Flow propagation velocity is not a simple index of diastolic function in early filling. A comparative study of early diastolic strain rate and strain rate propagation, flow and flow propagation in normal and reduced diastolic function

BACKGROUND: Strain Rate Imaging shows the filling phases of the left ventricle to consist of a wave of myocardial stretching, propagating from base to apex. The propagation velocity of the strain rate wave is reduced in delayed relaxation. This study examined the relation between the propagation velocity of strain rate in the myocardium and the propagation velocity of flow during early filling. METHODS: 12 normal subjects and 13 patients with treated hypertension and normal systolic function were studied. Patients and controls differed significantly in diastolic early mitral flow measurements, peak early diastolic tissue velocity and peak early diastolic strain rate, showing delayed relaxation in the patient group. There were no significant differences in EF or diastolic diameter. RESULTS: Strain rate propagation velocity was reduced in the patient group while flow propagation velocity was increased. There was a negative correlation (R = -0.57) between strain rate propagation and deceleration time of the mitral flow E-wave (R = -0.51) and between strain rate propagation and flow propagation velocity and there was a positive correlation (R = 0.67) between the ratio between peak mitral flow velocity / strain rate propagation velocity and flow propagation velocity. CONCLUSION: The present study shows strain rate propagation to be a measure of filling time, but flow propagation to be a function of both flow velocity and strain rate propagation. Thus flow propagation is not a simple index of diastolic function in delayed relaxation

Nastal čas prodloužit dobu expirace kryoprezervovaných alograftů srdečních chlopní

V současné době existuje velké množství umělých komerčních náhrad chlopní. Přesto jsou stále žádané a úspěšně transplantované kryoprezervované semilunární alografty srdečních chlopní (C-AHV). U těchto náhrad zatím není přesně definována doba expirace.Většina tkáňových bank používá pět let. Z fyziologického, funkčního a operačního pohledu představuje morfologie a mechanické vlastnosti aortálních a pulmonárních kořenů hlavní limitaci doby expirace C-AHV. Cílem této práce je podat přehled metod strukturní a mechanické analýzy tkání AHV, které jsou vhodné pro stanovení doby expirace. alograftů. Pro stanovení mikrostruktury je vhodná kvantitativní morfologie za použití stereologické testovací mřížky. Touto metodou lze snadno, efektivně a opakovatelně stanovit možství buněk a mezibuněčných komponent. Pro stanovení mechanických parametrů, jako Youngův modul pružnosti, mezní napětí a deformace, lze využít tahovou zkoušku. C-AHV jsou v různých tkáňových laboratořích připravovány podle různých protokolů. Je tedy nutné, aby každá laboratoř stanovila dobu expirace samostatně.Despite the wide choice of commercial heart valve prostheses, cryopreserved semilunar allograft heart valves (C-AHV) are required, and successfully transplanted in selected groups of patients. The expiration limit (EL) criteria have not been defined yet. Most Tissue Establishments (TE) use the EL of 5 years. From physiological, functional, and surgical point of view, the morphology and mechanical properties of aortic and pulmonary roots represent basic features limiting the EL of C-AHV. The aim of this work was to review methods of AHV tissue structural analysis and mechanical testing from the perspective of suitability for EL validation studies. Microscopic structure analysis of great arterial wall and semilunar leaflets tissue should clearly demonstrate cells as well as the extracellular matrix components by highly reproducible and specific histological staining procedures. Quantitative morphometry using stereological grids has proved to be effective, as the exact statistics was feasible. From mechanical testing methods, tensile test was the most suitable. Young’s moduli of elasticity, ultimate stress and strain were shown to represent most important AHV tissue mechanical characteristics, suitable for exact statistical analysis. C-AHV are prepared by many different protocols, so as each TE has to work out own EL for C-AHV