Search results for "Ventricle"

Die Verteilung von Noradrenalin und Adrenalin im Herzen der Katze, des Kaninchens und der Ratte

1958

The concentration of noradrenaline in different parts of the heart was estimated in cats, rabbits, and rats. In each heart, the concentration of noradrenaline was much higher in the right atrium than in the left atrium and higher in the right ventricle than in the left one.

Die Wirkung von Theophyllin, Coffein und Theobromin auf Kontraktionskraft, Erregbarkeit, Refrakt�rzeit und Spontanfrequenz des isolierten Herzmuskels…

1956

In the electrically driven papillary muscle of the cat's right ventricle theophylline, caffeine and theobromine exerted a positive inotropic action. Log. dose-effect regression lines for the three drugs were parallel; the effect of theophylline was significantly greater than those of caffeine and theobromine. The range of concentrations used was 1/32–1/2 mM/1.

Die Konzentration von Noradrenalin und Adrenalin in den einzelnen Abschnitten des Herzens

1959

1. A method for the assay of noradrenaline and adrenaline in small pieces of heart tissue is described. The amines were extracted with acid ethanol and separated by paper chromatography. The regions containing the amines were eluted and the amount of amines in the eluates was determined by bioassay. Noradrenaline was assayed on the blood pressure of the pithed rat. Adrenaline was assayed on the isolated atropinized rat's uterus stimulated with oxytocin. 2. The identity of the substances tested by bioassay with noradrenaline and adrenaline was confirmed by a number of chemical and pharmacological tests. 3. The concentration of catechol amines in different parts of the heart was studied in ca…

Response of human ventricular heart muscle to histamine

1981

Elektrische Registrierung der Druckanstiegsbeschleunigung und ihre Beziehung zur isometrischen Kontraktion des linken Herzventrikels

1967

Aus der zweimaligen Differentiation der Ventrikeldruckkurve nach der Zeit ergibt sich die Druckanstiegsbeschleunigung. Dieser Parameter wurde mittels RC-Glieder bei der Kontraktion des linken Ventrikels der Katze registriert. Sein Maximum lag in der Phase der isometrischen Kontraktion. Die maximale Druckanstiegsbeschleunigung nahm bei Erhohung der isometrischen Kontraktion starker zu als die maximale Druckanstiegsgeschwindigkeit. Es wird gefolgert, das zwischen der Kraft der isometrischen Kontraktion und der maximalen Druckanstiegsbeschleunigung eine Proportionalitat besteht.

Meßfehlerschätzung bei der MR-tomographischen Volumetrie des linken Ventrikels mit Mehrschicht-Technik

1992

A multi-slice technique for MRT measurements of the left ventricular volume is much faster than the use of single-slice methods and is therefore better tolerated, leaving time for additional measurements. The end-diastolic left ventricular volume can be reliably measured by this method (123.3 +/- 13.5 ml vs. 124.1 +/- ml). The end-systolic volume is consistently overestimated by 23.7 +/- 18.3% compared with the reference value obtained by single slice measurements (47.9 +/- 8.9 ml vs 39.1 +/- 7.9 ml). Correspondingly, stroke volume and ejection fraction is underestimated on average by 10.6 +/- 9.7% and 10.6 +/- 7.6% respectively).

Autoradiographic technique to assess distribution of blood flow within organs

1969

A method is described for assessing the distribution of blood flow within organs. Microspheres, 5–50 μ in diameter, labelled with a beta-emitting isotope were injected into the left ventricle of experimental animals. The distribution of the indicator within the tissues, which is assumed to represent the regional distribution of flow, was visualized and measured quantitatively by autoradiography. Local flow rates in areas of about 1,2 mm in diameter could be determined. Application of the technique for the study of regional myocardial and renal circulation is demonstrated.

Left Ventricle Biomechanics of Low-Flow, Low-Gradient Aortic Stenosis: A Patient-Specific Computational Model

2022

This study aimed to create an imaging-derived patient-specific computational model of low-flow, low-gradient (LFLG) aortic stenosis (AS) to obtain biomechanics data about the left ventricle. LFLG AS is now a commonly recognized sub-type of aortic stenosis. There remains much controversy over its management, and investigation into ventricular biomechanics may elucidate pathophysiology and better identify patients for valve replacement. ECG-gated cardiac computed tomography images from a patient with LFLG AS were obtained to provide patient-specific geometry for the computational model. Surfaces of the left atrium, left ventricle (LV), and outflow track were segmented. A previously validated …

Über den Einfluß von Calcium++ und Hypothermie auf den mechanischen Systolenbeginn beider Ventrikel des isolierten Katzenherzens

1967

Experiments in isolated cat hearts showed, that with increased Ca++-concentration of the perfusion-medium (0,56 g CaCl2/1000 ml) the onset of mechanical systole of left ventricle occurred earlier (21,9±3,3 msec after the onset ofQRS-complex in the ECG) than in experiments with a normal Ca++-concentration (0,28 g CaCl2/1000 ml). The onset of mechanical systole of the right ventricle was not effected.

QT interval heterogeneities induced through local epicardial warming/cooling. An experimental study

2014

[EN] ntroduction and objectives Abnormal QT interval durations and dispersions have been associated with increased risk of ventricular arrhythmias. The present study examines the possible arrhythmogenic effect of inducing QT interval variations through local epicardial cooling and warming. Methods In 10 isolated rabbit hearts, the temperatures of epicardial regions of the left ventricle were modified in a stepwise manner (from 22 °C to 42 °C) with simultaneous electrogram recording in these regions and in others of the same ventricle. QT and activation-recovery intervals were determined during sinus rhythm, whereas conduction velocity and ventricular arrhythmia induction were determined dur…