Intracardiac measurement of pre-ejection myocardial velocities estimates the transmural extent of viable myocardium early after reperfusion in acute myocardial infarction

OBJECTIVES We hypothesized that wall motion velocity during pre-ejection is proportional to the regional content of viable myocardium after reperfusio n for acute myocardial infarction (AMI). BACKGROUND Pre-ejection wall motion consists of short and fast inward and o utward movement towards and away from the center of the left ventricle (LV) and is altered during regional ischemia. This short-lived event can be acc urately quantified by Doppler myocardial imaging (DMI). METHODS Fourteen open-chest pigs underwent 60 to 120 min of left anterior d escending coronary artery occlusion followed by 30 min of reperfusion. The DMI data were collected using a phased-array intracardiac catheter (LV cavi ty) from ischemic and nonischemic myocardium encompassed within a plane pas sing through two epicardial bead markers. Peak tissue velocities during iso volumic contraction (IVC) (peak positive and peak negative), ejection (S) a nd early filling (E) were measured. The cardiac specimen was sliced through the epicardial markers in a plane approximating the ultrasound imaging pla ne. The transmural extent of necrosis (TEN) (%) was measured by triphenylte trazolium chloride staining. RESULTS During ischemia, positive IVC velocity was zero in ischemic walls w ith TEN > 20%. At reperfusion, positive IVC velocity correlated better with TEN (r = -0.94, p < 0.0001) than it did S (r = -0.70, p < 0.01) and E (r = -0.81, p < 0.01). Differential IVC (the difference between peak positive a nd peak negative velocity) highly correlated with TEN, during ischemia (r = -0.78, p < 0.001) and during reperfusion (r = -0.93, p < 0.0001). CONCLUSIONS Pre-ejection tissue velocity, as measured by intracardiac ultra sound, allows rapid estimation of the transmural extent of viable myocardiu m after reperfusion for AML. (C) 2001 by the American College of Cardiology .