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La circulation artérielle coronaire est un système complexe dont les méthodes de mesures invasivespermettent une évaluation en pratique clinique.Matériels et méthodes Nous développons, dans deux revues, les principes et méthodes des différentes techniques invasivesde mesure du flux coronaire en pratique clinique. Puis nous étudions l’impact clinique de l’utilisationde la Fractional Flow Reserve (FFR) dans l’évaluation des sténoses coronaires intermédiaires, lesmoyens pharmacologiques pour mesurer la FFR et sa corrélation avec l’évaluation angiographique enfonction des facteurs de risque cardiovasculaires. Enfin, nous décrivons les principes et méthodesd’une technique de mesure du flux coronaire segmentaire permettant d’obtenir la FFR, le flux et lesrésistances absolues avec un microcathéter de perfusion qui, sur un principe de thermodilutionpermet d’évaluer distinctement la macro et la microcirculation coronaire.Résultats Nous recommandons une valeur seuil de FFR de 0,80 pour guider la revascularisation car le nombred’événements cardiovasculaires et la mortalité sont spontanément supérieurs chez les patients avecune FFR <0,80 comparativement à une FFR ≥0,80 (9,4 vs. 4,8%, P=0,06 et 7,5 vs. 3,2%, P=0,06;respectivement). Nous avons étudié différents agents hyperémiants permettant de mesurer la FFR:l’adénosine (100 μg à 200 μg) permettant d’obtenir une hyperémie maximale, et le produit decontraste permettant d’atteindre 65% de cette hyperémie maximale. La mesure de la FFR avec duproduit de contraste permet de meilleures performances diagnostiques que les indices de reposcomparé à la FFR sous adénosine. Nous avons établi que la corrélation entre la FFR et le degré desténose angiographique est faible et inversement proportionnel au nombre de facteurs de risquecardiovasculaires, particulièrement chez les patients diabétiques. Enfin, nous avons décrit dans troisétudes, le principe de thermodilution coronaire et la méthode de mesures du flux coronaire et desrésistances microvasculaires avec un microcathéter de perfusion intracoronaire spécifique. Nousavons montré que cette technique est précise (R=0,98), qu’elle induit une hyperémie maximale etlocale sans agent hyperémiant et quelle est reproductible chez l’homme (R=0,91).Conclusion La compréhension de la circulation coronaire et l’application chez l’homme des techniques demesure du flux coronaire segmentaire sont essentielles tant en pratique clinique courante qu’enrecherche. / Coronary circulation is complex and highly regulated while invasive coronary flow measurements techniques allow the assessment of coronary physiology in clinical practice. Material et methods We describe in two reviews the principles and methods of different invasive coronary flowmeasurements techniques in clinical practice. We study the clinical impact of fractional flow reserve(FFR) in intermediate coronary stenosis, the hyperemic agents and dosage to measure FFR and FFRcorrelation with angiographic indices according to risk factors accumulation. Finally, we describe the principle and method of coronary flow and microvascular resistances measurements with a dedicated infusion microcatheter for coronary thermodilution to obtain assessment of macro and microvascular components of coronary circulation. Results We recommend the FFR cut off value of 0.80 to guide revascularization based on our study showing higher myocardial infarction and death rate in patients treated with medical therapy and FFR<0.80compared to those with FFR>0.80, respectively 9.4 versus 4.8%, P=0.06 and 7,5 versus 3,2%, P=0.06. We studied different hyperemic agents and dosages and showed that intracoronary adenosine at 100μg to 200 μg induce maximal hyperemia while contrast medium induce 65% of maximal hyperemia. Therefore, FFR measurements with contrast medium is feasible and has better accuracy than restindices compared to FFR. We establish the weak correlation between FFR and angiographic indicesand weakens correlation as risk factors accumulates, especially in diabetic patients. Finally, we described in three studies the method of absolute coronary flow and microvascular resistancesmeasurements based on thermodilution principle with a dedicated infusion catheter. We showed anaccurate measurement with this technique (R=0.98), which induces maximal hyperemia without theneed of hyperemic agent with reproducible measurements in humans (R=0,91).Conclusion The use of invasive coronary flow measurements to study the coronary circulation is essential inclinical practice and in research.

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Aims: Noninvasive fractional flow reserve (FFR) measurement with computed tomography (FFRCT) is a newly described method for assessing functional significance of coronary disease. The objective of this metaanalysis is to determine the diagnostic performance of FFRCTin the assessment of hemodynamically significant coronary artery stenosis. Methods: PubMed and the Cochrane Center Register of Controlled Trials were searched from January 2000 through February 2015. Six original studies were found comparing FFRCTto invasive FFR in evaluating hemodynamic significance of coronary lesions (1354 vessels; 812 patients). Lesions were considered hemodynamically significant if invasive FFR was 0.80 or less. FFRCTused the same cutoff as invasive FFR to be considered as a positive test. Sensitivity, specificity, positive and negative likelihood ratios, and diagnostic odds ratio were calculated. Results: One-third of the lesions (n=443) were hemodynamically significant. The pooled per-vessel analysis showed that the sensitivity, specificity, negative and positive likelihood ratios, and diagnostic odds ratio of FFRCTto diagnose hemodynamically significant coronary disease were 0.84 [95% confidence interval (CI):0.80-0.87], 0.76 (95% CI: 0.73-0.79), 0.22 (95% CI: 0.17-0.29), 3.48 (95% CI: 2.21-5.47), and 16.82 (95% CI: 8.20-34.49), respectively. Conclusion: The results of this meta-analysis demonstrate that FFRCTresults correlate closely with invasive coronary angiography and FFR measurement. It is a feasible noninvasive method to assess hemodynamic significance of coronary lesions in patients with stable coronary artery disease.