Coronary Flow in Patients with Three-Vessel Disease: Simulated Hemodynamic Variables in relation to Angiographically Assessed Collaterality and History of Myocardial Infarction.

International audienceWe study patients with stenoses of the left main coronary artery (LMCA), left anterior descending artery (LAD), and left circumflex branch (LCx) and with chronic occlusion of the right coronary artery (RCA), undergoing off-pump coronary surgery. An analog electrical model is used to provide quantitative estimations of the distribution of flows and pressures across the coronary network (in the stenosed native arteries, the collateral branches, the capillary areas, and so forth). The present paper demonstrates that the clinical information collected for the 10 patients included in the study (Rentrop score, history of myocardial infarction, left ventricular ejection fraction (LVEF)) are well correlated with the predicted hydrodynamic data. Patients with a good collaterality (Rentrop score = 3) or patients without anterior myocardial infarction have (i) less severe stenoses on the LMCA, (ii) lower microvascular resistances, (iii) higher grafts flow rates when the revascularization is performed, (iv) higher collateral flow rates towards the territory of the occluded artery, (v) better perfusion of this area, and (vi) better total perfusion of the heart

Images in cardiovascular medicine. Mitral valve varix.

International audienceA 39-year-old man presented with atypical angina and hemoptysis. This soldier traveled regularly to the Middle-East and Africa. Initial clinical examination was within normal limits, as were also the ECG, biochemistry, and hematologic blood samples..

Uncontrolled daily pulmonary oedema due to severe mitral regurgitation emergently and effectively corrected by Mitraclip® implantation.

International audienceMitraClip® is usually implanted in stable patients. We report the case of a patient having a severe, refractory and daily pulmonary oedema, related to a severe restrictive mitral regurgitation secondary to a primitive dilated cardiomyopathy. A Mitraclip® was emergently implanted, with a dramatic long-term clinical success. The critical unstable status of a patient should not prevent any Mitraclip® implantation

Impact of revascularization on the distal to proximal pressure ratio in case of multiple coronary stenoses

International audienceObjective: In order to take a decision about the revascularization approach to be adopted, it is of fundamental importance to determine whether coronary artery stenoses induce ischemia or not. An index, named (Fractional Flow Reserve), based on pressure measurements has been proposed to this aim and is usually interpreted in terms of flows. The objective of this work is to compute simultaneously pressures and flow rates in the coronary network of patients with three-vessel disease, in order to study more precisely the relationship between these two quantities. Approach: 22 patients have been included in the study. Some pressure and flow rates measurements were collected during by-pass surgery. These clinical data allow to determine parameters for a patient’s specific model, based on the electric / hydraulic analogy. Collateral pathways are included in the model, as well as the severity of the disease and the impact of revascularization. Main Results: For patients with stenoses on LAD, LCx, LMCA and occlusion of the RCA, the flow rate delivered to the right territory is of course a function of the aortic pressure, the left stenoses severity, and the pressure distal to the thrombosis. But it mainly depends on the capillary and collateral resistances, and on the proportion between them. Abnormal microvascular hemodynamics, may be present in patients with non-hemodynamic significant lesions as assessed by the pressure ratio. Complete revascularization with the 3 grafts is demonstrated to be fully justified. The direction of collateral flows may be reversed, depending on the pressure gradient. In any case, they remain low and become negligible when the 3 grafts are operating. Significance: Surgical decision based only on pressure measurements may miss some real hemodynamic problem due to the considered stenosis. This risk is even greater in case of serial stenoses

Impact of revascularization on the distal to proximal pressure ratio in case of multiple coronary stenoses

Objective: In order to take a decision about the revascularization approach to be adopted, it is of fundamental importance to determine whether coronary artery stenoses induce ischemia or not. An index, named (Fractional Flow Reserve), based on pressure measurements has been proposed to this aim and is usually interpreted in terms of flows. The objective of this work is to compute simultaneously pressures and flow rates in the coronary network of patients with three-vessel disease, in order to study more precisely the relationship between these two quantities. Approach: 22 patients have been included in the study. Some pressure and flow rates measurements were collected during by-pass surgery. These clinical data allow to determine parameters for a patient’s specific model, based on the electric / hydraulic analogy. Collateral pathways are included in the model, as well as the severity of the disease and the impact of revascularization. Main Results: For patients with stenoses on LAD, LCx, LMCA and occlusion of the RCA, the flow rate delivered to the right territory is of course a function of the aortic pressure, the left stenoses severity, and the pressure distal to the thrombosis. But it mainly depends on the capillary and collateral resistances, and on the proportion between them. Abnormal microvascular hemodynamics, may be present in patients with non-hemodynamic significant lesions as assessed by the pressure ratio. Complete revascularization with the 3 grafts is demonstrated to be fully justified. The direction of collateral flows may be reversed, depending on the pressure gradient. In any case, they remain low and become negligible when the 3 grafts are operating. Significance: Surgical decision based only on pressure measurements may miss some real hemodynamic problem due to the considered stenosis. This risk is even greater in case of serial stenoses

Quantification des Flux Collatéraux chez des Patients Présentant des Coronaropathies Sévères

International audienceThe aim of this work is to obtain an indirect evaluation of the pressures and flow rates in the coronary network, in locations where direct measurements are not possible, or invasive, or too expansive, … More precisely, the study is focused on the role of collateral flows in three-vessel disease patients, before and after bypass grafting, depending on the severity of the stenoses and thromboses. A model of the coronary circulation based on hydraulic / electric analogy has been developed; it is patient's specific because some of the parameters are determined using per-operative classical measurements. Results show that the complete revascularization is fully justified for these patients, that collateral flows remain low in any cases, and that capillary and collateral resistances have a major impact on the flows and pressures everywhere in the network. The simulations also bring some arguments to current medical debates, such as flow competitions between the grafts and native vessels, or long-term effect of Drug Eluting Stents, or the use of the FFR index to evaluate the severity of stenoses.Nous pré sentons ici une dé marche d'évaluation indirecte de quantité s difficiles à mesurer de maniè re directe. Il s'agit de connaî tre les pressions et les dé bits dans le ré seau des artè res coronaires, chez des patients qui pré sentent des problè mes sé vè res de sté noses ou thromboses en trois endroits diffé rents. En particulier, le but est d'évaluer l'efficacité du ré seau collaté ral chez chacun de ces patients, et son influence sur la ré partition des pressions et des dé bits aprè s la pose des ponts. Et ainsi de constituer une banque de donné es, à laquelle il sera possible de se ré fé rer par la suite pour de nouveaux patients, au lieu de recourir à des examens invasifs, compliqué s, et/ou coûteux. La mé thode combine l'acquisition de mesures classiquement ré alisé es lors de la chirurgie à coeur battant pour l'implantation des ponts et un modè le dé veloppé sous Matlab en se basant sur l'analogie entre ré seaux hydrauliques et ré seaux é lectriques. Les ré sultats confirment la né cessité des 3 ponts pour ces patients. Ils montrent que la supplé ance naturelle par le ré seau collaté ral reste faible, et que les ré sistances capillaires (collaté rales ou pé riphé riques) jouent un rôle trè s important dans le succè s à long terme des pontages. Les ré sultats peuvent aussi apporter des arguments aux dé bats qui existent actuellement dans la communauté chirurgicale : les compé titions de flux entre les ponts et les vaisseaux natifs, l'impact à long terme des Drug Eluting Stents (DES), ou l'utilisation de l'indice FFR pour é valuer la sé vé rité des sté noses en pré-opé ratoire

Patient's specific computer simulations to assist coronary artery bypass surgery

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Analog electrical model of the coronary circulation in case of multiple revascularizations.

International audienceIn this work, we propose an analog electrical model of the coronary circulation for patients with obstructive disease undergoing revascularization. In this clinical situation, the collateral circulation to the occluded artery is difficult to ascertain via preoperative measurements and well-developed collaterals might induce long-term restenosis of the revascularized artery due to flow competition mechanisms. The proposed model allows an original biomechanical analysis of per-operative hemodynamic data in order to assess quantitative evaluation of pressures and flows inside the native stenosed arteries, the collateral network and the bypass grafts. Average cardiac cycle values are analysed. In the case of 3-vessel disease and chronic occlusion of the right coronary artery, the quantitative results confirm the protective effects of the collateral flows in the pathological situation, but also show that the revascularization of the occluded right artery is fully justified since the collateral flows remain low, even when the left territory is revascularized. The model thus provides a computational tool to evaluate therapeutic strategies for each patient

Preliminary study of collateral flows in patients with aortic coarctation

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