this anastomotic technique on atrial natriuretic peptide plasma levels at rest and with exercise, nine patients were submitted to a symptom-limited supine exercise test. Atrial natriuretic peptide plasma levels in samples obtained from the right atrium were elevated at rest (274.4 ± 60.4 pg/ml), at peak exercise (438.1 ± 71.7 pg/ml), and thereafter (328.1 ± 71.2 pg/ml) with respect to normal reference values of 21 ± 1 pg/ml at rest and 92 ± 14 at peak exercise. Renin, angiotensin, and aldosterone plasma levels were almost normal and did not indicate any pathologic processes in volume homeoostasis. Right-sided hemodynamic parameters were not correlated with atrial natriuretic peptide secretion. An adverse relationship between cold ischemic time of the donor organ and atrial natriuretic peptide release was found ( r = 0.88, p < 0.0008), indicating that endocrine cardiocytes are sensitive to prolonged ischemia. Atrial natriuretic peptide release may thus be independent of the surgical approach, and other unique characteristics of the transplanted heart, such as denervation, are more likely to be responsible for elevated atrial natriuretic peptide plasma concentrations after orthotopic heart transplantation. (J THORAC CARDIOVASC SURG 1995;110:1600-5

Environment mapping enabling safety and usability of an electronic tow bar

Cost efficiency and productivity as well as drivers comfort and usability are significant innovation drivers for agricultural machinery. The proposed electronic tow bar system for tillage processes consists of two vehicles, coupled by wireless data connection. An unmanned slave tractor follows a master tractor with a position dependent lateral and longitudinal offset. Operating two tractors with one driver only, increases productivity and improves the capacity load due to higher flexibility in fleet management. In return, the usability and safety of the tow bar becomes a major concern, which is addressed by an elaborate safety concept enabled by sensor based obstacle detection and mapping. Web-based geo-information, are used to support proactive path planning.This paper presents a solution to achieve both, safety and usability, for a complex platoon system. The interaction of the operator with the local and global obstacle map is designed to meet the requirements of both target functions

BOLD cardiovascular magnetic resonance at 3.0 tesla in myocardial ischemia

Background: The purpose of this study was to determine the ability of Blood Oxygen Level Dependent (BOLD) cardiovascular magnetic resonance (CMR) to detect stress-inducible myocardial ischemic reactions in the presence of angiographically significant coronary artery disease (CAD). Methods: Forty-six patients (34 men; age 65 ± 9 years,) with suspected or known coronary artery disease underwent CMR at 3Tesla prior to clinically indicated invasive coronary angiography. BOLD CMR was performed in 3 short axis slices of the heart at rest and during adenosine stress (140 μg/kg/min) followed by late gadolinium enhancement (LGE) imaging. In all 16 standard myocardial segments, T2* values were derived at rest and under adenosine stress. Quantitative coronary angiography served as the standard of reference and defined normal myocardial segments (i.e. all 16 segments in patients without any CAD), ischemic segments (i.e. supplied by a coronary artery with ≥50% luminal narrowing) and non-ischemic segments (i.e. supplied by a non-significantly stenosed coronary artery in patients with significant CAD). Results: Coronary angiography demonstrated significant CAD in 23 patients. BOLD CMR at rest revealed significantly lower T2* values for ischemic segments (26.7 ± 11.6 ms) compared to normal (31.9 ± 11.9 ms; p < 0.0001) and non-ischemic segments (31.2 ± 12.2 ms; p = 0.0003). Under adenosine stress T2* values increased significantly in normal segments only (37.2 ± 14.7 ms; p < 0.0001). Conclusions: Rest and stress BOLD CMR at 3Tesla proved feasible and differentiated between ischemic, non-ischemic, and normal myocardial segments in a clinical patient population. BOLD CMR during vasodilator stress identified patients with significant CAD

A reference dataset for verifying numerical electrophysiological heart models

<p>Abstract</p> <p>Background</p> <p>The evaluation, verification and comparison of different numerical heart models are difficult without a commonly available database that could be utilized as a reference. Our aim was to compile an exemplary dataset.</p> <p>Methods</p> <p>The following methods were employed: Magnetic Resonance Imaging (MRI) of heart and torso, Body Surface Potential Maps (BSPM) and MagnetoCardioGraphy (MCG) maps. The latter were recorded simultaneously from the same individuals a few hours after the MRI sessions.</p> <p>Results</p> <p>A training dataset is made publicly available; datasets for blind testing will remain undisclosed.</p> <p>Conclusions</p> <p>While the MRI data may provide a common input that can be applied to different numerical heart models, the verification and comparison of different models can be performed by comparing the measured biosignals with forward calculated signals from the models.</p

Elektronische Deichsel für landwirtschaftliche Arbeitsmaschinen mit Umfeldsensorik und zusätzlichen Geoinformationen

Während die Leistungsnachfrage landwirtschaftlicher Unternehmen bei Großtraktoren und selbstfahrenden Landmaschinen stetig wächst, erreichen Landmaschinenhersteller bezüglich Fahrzeuggröße und -masse insbesondere für den Straßenverkehr zunehmend kritische Werte. Das Konzept der elektronischen Deichsel hingegen ermöglicht durch den Einsatz fahrerloser Maschinen annähernd eine Verdopplung der Flächenleistung ohne zusätzlichen Personalaufwand und steigert somit Produktivität und Wirtschaftlichkeit, unter Beibehaltung gängiger Maschinen/Traktoren

Elektronische Deichsel für landwirtschaftliche Arbeitsmaschinen - Folgsame Traktoren

Die Teilautomatisierung eines Arbeitsgespanns aus Traktoren war Ziel eines von 2007 bis 2010 durchgeführten Forschungsprojekts am Karlsruher Institut für Technologie. Mit definiertem Versatz in Längs-und Querrichtung folgt ein unbemannter der Spur eines bemannten Traktors und führt dabei den gleichen Arbeitsprozess durch - diese Idee wurde am Lehrstuhl für Mobile Arbeitsmaschinen (Mobima) gemeinsam mit den Projektpartnern Geo-konzept und AGCO Fendt in ein System umgesetzt, mit dem die Produktivität moderner landwirtschaftlicher Unternehmen weiter gesteigert werden soll. Verbunden per Datenfunk und ausgestattet mit hochgenauen GPS-Empfängern konnten bereits die im Projekt ausgerüsteten Prototypen auf dem Acker die Arbeit aufnehmen

Односторонний и двусторонний эффект памяти формы в [([3)12]]-монокристаллах сплава Ni[49]Fe[18]Ga[27]Co[6]

This study was performed to assess the role of additional myocardial perfusion imaging during high dose dobutamine/atropine stress magnetic resonance (DSMR-wall motion) for the evaluation of patients with intermediate (50-70%) coronary artery stenosis. Routine DSMR-wall motion was combined with perfusion imaging (DSMR-perfusion) in 174 consecutive patients with chest pain syndromes who were scheduled for a clinically indicated coronary angiography. When defining CAD as the presence of a ≥ 50% stenosis, the addition of perfusion imaging improved sensitivity (90 vs. 79%, P < 0.001) with a non-significant reduction in specificity (85 vs. 90%, P = 0.13) and an improvement in overall diagnostic accuracy (88 vs. 84%, P = 0.008). Adding perfusion imaging improved sensitivity in patients with intermediate stenosis (87 vs. 72%, P = 0.03), but not in patients with severe (≥70%) stenosis (93 vs. 84%, P = 0.06). In patients with severe stenosis specificity of DSMR-perfusion versus DSMR-wall motion decreased (61 vs 70%, P = 0.001) resulting in a lower overall accuracy (71 vs 74%, P = 0.03). Using a cutoff of ≥50% for the definition of CAD, sensitivity of DSMR-perfusion compared to DSMR-wall motion was significantly higher in patients with single vessel (88 vs. 77%, P = 0.03) and multi vessel disease (93 vs. 79%, P = 0.03), whereas no significant differences were found using a cutoff of ≥70% stenosis for the definition of CAD. The addition of perfusion imaging during DSMR-wall motion improved the sensitivity in patients with intermediate coronary artery stenosis. Overall diagnostic accuracy increased only when defining CAD as ≥50% stenosis. In patients with ≥70% stenosis DSMR-wall motion alone had higher accuracy due to more false-positive cases with DSMR-perfusion