During a microbubble infusion, guided high mechanical index impulses from a diagnostic two dimensional transducer improve microvascular recanalization in acute ST segment elevation myocardial infarction (STEMI). The purpose of this study was to further elucidate the mechanism of improved microvascular flow in normal and hyperlipidemic, atherosclerotic pigs. In 14 otherwise normal pigs, an acute left anterior descending thrombotic coronary occlusion was created. Pigs subsequently received aspirin, heparin and ½ dose fibrinolytic agent (Tenecteplase or tissue plasminogen activator), followed by randomization to either no additional treatment (Group I), or a continuous infusion of non-targeted microbubbles and guided high mechanical index impulses from a three dimensional transducer (3D/mechanical index; Group II). Epicardial recanalization rates, ST segment resolution, microsphere-derived myocardial blood flow (MBF), and ultimate infarct size using myocardial contrast echocardiography were compared. The same coronary thrombosis was created in a set of 12 hypercholesterolemic pigs who were then treated with the same pharmacologic and ultrasound regimen (Group III; n=6) or the pharmacologic regimen alone (Group IV; n=6). Epicardial recanalization rates in Group I and II pigs were the same (29%), however, peri-infarct MBF and ultimate infarct size improved following treatment in Group II pigs (p <0.01 versus Group I). In Group III pigs, epicardial recanalization was 100% (compared to 50% in Group IV), and there were significant reductions in ultimate infarct size (p=0.02 compared to Group IV). We conclude that guided high mechanical index impulses from a diagnostic transducer and non-targeted microbubbles improve peri-infarct microvascular flow in acute STEMI, even when epicardial recanalization does not occur.

In this experimental pilot study, the addition of contrast-enhanced US accelerated the thrombolytic effect of low-dose intra-arterial thrombolysis in peripheral arterial occlusions. Further clinical studies are warranted.

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One of the earliest applications of clinical echocardiography is evaluation of left ventricular (LV) function and size. Accurate, reproducible and quantitative evaluation of LV function and size is vital for diagnosis, treatment and prediction of prognosis of heart disease. Early three-dimensional (3D) echocardiographic techniques showed better reproducibility than two-dimensional (2D) echocardiography and narrower limits of agreement for assessment of LV function and size in comparison to reference methods, mostly cardiac magnetic resonance (CMR) imaging, but acquisition methods were cumbersome and a lack of user-friendly analysis software initially precluded widespread use. Through the advent of matrix transducers enabling real-time three-dimensional echocardiography (3DE) and improvements in analysis software featuring semi-automated volumetric analysis, 3D echocardiography evolved into a simple and fast imaging modality for everyday clinical use. 3DE provides the possibility to evaluate the entire LV in three spatial dimensions during the complete cardiac cycle, offering a more accurate and complete quantitative evaluation the LV. Improved efficiency in acquisition and analysis may provide clinicians with important diagnostic information within minutes. The current article reviews the methodology and application of 3DE for quantitative evaluation of the LV, provides the scientific evidence for its current clinical use, and discusses its current limitations and potential future directions.