Avtor/Urednik		Potočnik, N; Kirn, B; Cesar, S; Starc, V
Naslov		Relaxion of epicardial segment lengths and pressure in the isolated guinea pig left ventricle
Tip		članek
Vir		Med Biol Eng Comput
Vol. in št.		Letnik 37, št. Suppl 2
Leto izdaje		1999
Obseg		str. 1428-9
Jezik		eng
Abstrakt		Cardiac muscle is a soft, porous, biaxial, viscoelastic material, exhibiting stress relaxation and hysteresis after being passively streched. The left ventricular pressure (LVp) changes during cyclic stepwise volume loading and unloading of the left ventricle (LV) and could be separated into elastic and viscoelastic part. The latter could be decomposed further into the fast and the slow component with time constants of relaxation equal to 1 and 20s revealing different mechanisms governing the viscoelastic behavior. We investigated whether these material properties are also manifested in relaxation of epicardial segment lengths and we speculated whether the epicardial segment lengths changing with the same volume loading and unloading procedure also exhibit relaxation with the same time constants. For this purpose LV pressure and biaxial epicardial strains were measured simultaneously in ioslated guinea pig hearts, arrested in diastole and instrumented to manipulate LV volume. Our study confirmed the existence of epicardial strain relaxation in both axial (A) and circumferential (B) directions, though it was much less expressed than LV pressure relaxation. The strain relaxation is much faster then the stress relaxation. The slow decaying component of the strain relaxation was found to be almost absent.
Deskriptorji		VENTRICULAR FUNCTION, LEFT CARDIAC VOLUME MYOCARDIAL CONTRACTION PERICARDIUM GUINEA PIGS