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Doctoral Thesis
DOI
10.11606/T.5.2008.tde-24062008-120747
Document
Author
Full name
Daniela Calderaro
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2008
Supervisor
Committee
Monachini, Maristela Camargo (President)
Cesar, Luiz Antonio Machado
Malbouisson, Luiz Marcelo Sá
Ramires, Jose Antonio Franchini
Santos Filho, Raul Dias dos
Title in Portuguese
Análise funcional do endotélio no perioperatório de operações vasculares
Keywords in Portuguese
Aneurisma da aorta abdominal/cirurgia
Assistência perioperatória
Aterosclerose
Claudicação intermitente/cirurgia
Endotélio vascular
Infarto do miocárdio
Abstract in Portuguese
Apesar dos grandes avanços na medicina perioperatória, as operações vasculares ainda estão associadas a elevada morbi-mortalidade. A fisiopatologia dos eventos perioperatórios é complexa, envolvendo a instabilização de placas ateroscleróticas, o que não é contemplado nos algoritmos para estratificação de risco cardíaco perioperatório. Acreditamos que a identificação de características relacionadas à instabilização de placas incipientes, como alterações na reatividade vascular e maior atividade inflamatória, pode melhorar a acurácia da estimativa de risco e a análise do comportamento perioperatório destas características pode elucidar importantes mecanismos fisiopatológicos. Estudamos 100 pacientes com indicação de operação vascular e aferimos por meio de ultrassom-Doppler de artéria braquial, a hiperemia reativa (HR), marcador de função microvascular, e a dilatação mediada pelo fluxo (DMF), marcador de função endotelial, antes e após a operação. Analisamos também os níveis de proteina-C reativa ultra-sensível (PCR-us). A operação foi realizada em 96 pacientes e 27 deles apresentaram algum evento até o 30º dia pós-operatório: 4 óbitos cardíacos, 5 infartos agudos do miocárdio, 2 acidentes vasculares cerebrais isquêmicos, 2 elevações isoladas de troponina, 1 embolia de pulmão, 2 reoperações e 11 óbitos não cardíacos. Detectamos disfunção endotelial em 70% dos pacientes, mas não observamos nenhum padrão característico de comportamento perioperatório da DMF, ou associação significativa entre a mesma e os eventos. Observamos significativo aumento da PCR-us após a intervenção cirúrgica (0,5mg/dL x 3,01mg/dL, P=0,001), mas sem associação com eventos. Identificamos forte associação entre disfunção microvascular, representada pela menor velocidade de fluxo na artéria braquial durante a hiperemia reativa, e eventos: 81 cm/s + 20 x 95 cm/s + 28 ( P= 0,02). Concluímos que a identificação de disfunção microvascular no pré-operatório pode estratificar o risco de complicações perioperatórias e que embora não tenhamos observado piora da vasodilatação mediada pelo fluxo, não podemos afastar que haja piora da função endotelial no perioperatório. O aumento de PCR-us denota grande diátese inflamatória, que pode estar relacionada à disfunção endotelial.
Title in English
Perioperative evaluation of endothelial function in patients undergoing vascular surgery
Keywords in English
Aortic aneurysm abdominal/surgery
Atherosclerosis
Endothelium vascular
Intermittent claudication/surgery
Myocardial infarction
Perioperative care
Abstract in English
Despite great advances in perioperative care, major vascular surgeries are still related to high morbidity and mortality. The pathophysiology of perioperative cardiac events is complex and comprehends atherosclerotic plaque instability, witch is not contemplated in the current algorithms for cardiac risk estimation. We hypothesized that the identification of characteristics related to predisposition for plaque instability, such as abnormalities in the vascular reactivity, is very promising and the characterization of this parameter`s behavior in the perioperative setting contributes to the better understanding of event's pathophysiology. We prospectively studied a cohort of 100 patients, candidates for elective major vascular surgery and assessed, by Doppler ultrasound in the brachial artery, reactive hyperemia(RH), a marker of microvascular function, and flow mediated dilation(FMD), a marker of endothelial function, before and after surgery. We also obtained C-reactive protein-high sensitive assay (CRP-hs) before and after surgery. Ninety six patients were submitted to the planned vascular surgery and 27 patients had an event up to the 30º postoperative day. We observed 4 cardiac deaths, 5 acute myocardial infarctions, 2 isolated troponin elevations, 2 ischemic strokes, 1 pulmonary embolism, 2 reoperations and 11 noncardiac deaths. Results: although there was no significant difference in the preoperative FMD between patients with and without events: 4.83% + 6.81 x 5.88% + 6.00 (p= .457), respectively, low RH response, measured as lower peak flow velocity in RH, was associated to events: 81 cm/s + 20 x 95 cm/s + 28 (p=0,02). There was no significant difference in the preoperative CRP-hs between groups (median: 0.51mg/dL (IQR 2.12) x 0.41mg/dL (IQR 0.59), p= .234). There was no significant difference between FMD before and after surgery but we detected an almost 6-fold increase in CRP-hs after surgery: 0.50mg/dL x 3.01mg/dL (p < .001), respectively. Our study demonstrated that microvascular dysfunction is closely related to perioperative events after major vascular surgery and is a better marker of perioperative risk than endothelial dysfunction, in specific conditions.
 
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Publishing Date
2008-06-27
 
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