Assessment of myocardial postreperfusion viability by intravenous myocardial contrast echocardiography: analysis of the intensity and texture of opacification.

Background: Although defects on intracoronary myocardial contrast echocardiography (MCE) indicate loss of viability after reperfusion, opacified segments may also exhibit persistent dyssynergy. Therefore, we related the intensity and texture of opacification produced by an intravenous contrast agent to histological findings to determine the characteristics of necrotic tissue by postreperfusion MCE.

Methods And Results: MCE was performed by intravenous injection of 0.

Quantitative assessment of myocardial perfusion during graded coronary artery stenoses by intravenous myocardial contrast echocardiography.

Objectives: The purpose of this study was to examine whether coronary stenoses of variable severity could be quantitatively assessed by analysis of myocardial perfusion as determined by intravenous (IV) myocardial contrast echocardiography.

Background: Recently, new contrast agents and imaging technology have been developed that may enable improved assessment of myocardial perfusion by IV contrast injection.

Methods: Variable obstruction of the left anterior descending (LAD) coronary artery in dogs was produced by a screw occluder.

Persistence of Atrial Fibrillation After Its Induction-Importance of the Duration and Dispersion of Atrial Refractoriness and Electrical Remodeling.

BACKGROUND: The electrophysiologic mechanisms of the persistence of atrial fibrillation (AF) after its initiation are not well understood. Therefore, the electrophysiologic characteristics of the right atrium were evaluated in an acute, pacing-induced model of AF in the pig in order to identify parameters associated with persistence of AF. METHODS AND RESULTS: AF was induced by rapid atrial pacing in 30 anesthetized, open-chest, juvenile pigs.

Electrophysiological and antiarrhythmic effects of the atrial selective 5-HT(4) receptor antagonist RS-100302 in experimental atrial flutter and fibrillation.

Background: Stimulation of 5-HT(4) receptors increases atrial chronotropic and inotropic responses. Whether other electrophysiological effects are produced is unknown. In humans and swine, 5-HT(4) receptors are present only in atrium.

Atrial systolic pressure, as well as stretch, is a principal stimulus for release of ANF.

The mechanism for increased secretion of atrial natriuretic factor (ANF) during tachycardia and atrial fibrillation has remained unsettled. In seven open-chest pigs, the plasma concentration of ANF increased from 49.8 +/- 12.