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The current understanding is that longitudinal muscle contraction begins before and outlasts circular muscle contraction during esophageal peristalsis in normal subjects. The goal of our study was to reassess the relationship between the contractility of two muscle layers using novel ways to look at the muscle contraction. We studied normal subjects using(More)
The present study reports the development and characterization of a murine model of right ventricular dysfunction following graded constriction in the pulmonary artery via microsurgical approaches. To analyze in vivo ventricular function, a technique of x-ray contrast microangiography was developed to allow the quantitative analysis of ventricular volumes(More)
We hypothesized that electrocardiogram (ECG) spatial phase analysis would define a spectrum of intracardiac organization from atrial fibrillation (AF), nonisthmus-dependent and isthmus-dependent atrial flutter (AFL) to supraventricular tachycardias (SVT), and similarly for ventricular arrhythmias. We analyzed arrhythmia ECGs of 33 patients with isthmus (n =(More)
Electrical activation of the ventricles via the His-Purkinje system is represented on the body surface by a waveform with a broad range of frequency components. We speculate that this process is mediated by current flow through a fractal-like conduction network and therefore that the broadband spectrum of the depolarization waveform should be scaled as a(More)
The average dimensions (diameter, length, and volume) of the airways in the mammalian bronchial tree, long thought to be exponential functions of the generation number, are shown to be power laws in generation number modulated by a harmonic variation. These data are satisfactorily described by means of a functional scaling relation--renormalization group(More)
We recently found that an orally directed stretch of the esophagus activates a neurally mediated relaxation of the lower esophageal sphincter (LES). Goals of our study were to characterize the neural mechanisms responsible for axial and transverse stretch-activated responses in the LES. LES pressure was monitored in anesthetized and artificially ventilated(More)
Intravascular ultrasound uses a high-frequency, miniaturized, ultrasound transducer positioned on the tip of a coronary catheter to provide detailed cross-sectional images of the coronary vessel wall. Unlike angiography, which details only luminal encroachment, this imaging technique has the unique potential to provide an image of the atherosclerotic(More)
BACKGROUND Esophageal multiple intraluminal impedance (MII) measurement has been used to detect gastro-esophageal reflux and bolus transport. It is not clear if MII can detect changes in luminal cross sectional area (CSA) during bolus transport. Intraluminal ultrasound (US) images, MII, and high resolution manometry (HRM) were recorded simultaneously to(More)
Contact sensors to monitor fetal heart, breathing, and movement sounds with increased sensitivity and bandwidth are under development. To understand the inherent acoustical properties of the maternal abdomen and its interaction with these sensors, the driving-point impedance Z(j omega) was measured in nine women during their last trimester of pregnancy. An(More)