M.H., CASO. R., AND GREENBERG, P.S.: Permanent pacemaker imp/antation using tbe femoral vein: A preliminary report. A permanent pacemaker was implanted through the femoral vein in 23 patients using the percutaneous puncture technique. The pulse generator was placed in the lower abdominai wail. The method is simple and reduces the time necessary to accomplish implantation. Catheter extrusion in one patient was easily corrected. Another patient had lale thrombophJebitis, possibly unrelated to the procedure. Catheter dislodgement occurred in four (4) patients and penetration of the right atrial appendage and right ventricular apex each occurred once. We beiieve these probiems can be circumvented with more experience and expect the femoral approach to he a simple and practical method of permanent pacemaker implantation. fPACE, Vol. 3, July-August. 1980) pacemaker implantation, atria/ pacing, permanent pacing, femoral pacing Transvenous endocardial lead placement for permanent cardiac stimulation has supplanted epicardial lead placement because of the former's relative ease, safety, and low morbidity and mortality.'"' The veins of the neck and shoulder have been used almost exclusively in permanent transvenous electrode placement,The use of the neck and shoulder veins necessitates the placement of the pulse generator in either the right or left pectoral areas. A small cephalic vein often makes it difficult to introduce the electrode catheter and an additional external or internal jugular vein cut-down may be necessary. The recent popularity of the subclavian approach adds another avenue of entry, Although the newer pulse generators are less bulky than the older models, the pulse generator outline is still visible and, in thin individu-

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In the rainbow schlieren apparatus, a continuously graded rainbow filter is placed in the back focal plane of the decollimating lens. Refractive-index gradients in the test section thus appear as gradations in hue rather than irradiance. A simple system is described wherein a conventional color CCD array and video digitizer are used to quantify accurately the color attributes of the resulting image, and hence the associated ray deflections. The present system providesva sensitivity comparable with that of conventional interferometry, while being simpler to implement and less sensitive to mechanical misalignment.

Absolute concentrations of water vapor are measured in microgravity (µ-g), nonpremixed methane, and propane jet flames with diode-laser wavelength modulation spectroscopy. These experiments are performed in the 2.2-s µ-g drop facility at the NASA Lewis Research Center. Abel inversion methods are used to determine time-dependent radial profiles from eight line-of-sight projections across the flames. At all measured heights above the nozzle, water vapor spatial distributions in µ-g flames are much wider than their 1-g counterparts. Radial growth of the water signal continues throughout the drop, verifying earlier suggestions that a steady state is not reached during the duration of the test, despite a quasi-steady flame shape. Large amounts of water vapor are observed at larger radii, at odds with visual (video) observations and numerical predictions.

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Exercise ECGs and coronary angiograms were reviewed in 266 patients (81 normals and 185 with significant coronary artery disease). Thirty-three false positive and 96 false negative ST responses to stress testing were purposely chosen to determine if the R wave could reduce the number of false ST responses. R wave amplitude changes were measured in the control and in the immediate postexercise period. An increase or no change in R wave was taken as evidence of an abnormal response, while a decrease in the R wave was a normal response. The sensitivity by ST segment was 48% and the specificity was 59%. These values were low because of the large number of false positive and negative ST responses in the study. It was our purpose to determine if these lowered values could be significantly improved by the R wave. Using R wave criteria, the sensitivity was 63% (P is less than 0.01) while the specificity was 79% (P is less than 0.01). The sensitivity and specificity of stress testing can be significantly improved using R wave changes.

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