We could show previously, however, that applying resolution modeling, ECG triggering and respiratory gating to the PET data leads to an improved representation of regional metabolism. 10 Clinical PET images, however, suffer from a low spatial resolution, 11 and acquisitions are further blurred by heart motion because of both beating and breathing, which hampers their ability to differentiate between thin walls with normal metabolism and thick walls with reduced metabolism because since both may result in comparable apparent tracer activity in a given region. 9ġ8F-fluorodeoxyglucose (FDG) tracer uptake by positron emission tomography (PET) is commonly interpreted as reflecting glucose metabolism in the myocardium. Although several authors suggest that regional LV work is closely associated with metabolism, 7, 8 empirical data on such relation are scarce. Methods that allow to assess myocardial work on a regional level would, therefore, provide important information on the effect of regional function and loading conditions on remodeling. Inhomogeneities in ventricular shape 4 and workload 3, 5, 6 in pathologies, such as dilated cardiomyopathy with dyssynchrony, have been suggested as the underlying pathophysiological mechanism of LV remodeling, but the relation is difficult to prove in a clinical setting. 2 Measuring such stress-strain loops before and 1 year after treatment, we could demonstrate in responders to cardiac resynchronization therapy (CRT) that the pathological workload distribution of dyssynchronous hearts normalizes with the treatment. 1 Similarly, regional stress-strain loops can be understood as representation of regional myocardial work per volume-unit. The external work performed by the left ventricle (LV) can be described by the area of invasively measured pressure-volume loops. Redistribution of regional loading appears as mode of action of cardiac resynchronization therapy so that myocardial mechanics should be the main treatment target of cardiac resynchronization therapy. In reverse, cardiac resynchronization therapy implantation leads acutely to an inhomogeneous distribution of workload, which homogenizes over time because of reverse remodeling. Inhomogeneous regional distribution of myocardial workload because of left bundle branch block triggers adaptive remodeling of the left ventricle leading toward a more homogeneous load distribution per volume-unit myocardium. Regional myocardial glucose metabolism and workload parallel each other closely in absolute terms in a wide range of loading conditions, so that both approaches can deliver valid data in a clinical setting.Ĭardiac positron emission tomography assessment of myocardial glucose metabolism requires motion compensation and anatomic correction to provide reliable regional estimates. ![]() Customer Service and Ordering Information.About Circ: Arrhythmia and Electrophysiology.Stroke: Vascular and Interventional Neurology.Journal of the American Heart Association (JAHA).Circ: Cardiovascular Quality & Outcomes.Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB).
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