J. Meyer

Intracoronary Application of C1 Esterase Inhibitor Improves Cardiac Function and Reduces Myocardial Necrosis in an Experimental Model of Ischemia and Reperfusion

BACKGROUNDnMyocardial injury from ischemia can be aggravated by reperfusion of the jeopardized area. The precise underlying mechanisms have not been clearly defined, but proinflammatory events, including complement activation, leukocyte adhesion, and infiltration and release of diverse mediators, probably play important roles. The present study addresses the possibility of reducing reperfusion damage by the application of C1 esterase inhibitor (C1-INH).nnnMETHODS AND RESULTSnCardioprotection by C1-INH 20 IU/kg IC was examined in a pig model with 60 minutes of coronary occlusion, followed by 120 minutes of reperfusion. C1-INH was administered during the first 5 minutes of coronary reperfusion Compared with the NaCl controls, C1-INH reduced myocardial injury (48.8 +/- 7.8% versus 73.4 +/- 4.0% necrosis of area at risk, P < or = .018). C1-INH treatment significantly reduced circulating C3a and slightly attenuated C5a plasma concentrations. Myocardial protection was accompanied by reduced plasma concentration of creatine kinase and troponin-T. C1-INH had no effect on global hemodynamic parameters, but local myocardial contractility was markedly improved in the ischemic zone. In the short-axis view, 137 degrees of the anteroseptal region showed significantly improved wall motion at early and 29 degrees at late reperfusion with C1-INH treatment.nnnCONCLUSIONSnC1-INH significantly protects ischemic tissue from reperfusion damage, reduces myocardial necrosis, and improves local cardiac function.

Comparison of Myocardial Perfusion Reserve Before and After Coronary Balloon Predilatation and After Stent Implantation in Patients With Postangioplasty Restenosis

BACKGROUNDnStents provide a scaffold for coronary arteries after angioplasty and inhibit elastic recoil.nnnMETHODS AND RESULTSnIn 25 patients with postangioplasty restenosis of the left anterior descending artery, ECG-gated digital subtraction coronary angiograms were recorded at baseline and during hyperemia (12 mg papaverine IC) before and after balloon predilatation (PTCA), after implantation of a Palmaz-Schatz stent, and after 6 months. Densitometric evaluation revealed different time and density parameters to calculate two definitions of myocardial perfusion reserve (MPR1 and MPR2) and maximum flow ratio (MaxFR). Poststenotic MPR1 increased from 1.57 +/- 0.14 to 2.59 +/- 0.86 after PTCA and to 3.10 +/- 0.41 after stenting, with 2.90 +/- 0.65 at follow-up (ANOVA, P < .05), while reference MPR1 remained unchanged at 3.10 +/- 0.40. Poststenotic MPR2 increased from 1.36 +/- 0.28 to 2.50 +/- 1.20 and to 3.40 +/- 0.58, respectively, with 3.20 +/- 0.92 at follow-up (ANOVA, P < .05), while reference MPR2 remained unchanged at 3.40 +/- 0.60. MaxFR was 2.13 +/- 0.53 after PTCA, elasticity 2.83 +/- 0.35 after stenting, and 2.73 +/- 0.58 at follow-up (ANOVA, P < .05). A good correlation was found between minimal stenotic luminal diameter and MPR1 or MPR2 (r = .87 and r = .94) and between luminal gain and MaxFR (r = .75). A negative correlation was measured between recoil and MPR1, MPR2, and MaxFR (r = -.80, r = -.86, and r = -.83). At follow-up, a steeper correlation was found between MPR and minimal stenosis diameter (MPR1: slope, 0.52 versus 0.91; MPR2: slope, 1.48 versus 1.95) and between MaxFR and net lumen gain (slope, 0.78 versus 1.27).nnnCONCLUSIONSnCoronary stent implantation in patients with postangioplasty restenosis normalized poststenotic myocardial perfusion immediately as a result of a larger postprocedural lumen and a more pronounced inhibition of elastic recoil. After 6 months this benefit was sustained despite progressive lumen loss.

Cardiac output in single-lead VDD pacing versus rate-matched VVIR pacing

The importance of atrioventricular synchronous pacing compared with single-chamber rate-responsive pacing is still under discussion, especially for low-intensity workload representing daily life activities. We evaluated hemodynamics in single-lead VDD pacing versus VVIR pacing in 11 patients (8 men and 3 women, aged 58.6 +/- 13.8 years) with normal left ventricular function and a previously implanted single-lead VDDR pacemaker. A low-intensity steady-state treadmill test at 1 to 2.5 mph with a gradient of 2% to 4% was performed. Cardiac output was determined using a standard carbon dioxide rebreathing technique. Initially, the VDD mode was programmed, and after 5 minutes of exercise, cardiac output was measured in steady-state conditions. The pacemaker was then reprogrammed to the VVI mode at a rate 5 to 10 beats above the maximal atrial tracking rate to simulate rate-matched VVIR pacing (VVIRm). After 5 additional minutes of steady-state exercise, cardiac output was measured again. The maximal atrial rate in the VDD mode was 119 +/- 19 beats/min versus a programmed rate of 129 +/- 18 beats/min in the VVIRm mode. VDD pacing resulted in a significantly higher cardiac output than VVIRm pacing (10.6 +/- 1.9 vs 9.2 +/- 1.4 L/min; p < 0.002), with a mean difference of 1.6 +/- 1.2 L/min between the 2 modes. In the VDD mode, stroke volume (90.7 +/- 20.1 vs 71.6 +/- 13.0 ml; p < 0.001) and maximal oxygen uptake (1,183 +/- 264 vs 1,076 +/- 289 ml/min, p < 0.01) were also higher than in VVIRm.(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular function analyzed by Doppler and echocardiographic methods in short-term hypothyroidism

Abstract In conclusion, a significant reversible decrease in contractility and an impaired diastolic relaxation was demonstrated in patients with short-term hypothyroidism. This must be considered in patients with preexisting heart disease.

Reversibilität von Veränderungen der links- und rechtsventrikulären Geometrie und Hämodynamik bei pulmonaler Hypertonie. Echokardiographische Charakterisierung bei Patienten vor und nach pulmonaler Thrombendarteriektomie

Durch pulmonale Thrombendarteriektomie kann bei Patienten mit chronischer embolisch bedingter pulmonaler Hypertonie eine akute rechtsventrikuläre Nachlastsenkung erzielt werden. Der Einfluß auf die rechts- und linksventrikuläre Geometrie und Hämodynamik wurde prospektiv mit Hilfe der transthorakalen Echokardiographie an einem Kollektiv von 14 Patienten (8 Frauen, 6 Männer; Alter 55 ± 20 Jahre) vor und nach 18 ± 12 Tagen postoperativ untersucht. Nach operativer Desobliteration der Pulmonalarterien fand sich eine Abnahme des invasiv bestimmten totalen pulmonalen Gefäßwiderstands von 986 ± 318 auf 323 ± 280 dyn x s/cm5; p < 0,05. Der echokardiographisch erfaßte systolische pulmonalarterielle Druck sank von 71 ± 40 auf 41 ± 40 mm Hg + ZVD; p < 0,05. Die enddiastolische sowie endsystolische rechtsventrikuläre Fläche nahm von 33 ± 12 auf 23 ± 8 cm2 bzw. von 26 ± 10 auf 16 ± 6 cm2 ab; p < 0,05. Die systolische rechtsventrikuläre Flächenverkürzungsfraktion stieg von 20 ± 12 auf 30 ± 16%; p < 0,05. Die rechtsventrikuläre systolische Druckanstiegsgeschwindigkeit blieb unverändert (516 ± 166 vs. 556 ± 128 mm Hg/sec). Die linksventrikuläre Ejektionsfraktion war prä- und postoperativ normal (64 ± 16 vs. 62 ± 12%). Der echokardiographisch bestimmte Herzindex stieg von 2,8 ± 0,74 auf 4,1 ± 1,74 l/min/m2. Eine Normalisierung der präoperativ alterierten Septumbewegung war anhand der linksventrikulären Exzentrizitätsindizes nachweisbar (enddiastolischer Index: 1,9 ± 1 vs. 1,1 ± 0,3, endsystolischer Index: 1,7 ± 0,6 vs. 1,1 ± 0,4; p < 0,05). Das diastolische Füllungsverhalten der linken Kammer normalisierte sich (E-zu-A-Verhältnis: 0,62 ± 0,34 vs. 1,3 ± 0,8; p < 0,05). Bereits kurzfristig nach pulmonaler Thrombendarteriektomie findet sich eine ausgeprägte Abnahme der rechtsventrikulären Nachlast. Die Folge ist – selbst wenn eine schwerste pulmonale Hypertonie bestand – eine deutliche Erholung der systolischen rechtsventrikulären Funktion. Gleichzeitig kommt es aufgrund der Normalisierung der paradoxen Septumbewegung zur Normalisierung des diastolischen linksventrikulären Füllungsverhaltens. Aus beiden resultiert ein signifikanter Anstieg des Herzzeitvolumens. Patienten mit chronischer embolisch bedingter pulmonaler Druckerhöhung profitieren kardial von der pulmonalen Thrombendarteriektomie und sollten bei gegebener Indikation einer solchen Operation zugeführt werden. Pulmonary thrombendarterectomy (PTE) leads to an acute decrease of right ventricular (RV) afterload in patients with chronic thromboembolic pulmonary hypertension. We investigated the changes in right and left ventricular (LV) geometry and hemodynamics by means of transthoracic echocardiography. The prospective study was performed in 14 patients (8 female, 6 male; age 55 ± 20 years) before and 18 ± 12 days after PTE. Total pulmonary vascular resistance and systolic pulmonary artery pressure were significantly decreased (PVR: preoperative 986 ± 18, postoperative 323 ± 280 dyn x s/cm5, p < 0.05; PAP preoperative 71 ± 40, postoperative 41 ± 40 mm Hg + right atrial pressure, p < 0.05). Enddiastolic and endsystolic RV area decreased from 33 ± 12 to 23 ± 8 cm2, respectively, from 26 ± 10 to 16 ± 6 cm2, p < 0.05. There was an increase in systolic RV fractional area change from 20 ± 12 to 30 ± 16% , p < 0.05. RV systolic pressure rise remained unchanged (516 ± 166 vs. 556 ± 128 mm Hg/sec). LV ejection fraction remained within normal ranges (64 ± 16 vs. 62 ± 12%). Echocardiographically determined cardiac index increased from 2.8 ± 0.74 to 4.1 ± 1.74 l/min/m2. A decrease in LV excentricity indices (enddiastolic: 1.9 ± 1 vs. 1.1 ± 0.3, endsystolic: 1.7 ± 0.6 vs. 1.1 ± 0.4, p < 0.05) proved a normalization of preoperatively altered septum motion. LV diastolic filling returned to normal limits: (E/A ratio: 0.62 ± 0.34 vs. 1.3 ± 0.8; p < 0.05); Peak E velocity: 0.51 ± 0.34 vs. 0.88 ± 0.28 m/sec, p < 0.05; Peak A velocity: 0.81 ± 0.36 vs. 0.72 ± 0.42 m/sec, ns; E deceleration velocity: 299 ± 328 vs. 582 ± 294 cm/sec2, p < 0.05; Isovolumic relaxation time: 134 ± 40 vs. 83 ± 38 m/sec, p < 0.05). We could show a marked decrease in RV afterload shortly after PTE with a profound recovery of right ventricular systolic function – even in case of severe pulmonary hypertension. A decrease in paradoxic motion of the interventricular septum and normalization of LV diastolic filling pattern resulted in a significant increase of cardiac index.

Intraventrikuläre Obstruktionen bei der Dobutamin-Streßechokardiographie: Determinanten ihrer Entstehung und klinische Folgen

Die Dobutamin-Streßechokardiographie (DSE) führt zu einer starken Hyperkontraktilität des Myokards bei Tachykardie und Vesodilatation. Diese Effekte können zu einer unphysiologischen Abnahme des endsystolischen Volumenindex (ESVI) mit Obstruktion des linksventrikulären Ausflußtraktes (LVOT) führen. Bei 100 Patienten (Pat.), die sich einer DSE (5–40) μg/kg/min) unterzogen, wurde die kontinuierliche Dopplerregistrierung (DW-Doppler) vor Infusion und bei maximaler Herzfrequenz durchgeführt. Eine dynamische, spät-systolische, Flußakzeleration auf mehr als 2 Meter/Sekunde (m/s) unter maximaler Stimulation wurde als systolische Obstruktion des LVOT interpretiert. Manifestationsfaktoren systolischer Flußobstruktionen sollten untersucht werden. Analyseparameter waren die Ejektionsfraktion (EF, 2D-Volumetrie mittels Scheibchensummationsmethode), die Wanddicke des linken Ventrikels, klinische Symptome und das Auftreten von Herzrhythmusstörungen. Zur invasiven Abklärung diente die femorale Katheterisierung nach Judkins mit semiquantitativer Schätzung des Stenosegrades. Stenosen > 50% galten als signifikant. Ergebnisse: 73 Pat. waren echokardiographisch und dopplersonographisch auswertbar. 39 Pat., Gruppe A (Grp A), 26 Männer, 13 Frauen, Durchschnittsalter 64 ± 8 Jahre entwickelten eine Obstruktion. Gruppe B (Grp B) 34 Pat., 26 Männern und 8 Frauen, mittleres Alter 66 ± 10 Jahre wiesen auch zum Zeitpunkt der maximalen Herzfrequenz ein parabolisches Geschwindigkeitszeitintegral im LVOT auf. Für 41 Pat. standen die invasiven Vergleichsdaten zur Verfügung. Beide Gruppen unterschieden sich im Testverlauf hinsichtlich Frequenzanstieg, Produkt der Maxima für systolischen Blutdruck und Herzfrequenz sowie Häufigkeit der submaximalen Ausbelastung (220 – Alter × 0,85) nicht signifikant. Pat. in Grp A entwickelten im Mittel 0,12 ± 0,04 Sekunden (s) nach dem Gipfel der R-Zacke eine maximale, spätsystolische und dynamisch akzelerierende Geschwindigkeit von 315,4 ± 139,8 cm/s, entsprechend einem Druckgradienten von 47,5 ± 39,7 mm Hg. In Grp B erreichten die Pat. nach 0,09 ± 0,04 s eine maximale Geschwindigkeit von 158,2 ± 37,6 cm/s. Daraus errechnete sich ein mittlerer Druckgradient von 10,6 ± 4,9 mm Hg (p < 0,001). In Grp A war die EF bereits vor Testbeginn höher (68,2 ± 8%) als in Grp B (55,7 ± 10,4%). Unter Belastung fiel dieser signifikante Unterschied (p < 0,001) noch deutlicher aus (74,1 ± 7,7% und 59,5 ± 12,8%). Der enddiastolische Volumenindex (EDVI) und der ESVI waren ebenfalls in Grp A signifikant niedriger. Eine Hypertrophie des linken Ventrikels (LV) lag häufiger bei Grp A vor (p < 0,001). Die Dicke des Septums betrug 1,45 ± 0,34 cm im Vergleich zu 1,13 ± 0,27 cm bei Grp B. Die entsprechenden Werte an der Hinterwand betrugen für A 1,03 ± 0,28 cm gegenüber 0,83 ± 0,23 cm für B (p < 0,01). Ischämische Wandbewegungsstörungen traten häufer in Grp B auf. Der Score index berechnete sich bei gleichem Ausgangswert unter maximaler Dobutaminstimulation mit 1,30 (1,0–1,90), verglichen mit 1,18 (1,0–1,75) bei A. Häufiger klagten Pat. der Grp B über Angina pectoris. Bei 27 Pat. in Grp B und 9 Pat. in Grp A bestanden Hinweise auf einen vorangegangenen transmuralen oder intramuralen Myokardinfarkt. Bigeminusartig auftretende ventrikuläre Extrasystolen (VES) waren unter Belastung häufiger in Grp B zu beobachten. Unspezifische Nebenwirkungen (Palpitationen) und andere Herzrhythmusstörungen traten gleich häufig auf. Der diastolische Blutdruck zeigte nur bei schwerer Obstruktion (> 3,5 m/s) einen signifikanten Abfall (p < 0,05). Die Sensitivität der DSE betrug 84%, die Spezifität 79% ohne Unterschied zwischen Grp A und B. Zusammenfassend läßt sich festhalten: Intraventrikuläre Obstruktionen sind gehäuft mit einer guten systolischen Funktion und einer linksventrikulären Hypertrophie verbunden. Komplikationen und Symptome sind nicht regelhaft assoziiert. Die Zuverlässigkeit der DSE hinsichtlich des Ischämienachweises wurde im untersuchten Patientenkollektiv nicht beeinträchtigt. Dobutamine stress echocardiography (DSE) leads to strong hypercontraction, tachycardia, and peripheral vasodilatation. In previous studies systolic obstruction of the left ventricular outflow tract (LVOT) was observed as a result of these factors. To evaluate left ventricular function and morphology in patients (pts) with induced systolic LVOT obstruction, we used continuous wave (CW) doppler registrations in combination with quantitative 2-D-echocardiography in 100 pts during routinely performed DSE (5–40 μg/kg/min). In addition left ventricular wall thickness was measured. Symptoms were registrated using a standardised questionaire and cardiac arrhythmias were counted over a two minute intervall at rest and during the maximal heart rate of each patient. During DSE dynamic flow acceleration with late systolic peak velocity above 2 m/second (s) was considered to represent LVOT obstruction in pts with normal flow profiles in the LVOT before infusion of dobutamine. For invasive studies pts were investigated with femoral catheterisation by the method of Judkins. A greater than 50% stenosis was judged to be significant. Results: Examinations in 73 pts provided data of sufficient quality for echocardiographic and Dopplersonographic evaluations. 39 pts, 26 men, 13 women, mean age 64 ± 8 years, developed late systolic flow velocities above 2 m/s and therefore formed the obstructive group (grp A). Grp B consisted of 34 pts, 26 men and 8 women, mean age 66 ± 10 years, who showed normal time velocity integrals during DSE. In 41 pts invasive data provided information concerning the existence and severity of coronary artery disease. There were no significant differences in the increase of heart rate, the product of maximal systolic blood pressure and maximal heart rate or the percentage of pts, who reached their age corrected submaximal heart rate during DSE. Obstructive pts (group A) showed late systolic dynamic acceleration of systolic flow with a mean maximal speed of 315.4 ± 139.8 cm/s, which peaked 0.12 ± 0.04 s after the R-wave. From the velocities we calculated a mean pressure gradient of 47.5 ± 39.7 mm Hg using the modified Bernoulli equation. Group B patients showed lower and earlier maximal speeds with a mean value of 158.2 ± 37.6 cm/s, 0.09 ± 0.04 s after the R-wave, corresponding to a pressure gradient of 10.6 ± 4.9 mm Hg (p < 0.001). Ejection fractions were higher (p < 0.001) before the test in grp A: 68.2 ± 8% compared to 55.7 ± 10.4% in B. This difference increased during peak stress: 74.1 ± 7.7% compared to 59.5 ± 12.8%. Enddiastolic (EDVI) and endsystolic volume indexes (ESVI) were lower in grp A (p < 0.001). During DSE, the decrease in ESVI was somewhat stronger for pts in grp A. Left ventricular hypertrophy was more often seen with obstruction. Septal thickness was increased in A: 1.45 ± 0.34 cm compared to 1.13 ± 0.27 cm in B (p < 0.001). Left ventricular posterior wall measured 1.03 ± 0.28 cm in A and 0.83 ± 0.23 cm in B (p < 0.01). 27 pts in grp B and only 9 in grp A had a history of previous myocardial infarction. Showing no difference at rest, wall motion score indexes raised under DSE in both groups and developed significantly higher scores in grp B at peak stress: 1.30 (1.0–1.90) compared to 1.18 (1.0–1.90) compared to 1.18 (1.0–1.75) in A. We observed typical chest pain more often in grp B. Unspecific symptoms and arrhythmogenic complications were not statistically different, with the exception of ventricular bigeminy which was more often observed in grp B. A decline in the diastolic blood pressure was observed in pts with very severe obstruction (> 3.5 m/s, p < 0.05). Sensitivity of DSE was 84%, specificity 79%. No significant differences between pts with and without obstruction were observed. Summary: Intraventricular obstructions during DSE are often observed in pts with normal systolic function at rest and during peak stress, especially in the case of left ventricular hypertrophy. This flow pattern is not regularly correlated to clinical signs, symptoms or complications. It did not impair diagnostic accuracy concerning the detection of significant coronary artery disease in our pts.

A framework for PACS development in cardiology

The authors develop a framework for the integration of cardiology into hospitalwide picture archiving and communication systems (PACSs) by the definition of user requirements in cardiology image information systems. These user requirements have to be based on the consensus of users and industry. A topdown layered scheme is proposed for the development of documents based on user requirements. The structure of committees within the European Society of Cardiology that are working in this field is discussed.<<ETX>>

Assessment of image quality of intracoronary ultrasound systems with tissue-equivalent vessel phantoms

Imaging of vascular structures by intracoronary ultrasound (ICUS) is finding more and more applications in coronary diagnosis and in the assessment of interventional access. The authors describe a method for easy and quick production of tissue-equivalent vessel phantoms from a special hydrocolloid. The mechanical tolerance is less than 3/100 mm. With these phantoms the authors tested the calibration and measured the resolution properties of the SONOS intravascular ultrasonic system (Hewlett Packard). The measurements revealed a slight space related underestimation of diameters up to 280 /spl mu/m. Using cross correlation and auto correlation functions the authors analyzed digitized ultrasonic pictures to determine the correlation length of speckle in three dimensions and derived an estimate of the space related resolution cell size.<<ETX>>

Three dimensional reconstruction of intracoronary ultrasound images: roadmapping with simultaneously digitised coronary angiograms

Three dimensional reconstruction of intracoronary ultrasound images offers a better appreciation of the axial relationship of vessel features and permits volumetric assessment, both of which depend critically on the spatial accuracy of the technique. This in turn is dependent on precise longitudinal orientation of the transducer in the vessel. The authors have developed a system which utilises simultaneously digitised fluoroscopic tracking of the radio-opaque transducer to orient the corresponding 2D ICUS images. This system may offer improved spatial accuracy of the three dimensional reconstruction and a means of precise identification of the 2D ICUS image which corresponds with a selected point of interest on the angiogram.<<ETX>>

Effect of qualitative stenosis characteristics on the quality of measurements of various QCA systems

Die neueren QCA-Systeme weisen bei In-vitro-Messungen eine vergleichbare Reproduzierbarkeit und Genauigkeit der Meßergebnisse auf. Wir untersuchten, welchen Einfluß die Morphologie von Koronararterienstenosen und die Bildqualität auf die Meßergebnisse von drei führenden QCA-Systemen (AWOS, Cardio und CMS) hat. Hierzu wählten wir 57 Stenosen aus, die eine klinisch repräsentative Verteilung bezüglich des Stenosegrades, verschiedener Läsionscharakteristika und der Bildqualität aufwiesen. Prozedurale Fehlerquellen wurden, soweit möglich, eliminiert. Drei Untersucher führten je Stenose fünf Messungen mit jedem der drei Systeme durch. Bei drei Stenosen war eine Auswertung nicht möglich. Die Auswertungen wurden nur für den minimalen Stenosedurchmesser durchgeführt. Die Reproduzierbarkeit bei allen Messungen mit dem AWOS-, Cardio- und CMS-System war mit 0,04, 0,05 und 0,06 mm sehr hoch. Zu einer stärkeren Streuung der Meßwerte kam es bei Vorliegen der folgenden Kriterien: Ambrose-III-Morphologie (CMS 0,082 mm), unregelmäßige Oberfläche (Cardio 0,069 mm, CMS 0,073 mm), TIMI I (Cardio 0,084 mm, CMS 0,121 mm) und mittlere Bildqualität (CMS 0,07 mm). Die übrigen Stenosecharakteristika hatten keinen Einfluß auf die Reproduzierbarkeit der Messungen. Zwischen den Systemen ergaben sich keine relevanten Meßdifferenzen (AWOS-Cardio –0,07 mm, AWOS-CMS –0,11 mm, Cardio-CMS –0,04 mm). Bei Vorhandensein von Gefäßkalk wurden mit dem AWOS-System kleinere Durchmesser bestimmt als mit dem CMS- und Cardio-System (AWOS-Cardio –0,109 mm, AWOS-CMS –0,161 mm). Dieser Trend war aber statistisch nicht signifikant ebenso wie auch die übrigen Differenzen zwischen den Meßwerten der Systeme bei der Klassifizierung hinsichtlich unterschiedlicher Läsionscharakteristika. Zusammenfassend ergab sich durch qualitative Stenosemerkmale sowie die Bildqualität keine relevante Beeinträchtigung der Meßqualität der untersuchten QCA-Systeme. Reproducibility and accuracy of in vitro measurements are very high using recently developed QCA systems. We analyzed the impact of lesion characteristics and the image quality on the quality of measurements under clinical conditions. For the study we selected 57 coronary artery lesions which had a clinically relevant distribution for stenosis severity, lesion characteristics, and image quality. Every effort was made to eliminate procedural sources of error. Three investigators measured each lesion five times with each of three QCA systems (AWOS, Cardio and CMS). Only the measurements of the minimal stenosis diameter were analyzed. The precision of all the measurements was high with the AWOS (0.04 mm), the Cardio (0.05 mm), and the CMS systems (0.06 mm). Variability of measurements increased for the following criteria: Ambrose-III morphology (CMS 0.082 mm), surface irregularities (Cardio 0.069 mm, CMS 0.073 mm), TIMI I (Cardio 0.084 mm, CMS 0.121 mm), and moderate image quality (CMS 0.07 mm). There were no differences in the precision of the measurements in the other groups of lesion characteristics. There were no relevant differences in any of the measurements between the systems (AWOS-Cardio –0.07 mm, AWOS-CMS –0.11 mm, Cardio-CMS –0.04 mm). Smaller diameters were measured with the AWOS system than with the CMS and the Cardio systems when the lesion was calcified (AWOS-Cardio –0.109 mm, AWOS-CMS –0.161 mm). This was only a trend, however, and did not reach statistical significances, which was also true for the other differences found between the systems according to various lesion characteristics. In summary, we found that the measurement quality of the QCA systems used in this study is not altered by the underlying lesion characteristics or the image quality.