Purpose: Cardiac and respiratory motion artifacts are major challenges in cardiac MRI, and are conventionally suppressed by prospective ECG and diaphragm navigator gating, respectively. However, these approaches require time-consuming setup and prolonged acquisition times, and are susceptible to variations of heart rate or respiratory pattern. Further, they can become unreliable at higher field...

Recent developments in MRI enable the acquisition of image sequences with high spatio-temporal resolution. Cardiac motion can be captured without gating and triggering. Image size and contrast relations differ from conventional cardiac MRI cine sequences requiring new adapted analysis methods. We suggest a novel segmentation approach utilizing contrast invariant polar scanning techniques. It ha...

Chandra, Rashmi, C. Frank Starmer, and Augustus O. Grant. Multiple effects of KPQ deletion mutation on gating of human cardiac Na1 channels expressed in mammalian cells. Am. J. Physiol. 274 (Heart Circ. Physiol. 43): H1643–H1654, 1998.—Several aspects of the effect of the KPQ deletion mutation on Na1 channel gating remain unresolved. We have analyzed the kinetics of the early and late currents ...

Long QT syndrome is an inherited disorder of cardiac repolarization caused by mutations in cardiac ion channel genes, including KVLQT1. In this study, the functional consequences of three long QT-associated missense mutations in KvLQT1 (R243C, W248R, E261K) were characterized using the Xenopus oocyte heterologous expression system and two-microelectrode voltage clamp techniques. These mutations...

A simulation environment has been developed to aid the development of three-dimensional (3D) angiographic imaging of the coronary arteries for use during minimally invasive robotic cardiac surgery. We have previously developed a dynamic model of the coronary arteries by non-linearly deforming a high-resolution 3D image of the coronaries of an excised human heart, based on motion information fro...

Muscarinic potassium channels (KACh) are composed of two subunits, GIRK1 and GIRK4 (or CIR), and are directly gated by G proteins. We have identified a novel gating mechanism of KACh, independent of G-protein activation. This mechanism involved functional modification of KACh which required hydrolysis of physiological levels of intracellular ATP and was manifested by an increase in the channel ...