Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF. Current technologies for CMR are time consuming and difficult to implement in clinical practice. Feature tracking is a technology that can lead to more automization and robustness of quantitative analysis of medical images with less time consumption than comparable methods.Methods: An automatic or manual input in a single phase serves as an initialization from which the system starts to track the displacement of individual patterns representing anatomical structures over time. The specialty of this method is that the images do not need to be manipulated in any way beforehand like e.g. tagging of CMR images.Results: The method is very well suited for tracking muscular tissue and with this allowing quantitative elaboration of myocardium and also blood flow.Conclusions: This new method offers a robust and time saving procedure to quantify myocardial tissue and blood with displacement, velocity and deformation parameters on regular sequences of CMR imaging. It therefore can be implemented in clinical practice.
The present study describes, for the first time, the progression of IV flow energetic properties in patients with acute myocardial infarction at different stages of LV dysfunction when compared with healthy controls. Further data are needed to assess the role of these parameters in the development and maintenance of LV dysfunction.
In patients receiving permanent cardiac electrical stimulation, a high burden of apical right ventricular pacing is associated with an increased incidence of heart failure. Despite the large body of electrocardiographic, echocardiographic, and pathological data, mechanisms underlying this serious complication are not fully understood. Moreover, the empirical use of alternative right ventricular pacing sites, both in the experimental and in the clinical setting, has not provided better results in terms of clinical outcome. Recent data derived by echocardiographic particle image velocimetry of intracardiac flows have shown abnormal flow patterns in patients with dyssynchrony of left ventricular wall contraction, and the reversion to normal flow dynamics after successful electrical cardiac resynchronization therapy. This suggests that a normal intraventricular flow pattern is strongly dependent on the highly coordinated contraction of the ventricular wall segments and that an abnormal sequence of wall contraction may trigger the development of overt heart failure. This review summarizes the state of the art on this topic, highlighting postulated underlying basic mechanisms linking abnormal flow with the development of pacing-induced heart failure. This research line suggests the importance of studying intraventricular fluid dynamics as a new powerful tool for a more complete understanding of mechanisms involved, and ultimately to prevent pacing-related heart failure.
The introduction of stable microbubble contrast agents and technological advances have recently made it feasible to perform quantitative measurements of microvascular damage by myocardial contrast echocardiography (MCE). Qontrast is a new software system far such measurements. It includes physiological filters, global rescale, regional rescale, automatic myocardial tracking, manual ECG trigger and parametric imaging. Qontrast was tested on 5 pigs given sulphur hexafluoride bubbles (I ml/min) and fluorescent microspheres (reference) after the induction of 50% and 100% stenosis of left anterior descending coronary artery. The image sequences were repeated four times using different ultrasound (US) equipment. A close correlation was found between the ratio risk area/control area by microspheres and the equivalent ratio risk area/control area (Sl x beta) by MCE, being approximately 0.9 far any contrast modality tested. Parametric MCE and SPELT were compared in 12 patients with recent myocardial infarction, including 119 segments. Agreement amounted to 83% (kappa: 0.53 far peak SI and 0.55 far SI x beta). The sensitivity and specificity of peak SI far detecting abnormal segmental tracer uptake were 67% and 88%; the values far Sl x beta were 70% and 87%. Parametric MCE is a promising imaging technique far the assessment of myocardial perfusion in patients with suspected or known coronary artery disease.
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