Quantitative Coronary Arteriography Research Articles

Towards a gold standard for quantitative coronary arteriography

Densitometric quantification of coronary artery stenoses in angiographic images can be problematic for two reasons: (i) the x-rays are inadequately oriented with respect to the vessel segments of interest at image acquisition; (ii) non-linear effects due for instance to beam hardening, scattered radiation and veiling glare may reduce the accuracy. As a consequence, appreciable discrepancies between degrees of stenosis measured in two different projections can occur. To overcome these limitations, we have designed and tested a combined correction that compensates (at subsequent analysis) for the error contributions due to the cited sources. It implies 3D reconstruction of the vessel segments of interest and consequently requires an appropriate biplane coronary angiogram. In experiments performed with a dedicated phantom, application of the correction improved the correlation between measured and true area reduction percentages (without correction: y = 1.04x - 4%, r = 0.97, SEE = 6%, n = 35; with correction: y = 1.02x - 0%, r = 0.99, SEE = 3%, n = 35). Applied to ten area stenoses measured biplane in patients and exhibiting strong interplane discrepancies, the correction had a comparable effect (without correction: y = 0.83x - 11%, r = 0.86, SEE = 9%, n = 10; with correction: y = 0.83x + 2%, r = 0.98, SEE = 4%, n = 10). The new densitometric method could possibly be used as a gold standard in the objective evaluation of geometric methods in patients.

Bradykinin-Induced Vasodilation of Human Coronary Arteries In Vivo: Role of Nitric Oxide and Angiotensin-Converting Enzyme

Objectives. The present study aimed to determine the role of nitric oxide (NO) and angiotensin-converting enzyme (ACE) in bradykinin (BK)-induced dilation of human coronary arteries in vivo.Background. BK, produced by way of the kinin-kallikrein system, causes endothelium-dependent vasodilation. However, little is known about the mechanism of BK-induced dilation of coronary arteries in humans in vivo.Methods. The effects of an inhibitor of NO synthesis and of an ACE inhibitor on BK-induced coronary vasodilation were examined in 20 patients who had no significant atherosclerotic stenosis in the artery under study. Lumen diameters of the large epicardial coronary arteries and coronary blood flow (CBF) were measured by quantitative coronary arteriography and intracoronary Doppler technique.Results. Intracoronary infusion of BK (0.6 and 2.0 μg/min) increased coronary artery diameter and CBF with no change in arterial pressure or heart rate. The BK-induced increases in coronary artery diameter and CBF were significantly reduced (p < 0.01) after pretreatment with NG-monomethyl-l-arginine (200 μmol) and were significantly increased (p < 0.01) after pretreatment with enalaprilat (50 μg).Conclusions. BK-induced dilation of human large epicardial and resistance coronary arteries is mediated by NO and increased by prior ACE inhibition.(J Am Coll Cardiol 1997;30:108–12)

Coronary vasodilation without myocardial erection. Simultaneous haemodynamic, echocardiographic and arteriographic findings during adenosine and dipyridamole infusion.

The aim of this study was to evaluate simultaneously echocardiographic, haemodynamic and angiographic changes that occur during adenosine and dipyridamole infusion, in patients with one-vessel coronary artery stenosis. This would assess whether deterioration in left ventricular haemodynamics during vasodilator agent infusion is influenced by vasodilation per se, or the development of myocardial ischaemia. We performed adenosine (140 micrograms.kg-1.min-1 over 4 min) and dipyridamole (up to 0.84 mg.kg-1 over 10 min) stress echocardiography tests, together with angiographic and haemodynamic assessment, in 26 patients undergoing elective coronary angioplasty. In 12 of 26 patients, adenosine and dipyridamole tests were repeated 24 h after angioplasty. The criterion for echocardiography test positivity was the appearance of a new transient regional wall motion abnormality. Coronary angiograms were analysed with quantitative coronary arteriography. Adenosine and dipyridamole induced regional dysfunction in 18/26 (69%) and 14/26 (54%) patients before angioplasty, respectively (P = ns). In the echocardiography-positive patients, the percent diameter stenosis was significantly (P < 0.05) tighter stenosis than in the echocardiography-negative patients (adenosine, 66.6 +/- 8.3% vs 58.0 +/- 8.9%; dipyridamole, 69.2 +/- 7.1% vs 57.7 +/- 7.6%). During both tests, left ventricular end-diastolic pressure significantly increased (P < 0.05) in echocardiography-positive patients (adenosine, 9.8 +/- 2.7 mmHg to 13.5 +/- 4.1 mmHg; dipyridamole, 10.1 +/- 2.8 mmHg to 14.1 +/- 4.3 mmHg), but not in echocardiography-negative patients. In the patients who had undergone successful angioplasty (reduction to < 50% diameter stenosis), both adenosine and dipyridamole confirmed the arteriographic success of the procedure (echocardiography negative in all patients). In this group of patients, no significant change was observed in left ventricular end-diastolic pressure during adenosine or dipyridamole infusion. Intravenous infusion of either adenosine or dipyridamole was accompanied by an obvious increase in left ventricular end-diastolic pressure only in patients with induced wall motion abnormalities. Coronary vasodilation per se has no significant effect on left ventricular end-diastolic pressure when no ischaemia is induced, disproving any clinically significant 'erectile' and adverse effects of coronary vasodilation per se.

Role of endothelium-derived nitric oxide in coronary vasodilatation induced by pacing tachycardia in humans: K. Egashira, Y. Katsuda, M. Mohn, T. Kuga, T. Tagawa, T. Kubota, Y. Hirakawa, A. Takeshita. RIACC, Kyushu University School of Mediane, Fukuoka, Japan. Circ Res 1996;79:331–5

Endothelium-derived NO contributes to the control of coronary perfusion. We investigated the roles of NO in the metabolic coronary vasodilatation induced by rapid pacing in humans. We evaluated the dilatation of large epicardial and resistance coronary arteries during rapid atrial pacing before and after intracoronary infusion of NG-monomethyl-l-arginine (L-NMMA), an inhibitor of NO synthesis, in 19 patients without significant coronary artery disease. The diameter of the large epicardial coronary artery and coronary blood flow (CBF) were assessed by quantitative coronary arteriography and by a Doppler flow velocity measurement. An increase in the heart rate increased CBF (P<.01) and the coronary artery diameter (P<.05). L-NMMA at a total dose of 200 μmol reduced basal CBF but did not significantly affect basal coronary artery diameter, arterial pressure, or heart rate. L-NMMA inhibited the pacing-induced dilatation of the large coronary arteries (P<.05) but did not affect pacing-induced increases in CBF....

Validation of a New System in Quantitative Coronary Arteriography

Validation of a New System in Quantitative Coronary Arteriography

Validation of a new UNIX-based quantitative coronary angiographic system for the measurement of coronary artery lesions.

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.

Relation of Coronary Calcium Score by Electron Beam Computed Tomography to Arteriographic Findings in Asymptomatic and Symptomatic Adults

Coronary arteriography was performed on 18 asymptomatic, apparently healthy adults with elevated coronary calcium scores. To extend the range of observation to subjects with low calcium scores, arteriograms from 18 patients with exertional dyspnea and/or valvular heart disease and low calcium scores were also analyzed; these 18 patients were considered asymptomatic from the point of view of coronary artery disease (CAD). For the comparison of symptomatic and asymptomatic persons, 3 age and sex-matched symptomatic patients were also selected for each of the original 18 asymptomatic subjects. Arteriograms were analyzed by computer-assisted quantitative coronary arteriography at a remote site without knowledge of the calcium score or any other patient characteristics. In the 18 asymptomatic subjects with elevated calcium scores, the mean calcium score was 573 ± 504 (Agatston method) and the mean worst stenosis was 45% ± 16%. For all 36 patients without symptoms of CAD, worst stenosis was closely correlated with the square root of the calcium score (r = 0.85, p <0.0001). Patients with symptomatic coronary disease and calcium scores <1,000 had stenoses more severe than asymptomatic persons with similar calcium scores. Most asymptomatic adults with elevated calcium scores have nontrivial, nonobstructive CAD or preclinical obstructive CAD, and the relation between coronary calcium score and severity of stenosis is highly significant. These data indicate that electron beam tomography can be used to estimate the severity of CAD in asymptomatic persons.

Parameters that influence accuracy and precision of quantitative coronary arteriography.

The limited resolution of any imaging system causes edge blurring of objects acquired with X-ray. In digital angiography, this effect combined with noise gives rise to systematic and random errors in the determination of vessel dimensions. The influence of bandwidth limitation on the estimation of tube diameter is established by a theoretical approach: it leads to over and underestimations of catheter and vessel diameter dimensions. Therefore a correction is proposed that counterbalances the point spread function (PSF) offset. The residual inaccuracy and the variability of measurement of phantom tubes are analyzed and evaluated in controlled conditions. Some of the parameters which govern their extent are identified: field-of-view, catheter size, concentration of contrast agent.

Variations in normal coronary vasodilatory reserve stratified by artery, gender, heart transplantation and coronary artery disease

The purpose of the study was to assess the spectrum of coronary vasodilatory reserve values in patients with angiographically normal arteries who had atypical chest pain syndromes or remote coronary artery disease or were heart transplant recipients. The measurement of post-stenotic coronary vasodilatory reserve, now possible in a large number of patients in the cardiac catheterization laboratory, is increasingly used for decision making. Controversy exists regarding the range of normal values obtained in angiographically normal coronary arteries in patients with different clinical presentations. Quantitative coronary arteriography was performed in 214 patients classified into three groups: 85 patients with chest pain syndromes and angiographically normal arteries (group 1); 21 patients with one normal vessel and at least one vessel with > 50% diameter lumen narrowing (group 2); and 108 heart transplant recipients (group 3). Coronary vasodilatory reserve (the ratio of maximal to basal average coronary flow velocity) was measured in 416 arteries using a 0.018-in. (0.04 cm) Doppler-tipped angioplasty guide wire. Intracoronary adenosine (8 to 18 micrograms) was used to produce maximal hyperemia. Coronary vasodilatory reserve was higher in angiographically normal arteries in patients with chest pain syndromes (group 1:2.80 +/- 0.6 [group mean +/- SD]) than in normal vessels in patients with remote coronary artery disease (group 2: 2.5 +/- 0.95, p = 0.04); both values were significantly higher than those in the post-stenotic segment of the diseased artery (1.8 +/- 0.6, p < 0.007). Coronary vasodilatory reserve in transplant recipients (group 3) was higher than that in the other groups (3.1 +/- 0.9, p < 0.05 vs. groups 1 and 2) as a group and for individual arteries. When stratified by vessel, coronary vasodilatory reserve was similar among the left anterior descending, left circumflex and right coronary arteries. There were no differences between coronary vasodilatory reserve values on the basis of gender for patients with coronary artery disease and transplant recipients. In group 1 (chest pain), there was a trend toward higher coronary vasodilatory reserve in men than in women (2.9 +/- 0.6 vs 2.7 +/- 0.6, p = 0.07). These findings identify a normal reference range for studies assessing the coronary circulation and post-stenotic coronary vasodilatory reserve in patients with and without coronary artery disease encountered in the cardiac catheterization laboratory.

Abnormal Coronary Vasomotion in Hypertension: Role of Coronary Artery Disease

Objectives. This study sought to evaluate the effect of dynamic exercise on coronary vasomotion in hypertensive patients in the presence and absence of coronary artery disease.Background. Endothelial dysfunction with abnormal coronary vasodilation in response to acetylcholine has been reported in patients with arterial hypertension.Methods. Coronary artery dimensions of a normal and stenotic vessel segment were determined in 64 patients by biplane quantitative coronary arteriography at rest and during supine bicycle exercise. Patients were classified into two groups: 20 patients without evidence of coronary artery disease (10 normotensive, 10 hypertensive [group 1]) and 44 patients with coronary artery disease (26 normotensive, 18 hypertensive [group 2]). Both groups were comparable with regard to clinical characteristics, serum cholesterol levels, body mass index, exercise capacity and hemodynamic data.Results. Mean aortic pressure was significantly higher in hypertensive than normotensive patients. Exercise-induced vasodilation of the normal vessel segment was similar in normotensive and hypertensive patients without coronary artery disease (group 1), namely, +19% versus +20%. However, in hypertensive patients with coronary artery disease, exercise-induced vasodilation was significantly less in both normal and stenotic vessel segments than in normotensive subjects (+1% vs. +20% for normal [p < 0.003] and −20% vs. −5% for stenotic vessels [p < 0.025]). Administration of 1.6 mg of sublingual nitroglycerin at the end of exercise led to a normalization of the vasodilator response in normotensive as well as hypertensive patients. However, this response became progressively abnormal in group 2 when coronary artery disease was present.Conclusions. In the absence of coronary artery disease, the vasomotor response to exercise is normal in both normotensive and hypertensive patients. However, in hypertensive patients with coronary artery disease, an abnormal response of the coronary vessels can be observed, with a reduced vasodilator response to exercise in normal arteries but an enhanced vasoconstrictor response in stenotic arteries. This behavior of the epicardial vessels during exercise suggests the occurrence of endothelial dysfunction (i.e., functional defect) that is not evident in the absence of coronary artery disease. Nitroglycerin reverses impaired coronary vasodilation, but this effect is blunted in the presence of coronary artery disease (i.e., structural defect).

Dobutamine positron emission tomography: Absolute quantitation of rest and dobutamine myocardial blood flow and correlation with cardiac work and percent diameter stenosis in patients with and without coronary artery disease

Objectives. This study sought to measure myocardial blood flow at rest and during dobutamine infusion and to correlate flow with cardiac work and severity of coronary artery disease.Background. Dobutamine is used with cardiac imaging to induced possible ischemia in patients with known or suspected coronary artery disease. Positron emission tomography permits noninvasive quantitation of myocardial blood flow.Methods. Fifteen patients with quantitative coronary arteriography were studied at rest and during dobutamine infusion using nitrogen-13 ammonia flow imaging with positron emission tomography. Myocardial blood flow was determined in regions corresponding to the three major coronary arteries for myocardium with and without dobutamine flow defects and with and without a >50% diameter stenosis.Results. Eight patients had at least one dobutamine flow defect; four of whom had a previous myocardial infarction. One patient with >50% diameter stenosis had no flow defects, and one with < 50% diameter stenosis (49%) had one defect. Dobutamine significantly increased myocardial blood flow in regions with and without a dobutamine flow defect or >50% diameter stenosis, with a greater increase when a defect or >05% diameter stenosis was not present. Rest and dobutamine flows in regions without >50% diameter stenosis were 0.93 ± 0.20 (mean ± SD) and 2.16 ± 0.52 ml/min per g (p < 0.01), respectively. The corresponding flows in regions without a defect were 0.94 ± 0.21 and 2.17 ± 0.53 ml/min per g (p < 0.01), respectively. This 2.4-fold increase in flow was significantly correlated (p < 0.001) with a 2.2-fold increase in rate-pressure product induced by dobutamine. The rest and dobutamine flows for regions subtended by a vessel with >50% diameter stenosis were 0.70 ± 0.33 and 1.20 ± 0.54 ml/min per g (p < 0.05), respectively, whereas the corresponding values for regions with a dobutamine flow defect were 0.69 ± 0.33 ml/min per g at rest and 1.23 ± 0.54 ml/min per g during dobutamine (p < 0.05). Dobutamine increased flow inversely proportional to percent diameter stenosis. The rest flow for regions with a dobutamine flow defect were not significantly different from that in regions without defects.Conclusions. Dobutamine resulted in a significant increase in myocardial blood flow that correlated significantly with both increased cardiac work and degree of stenosis.

Role of endothelium-derived nitric oxide in coronary vasodilatation induced by pacing tachycardia in humans.

Endothelium-derived NO contributes to the control of coronary perfusion. We investigated the roles of NO in the metabolic coronary vasodilatation induced by rapid pacing in humans. We evaluated the dilatation of large epicardial and resistance coronary arteries during rapid atrial pacing before and after intracoronary infusion of NG-monomethyl-L-arginine (L-NMMA), an inhibitor of NO synthesis, in 19 patients without significant coronary artery disease. The diameter of the large epicardial coronary artery and coronary blood flow (CBF) were assessed by quantitative coronary arteriography and by a Doppler flow velocity measurement. An increase in the heart rate increased CBF (P < .01) and the coronary artery diameter (P < .05). L-NMMA at a total dose of 200 mumol reduced basal CBF but did not significantly affect basal coronary artery diameter, arterial pressure, or heart rate. L-NMMA inhibited the pacing-induced dilatation of the large coronary arteries (P < .05) but did not affect pacing-induced increases in CBF. L-NMMA inhibited the acetylcholine-induced increase in CBF (P < .01) and acetylcholine-induced dilatation of the large epicardial coronary artery (P < .05). These results show that the contribution of NO to the metabolic vasodilatation during rapid pacing may differ between large epicardial and resistance coronary arteries in patients without significant coronary artery disease.

Comparison of angioscopy, intravascular ultrasound imaging and quantitative coronary angiography in predicting clinical outcome after coronary intervention in high risk patients

Objectives. The purpose of this study was to identify qualitative or quantitative variables present on angioscopy, intravascular ultrasound imaging or quantitative coronary arteriography that were associated with adverse clinical outcome after coronary intervention in high risk patients.Background. Patients with acute coronary syndromes and complex lesion morphology on angiography are at increased risk for acute complications after coronary angioplasty. Newer devices that primarily remove atheroma have not improved outcome over that of balloon angioplasty. Intravascular imaging can accurately identify intraluminal and intramural histopathologic features not adequately visualized during coronary arteriography and may provide mechanistic insight into the pathogenesis of abrupt closure and restenosis.Methods. Sixty high risk patients with unstable coronary syndromes and complex lesions on angiography underwent angioscopy (n = 40) and intravascular ultrasound imaging (n = 46) during interventional procedures. In 26 patients, both angioscopy and intravascular ultrasound were performed in the same lesion. All patients underwent off-line quantitative coronary arteriography. Coronary interventions included balloon (n = 21) and excimer laser (n = 4) angioplasty, directional (n = 19) and rotational (n = 6) atherectomy and stent implantation (n = 11). Patients were followed up for 1 year for objective evidence of recurrent ischemia.Results. Patients whose clinical presentation included rest angina or acute myocardial infarction or who received thrombolytic therapy within 24 h of procedure were significantly more likely to experience recurrent ischemia after intervention. Plaque rupture or thrombus on preprocedure angioscopy or angioscopic thrombus after intervention were also significantly associated with adverse outcome. Qualitative or quantitative variables on angiography, intravascular ultrasound of off-line quantitative arteriography were not associated with recurrent ischemia on univariate analysis. Multivariate predictors of recurrent ischemia were plaque rupture on preprocedure angioscopy (p < 0.05, odds ratio [OR] 10.15) and angioscopic thrombus after intervention (p < 0.05, OR 7.26).Conclusions. Angioscopic plaque rupture and thrombus were independently associated with adverse outcome in patients with complex lesions after interventional procedures. These features were not identified by either angiography or intravascular ultrasound.

Micro stent, quantitative coronary angiography, and procedural results.

The Micro stent (MS) is a radiopaque stainless steel balloon expandable intracoronary stent. The stent is mounted on a rapid-exchange delivery system. From August 1994-March 1995, 127 MS were implanted in 85 patients (pts, 1.5 stents/pt, 85 in native vessels and 42 in bypass vein grafts, 61 males and 24 female, age 33-77 yr, mean age 61 +/- 10 yr). Pts studied were scheduled for either elective PTCA (n = 62, 73%) or PTCA for acute myocardial infarction (n = 23, 27%). Elective stent implantation was performed in 45 pts (53%). An MS was implanted because of a suboptimal balloon angioplasty result in 26 pts (31%). The stent was implanted because of threatened or acute vessel closure after balloon angioplasty in 14 pts (16%). During the procedure, 500 mg aspirin and 2 x 7,500 units of heparin were administered intravenously, followed by systemic heparinization for 48 hr. Pts were discharged with 100 mg aspirin daily (n = 50, 59%), or anticoagulant drugs and 100 mg aspirin daily (n = 19, 22%), or anticoagulant drugs only (n = 16, 19%). Angiographic results were analyzed with computer-assisted quantitative coronary arteriography. Angiographic success (defined as a residual stenosis of < 30%) was achieved in 124 of 127 attempts (98%). The mean minimal luminal diameter of the target lesions increased from 0.88 +/- 0.79 mm before stent implantation to 3.08 +/- 0.56 mm (P < 0.001). The percentage of diameter stenosis was reduced from 77.9 +/- 20.9% before to 13.3 +/- 10.5% (P < 0.001) after stent implantation. The average initial gain was 2.53 +/- 1.37 mm. The procedural success rate (defined as a residual stenosis of < 30% without occurrence of major clinical events within 3 wk after procedure) was 84%. Major clinical events included: death 1 pt (1%); cerebrovascular accident, 1 pt (1%); subacute stent closure, 5 pts (6%); coronary artery bypass grafting, 3 pts (4%); false femoral aneurysm, 2 pts (2%). The initial results of Micro stent implantation are promising. No anticoagulant therapy was given to most of the patients (59%). Few vascular and bleeding complications were observed. However, at this stage, no data about the restenosis rate after implantation of a Micro stent are available.

Performance standards and edge detection witk computerized quantitative coronary arteriography

Quantitative coronary angiography (QCA) has become an important tool for evaluating coronary angiograms. Many methodologic factors, such as the choice of frame to analyze, the selection of the "normal," segment and the method of edge detection used may affect the results of QCA. The sequential steps in performing QCA, including a comparison of visual and automated edge-detection methodologies, were evaluated using 12 precision-drilled phantoms and 20 patient films. Normal diameter, minimal lumen diameter, and diameter stenosis were measured. In the phantom studies, the measurements from both visual and automated systems correlated well with the true measurements of the phantoms and between systems (all r values >0.92). To study the difference between methodologies on QCA results as influenced by the choice of frame and normal segment analyzed, the patient films were analyzed independently in 3 separate rounds of interpretation. In round 1, each system's operator individually chose frames and normal segments for analysis. In round 2, both systems analyzed the same preselected frames, but independently chose normal segments. In round 3, both systems analyzed the same preselected normal segments and frames. The intersystem correlations between visual and automatic systems for rounds 1, 2, and 3 were: normal diameter, r = 0.25, r = 0.37, and r = 0.75, respectively; minimal lumen diameter, r = 0.79, r = 0.86, and r = 0.85, respectively; and diameter stenosis, r = 0.65, r = 0.73, and r = 0.87, respectively. The manual edge-detection and automated edge-detection systems used in this study are reasonably accurate and consistent on phantom studies. In patient studies, the nonautomated processes (choice of frame and normal segment for analysis) produced significant differences in the QCA results, thus illustrating that operator-dependent factors other than edge detection are very important in QCA.

Normalization of abnormal coronary vasomotion by calcium antagonists in patients with hypertension.

Endothelial dysfunction with a loss of endothelium-dependent vasodilation has been reported in patients with arterial hypertension. The purpose of the present study was to evaluate coronary vasomotor response to dynamic exercise in patients with coronary artery disease with and without arterial hypertension and to determine the effect of calcium antagonists on coronary vasomotion. Cross-sectional areas of a normal and a stenotic coronary vessel segment were examined in 79 patients with coronary artery disease at rest and during supine bicycle exercise (Ex). Change in luminal area after acute administration of a calcium antagonist (diltiazem or nicardipine), during exercise, and after sublingual nitroglycerin (percent change compared with rest = 100%) was assessed by biplane quantitative coronary arteriography. Patients were divided into two groups: Group 1 (control) consisted of 48 patients without (normotensive subjects, n = 30; hypertensive subjects, n = 18) and group 2 of 31 patients with (normotensive subjects, n = 15; hypertensive subjects, n = 16) pretreatment with a calcium antagonist immediately before exercise. The groups did not differ with regard to clinical characteristics or hemodynamic data measured during exercise. Mean aortic pressure at rest, however, was significantly increased in hypertensive patients compared with normotensive subjects in group 1 (103 mm Hg versus 92 mm Hg, P < .01) and group 2 (110 mm Hg versus 98 mm Hg, P < .025). In group 1, exercise-induced vasomotor response was significantly different between normotensive and hypertensive patients in normal (+20% versus +1%, P < .003) and stenotic vessels (-5% versus -20%, P < .025). However, in group 2 there was coronary vasodilation in normotensive and hypertensive patients for both normal (delta Ex +23% versus +21%, P = NS) and stenotic vessel segments (+24% versus +26%, P = NS). Abnormal coronary vasomotion during exercise can be observed in hypertensive patients with reduced vasodilator response in normal arteries and enhanced vasoconstrictor response in stenotic arteries. Calcium antagonists prevent the abnormal response of normal and stenotic coronary arteries to exercise in hypertensive patients and thus may compensate for endothelial dysfunction with reduced vasodilator response to exercise.

Editorial comment

Catheterization and Cardiovascular DiagnosisVolume 37, Issue 1 p. 23-23 Feature Topic: Quantitative Coronary Arteriography Editorial comment Johan H.C. Reiber PhD, Corresponding Author Johan H.C. Reiber PhD Department of Diagnostic Radiology, University Hospital Leiden, The NetherlandsDepartment of Diagnostic Radiology, University Hospital Leiden, The NetherlandsSearch for more papers by this author Johan H.C. Reiber PhD, Corresponding Author Johan H.C. Reiber PhD Department of Diagnostic Radiology, University Hospital Leiden, The NetherlandsDepartment of Diagnostic Radiology, University Hospital Leiden, The NetherlandsSearch for more papers by this author First published: January 1996 https://doi.org/10.1002/(SICI)1097-0304(199601)37:1<23::AID-CCD6>3.0.CO;2-6AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume37, Issue1January 1996Pages 23-23 SCAI Member Sign in RelatedInformation

Editorial comment

Catheterization and Cardiovascular DiagnosisVolume 37, Issue 1 p. 46-46 Feature Topic: Quantitative Coronary Arteriography Editorial comment Johan H.C. Reiber PhD, Corresponding Author Johan H.C. Reiber PhD Department of Diagnostic Radiology, University Hospital Leiden, The NetherlandsDepartment of Diagnostic Radiology, University Hospital Leiden, The NetherlandsSearch for more papers by this author Johan H.C. Reiber PhD, Corresponding Author Johan H.C. Reiber PhD Department of Diagnostic Radiology, University Hospital Leiden, The NetherlandsDepartment of Diagnostic Radiology, University Hospital Leiden, The NetherlandsSearch for more papers by this author First published: January 1996 https://doi.org/10.1002/(SICI)1097-0304(199601)37:1<46::AID-CCD10>3.0.CO;2-UCitations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume37, Issue1January 1996Pages 46-46 SCAI Member Sign in RelatedInformation

Inaccuracy of quantitative coronary arteriography when analyzed from S-VHS videotape.

In the transition period between 35-mm cinefilm as the medium for coronary arteriographic data and digital media such as CD-R, S-VHS videotape has been used both as an exchange and store medium, and for quantitative coronary arteriographic (QCA) studies. To determine the extent to which S-VHS video tape affects QCA measurements, an X-ray phantom study was completed. A plexiglass phantom with 12 straight circular tubes (0.51-5.00 mm in diameter) filled with contrast medium was recorded under clinical conditions using both the 5" and 7" modes of the image intensifier with the phantom tubes positioned horizontally as well as vertically in the field of view. The digitally acquired images were recorded on S-VHS tape without any image enhancement (raw data) and with default image enhancement. Video frames were then selected on a professional VCR such that individual tubes were positioned in the center of the field of view and digitized (512(2) x 8 bits) with a high-quality frame grabber onto a QCA workstation. The contours along the individual tubes were defined using previously validated automated contour detection techniques. For each tube, an average diameter (mm) and a standard deviation (mm) were calculated. Calibration was based on a cm-grid acquired at the same geometry as the phantom. Due to the poor signal-to-noise ratio and the limited bandwidth of the S-VHS video tape, the following objective observations were made: 1) large overestimations (up to 0.87 mm) occur for tube sizes below 1 mm for vertically positioned tubes; 2) random errors in measurements are much larger for vertically positioned tubes (0.36 mm, 7" II) than for horizontally positioned tubes (0.17 mm, 7" II); and 3) little differences in results between enhanced and nonenhanced images were found due to these deteriorating factors. In conclusion, S-VHS video tape is unacceptable for QCA and should be excluded from quantitative angiographic clinical trials.

Inaccuracy of quantitative coronary arteriography when analyzed from S‐VHS videotape

Inaccuracy of quantitative coronary arteriography when analyzed from S‐VHS videotape