The reliability of a modified videodensitometric and photodensitometric sampling technique for measuring phasic flow rates in the coronary artery system was examined. Electromagnetic flow measurements were performed in a circulatory model with continuous and pulsatile flow and intraoperatively in aortocoronary bypass grafts; cineangiograms were made simultaneously. Based on the front velocities of injected boluses of contrast medium, the densitometric measurement overestimated the electromagnetically measured flow systematically by about 20%. Systolic and diastolic flow rates in aortocoronary bypass grafts and coronary arteries determined from biplane cineangiograms in 34 patients generally revealed the typical pulsatile flow pattern familiar from electromagnetic and ultrasonic flow measurements. Flow velocities in unstenosed coronary arteries were nearly identical before and after branchings of the vessels, whereas the corresponding flow rates were higher in proximal than in distal segments. The identical flow velocities in different branches of the same vessel and the low variability of this parameter in different patients may be a suitable index of the effect of stenoses on coronary arterial blood flow.

Im Rahmen koronarchirurgischer Eingriffe wurden elektromagnetische Flußmessungen in aortokoronaren Bypassgefäßen mit simultaner cineangiographischer Darstellung vorgenommen. Der aus den Frontgeschwindigkeiten der injizierten Kontrastmittelboli videodensitometrisch bestimmte Fluß (QVD) überschätzt den elektromagnetisch gemessenen Fluß (QEM) systematisch um ca. 20 % (QVD = 1,26 · QEM - 4 ml/min; syx = 10,8 ml/min; r = 0,97). Ein Vergleich des elektromagnetisch gemessenen Flusses während der Passage der Kontrastmittelfront mit dem Fluß im entsprechenden Intervall des unmittelbar vor der Injektion liegenden Herzzyklus ergab eine durch die Kontrastmittelinjektion bedingte Flußzunahme von im Mittel + 13,6 ml/min.

Electromagnetic flow measurements in aorto coronary bypass grafts and cine angiography were performed simultaneously during bypass surgery. Using the front velocities of injected boli of contrast medium the videodensitometric measurement (QVD) overestimates the electromagnetically measured flow (QEM) systematically about 20% (QVD = 1.26 . QEM = 4 ml/min; Syx = 10.8 ml/min; r = 0.97). During the passage of the front of the contrast medium through the videodensitometric measuring windows, the flow is altered by the injection about + 13.6 ml/min on an average.

Bei der Erfolgsbeurteilung eines koronarchirurgischen Eingriffs wird die Röntgenkon-trastdarstellung der Bypass-Gefäße von zahlreichen Arbeitsgruppen nicht nur zur Beurteilung der anatomischen Situation, sondern auch zur qualitativen Beurteilung des Bypass-Flusses herangezogen. Dabei wird aus dem Ein- und Abströmen des Kontrastmittels, dem sogenannten „Run off“, auf das Flußverhalten geschlossen. Es stellt sich die Frage, ob und inwieweit eine derartige subjektive Beurteilung eine Aussage über den Fluß im Bypass-Gefäß machen kann. Im folgenden wurde diese Frage anhand quantitativer Flußmessungen an aorto-koronaren Bypass-Gefäßen überprüft.

Article SIMULTANE HINTERGRUNDSKORREKTUR ZUR VIDEODENSITOMETRISCHEN FLUSSMESSUNG AM KORONARGEFÄSSYSTEM was published on January 1, 1979 in the journal Biomedical Engineering / Biomedizinische Technik (volume 24, issue s1).

The function of aorto-coronary bypass grafts is usually assessed by the run-off, determined from postoperatively performed cineangiograms. The reliability of this method was tested by comparing the electromagnetically measured graft flow with the run-off, qualitatively estimated from cineangiograms. The electromagnetic flow measurements and cineangiography were performed simultaneously during bypass surgery. The run-off was classified by three independent observers into three classes (poor, moderate, and good). The average mean flow rates corresponding to the three classes were: poor: Q = (43 +/- 11)ml/min; moderate: Q = (48 +/- 14)ml/min; good; Q = (63 +/- 22)ml/min. Although the differences between the flow rates of the three classes were found significant (except between poor and moderate run-off), there was a wide range of overlapping. Especially in grafts with low flow rates (Q less than 70 ml/min) there were pronounced disagreements between the qualitative estimation of flow and the electromagnetically measured flow. Using videodensitometric flow measurements as a check test, the uncertainties in classification proved to be caused by the lack of reliability of the observer. The flow rates in aorto-coronary bypass grafts can be determined reliably only by means of quantitative methods, e.g., electromagnetic or videodensitometric flow measurements.