Holger Mühling

Usefulness of collagen plugging with VasoSeal® after PTCA as compared to manual compression with identical sheath dwell times

This study investigated the usefulness of collagen plugging with VasoSeal in patients after PTCA compared to a control group having identical sheath dwell times and therefore comparable levels of anticoagulation. A total of 150 patients were enrolled in this prospective and randomized study. Sheaths were pulled at exactly 5 h after arterial puncture. Time to hemostasis and local complications were determined. There were no statistical differences in baseline characteristics. The mean time to hemostasis in the collagen group was significantly shorter (3 +/- 3 min) than that of the control group (17.4 +/- 7 min). At 24 h, 23% of the collagen group patients had a small, 1% a medium and 4% a large hematoma. In the control group, 32% had a small, 4% a medium sized, but no patient a large hematoma. After collagen, one patient developed a pseudoaneurysm needing vascular surgery. In the control group, no major complication occurred. Compared to patients with manual compression at an identical sheath dwell time and an identical level of anticoagulation, there was a significant reduction in time to hemostasis but no statistical difference regarding local complications. Although the incidence of medium or large hematoma was low, the trend towards a decreased risk of smaller hematomas seemed to be counterbalanced by an increased risk of larger hematomas.

Impact of various compression rates on interpretation of digital coronary angiograms

According to the ACC/ACR/NEMA/ESC-guidelines, digital techniques should be replaced by cinefilm for coronary angiography. The ad hoc group of experts recently chose CD-R (CD recordable) as transport media and the JPEG standard for image compression. To avoid a possible loss of image quality, the guidelines allow a maximal data compression of only 2:1. This, however, leads to a considerable limitation: coronary angiograms cannot be viewed in real-time directly from CD. Since the possible influence of higher compression rates on image quality of coronary angiograms had not been investigated in a controlled study, we evaluated 8 various compression rates (ranging from 5:1 to 43:1) according to a prospective, randomized and blinded protocol. Four independent observers assessed 1440 angiograms using a semiquantitative score. We found that angiograms with a compression rate of 5:1 and 6:1 did not lead to a clinically relevant deterioration of image quality, whereas 11:1 was still acceptable, but 43:1 becomes unacceptable. Since no clinically relevant loss of information at a compression rate of 6:1 was experienced in our study, a modification of the ACC/ACJ/NEMA/ESC-guidelines allowing higher compression rates should be considered.

Nichtinvasive Angiographie koronarer Bypassgefäße mit dem Cardio-CT in einer kardiologischen Praxis

Hintergrund: Die koronare Bypassoperation stellt unverändert eine tragende Säule in der Behandlung der koronaren Herzerkrankung dar: So wurden im Jahr 2001 in Deutschland 75 537 koronare Bypassoperationen durchgeführt. Die “Haltbarkeit” koronarer Bypassgefäße ist jedoch limitiert: Nach 3 Jahren sind 20–30% der Bypassgefäße verschlossen, die Herzinfarktrate steigt 8 Jahre nach einer Bypassoperation deutlich an. Da der klinische Verlauf der Patienten eng mit der Offenheitsrate der Bypassgefäße korreliert, wäre es für die Patienten wichtig, die Offenheitsrate ihrer Bypassgefäße rechtzeitig zu überprüfen und einen Bypassverschluss zu erkennen, bevor die Mehrzahl der Bypassgefäße verschlossen ist. Hierzu bietet sich die ultraschnelle Computertomographie mittels Mehrschichtaufnahmetechnik (MSCT) an. Die vorliegende Arbeit beschreibt unsere ersten Erfahrungen mit dem MSCT in einer kardiologischen Praxis mit der Fragestellung, ob diese neue Methode praxisrelevante Informationen liefert. Patienten und Methodik: Die Untersuchungen wurden im Herzdiagnostikzentrum München mit einem Mx 8000 4-Zeilen-Spiral-CT bei einer effektiven Schichtdicke von 1,3 mm, 120 kV und 300 mA mit ca. 120 ml Kontrastmittel in Doppelbolustechnik durchgeführt. Die Bildrekonstruktion erfolgte für fünf Herzphasen zwischen 50% und 70% des R-R-Intervalls. Somit wurden insgesamt ca. 1 500 Schichten rekonstruiert. 74 Patienten ohne Angina pectoris oder Ischämienachweis wurden im Mittel 5 Jahre nach der Operation untersucht. Ergebnisse: Von den insgesamt 220 untersuchten Bypassgefäßen waren 132 venös und 88 arteriell. 177 Bypassgefäße wurden als offen und 42 als verschlossen eingestuft, ein Venenbypass als hochgradig stenosiert. Im Vergleich zur Herzkatheteruntersuchung ergaben sich eine Sensitivität des Cardio-CT hinsichtlich der Erkennung eines Bypassverschlusses von 100% und eine Spezifität von 96%. Der einzige “falsch positive” Verschluss war eine dünnkalibrige LIMA. Schlussfolgerung: Unsere Ergebnisse zeigen, dass die nichtinvasive Bypassangiographie mit dem ultraschnellen MSCT praxisrelevante Informationen liefert. Die nichtinvasive Bypassangiographie mit dem Cardio-CT richtet sich vor allem an beschwerdefreie Patienten ohne Ischämienachweis (“Bypass-TÜV”), um rechtzeitig asymptomatische Bypassverschlüsse zu erkennen. Bei einem asymptomatischen Bypassverschluss wäre es sinnvoll, über eine Koronar- bzw. Bypassintervention aus prognostischen Gründen nachzudenken. Immerhin hatte im Mittel 5 Jahre postoperativ fast jeder dritte Patient einen unerwarteten Bypassverschluss.Background: The role of coronary artery bypass surgery as a key foundation in the therapy of coronary artery disease remains unchanged: in Germany in 2001, 75,537 coronary bypass procedures were performed. However, the endurance of coronary bypass grafts is limited: after 3 years, 20–30% of the bypass grafts have occluded. The myocardial infarct rate significantly increases 8 years after bypass surgery. Since the clinical outcome of the patients is closely related to the patency rate of their bypass grafts, it would be important for the patients to have the patency rate of their bypass grafts assessed on time to detect any occluded bypass grafts before the majority of the grafts become occluded. Recently, multi-slice computed tomography (MSCT) offers an attractive tool for this purpose. This paper describes our first experiences with MSCT in our cardiology practice and regards whether this new method provides relevant information for a cardiology practice. Patients and Methods: Studies were performed at the Heart Diagnostic Center in Munich with an Mx 8000 four-row spiral CT with an effective slice thickness of 1.3 mm, 120 kV at 300 mA and approximately 120 ml of contrast medium in double bolus technique. Image reconstruction was performed for 5 heart phases between 50% and 70% of the RR intervals. Thus, a total of over 1,500 slices were reconstructed. 74 patients without angina or proof of myocardial ischemia had noninvasive bypass angiography at a mean of 5 years after surgery. Results: Of the total of 220 investigated bypass grafts, 132 were venous and 88 were arterial. 177 bypass grafts were classified as open, 42 as occluded; and one venous bypass graft was highly narrowed. Compared with cardiac catheterization, the sensitivity of the cardio-CT regarding the occlusion of a bypass graft was 100% with a specificity of 96%. The only “false positive” occlusion was a LIMA with a small lumen. Conclusions: Our results show that noninvasive bypass angiography with the ultrafast multi-slice CT (MSCT) provides relevant information for the practicing cardiologist. Noninvasive bypass angiography with a cardio-CT predominantly aims at asymptomatic patients without proof of myocardial ischemia (“bypass check”) for the detection of asymptomatic occluded bypass grafts as early as possible. In patients with asymptomatic bypass occlusion, considering a coronary or bypass intervention for prognostic reasons is an option. It is important to note that in our study in a mean of 5 years after bypass surgery almost every third patient had an unexpected bypass graft occlusion.

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