Tomasz A. Timek

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The afterload dependence of the intracellular calcium transient in isolated working human myocardium was analyzed in both donor and recipient hearts of seven patients undergoing transplantation because of dilated cardiomyopathy. The intracellular calcium transient (recorded by the fura 2 ratio method), force development, and muscle shortening were(More)
The amino-terminal domain of the essential myosin light chain (MLC-1) binds to the carboxy terminus of the actin molecule. We studied the functional role of this interaction by two approaches: first, incubation of intact and chemically skinned human heart fibers with synthetic peptide corresponding to the sequences 5 through 14 (P5-14), 5 through 8 (P5-8),(More)
BACKGROUND The purpose of this investigation was to study mitral valve 3D geometry and dynamics by using a coordinate-free system in normal and ischemic hearts to gain mechanistic insight into normal valve function, valve dysfunction during ischemic mitral regurgitation (IMR), and the treatment effects of ring annuloplasty. METHODS AND RESULTS Radiopaque(More)
OBJECTIVE Left ventricular torsion reduces transmural systolic gradients of fiber strain, and torsional recoil in early diastole is thought to enhance left ventricular filling. Left ventricular remodeling in dilated cardiomyopathy may result in changes in torsion dynamics, but these effects are not yet characterized. Tachycardia-induced cardiomyopathy is(More)
UNLABELLED Two questions were analysed: (1) Is the Frank-Starling mechanism operative in failing human myocardium? (2) Are length-dependent changes in force accompanied by length-dependent changes in intracellular calcium transients in human myocardium? METHODS (I) in electrically stimulated left-ventricular trabeculae [normal donor heart (NDH), n = 8;(More)
BACKGROUND Current surgical methods for treating aortic valve and aortic root pathology vary widely, and the basis for selecting one repair or replacement alternative over another continues to evolve. More precise knowledge of the interaction between normal aortic root dynamics and aortic valve mechanics may clarify the implications of various surgical(More)
BACKGROUND Dilated cardiomyopathy is often associated with mitral regurgitation (MR), or so-called functional MR, the mechanism of which continues to be debated. We studied the valvular and ventricular 3D geometric perturbations associated with MR in an ovine model of tachycardia-induced cardiomyopathy (TIC). METHODS AND RESULTS Nine sheep underwent(More)
BACKGROUND Acute posterolateral left ventricular ischemia in sheep results in ischemic mitral regurgitation, but the effects of ischemia in other left ventricular regions on ischemic mitral regurgitation is unknown. METHODS Six adult sheep had radiopaque markers placed on the left ventricle, mitral annulus, and anterior and posterior mitral leaflets at(More)
BACKGROUND Mechanical circulatory support with the Berlin Heart EXCOR pediatric ventricular assist device (VAD) has been used successfully in Europe for children with cardiac failure. Eighty-seven devices have been placed in North America through February 2007. We describe our single-center experience in 8 children. METHODS Eight children (ages 4 to 55(More)
BACKGROUND The aortic and mitral valves are coupled through fibrous aorto-mitral continuity, but their synchronous dynamic physiology has not been completely characterized. METHODS Seven sheep underwent implantation of five radiopaque markers on the left ventricle, 10 on the mitral annulus, and 3 on the aortic annulus. One of the mitral annulus markers(More)