Method for High Accuracy Differential Pressure Measurements Using Fluid-Filled Catheters
The advantage of measuring differential pressure using fluid-filled catheters is that the system is relatively inexpensive, but the readings are not accurate and affected by the common mode pressure (CMP) distortion. High accuracy differential pressure measurements are required in various biomedical applications, such as in fluid-dynamic test rigs, or in the cath-lab, from cardiac valves efficacy to functional assessment of arterial stenoses. We have designed and built a unique system in which the pressure difference was measured along the fluid flow inside a rigid circular tube using a fluid-filled double-lumen catheter. The differential pressure measurements were taken across two side-holes near the catheter distal tip, spaced apart by 3 cm. The goal was to overcome the CMP error, which significantly distorted the output differential pressure signal and to formulate a restoration factor. A restoration formula was developed based on simultaneous gauge pressure measurements, and was tested in several different cases. Several representative cases are presented and show that the common mode artifact was reduced by factors of 12–27. The restored pressure gradient signal was validated using direct pressure drop measurements, and showed very good agreement.
Aortic stenosis catheterization revisited: a long sheath single-puncture technique.
OBJECTIVES
To evaluate the accuracy of a new long sheath single-puncture technique in obtaining accurate transvalvular gradients in aortic stenosis.


BACKGROUND
Despite advances in echo Doppler, the evaluation of aortic stenosis continues to be a common procedure in the cardiac catheterization laboratory. Experts agree that simultaneous evaluation of the proximal aortic and left ventricular pressures yields the most accurate data; however, this is difficult to achieve unless two arterial punctures are performed.


METHODS
We postulated that using a 4 Fr pigtail catheter inside a 55-cm long 6 Fr sheath would provide accurate simultaneous pressure data, yet avoid the complications of two arterial punctures. We performed this technique in 13 male patients, and placed a second arterial catheter in the aortic root as a control aortic pressure. We then performed this technique in 55 other male patients without placing an additional control arterial catheter.


RESULTS
In the test population, correlation of aortic valve areas and transvalvular gradients was excellent. In the larger population, adequate hemodynamic data was obtained in 52 patients, with no difficulty engaging coronary arteries or grafts via the long sheath, and with an acceptable major complication rate of 1.5%.


CONCLUSIONS
Using a 4 Fr pigtail catheter with a 55-cm long 6 Fr sheath is a safe, efficient way to obtain excellent hemodynamic data in an aortic stenosis catheterization procedure.
New approach to vision-based BGA package inspection
Ball grid array (BGA) techniques have developed very fast due to the advantages of more I/O ports, small size, and so on. In this paper, a vision-based algorithm for BGA package inspection is proposed to accurately estimate center and diameters of solder-balls of BGA packages, so that defects of BGA packages, such as missing or extra balls, oversize or undersize balls, over-height or under-height balls, and pitch can be detected for ensuring the quality of BGA packages.