K. Giuliano1, X. Zhou1, E. Etchill1, Z. Zhang3, A. Suarez-Pierre1, C. Lui1, H. Halperin2, J. Katz3, C. Choi1 1Johns Hopkins University School Of Medicine,Cardiac Surgery,Baltimore, MD, USA 2Johns Hopkins University School Of Medicine,Cardiology,Baltimore, MD, USA 3Johns Hopkins University,Mechanical Engineering,Baltimore, MD, USA
Introduction: Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is a potentially life-saving technology for acute cardiogenic shock. Left ventricular (LV) distention is a predictor of poor outcomes. The increased afterload caused by VA-ECMO with peripheral cannulation may result in left heart dysfunction and distension requiring a LV vent. Although stroke work (SW) has been proposed as a marker of LV dysfunction, it requires invasive measurement. We propose a novel contrast echocardiographic technique to characterize LV dysfunction during ECMO noninvasively.
Methods: Coronary balloon occlusion was used to induce myocardial infarction in 12 adult Yorkshire pigs who were subsequently supported with VA-ECMO through peripheral cannulation. Contrast-enhanced transesophageal echocardiography was performed at varying levels of ECMO flow. Particle image velocimetry and particle tracking velocimetry (PIV-PTV) of the individual contrast particles was used to characterize flow patterns in the aortic root and compared to measurements of SW calculated from left heart catheterization.
Results: In mildly injured pigs (Ejection fraction [EF]>40%), full ECMO support (4L/min) was associated with significantly increased SW (1381.5 mmHg mL) when compared to minimal ECMO support (1-2L/min, SW 575.7 mmHg mL). In severely injured pigs (EF<40%), SW was similar during full ECMO support (1087.0 mmHg mL) and minimal ECMO support (831.2 mmHg mL). The increased SW seen in mildly injured pigs with full support was driven primarily by changes in LV pressure (LV end-systolic pressure +136.6%), while stroke volume was less affected (+33.8%). Differences in SW could be characterized by examining aortic root flow patterns with PIV-PTV (Figure 1). Increased SW was associated with admixture between left ventricular ejection and retrograde ECMO flow at a more distal site in the aortic root.
Conclusion: PIV-PTV contrast echocardiography may represent a novel and noninvasive method of characterizing LV dysfunction during ECMO, helping to predict myocardial recovery or the need for a LV vent better than conventional echocardiography.
