[Evaluation of treatment adaptation for low response to ASA in vascular surgery]

Hintergrund

Eine verminderte antithrombozytäre Prophylaxe („Low-Response [LR]“/„high on-treatment platelet reactivity [HPR]“) mit Acetylsalicylsäure (ASS) ist mit einem erhöhten Risiko für thrombembolische Ereignisse assoziiert. Die Prävalenz einer Low-Response ist mit ca. 20 % häufig und ein Therapieregime wurde bisher noch nicht etabliert. Das Ziel dieser prospektiven Studie war es, die Effektivität eines Therapieschemas zur Therapieanpassung bei detektierter LR/HPR bei gefäßchirurgischen Patienten zu evaluieren.

Methodik

Insgesamt wurden 36 gefäßchirurgischen Patienten mit einer antithrombozytären Dauermedikation mit ASS 100 mg/Tag und einer nachgewiesenen ASS-Low-Response (ALR) in die Studie eingeschlossen. Entsprechend dem festgelegten Therapieplan wurde bei diesen Patienten eine Therapieanpassung durchgeführt und eine Kontrollaggregometrie zur Erfolgskontrolle durchgeführt. Das verwendete Therapieschema folgte dem Test-and-treat-Prinzip. Zur Beurteilung der Wirkung von ASS diente die Impedanzaggregometrie mittels Mehrelektrodenaggregometer (Multiplate).

Ergebnisse

Insgesamt konnten alle 36 Patienten erfolgreich in eine Response überführt werden. Bei 32 (88,89 %) Patienten erfolgte eine Dosiserhöhung auf 300 mg ASS, 2 (5,56 %) Patienten wurden von ASS auf Clopidogrel umgestellt. Bei weiteren 2 (5,56 %) Patienten wurde auf eine orale Antikoagulation mit Phenprocoumon aufgrund anderer Indikationen umgestellt. Blutungskomplikationen oder Nebenwirkungen traten nicht auf.

Schlussfolgerung

Das gewählte Therapieschema zur Behandlung einer Low-Response erwies sich als effektiv und sicher bei gefäßchirurgischen Patienten. Überwiegend führte eine leitliniengerechte Dosiserhöhung der Prophylaxe von 100 mg auf 300 mg ASS zu einer effektiven Thrombozytenaggregationshemmung in der Aggregometrie.

[Prevalence of acetylsalicylic acid (ASA) - low response in vascular surgery]

BACKGROUND

Research has revealed that a decreased antiplatelet effect (low response [LR]/high on-treatment platelet reactivity [HPR]) of acetylsalicylic acid (ASA) and clopidogrel is associated with an increased risk of thromboembolic events. There are extensive ASA low response (ALR) and clopidogrel low response (CLR) prevalence data in the literature, but there are only a few studies concerning vascular surgical patients. The aim of this study was to examine the prevalence and risk factors of ALR and CLR in vascular surgical patients.

MATERIALS AND METHODS

We examined n = 154 patients with an antiplatelet long-term therapy, who were treated due to peripheral artery occlusive disease (PAD) and/or arteria carotis interna stenosis (CVD). To detect an ALR or CLR, we examined full blood probes with impedance aggregometry (ChronoLog® Aggregometer model 590). Risk factors were examined by acquisition of concomitant disease, severity of vascular disease, laboratory test results and medication.

RESULTS

We found a prevalence of 19.3 % in the ALR group and of 21.1 % in the CLR group. Risk factors for ALR were an increased platelet and leucocyte count and co-medication with pantoprazole. We found no significant risk factors for a decreased antiplatelet effect of clopidogrel treatment.

CONCLUSION

The investigated prevalence for ALR and CLR are in the range of other studies, particularly based on cardiological patients. More investigations are needed to gain a better evaluation of the risk factors for HPR and to develop an effective antiplatelet therapy regime to prevent cardiovascular complications.

Frequency and exact position of valves in the saphenofemoral junction

Background: Varicose veins are common. As venous valves are included in the pathological development of varices they have been studied by many authors. Nonetheless, the exact position of valves is unclear. Material and method: The exact position of the valves in the greater saphenous vein was studied macroscopically from the saphenofemoral junction up to 25 cm distally in situ on 72 cadavers with a total of 140 veins. Results: A terminal valve existed in 88.5% in the range of 0 to 1.4 cm and a preterminal valve was present in 89.2% in the range of 1.4 cm to 8.2 cm distally to the saphenofemoral junction. In about a fifth of the cases a third valve could be identified. Conclusion: Our results suggest, that the recent general agreement that there are always a terminal and a preterminal valve has to be negated.

Functional regions of the human cytomegalovirus protein pUL97 involved in nuclear localization and phosphorylation of ganciclovir and pUL97 itself

In order to identify functional regions of the human cytomegalovirus protein pUL97 (i) different 5' fragments of the UL97 open reading frame (ORF) were fused to the coding region of the green fluorescent protein and (ii) recombinant vaccinia viruses (rVV) were generated carrying two full-length and 11 mutated UL97 ORFs. The results indicated the presence of an N-terminal region within pUL97 which changed the intracellular distribution of the fusion proteins. pUL97 was localized in the nucleus, but not in the nucleoli, and was detected in the nuclear matrix fraction. Expression of all pUL97 mutants could be confirmed by Western blot analysis. pUL97-associated ganciclovir (GCV) phosphorylation in rVV-infected cells, determined quantitatively by HPLC analysis, was abolished completely using individual UL97 deletion mutants. Phosphorylation of full-length and some of the mutated pUL97 was detected in cells infected with the rVVs. The UL97 constructs carrying point mutations from GCV-resistant HCMV isolates at positions 460M, 520H, 594V, and the 4 aa deletion 590AACR593, also resulted in decreased but not abolished phosphorylation of GCV in the rVV system, whereas the phosphorylation of pUL97 itself was not influenced. The rVV system is a suitable method for quantitatively testing the functional relevance of pUL97 mutations.