Search results for "Atrial function"
showing 10 items of 22 documents
A useful muscarinic parameter and the differential recording of atrial and ventricular tension in the perfused rabbit heart
1971
1. A simple method of recording right atrial tension from the Langendorff perfused rabbit has been described; it is based on the “transverse” method of recording cardiac contractions described by Beckett (1970). 2. Right atrial and ventricular tensions were recorded by transducers attached to threads stitched into the right atrium and right ventricle, the heart being retained and prevented from rotating by two threads stitched into the intraventricular septum as described by Beckett. 3. Right ventricular diastolic tension was adjusted to 7.5 g. Interference with the atrial record by ventricular systole was overcome by adjustment of diastolic right atrial tension to its optimal value between…
Importance of noninvasively measured respiratory muscle overload among the causes of hospital readmission of COPD patients.
2008
To evaluate the influence of respiratory muscle overload and right cardiac overload among the possible risk factors of hospital readmission in a 1-year follow-up of a cohort of patients with moderate-to-severe COPD.A total of 112 COPD patients who were admitted consecutively to the hospital for acute exacerbation. At hospital discharge, we evaluated the conventional clinical and functional determinations in addition to the pressure-time index (PTI), which is obtained using the equation PTI = (Pawo/Pimax) x (Ti/Ttot) x 100, where Pawo represents the mean airway pressure measured at the mouth during spontaneous breathing, Pimax is the maximal inspiratory pressure, Ti is the inspiratory time, …
Evidence for noradrenaline and adrenaline as sympathetic transmitters in the chicken.
1975
1 The concentrations of noradrenaline and adrenaline in various organs, arterial plasma and venous outflow from isolated hearts of adult chickens have been determined. 2 The relative adrenaline concentrations (percentage of the sum of noradrenaline and adrenaline) in the heart (33%), spleen (16%) and brain (26%) were higher than those found in mammalian organs. Chemical sympathectomy by pretreatment with 6-hydroxydopamine caused a decrease of the noradrenaline and adrenaline concentrations in the heart to 20 and 23% and in the spleen to 16 and 29%, respectively. 3 Stimulation of the right sympathetic nerves, infusion of tyramine or infusion of a modified Tyrode solution containing 108mM K+ …
Plasma levels of atrial natriuretic peptide and hemodynamic function in cardiac disease.
1993
Plasma concentrations of atrial natriuretic peptide were measured in eight patients with cardiac disease but normal resting right atrial pressure, during cardiac catheterization. No patient had clinical evidence of overt heart failure. An increase in peptide concentrations was observed between the aorta or the peripheral vein and the pulmonary artery. A linear relation was found between peripheral vein and pulmonary artery peptide concentration. Mean pulmonary artery and capillary wedge pressure also correlated with the peptide levels. No correlation was observed between mean right atrial pressure and peptide concentration. These findings demonstrate that atrial natriuretic peptide release,…
Tetrodotoxin slightly shortens action potential duration in ventricular but not in atrial heart muscle.
1988
Tetrodotoxin (TTX), at concentrations significantly decreasing maximal upstroke velocity (dV/dtmax) of the action potential, exerted variable effects on action potential duration (APD) in different myocardial preparations. APD was virtually unchanged by tetrodotoxin in the guinea pig atrium, but slightly shortened in the guinea pig ventricle at maximally effective concentrations. In the human ventricle, both dV/dtmax and APD were reduced in the same concentration range of TTX. These results suggest that a TTX-sensitive sodium current significantly contributes to the repolarization phase of the action potential in ventricular but not in atrial heart muscle.
Embolic stroke, sinus rhythm and left atrial mechanical function
2004
A 64-year-old man manifested a stroke two years after restoration of sinus rhythm through a radiofrequency catheter ablation. Transesophageal echo- cardiography demonstrated the presence of a thrombus in the left atrial appendage. Left atrial volumes and different parameters of atrial emptying showed that, de- spite the persistence of the sinus rhythm, atrial mechanical function was severely impaired. After atrial ablation procedures echocardiography can be useful to stratify pa- tients according to their risk of developing embolic events and hence be of help in deciding whether or not discontinuation of anticoagulant therapy is the appropri- ate choice.
Reduced right atrial contractile force in patients with left ventricular diastolic dysfunction: A study in human atrial fibers—contractile force and …
2017
Summary Background/Objective The aim of our study was to evaluate right heart contractile force in patients with diastolic dysfunction (DD) with preserved left heart ejection fraction undergoing cardiac surgery. We examined the contractile properties of skinned human fibers obtained from the right auricle in two groups (DD and controls). Methods Right atrial tissue from 64 patients, who were undergoing cardiac surgery, were collected before extracorporal circulation. Tissue was conserved and prepared as "skinned fibers". We exposed the dissected fibers to increasing calcium concentrations and recorded the force values. Results Patients with DD develop significantly less force at middle and …
Detailed Anatomical and Electrophysiological Models of Human Atria and Torso for the Simulation of Atrial Activation
2015
Atrial arrhythmias, and specifically atrial fibrillation (AF), induce rapid and irregular activation patterns that appear on the torso surface as abnormal P-waves in electrocardiograms and body surface potential maps (BSPM). In recent years both P-waves and the BSPM have been used to identify the mechanisms underlying AF, such as localizing ectopic foci or high-frequency rotors. However, the relationship between the activation of the different areas of the atria and the characteristics of the BSPM and P-wave signals are still far from being completely understood. In this work we developed a multi-scale framework, which combines a highly-detailed 3D atrial model and a torso model to study th…
5-Year Experience of In-Hospital Outcomes After Percutaneous Left Atrial Appendage Closure in Germany
2019
The aim of this study was to evaluate 5-year in-hospital trends and safety outcomes of left atrial appendage (LAA) closure in the German nationwide inpatient sample.The safety and efficacy of percutaneous LAA closure have been demonstrated in randomized trials and prospective cohort studies, but results from large samples are missing.Data on patient characteristics and in-hospital safety outcomes for all percutaneous LAA closures performed in Germany between 2011 and 2015 were analyzed. Overall, 15,895 inpatients were included.The annual number of LAA occlusions increased from 1,347 in 2011 to 4,932 in 2015 (β = 1.00; 95% confidence interval [CI]: 0.95 to 1.01; p 0.001), with a nonsignifica…
The ineffectiveness of the NO-cyclic GMP signaling pathway in the atrial myocardium
1995
1. This study was performed to determine whether nitric oxide (NO) has direct effects on force of contraction (Fc) in atrial myocardium from rats, rabbits, guinea-pigs, frogs, and man. 2. Glyceryl trinitrate, isosorbide dinitrate, 3-morpholino-sydnonimine hydrochloride (SIN-1), and S-nitroso-N-acetylpenicillamine (SNAP) did not significantly reduce Fc in the various preparations investigated, either given alone or after stimulation of alpha- or beta-adrenoceptors. 3. SNAP did not change the time course of contractions in rat, guinea-pig and human preparations. 4. 8-Bromo-guanosine-3':5'-cyclic monophosphate (8-Br-cyclic GMP) produced a negative inotropic effect in rat, guinea-pig and human …