Niclauss Lars, Masci Pier-Giorgio, Pavon Anna G, Rodrigues David, Schwitter Juerg
Division of Cardiovascular Surgery, Cardiovascular Department, University Hospital of Lausanne (CHUV), Lausanne, Switzerland -
Faculty of Medicine and Biology, University of Lausanne, Lausanne, Switzerland -
J Cardiovasc Surg (Torino). 2020 Jun;61(3):356-368. doi: 10.23736/S0021-9509.20.11150-9. Epub 2020 Jan 23.
The competitive coronary flow is influenced by the severity of the stenosis and may affect graft patency. Transit time flow measurement (TTFM) enables intraoperative graft evaluation and cardiac magnetic resonance (MRI) allows for graft evaluation during follow-up.
Competitive flow and target vessel diameters were determined in 35 patients undergoing off-pump coronary bypass graft surgery (CABG) and correlated to TTFM. Cardiac function, ischemia, and graft flow were evaluated using cardiac MRI during the follow-up period to determine the impact of above-mentioned parameters on graft patency.
Competitive flow led to reduced mean graft flow (MGF) and increased pulsatility index (PI) in arterial grafts. This effect to was not observed in veins. Smaller target coronary arteries (<1.5 mm) were associated with reduced MGF, more pronounced in veins, which presented increased PI and shortened diastolic flow fraction (DF). No death and no re-hospitalization for acute coronary syndrome occurred. Borderline values of TTFM (mean MGF 13±4 mL/min; PI 3.8±1) in left internal mammary artery (LIMA) were mainly observed due to increased native anterior descending artery (LAD) flow. These LAD's collateralized occluded right coronaries (RCA). The corresponding LIMA to LAD grafts showed a bypass flow increase at cardiac MRI follow-up. Two graft occlusions occurred: one in LIMA-to-LAD bypass with borderline TTFM, which did not collateralize the RCA and one in a vein graft with borderline TTFM bypassed on a narrow vascular target.
Competitive flow has an impact on arteries contrary to veins. Veins are at risk for occlusion when grafted to smaller targets. Borderline LIMA flow should be considered as potentially dangerous, if satisfactory explanations are missing, e.g. in the absence of a large coronary target without flow competition.
竞争性冠状动脉血流受狭窄严重程度影响，可能影响移植血管通畅性。通过渡越时间血流测量（TTFM）可在术中评估移植血管，而心脏磁共振成像（MRI）则可在随访期间评估移植血管。
对35例行非体外循环冠状动脉旁路移植术（CABG）的患者测定其竞争性血流和靶血管直径，并与TTFM进行相关性分析。在随访期间，利用心脏MRI评估心功能、缺血情况和移植血管血流，以确定上述参数对移植血管通畅性的影响。
竞争性血流导致动脉移植血管的平均移植血管血流（MGF）降低，搏动指数（PI）升高。静脉移植血管未观察到这种效应。较小的靶冠状动脉（<1.5 mm）与MGF降低相关，在静脉移植血管中更明显，其PI升高，舒张期血流分数（DF）缩短。未发生死亡病例，也没有因急性冠状动脉综合征再次住院的情况。左乳内动脉（LIMA）中TTFM的临界值（平均MGF 13±4 mL/min；PI 3.8±1）主要是由于自身前降支动脉（LAD）血流增加所致。这些LAD为右冠状动脉（RCA）提供侧支循环。相应的LIMA至LAD移植血管在心脏MRI随访时旁路血流增加。发生了2例移植血管闭塞：1例在TTFM临界的LIMA至LAD旁路移植血管，该血管未为RCA提供侧支循环；另1例在TTFM临界的静脉移植血管，该血管绕过了狭窄的血管靶标。
与静脉相反，竞争性血流对动脉有影响。当静脉移植到较小的靶血管时，有闭塞风险。如果缺乏满意的解释，例如在没有无血流竞争的大冠状动脉靶标的情况下，LIMA血流临界值应被视为潜在危险。
