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The acceptance of the Digital Imaging and Communication in Medicine (DICOM) standard and the Compact Disk-Recordable (CD-R) as the interchange medium have been critical developments for laboratories that need to move forward on the cine replacement front, while at the same time retain a means to communicate with other centers. One remaining essential component which has not been satisfactorily addressed is the issue of how digital image data should be archived within an institution. Every laboratory must consider the diverse issues which affect the choice of a digital archiving system. These factors include technical and economic issues, along with the clinical routines prevailing in their laboratory. A complete understanding of the issues will lead to the formulation of multiple options which may prove acceptable and will help to overcome the last obstacle which remains for the complete replacement of cine film in the cardiac catheterization laboratory.

Our objective was to document change in stent usage in a single practice over time and to study "off-label" compared to Food and Drug Administration (FDA)-approved indications. Although only two intracoronary stents have been approved by the FDA, the relatively limited approved indications do not account for the dramatic increase in stent implantation. This increase has important implications for patient health care delivery. This study of stent usage in a single center over a 36-mo period included all patients treated with coronary stents at the Mayo Clinic from January 1993-December 1995, and evaluated the relative difference in frequency between "off-label" and FDA-approved indications for implantation. During the 36-mo period of study, 3,614 interventional procedures were done and one or more stents were placed in 25.4% of patients. The proportion of patients receiving stents increased throughout this time: during the first 6-mo period, stents were placed in 6.2% of procedures; during the last 6-mo period, stents were placed in 46.3% of procedures, an eightfold increase. During the final 6 mo, an unapproved device or an unapproved indication for an approved device constituted 59.4% of all stent procedures. In addition, use of the non-FDA-approved adjunctive treatment regimen without warfarin increased from 2.9% in the first 6-mo period of observation to 82.7% in the last 6 mo. The use of stents increased strikingly over a 36-mo period, from 6% to 46% of all procedures. The majority of implantations were performed either for an "off-label" unapproved indication or with an unapproved device.

We describe a method of validation of computerized quantitative coronary arteriography and report the results of a new UNIX-based quantitative coronary arteriography software program developed for rapid on-line (digital) and off-line (digital or cinefilm) analysis. The UNIX operating system is widely available in computer systems using very fast processors and has excellent graphics capabilities. The system is potentially compatible with any cardiac digital x-ray system for on-line analysis and has been designed to incorporate an integrated database, have on-line and immediate recall capabilities, and provide digital access to all data. The accuracy (mean signed differences of the observed minus the true dimensions) and precision (pooled standard deviations of the measurements) of the program were determined x-ray vessel phantoms. Intra- and interobserver variabilities were assessed from in vivo studies during routine clinical coronary arteriography. Precision from the x-ray phantom studies (6-In. field of view) for digital images was 0.066 mm and for digitized cine images was 0.060 mm. Accuracy was 0.076 mm (overestimation) for digital images compared to 0.008 mm for digitized cine images. Diagnostic coronary catheters were also used for calibration; accuracy.varied according to size of catheter and whether or not they were filled with iodinated contrast. Intra- and interobserver variabilities were excellent and indicated that coronary lesion measurements were relatively user-independent. Thus, this easy to use and very fast UNIX based program appears to be robust with optimal accuracy and precision for clinical and research applications.

The immediate outcome of 271 procedures involving the intracoronary implantation of 305 stents was determined. Data were analyzed with regard to indication for stenting and stent size. Elective indication was associated with a higher success rate than emergency indication (95.6% vs. 86.6%, P = 0.013) and a lower Q-wave infarction rate (0 vs. 6.4%, P = 0.006). Univariate analysis showed that the odds ratio for procedural success was significantly favored by elective indication (3.37, P = 0.018) but was unrelated to stent size (1.10, P = 0.087). These findings were confirmed on multivariate analysis. The likelihood of Q-wave infarction was lower for elective placement (P = 0.0008) but was not related to size. Requirement for emergency bypass surgery, incidence of subacute closure, and death were not related to indication or to stent size on either univariate or multivariate analysis. Therefore, the immediate outcome of stent placement is related to the indication for stenting, but not to the size of stent implanted. Procedural success is significantly favored by elective indication.

This study compares the sensitivity and variability of four models of tau, the time constant of ventricular relaxation, to detect the presence of myocardial ischemia. High fidelity left ventricular pressure recordings were obtained in ten patients undergoing coronary angioplasty at baseline, during balloon inflation, and at recovery. Four models of tau were considered: 1) a semilogarithmic, zero asymptote model (TL), 2) a semilogarithmic model using data from the first 40 ms of isovolumic relaxation (T40), 3) an exponential non-zero asymptote model (TE), and 4) a derivative non-zero asymptote model (TD). TL, T40, and TE increased significantly during inflation and returned to near baseline values at recovery. TD showed no change during inflation. Comparisons of TL, T40, and TE using the derived relaxation half-time (T1/2), failed to reveal significant differences between the models at baseline, during inflation, or at recovery. The non-zero asymptote models were associated with a greater beat-to-beat variability than the semilogarithmic models. Thus, T1/2 using the semilogarithmic zero asymptote models (TL and T40) may be more useful and consistent when measuring the rate of isovolumic relaxation during myocardial ischemia.

Coronary angioplasty of chronic total occlusions is known to have a lower success rate and higher frequency of restenosis than angioplasty of subtotal stenoses, but there are no data describing the additional time, resources, and radiation exposure associated with this procedure. The purpose of this study was to compare these features in 90 consecutive patients who underwent angioplasty of a total occlusion (group 1) to those of 100 consecutive patients who underwent angioplasty of a subtotal stenosis (group 2). Angioplasty was successful in 60% of group 1 and in 94% of group 2 patients. Procedures were longer in group 1 and significantly more guide catheters, angioplasty balloon catheters, and guide wires were required per patient compared to group 2. The volume of contrast media used in each group was similar. Estimates of radiation entry exposure, calculated from fluoroscopy exposure times and using data from phantom studies, were 53 R (roentgen) per patient in group 1 vs. 34 R in group 2. These procedures were performed using pulsed progressive fluoroscopy; radiation exposure would be considerably higher using conventional fluoroscopic systems. Cineangiographic radiation exposures were similar for each group and accounted for an average additional exposure of 14-22 R for each procedure. Total radiation exposure was reduced in both groups when the angioplasty procedure was combined with the diagnostic angiogram. These observations should be considered when dilation of a total occlusion is planned. Efforts to reduce the amount of radiation exposure should remain a priority in interventional catheterization laboratories.