In vivo myocardial kinetics of air-filled albumin microbubbles during myocardial contrast echocardiography. Comparison with radiolabeled red blood cells.

Abstract

stages) demonstrated that removing the effect by deconvolution of the bolus spread before reaching the myocardium is not necessary to maintain the relation between mean myocardial transit rate and LAD blood flow if the duration and site of the tracer injection are constant. Additionally, the coefficient of variation for determining the mean microbubble transit rate during MCE was 21% in these dogs (five injections at a single flow in each dog). We conclude that the transit rates of microbubbles during MCE can be used to assess regional myocardial blood flow in the in vivo beating heart as long as the blood volume remains constant. (Circ Res. 1994;74: 1157-1165 rates and hence regional myocardial blood flow. For this purpose, the myocardial transit rates of sonicated albumin microbubbles were compared with those of technetium-99m-labeled RBCs at different coronary blood flows in the dog. We also evaluated two additional issues in the present study: (1) whether, despite its theoretical advantages, fitting a lagged normal density function13 to the time-intensity plots provides better results than a gamma-variate function,14 which is simpler and less computer intensive, and (2) whether deconvolution of timeintensity curves using an input function is necessary when microbubble injection duration and site are constant. Materials and MethodsEighteen adult mongrel dogs were used for the study. The 12 group I dogs were used to (1) derive the relation between left anterior descending coronary artery (LAD) blood flow and mean RBC transit rate, (2) determine the correlation between mean microbubble and RBC transit rates, and (3) determine which function, lagged normal density or gamma variate, best describes the myocardial time-intensity data. The six group II dogs were used to (1) determine whether removing the effect by deconvolution of the bolus spread before reaching the myocardium is necessary to maintain the relation between mean myocardial transit rate and blood flow if the rate and site of tracer injection into a coronary artery are constant and (2) estimate the coefficient of variation for the mean myocardial

Skeletal Muscle Microvascular Recruitment by Physiological Hyperinsulinemia Precedes Increases in Total Blood Flow

“…The albumin microbubbles used as the contrast-enhancing agent averaged 4 m in diameter, had similar rheology to red blood cells, and were contained entirely within the vascular space (21). As a result, they were an excellent perfusion tracer.…”

Quantification of Myocardial Blood Flow With Ultrasound-Induced Destruction of Microbubbles Administered as a Constant Venous Infusion

“…A model with an incised coronary artery (Fig 3B) was therefore chosen because autoregulation is virtually abolished in this model. 1 Accordingly, the proximal LAD was dissected free from the surrounding tissues. A cannula was inserted into the left carotid artery and connected to tubing that was attached to another cannula.…”

“…Taken together, the results of these studies indicate that direct coronary injection of adenosine increases MBF by dilating microvessels which form a small portion of the MBV or are not present within the myocardia. Thus, by determining both CBV (measurement of the mean transit rate of microbubbles after an intracoronary bolus injection 1,2 ) and MBV (measurement of microvascular CSA during an intravenous infusion of microbubbles), MCE could be used to separate changes in capillary dimension or density from those of larger microvessels.…”

Myocardial contrast echocardiography in the diagnosis of a left ventricular hemangioma

“…6,7 The patients receive an injection of a contrast agent directly into the bloodstream through a vein. High energy pulse of ultrasound is used to destroy the microbubbles and observation of the subsequent replenishment of microbubbles into the microcirculation permits evaluation of myocardial tissue perfusion.…”