Search results for "Heart Ventricles"

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.

Rheumatoid arthritis affects left ventricular mass: Systematic review and meta-analysis.

2015

Abstract Background Cardiovascular disease represents one of the most important extra-articular causes of morbidity and mortality in patients with rheumatoid arthritis (RA). Evidences showed that several cardiac structures can be affected during the course of the disease as well as abnormalities of left ventricular diastolic filling. Contrasting data are available about left ventricular mass (LVM) involvement in patients asymptomatic for cardiovascular disease. The purpose of this systematic review and meta-analysis is to summarize the effects of RA on LVM in rheumatoid arthritis patients without cardiovascular disease. Methods A systematic research of the current case–control studies was c…

Left ventricular noncompaction presenting like a double-chambered left ventricle

2015

Echocardiography in assessing acute pulmonary hypertension due to pulmonary embolism.

1980

Eighteen patients with acute pulmonary embolism were studied with right heart catheterization and M mode echocardiography. No patient had evidence of preexisting cardiopulmonary disease; pulmonary embolism was documented with pulmonary angiography. The mean pulmonary arterial pressure correlated with the angiographic severity index of embolic obstruction (r = 0.61, p 2 , p 2 ) and in 5 patients with acute pulmonary embolism and a mean normal pulmonary arterial pressure (10.9 ± 0.4 mm/m 2 ). For all measurements the index size of the right pulmonary artery correlated with the mean pulmonary arterial pressure (r = 0.84, p

Focus on right ventricular outflow tract septal pacing

2013

SummaryExperimental and clinical studies have shown that right ventricular apical pacing may result in long-term deleterious effects on account of its negative impact on left ventricular remodeling through desynchronization. This risk appears more pronounced in patients with even moderate left ventricular dysfunction and generally occurs after at least 1 year of pacing. As right ventricular apical pacing may be associated with the development of organic mitral insufficiency, other sites that allow for more physiological stimulation, such as right ventricular outflow tract septal pacing, have been developed, with good feasibility and reproducibility. However, the prospective randomized studi…

Right ventricular function after cardiac surgery: the diagnostic and prognostic role of echocardiography.

2019

Cardiac surgical techniques and circulatory supports have strongly evolved in the last years. Right ventricular (RV) function during the post-operatory period is still subject of study, although its relevant prognostic impact has been variably described in different papers. RV post-surgical dysfunction’s underlying mechanisms are still not clear and include a different hypothesis. Echocardiography, with both first and second level parameters, offers the possibility to accurately analyze the right ventricle and optimize these patients’ management. This paper describes the pathophysiology of the right ventricle, the most used echo indexes of RV function, whether they alter after surgery, the …

Changes in the Spectral Characteristics of Ventricular Fibrillation in Lesions Produced by Radiofrequency Ablation. An Experimental Study

2008

INTRODUCTION AND OBJECTIVES Although electro- physiological databases contain information about changes in the time domain in lesions produced by radiofrequency ablation, very few data on changes in the frequency domain are available. The aim of this study was to investigate changes in the spectral characteristics of ventricular fibrillation in zones with radiofrequency lesions. METHODS Recordings of ventricular fibrillation were obtained in 11 isolated perfused rabbit heart preparations using a multiple epicardial electrode located on the left ventricular free wall. Spectral parameters derived by Fourier analysis before and after the creation of transmural radiofrequency lesions were compa…

Microvascular obstruction in the right ventricle in reperfused anterior myocardial infarction. Macroscopic and pathologic evidence in a swine model.

2013

article i nfo Introduction: Data on right ventricular (RV) involvement in anterior myocardial infarction are scarce. The presence of RV microvascular obstruction (MVO) in this context has not been analyzed yet. The aim of the present study was to characterize the presence of MVO in the RV in a controlled experimental swine model of reperfused anterior myocardial infarction. Materials and Methods: Left anterior descending (LAD) artery-perfused area (thioflavin-S staining after selective infusioninLADartery),infarctsize(lackof triphenyltetrazolium-chloride staining) andMVO (lack of thioflavin-S staininginthe core oftheinfarctedarea) inthe RVwere studied.A quantitative(%of theventricularvolume…

Tomographic left ventricular volume determination in the presence of aneurysm by three-dimensional echocardiographic imaging. I: Asymmetric model hea…

1996

To improve the accuracy of measurements of left ventricular volume in the presence of an aneurysm, we used three-dimensional echocardiographic imaging to analyze the shape of left ventricles in 23 asymmetric model hearts with eccentric aneurysms of different sizes, shapes, and localizations. A standard 3.75 MHz ultrasound probe with a rotation motor device was used to obtain a three-dimensional data set. By rotating the probe stepwise 1 degree, 180 radial ultrasound pictures were digitized. On the basis of the three-dimensional data set, the following parameters were determined and compared with the dimensions of the model hearts obtained by direct measurement: total left ventricular volume…

Right ventricular volume determination in isolated human hearts

1986

For right ventricular volume determination a new method was developed that took into account right ventricular imaging by apical two-dimensional echocardiography in the four- and two-chamber views. Right ventricular volume was calculated by subtraction of the partial volume of the left ventricle and interventricular septum from the total heart volume of the right and left ventricles including the interventricular septum. Accuracy of the subtraction method was evaluated in isolated human hearts by two-dimensional echocardiography and radiography. Regression analysis indicated that for both the echocardiographic and radiologic procedures, the subtraction method gave the best correlation with …