Diastolic heart failure (DHF) is a major source of cardiac related morbidity and mortality in the world today. A major contributor to, or indicator of DHF is a change in cardiac compliance. Currently, there is no accepted clinical method to evaluate the compliance of cardiac tissue in diastolic dysfunction. Shear wave elasticity imaging (SWEI) is a novel ultrasound-based elastography technique that provides a measure of tissue stiffness. Coronary perfusion pressure affects cardiac stiffness during diastole; we sought to characterize the relationship between these two parameters using the SWEI technique. In this work, we demonstrate how changes in coronary perfusion pressure are reflected in a local SWEI measurement of stiffness during diastole. Eight Langendorff perfused isolated rabbit hearts were used in this study. Coronary perfusion pressure was changed in a randomized order (0-90 mmHg range) and SWEI measurements were recorded during diastole with each change. Coronary perfusion pressure and the SWEI measurement of stiffness had a positive linear correlation with the 95% confidence interval (CI) for the slope of 0.009-0.011 m/s/mmHg ( R(2) = 0.88 ). Furthermore, shear modulus was linearly correlated to the coronary perfusion pressure with the 95% CI of this slope of 0.035-0.042 kPa/mmHg ( R(2) = 0.83). In conclusion, diastolic SWEI measurements of stiffness can be used to characterize factors affecting cardiac compliance specifically the mechanical interaction (cross-talk) between perfusion pressure in the coronary vasculature and cardiac muscle. This relationship was found to be linear over the range of pressures tested.

The design of a fractional-N PLL in the 900 MHz ISM band is presented to enable 5-Mbps data transmission for neuro application using GMSK modulation. The frac-N PLL consists of a phase frequency detector (PFD), charge pump (CP), loop filter, LC-VCO, and a prescaler. To minimize the CP current, the VCO control node capacitance is used to realize the on-chip loop filter's 3rd pole. Measured results of the MASH-12 frac-N synthesizer at 925 MHz show a phase noise of -104dBc/Hz at 22.5 KHz offset, in-band rms phase error of 0.7deg over 2.25 MHz bandwidth and out-of-band rms phase error of 2.3 deg. The measured phase noise spectrum correlates well with behavioral noise model predictions, including noise due to CP and PFD non-linearities. The chip was designed in 1.8V TSMC0.18μm Mixed Signal and RF process.

A graphical display system for animating mapped cardiac potentials is described. The system displays recorded voltages from 121 epicardial electrodes simultaneously on a computer monitor using color to indicate the magnitude of the voltage. Numerous options accessible through the mouse-driven user interface provide the user with a high degree of interaction with the data. The user can observe the changes in the recorded voltages over time by defining a portion of the data over which to animate the voltages. Animation speeds of up to 2 1/4 frames per second can be achieved, depending on the workstation used. Use of the graphical display system provides a new tool for studying the electrical conduction properties of the heart. Through its use, a more complete understanding (and potentially a more effective treatment) of arrhythmias might be achieved.>

The authors note that knowledge of the extracellular potential gradient field of the defibrillation shock and the cardiac-tissue response to the shock should lead to better understanding of the mechanism of defibrillation and stimulate improvement of defibrillation techniques. By measuring the potential distribution of the defibrillation shock throughout the heart and the location of the recording electrodes, the potential gradient field may be calculated. By recording local electrograms throughout the heart immediately before and after the shock, the tissue response to the shock can be evaluated.>