Biomedical subjects

J H Reiber

Publications and source records attributed to J H Reiber.

At least 127 records · Page 7Linked to original sources

PubMed1991

Advantages and limitations of two software calipers in quantitative coronary arteriography.

Software calipers allowing the measurement of the distances between pairs of manually defined picture elements in digitized images may be useful tools for a rapid assessment of the morphology of coronary vessels, e.g. for choosing the appropriate balloon or stent sizes before or during cardiac intervention procedures. In this paper we have studied extensively the advantages and limitations of two manual software calipers--one developed for a PC-based cinefilm analysis workstation, the other for the Philips DCI system. Based on analyses of a perspex vessel phantom with 17 sectors of known size filled with different concentrations (50 and 100%) of the contrast agent and acquired at two kV-levels (68 and 92 kV), it was found that the cinefilm approach is characterized by a very small overall (averaged over te data from three observers) systematic overestimation of 0.03 mm, and the DCI system by a systematic underestimation of 0.07 mm; the worst case accuracy value for an individual observer on frames with 100% contrast dye concentration was 0.20 mm for cinefilm, and -0.34 mm for the DCI, respectively. The overall variabilities in the measurements (precision) were almost identical for the two approaches (overall 0.07 and 0.08 mm for the cinefilm and digital approaches, respectively, and worst case for individual observers on the 100% contrast frames, 0.16 and 0.13 mm, respectively. Inverting the images (bright or dark contrast containing structures) of the phantom at 100% contrast concentration and acquired at 62 kV had no significant effect on the results obtained with the cinefilm analysis system (overall accurary -0.12 mm for both situations), whereas it had on the results from the DCI system (overall accuracies -0.29 (dark vessels on bright background) and -0.08 mm (bright vessels on dark background), respectively). Enhancing the digital images on the DCI with unsharp masking techniques did not significantly influence the measurement accuracy and precision. Finally, it was found that woven dacron, polyurethane and polyvinylchloride catheters filled with 100% contrast dye can be measured with an overall accuracy of better than 0.13 mm on the DCI system. On the PC-based system the woven dacron and polyvinylchloride catheters would result in an overall accuracy better than 0.17 mm, and the polyurethane catheter better than 0.30 mm. The evaluation study has made clear that the nylon catheter should not be applied in QCA-studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗

PubMed1990

Usefulness of digital angiography in the assessment of left ventricular ejection fraction.

With modern digital cardiac systems the image data are digitized on-line and in real-time, allowing the replay and subsequent interpretation and analysis during or directly after the cardiac catheterization procedure. In this study we have evaluated the advantages and limitations of a manual tracing technique for left ventricular digital angiograms on the Phillips DCI system. Thirty-three patients who were catheterized for suspected coronary artery disease were studied. The manual tracings were performed by a senior cardiologist and an experienced function-analyst. It was found that the short- and long-term intraobserver variabilities in the assessment of the global ejection fraction were very small; short-term mean difference +/- standard deviation (correlation coefficient): 0.5 +/- 2.7 (r = 0.97) global EF%-units; long term; 0.7 +/- 2.7 (r = 0.96) EF%-units. The interobserver variabilities (5.1 +/- 4.8 (r = 0.93) EF%-units) were slightly higher than the intraobserver variabilities. A decrease by 25% in the amount of contrast medium administered did not significantly influence the variabilities in the contour tracings, which would suggest the use of smaller doses. At the average, the cardiologist and the function-analyst required 6 and 11 min of analysis time for a left ventricular study, respectively, emphasizing the need for further developments towards automated contour detection. Finally, an excellent correlation was found with a standard off-line cinefilm analysis procedure. Thus, it may be concluded that quantitative digital left ventricular angiography based on manual tracing of the outlines performed immediately following the cardiac catheterization (post-processing) is feasible as a routine procedure for the assessment of left ventricular function.

Aged↗

PubMed1990

A new approach for the automated definition of path lines in digitized coronary angiograms.

For the quantitative analysis of a coronary segment from a coronary (cine)angiogram, an initial path line is required which functions as a model for the subsequent automated contour detection. For on-line applications, a new method for the automated definition of arterial path lines has been developed. Required user-interaction consists of the manual definition of a beginning and an endpoint of the arterial segment to be analyzed. The method is based on a combination of a beam tracer and a box technique. A validation study was performed on 47 non obstructed arteries of various lengths and diameters, and on 56 arterial segments with obstructions (up to 86 percent diameter stenosis). In 89% of the cases an acceptable path line was found after the first iteration; the success score increased to 99%, if a simple manual correction was allowed (2 iterations). The method is extremely fast: the overall average search time for the first iteration was 266 ms, for the second iteration 211 ms. Therefore, it may be concluded that this new technique for the automated definition of arterial path lines is extremely suitable for on-line applications.

Algorithms↗

PubMed1990

Developments towards the slice-wise three-dimensional reconstruction of the distribution of the contrast perfusion in the myocardial muscle from biplane angiographic views.

In theory, radiographic myocardial perfusion imaging allows a quantitative assessment of the functional significance of a coronary stenosis. However, in the conventional two-dimensional projection images there does not exist a one-two-one relationship between a selected myocardial region of interest (ROI) and one particular coronary segment perfusing that area due to over-projection of myocardial regions in front of and behind the selected ROI perfused by other arterial segments, which may result in measurements which are difficult to interpret or even unreliable. To overcome these problems, we have developed two algorithms to determine the spatial distribution of perfusion levels in slices of the heart, selected approximately perpendicular to the left ventricular long axis, from two orthogonal angiographic views: the Segmental Reconstruction Technique (SRT) and the Network Programming Reconstruction Technique (NPRT). Both techniques require a priori geometric information about the myocardium, which can be obtained from the epicardial coronary tree (epicardial boundaries) and the left ventricular lumen (endocardial boundaries). Using the SRT approach, pie-shaped segments are defined for each slice within the myocardial geometric constraints such that superimposition of these segments when projected in orthogonal biplane views is minimal. The reconstruction process uses a model with identical myocardial geometry and definition of segments. Each segment of the model is assigned a relative perfusion level with unit one if no other a priori information is available. In this case, the model contains geometric information only. In case a priori information about expected segmental perfusion levels is available, a level between zero and one is assigned to each segment. The a priori information on the myocardial perfusion levels can be extracted from either anatomic information about the location and severity of existing coronary arterial obstructions, or from a slice adjacent to the one under reconstruction. Using the NPRT approach perfusion levels are computed for each volume picture element of a slice within the reconstructed myocardial geometry, thus resulting in a much higher spatial resolution than the SRT approach. A priori information of perfusion levels must be included in this approach, again based upon anatomical information, or upon the slice adjacent to the one under reconstruction. The very first slice of a myocardial study will be reconstructed by the SRT approach. Extensive computer simulations for the SRT have proved that the mean difference between the actual and reconstructed segmental perfusion levels, on a scale from 0 to 1, is smaller than 0.45 (SEE = 0.0033, REE = 1.80) for various coronary artery disease states without the use of a priori information on expected perfusion levels. This error becomes smaller than 0.36 (SEE = 0.0026, REE = 1.42), if a priori information in the reconstruction technique is included. Similar computer simulations for the NPRT have proved that these mean differences in geometric segments equal to those defined for the SRT, are smaller than 2.94 (SEE = 0.0308, REE = 0.77) on a scale from 0 to 16, without the use of a priori information on expected perfusion levels, and smaller than 1.72 (SEE = 0.0304, REE = 1.10) on the same scale when a priori information is included. Therefore, it may be concluded that slice-wise three-dimensional reconstruction of perfusion levels is feasible from biplane computer-simulated data, and that a similarity exists for mean perfusion levels in corresponding regions in the simulated and reconstructed slices, for various states of single coronary artery disease.

Algorithms↗

PubMed1989

How critical is frame selection in quantitative coronary angiographic studies?

To analyse quantitatively a coronary arterial segment from a cineangiogram, an end-diastolic or neighbouring frame is usually selected. However, different cardiologists may select other (although usually neighbouring) frames, even when the same selection criteria are followed. It is also possible that the frames are selected from different cardiac cycles. In this study the effects of such phase shifts on the reproducibility of the quantitative measurements were studied. In a total of 38 consecutive patient films obtained at a filmspeed of 25 frames s-1, the frame phi demonstrating the severity of a lesion optimally as judged by a senior cardiologist, the three preceding frames, the three following frames and one frame exactly one cycle prior to or following frame phi were selected; frame phi was always chosen in the end-diastolic phase of the cardiac cycle. In each film one coronary arterial segment with a focal lesion was analysed quantitatively in these total of 8 frames with the Cardiovascular Angiography Analysis System (CAAS). No significant differences were found in the mean difference and the standard deviations of the differences (variabilities) in the obstruction diameter, interpolated reference diameter, percent diameter stenosis, extent of the obstruction and area of atherosclerotic plaque obtained in the various frames with respect to frame phi. Therefore, it may be concluded that the selection of a cineframe for quantitative analysis in the end-diastolic phase of the cardiac cycle is not very critical.(ABSTRACT TRUNCATED AT 250 WORDS)

Cineangiography↗

PubMed1989

[Computer-assisted geometric measuring technic in coronary angiography interval studies: results of initial angiograms of the International Nifedipine Trial of Anti-atherosclerotic Therapy (INTACT) study].

In 396 of 423 (93.6%) patients with mild to moderate coronary artery disease participating in a coronary angiographic follow-up trial, diameters of the epicardial coronary arteries were measured with an automatic contour detection system (CAAS). The underlying INTACT study (International Nifedipine Trial on Antiatherosclerotic Therapy), a prospective, placebo-controlled, randomized, double-blind multicenter trial, investigates the influence of the calcium antagonist nifedipine (80 mg/day) on the progression of coronary atherosclerosis over a three-year interval. The study is based on coronary angiograms repeated in identical projections after premedication with 10 mg isosorbide dinitrate sublingually. For quantitative analysis the coronary artery system was, in consideration of all anatomical variations, subdivided into 25 segments. In the first angiograms of the 396 patients evaluated up to April 1, 1988, altogether 5,425 different coronary segments could be analyzed over their entire length in one or more angiographic projections--on the average 13.7 +/- 2.8 segments per patient. Analysis parameters were the mean diameters of the entire segments and of the individual subsegments (about 5 mm in length). The 10 major proximal segments could be evaluated in 76-94% of patients respectively in more than two different angiographic projections on the average; in 0-13% of patients the respective segments were occluded. In 1-4% of patients the evaluation of these segments was prevented by poor film quality and in 1-16% of patients prevented by anatomical abnormalities (e.g., segment too short or too small). 184 segments were found occluded (RCA 42%, LAD 30%, CX 28%) and 909 mostly low-grade to moderate stenoses (RCA 34%, CX 32%, LAD 30%, left main 4%) were analyzed with a special algorithm. The following obstruction parameters were derived: minimal diameter, percentage severity, length, and plaque area. The present data demonstrate that in an angiographical multicenter follow-up study such as INTACT a nearly complete quantitative morphometric analysis of the visualized coronary artery system can indeed be obtained in virtually all angiograms when a computer-assisted contour detection system is applied.

Clinical Trials as Topic↗

PubMed1988

Does intracoronary papaverine dilate epicardial coronary arteries? Implications for the assessment of coronary flow reserve.

Intracoronary papaverine is used as a means to induce a strong and short-lasting hyperemia in several recently developed methods to measure coronary flow reserve. Changes in stenosis geometry from papaverine would influence the measured coronary flow reserve. Therefore, we investigated the influence of intracoronary papaverine on stenosis geometry with quantitative analysis of the coronary angiogram and assessed the influence of papaverine on pressure-flow characteristics of the stenosis and coronary flow reserve. The cross-sectional areas (mean +/- SD) of the stenosis increased 18% +/- 7% after papaverine. The normal proximal and distal parts of the coronary artery dilated 5% +/- 2% after papaverine. This results in a decrease of the calculated pressure drop over the stenosis varying from 20% to 30%. Coronary flow reserve of a flow-limiting epicardial stenosis is overestimated by 16% when papaverine is used to induce hyperemia. These papaverine-induced changes can nevertheless be circumvented by maximal vasodilation of the major epicardial coronary artery with 3 mg intracoronary isosorbidedinitrate prior to the investigation of the coronary flow reserve with papaverine.

Angiography↗

PubMed1988

Variabilities in measurement of coronary arterial dimensions resulting from variations in cineframe selection.

To quantitatively analyze a coronary arterial segment from a cineangiogram, an end-diastolic or neighboring cineframe is usually selected, such that a possibly existing coronary lesion is visualized optimally, as judged by the cardiologist. However, different cardiologists may select different (although usually neighboring) frames, even when following the same selection criteria. It is also possible that the frames are selected from different cardiac cycles. In this study the effects of such phase shifts on the reproducibility of the quantitative measurements were studied. In a total of 38 consecutive patient films obtained at a filmspeed of 25 frames/sec, the frame 0 demonstrating the severity of a lesion optimally, as judged by a senior cardiologist, the three preceding frames, the three following frames and one frame exactly one cycle prior to or following frame 0 were selected; frame 0 was always chosen in the end-diastolic phase of the cardiac cycle. In each film one coronary arterial segment with a focal lesion was analyzed quantitatively in these eight frames with the Cardiovascular Angiography Analysis System (CAAS). No significant differences were found in the mean difference and the standard deviations of the differences (variabilities) in the obstruction diameter, interpolated reference diameter, percent diameter stenosis, extent of the obstruction and area of atherosclerotic plaque obtained in the various frames with respect to frame 0. Therefore, it may be concluded that the selection of a cineframe for quantitative analysis in the end-diastolic phase of the cardiac cycle is not very critical; in other words, the obstruction measurements are not time-dependent for frames in the end-diastolic phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Cineangiography↗

PubMed1988

Clinical application of quantitative coronary angiography using the CAAS system: preliminary results of the INTACT study (International Nifedipine Trial on Antiatherosclerotic Therapy).

It is the objective of the INTACT-study to test in man, whether a significant retardation of the progression of coronary artery disease is attainable with the Ca-antagonist nifedipine; this may be possible on the basis of numerous animal experiments. INTACT is a prospective, randomized, double blind, placebo controlled investigation in 423 patients with preferably early stages of coronary sclerosis in whom a progression of the disease seems likely. A proper coronary angiogram led to inclusion of the patients in the study (October 1983-June 1985). Over the following 3-years-period patients received either nifedipine 80 mg/day or placebo. The study is concluded by a control coronary angiogram with angiographic projections which are identical to those of the first coronary angiography. The extent of coronary sclerosis is objectivated by computer-assisted quantitative measurement of the entire coronary arterial system with the CAAS-system (Rotterdam). For definition purposes the coronary artery system subdivided into 25 segments. Parameters for progression assessment will be mean segment diameter, minimal obstruction diameter, percentage severity of obstruction, length of obstruction and plaque area. So far 4826 coronary segments have been analyzed from the first angiograms of 383 patients. Per patient an average of 12.6 different segments could be evaluated in at least one angiographic projection. The major coronary segments could be measured in 72-93% of the patients in one or more angiographic projections (at the average about 2 different projections). Five hundred and forty-six coronary obstructions were analyzed; 131 of these were total occlusions. Only 9% of the length of the vessel contours detected by the computer algorithm required manual correction by the operators, suggesting a high reliability of the system. It can be concluded that quantitative measurement of the complete coronary artery system can indeed be obtained in a large angiographical multicenter study such as INTACT.

Angiography↗

PubMed1988

Angioplasty for stable versus unstable angina pectoris: are unstable patients more likely to get restenosis? A quantitative angiographic study in 339 consecutive patients.

Current evidence with regard to the possible association between clinical expression of coronary disease prior to the time of angioplasty, and the subsequent risk of restenosis following successful dilatation, remains inconclusive. To prospectively compare the incidence of restenosis in stable versus unstable angina pectoris patients, follow-up angiography was performed in 85 percent of patients from a consecutive series with a successful PTCA, irrespective of presence or absence of recurrent ischemic symptoms. Furthermore, changes in lesion severity were assessed quantitatively by an automated edge-detection technique rather than visual analysis. Employing such a study design and follow-up protocol, it was found that the incidence of restenosis in patients with stable coronary artery disease was similar to that of patients with unstable rest angina, irrespective of the type of angiographic definition used.

Angina Pectoris↗

PubMed1988

Correlations between quantitative cineangiography, coronary flow reserve measured with digital subtraction cineangiography and exercise thallium perfusion scintigraphy.

The goal of this investigation was to establish which anatomical parameters of stenotic lesions correlate best with its functional severity. Therefore, thirty-eight patients with single vessel disease underwent coronary cineangiography and exercise/redistribution thallium-201 scintigraphy. Cross-sectional area at the site of obstruction (OA), percentage diameter stenosis (DS), the calculated pressuredrop over the stenosis (PD), as well as coronary flow reserve (CFR) derived from myocardial contrast appearance time and density were determined. The relations between CFR and the 3 anatomical parameters were described by the following equations: CFR = 4.6 - 0.053 DS, r = 0.82, SEE: 0.79, p less than 0.001 CFR = 0.5 + 0.75 OA, r = 0.87, SEE: 0.68, p less than 0.001 CFR = 3.6 - 1.5 log PD, r = 0.90, SEE: 0.62, p less than 0.001 The calculated pressuredrop was highly predictive of the thallium scintigraphic results with a sensitivity of 94% and a specificity of 90%. Therefore, the calculated pressuredrop is a better anatomical parameter for assessing the functional importance of a stenosis than percentage diameter stenosis or obstruction area. However, the 95% confidence limits of the relation between pressuredrop and coronary flow reserve are wide, making measurement of CFR a valuable addition to quantitative angiography, especially when determining the functional importance of moderately severe coronary artery lesions.

Adult↗

PubMed1988

Three-dimensional reconstruction of myocardial contrast perfusion from biplane cineangiograms by means of linear programming techniques.

The assessment of coronary flow reserve from the instantaneous distribution of the contrast agent within the coronary vessels and myocardial muscle at the control state and at maximal flow has been limited by the superimposition of myocardial regions of interest in the two-dimensional images. To overcome these limitations, we are in the process of developing a three-dimensional (3D) reconstruction technique to compute the contrast distribution in cross sections of the myocardial muscle from two orthogonal cineangiograms. To limit the number of feasible solutions in the 3D-reconstruction space, the 3D-geometry of the endo- and epicardial boundaries of the myocardium must be determined. For the geometric reconstruction of the epicardium, the centerlines of the left coronary arterial tree are manually or automatically traced in the biplane views. Next, the bifurcations are detected automatically and matched in these two views, allowing a 3D-representation of the coronary tree. Finally, the circumference of the left ventricular myocardium in a selected cross section can be computed from the intersection points of this cross section with the 3D coronary tree using B-splines. For the geometric reconstruction of the left ventricular cavity, we envision to apply the elliptical approximation technique using the LV boundaries defined in the two orthogonal views, or by applying more complex 3D-reconstruction techniques including densitometry. The actual 3D-reconstruction of the contrast distribution in the myocardium is based on a linear programming technique (Transportation model) using cost coefficient matrices. Such a cost coefficient matrix must contain a maximum amount of a priori information, provided by a computer generated model and updated with actual data from the angiographic views. We have only begun to solve this complex problem. However, based on our first experimental results we expect that the linear programming approach with advanced cost coefficient matrices and computed model will lead to acceptable solutions in the 3D-reconstruction of the myocardial contrast distribution from biplane cineangiograms.

Cineangiography↗

PubMed1988

Change in diameter of coronary artery segments adjacent to stenosis after percutaneous transluminal coronary angioplasty: failure of percent diameter stenosis measurement to reflect morphologic changes induced by balloon dilation.

To determine the changes in stenotic and nonstenotic segments of a dilated coronary artery, detailed quantitative angiographic measurements were performed in 342 patients (398 lesions) immediately after angioplasty and at a predetermined follow-up time of 30, 60, 90 or 120 days after the dilation. Measurements of the stenotic segments were expressed as minimal luminal diameter, and the adjacent nonstenotic segments were expressed as interpolated reference diameter (both in millimeters). A follow-up rate of 86% was achieved. In the patients followed up at 30 and 60 days, there was no significant change in either the mean minimal luminal diameter or the mean reference diameter. However, at 90 and 120 days, there was significant deterioration in both the mean minimal luminal diameter (-0.37 and -0.42 mm, respectively) and the mean reference diameter (-0.17 and -0.26 mm, respectively), all of the changes being highly significant (p less than 0.00001). The reference diameter is involved in the dilation process and may be subject to the same restenosis process that takes place in initially stenotic segments. Percent diameter stenosis measurements, which are conventionally used to express the change in the severity of a stenosis after angioplasty, will tend to underestimate the change when there is a simultaneous reduction in the reference diameter.

Aged↗

PubMed1988

Which cineangiographically assessed anatomic variable correlates best with functional measurements of stenosis severity? A comparison of quantitative analysis of the coronary cineangiogram with measured coronary flow reserve and exercise/redistribution thallium-201 scintigraphy.

The goal of this investigation was to establish which measured anatomic variable of stenotic coronary lesions correlates best with functional severity. Therefore, 38 patients with single vessel disease underwent coronary cineangiography and exercise/redistribution thallium-201 scintigraphy. The computer-based Cardiovascular Angiography Analysis System was used to determine the cross-sectional area at the site of obstruction (OA) and percent diameter stenosis (DS), and to calculate the pressure drop over the stenosis (PD) with use of fluid dynamic equations. Coronary flow reserve was measured radiographically. Myocardial perfusion defects on thallium scintigrams were analyzed quantitatively and by visual interpretation. The relations between coronary flow reserve (CFR) and the three anatomic variables were described by the following equations: 1) CFR = 4.6 - 0.053 DS, r = 0.82; SEE: 0.79, p less than 0.001. 2) CFR = 0.5 + 0.75 OA, r = 0.87; SEE: 0.68, p less than 0.001). 3 CFR = 3.6 - 1.5 log PD, r = 0.90; SEE: 0.62, p less than 0.001. The calculated pressure drop was highly predictive of the thallium scintigraphic results with a sensitivity of 94% and a specificity of 90%. The calculated pressure drop is a better anatomic variable for assessing the functional importance of a stenosis than is percent diameter stenosis or obstruction area. However, the 95% confidence limits of the relation between pressure drop and coronary flow reserve are wide, making the measurement of coronary flow reserve an indispensable addition to quantitative angiography, especially when determining the functional importance of moderately severe coronary artery lesions.

Adult↗

PubMed1988

Improvement in transient and 'persistent' perfusion defects on early and late post-exercise thallium-201 tomograms after coronary artery bypass grafting.

In order to assess the changes in the number and severity of transient and persistent myocardial perfusion defects before and after coronary artery bypass grafting (CABG), early and late post-exercise thallium-201 (tl-201) tomography was performed in 25 patients, on average 10 days before and 2.5 months after CABG. Six patients had a previous Q wave myocardial infarction. Comparing the pre- and post-CABG exercise test data (symptom limited bicycle ergometry) showed an improvement in working capacity (from 129 +/- 34 to 145 +/- 35 W, P less than 0.05) and a reduction in exercise induced angina from 77 to 9% of the patients (P less than 0.001). From the tomographic data, six short axis and three sagittal cross-sections of the left ventricular myocardium were reconstructed. In each patient study, a total of 51 myocardial segments were defined and analysed in a semi-quantitative manner by means of a five point scoring method indicative of the severity of a defect (from 0 = normal tl-201 uptake to 4 = absence of tl-201 activity). In this patient population the total number of segments with transient tl-201 perfusion defects decreased from 11.0 +/- 7 segments per patient (mean +/- SD) before surgery to 4.9 +/- 4 after surgery (P less than 0.01); the number of segments with 'persistent' tl-201 defects decreased as well, from 7.5 +/- 6 to 3.9 +/- 4 segments per patient (P less than 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Artery Bypass↗

PubMed1988

Prognosis and thallium-201 scintigraphy in patients admitted with chest pain without confirmed acute myocardial infarction.

Exercise and rest thallium scintigraphy and exercise electrocardiography were performed after discharge in 158 patients aged less than 76 years admitted with chest pain in whom a suspected diagnosis of acute myocardial infarction had not been confirmed. During a follow up of 12-24 months (median 14 months) there were 10 cardiac events--that is, non-fatal acute myocardial infarction or cardiac deaths. Transient thallium defects and abnormal ST response (that is ST segment deviation or uninterpretable ST segment) during exercise were correlated significantly with an unfavourable prognosis. One hundred and four patients with neither of these characteristics were at lower risk of a cardiac event than the 19 patients with both of these characteristics. The percentages of patients in these two groups without a cardiac event after one year were 98.1 and 78.8 respectively. Thallium scintigraphy, alone or in combination with exercise electrocardiography, can be used to identify groups at high and low risk of future cardiac events, in patients with chest pain in whom acute myocardial infarction is suspected but not found.

Chest Pain↗

PubMed1988

Incidence of restenosis after successful coronary angioplasty: a time-related phenomenon. A quantitative angiographic study in 342 consecutive patients at 1, 2, 3, and 4 months.

Data from experimental, clinical, and pathologic studies have suggested that the process of restenosis begins very early after coronary angioplasty. The present study was performed to determine prospectively the incidence of restenosis with use of the four National Heart, Lung, and Blood Institute and the 50% or greater diameter stenosis criteria, as well as a criterion based on a decrease of 0.72 mm or more in minimal luminal diameter. Patients were recatheterized at 30, 60, 90, or 120 days after successful percutaneous transluminal coronary angioplasty (PTCA). After PTCA all patients received 10 mg nifedipine three to six times a day and aspirin once a day until repeat angiography. Of 400 consecutive patients in whom PTCA was successful (less than 50% diameter stenosis), 342 underwent quantitative angiographic follow-up (86%) by use of an automated edge-detection technique. A wide variation in the incidence of restenosis was found dependent on the criterion applied. The incidence of restenosis proved to be progressive to at least the third month for all except NHLBI criterion II. At 4 months a further increase in the incidence of restenosis was observed when defined as a decrease of 0.72 mm or more in minimal luminal diameter, whereas the criteria based on percentage diameter stenosis showed a variable response. The lack of overlap between the different restenosis criteria applied affirms the arbitrary nature of angiographic definitions currently in use. Restenosis should be assessed by repeat angiography, and preferably ascertained according to the change in absolute quantitative measurements of the luminal diameter.

Adult↗

PubMed1988

Assessment of immediate and long-term functional results of percutaneous transluminal coronary angioplasty.

Assessment of the functional significance of coronary artery lesions during cardiac catheterization has recently become possible by calculating coronary flow reserve from both myocardial contrast appearance time and density in the resting and hyperemic states determined from digitized coronary cineangiograms. However, the interobserver and intraobserver variabilities, as well as the short-, medium-, and long-term variabilities of the coronary flow reserve measurements, have to be established before this technique becomes an acceptable means of assessing the immediate and long-term functional results of revascularization procedures such as percutaneous transluminal coronary angioplasty (PTCA). Variability was defined as the mean difference and standard deviation of the difference between duplicate determinations of coronary flow reserve. The intraobserver variability (mean difference +/- SD) in the measurement of coronary flow reserve was -0.01 +/- 0.07. Interobserver variability by two observers was +0.08 +/- 0.52. Short-term variability based on the analysis of two coronary cineangiograms taken 5 minutes apart was -0.02 +/- 0.26. Medium-term variability (coronary cineangiographies repeated 1-3 hours apart) was found to be -0.06 +/- 0.52. Long-term variability (coronary cineangiographies repeated 3-5 months apart) was 0.11 +/- 0.63. Having established the reproducibility of this radiographic method, we studied the prospective changes in coronary flow reserve in 25 patients undergoing PTCA for single vessel coronary artery disease. Coronary flow reserve measurements and quantitative coronary cineangiography were performed before, immediately after, and 3-5 months after PTCA. PTCA resulted in an immediate increase in coronary flow reserve from 1 +/- 0.3 to 2.3 +/- 0.6 with a concomitant increase in obstruction area from 0.9 +/- 0.3 to 3.3 +/- 0.7 mm2. Nine of the 25 patients developed restenosis defined as a diameter stenosis greater than 50% at follow-up. The other 16 patients had a coronary flow reserve of 3.3 +/- 0.6, which was measured 3-5 months after PTCA. Coronary flow reserve measurement from digitized coronary cineangiograms is a reproducible method for the assessment of the physiological importance of coronary artery obstructions. Short-, medium-, and long-term investigations of the functional results of interventions such as pharmacological therapy or revascularization can be performed reliably with this technique.

Adult↗