Left Ventricular Unloading Increases the Coronary Collateral Flow Index Before Reperfusion and Reduces Infarct Size in a Swine Model of Acute Myocardial Infarction

Figures

• 

  Figure 1. Infarct size associated with Impella or venoarterial extracorporeal membrane oxygenation (VA‐ECMO) plus delayed reperfusion. A, Illustration of the study design; (B) Representative pathologic specimens of the left ventricle with triphenyltetrazolium chloride and Evans Blue counterstaining; (C) Bar graph quantifying infarct size normalized to the area at risk for the continued occlusion (CO), Impella, and VA‐ECMO groups (n=5 per group). Red=Impella, blue=continued occlusion, green=VA‐ECMO. LAD indicates left anterior descending artery.

• 

  Figure 2. Hemodynamic association between left ventricular stroke work (LVSW) and the collateral flow index (CFI). (A) Changes in LVSW between groups (*, P<0.05 for comparisons shown); (B) Changes in the CFI between groups (*, P<0.05 vs 90 minutes, †, P<0.05 vs Continued occlusion (CO) and veno‐arterial extracorporeal membrane oxygenation (VA‐ECMO); (C) Correlation between changes in LVSW vs changes in the CFI. Red= Impella, blue=continued occlusion, green=VA‐ECMO. Solid line: linear regression, Dotted line: 95% CI.

• 

  Figure 3. Collateral flow index tracing analysis. A, Representative pressure tracings are shown from the continued occlusion (CO), Impella, and venoarterial extracorporeal membrane oxygenation (VA‐ECMO) groups. Blue and red tracings represent aortic pressure (Pa) and the distal coronary pressure, respectively. Onset of left anterior descending artery (LAD) balloon occlusion (*), followed by activation of either an Impella or VA‐ECMO after 90 minutes (vertical hashed line), and coronary reperfusion at 120 minutes (†) are shown. The red tracing between onset of LAD occlusion and coronary reperfusion represents the coronary wedge pressure (Pw). B, Changes between Impella and VA‐ECMO for the coronary wedge systolic, mean, and pulse pressures are shown (&ddagger; P<0.05 between groups).

• 

  Figure 4. Scatter plots illustrating correlations between ventricular and coronary indices and infarct size. A, Changes in left ventricular stroke work (LVSW) correlate with changes in coronary wedge (Pw) pulse pressure; (B) Changes in LVSW correlate with changes in Pw systolic pressure; (C and D) Infarct size normalized to the area at risk (AAR) correlate with changes in the collateral flow index (CFI) and Pw pulse pressure, respectively. Red=Impella, blue=continued occlusion, green=venoarterial extracorporeal membrane oxygenation. Solid line: linear regression line, dotted lines: 95% CI.

• 

  Figure 5. Impella activation promotes functional reperfusion. Illustration representing changes in infarct size and associated changes in the pressure‐derived collateral flow index (CFI) between groups. Compared with continued occlusion or venoarterial extracorporeal membrane oxygenation (VA‐ECMO), Impella activation before reperfusion increased the CFI and reduced infarct size without affecting average peak velocity (APV) in the left circumflex artery (LCx). Pa (aortic pressure), Pw (coronary wedge pressure), and (no change). LAD indicates left anterior descending artery.