Indexes of diastolic RV function: load dependence and changes after chronic RV pressure overload in lambs

Abstract

. Indexes of diastolic RV function: load dependence and changes after chronic RV pressure overload in lambs. Am J Physiol Heart Circ Physiol 282: H1350-H1358, 2002. First published December 13, 2001; 10.1152/ajpheart.00782.2001.-Diastolic function is a major determinant of ventricular performance, especially when loading conditions are altered. We evaluated biventricular diastolic function in lambs and studied possible load dependence of diastolic parameters [minimum first derivative of pressure vs. time (dP/dt min) and time constant of isovolumic relaxation ()] in normal (n ϭ 5) and chronic right ventricular (RV) pressure-overloaded (n ϭ 5) hearts by using an adjustable band on the pulmonary artery (PAB). Pressure-volume relations were measured during preload reduction to obtain the end-diastolic pressure-volume relationship (EDPVR). In normal lambs, absolute dP/dt min and were lower in the RV than in the left ventricle whereas the chamber stiffness constant (b) was roughly the same. After PAB, RV and dP/dt min were significantly higher compared with control. The RV EDPVR indicated impaired diastolic function. During acute pressure reduction, both dP/dt min and showed a relationship with end-systolic pressure. These relationships could explain the increased dP/dt min but not the increased -value after banding. Therefore, the increased after banding reflects intrinsic myocardial changes. We conclude that after chronic RV pressure overload, RV early relaxation is prolonged and diastolic stiffness is increased, both indicative of impaired diastolic function.hemodynamics; hypertrophy; pressure-volume relation; ventricular function, diastole THE IMPORTANCE of diastolic function as a major determinant of ventricular performance has long been recognized. Impaired diastolic function may precede systolic ventricular dysfunction (13,14), and it influences the performance of the contralateral ventricle via ventricular interdependence (23,34,39). The gold standard for determination of right ventricular (RV) [and left ventricular (LV)] diastolic function is still considered to be cardiac catheterization with simultaneous high-fidelity pressure and volume measurements (32).Because RV cineangiography is only sporadically performed during routine diagnostic catheterization and because complex RV geometry hampers adequate RV volume determination, few data are available about RV diastolic function. With the combined pressureconductance catheter it has recently become possible to determine ventricular pressure and volume simultaneously and independently of ventricular geometry in the LV as well as in the RV (3,11).Using this method, we are able to determine parameters of diastolic function such as the end-diastolic pressure-volume relationship (EDPVR) and chamber stiffness constant (b) that are well accepted for LV diastolic analysis. Furthermore, some of the LV relaxation parameters have shown a relationship with load (systolic pressure) that may render them less reliable to characterize intrinsic diastolic properties (26, 33)...

Maintained right ventricular pressure overload induces ventricular–arterial decoupling in mice

“…Basically, optimal coupling efficiency is achieved if contractility is matched to vascular load (Naeije & Manes, 2014). Pulmonary artery constriction selectively elevates RV afterload leading to a hyper-contractile response of the RV which was also shown at different time points after pressure overload induction in other species (Leeuwenburgh et al, 2002;Gaynor et al, 2005;Apitz et al, 2012). These and our data suggest that the observed contractility elevation together with RV dilatation and hypertrophy is insufficient to compensate for a dramatically increased afterload leading to ventricular-arterial decoupling and diminished RV ejection volumes.…”

Bandagem reversível do tronco pulmonar IV: análise da hipertrofia aguda do ventrículo direito em modelo experimental de sobrecarga intermitente

“…The periods of intermittent resting during the protocol may optimize the subendocardial coronary flow and, consequently, enlarge the quantity of substrates in the myocardial hypertrophic process, which limits the seriousness of a continuous systolic overload imposed upon the RV. This improvement in prerformance of the RV contrasts with the findings of Leeuwenburgh et al [26], which showed a drop in the cardiac debt in protocol of PT chronic banding in young sheep, despite the increase of RV contractility. The authors concluded that the chronic banding of the RV causes an increase in RV relaxation and decrease of the diastolic compliance, both indicative of diastolic dysfunction of the RV.…”

Evaluation of Right Ventricular Tei Index (Index of Myocardial Performance) in Healthy Dogs and Dogs with Tricuspid Regurgitation

“…We used RV +/-dP/dt as reference values to evaluate RV systolic and diastolic functions. The RV peak +/-dP/dt are the most commonly used indices for assessing ventricular function [15,23,25,42]. However, these indices are influenced by ventricular preload and afterload.…”

“…However, these indices are influenced by ventricular preload and afterload. Therefore, other invasive indices of the ventricular function, such as maximal elastance (Emax), preload recruitable stroke work, chamber stiffness, and the time constant of relaxation (Tau), may reduce the impact from ventricular preload and afterload [15,25,42].…”

“…In particular, the RV Tei index in dogs with PH markedly increased. The RV diastolic function was impaired by chronic PH (pressure overload) in experimental canine and lamb models [25,31]. Tei et al [37] reported that the RV Tei index, which is the strongest predictor of clinical status and survival, increased significantly in human patients with primary PH.…”