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J Appl Physiol 105: 1015–1016, 2008; doi:10.1152/japplphysiol.zdg-8134-vpcomm.2008. Letters To The Editor Commentaries on Viewpoint: Is left ventricular volume during diastasis the real equilibrium volume, and what is its relationship to diastolic suction? TO THE EDITOR: REFERENCES 1. Kenner HM, Wood EH. Intrapericardial, intrapleural, and intracardiac pressures during acute heart failure in dogs studied without thoracotomy. Circ Res 19: 1071–1079, 1966. 2. Vogel WM, Apstein CS, Briggs LL, Gaasch WH, Ahn J. Acute alterations in left ventricular diastolic chamber stiffness. Role of the “erectile” effect of coronary arterial pressure and flow in normal and damaged heart. Circ Res 51: 465– 478, 1985. 3. Zhang W, Chung CS, Shmuylovich L, Kovacs SJ. Viewpoint: Is left ventricular volume during diastasis the real equilibrium volume, and what is its relationship to diastolic suction? J Appl Physiol; doi:10.1152/ japplphysiol.00799.2007. Erik L. Ritman, MD, PhD Professor, Physiology and Medicine Mayo Clinic TO THE EDITOR: Functional imaging (FI) combines imaging datasets and computational fluid dynamics to simulate cardiac flows (2). It has revealed previously inaccessible subtleties in ventricular filling dynamics (2– 4). Their important implications for measuring filling pressures and demonstrating “suction” were overlooked by Zhang et al. (5). During the E-wave upstroke, flow is confluent between atrial endocardium and atrioventricular orifice (AVO) and diffluent between AVO and ventricular walls. There is convective acceleration up to AVO and deceleration beyond it (3); flow velocity decreases from AVO to apex, creating a convective pressure rise. The measured time-dependent total transvalvular gradient (䡠PT) depends strongly on the exact placement of upstream and downstream measurement sites (3), which bears http://www. jap.org on its local (䡠PL) and convective (䡠PC) components, and on whether “suction” is demonstrable. FI has revealed the mutually opposed effects on intraventricular 䡠PT of local acceleration and convective deceleration during the E-wave upstroke (2– 4), when 䡠PC counterbalances 䡠PL. The smallness of nonobstructive early diastolic 䡠PTs renders catheter measurements unreliable (3) and confounds filling “suction” demonstrations. During ejection, both components act synergistically (1, 3) yielding larger 䡠PTs. At E-wave peak, 䡠PL vanishes and the whole 䡠PT is convective. During the E-wave downstroke, the strongly adverse intraventricular 䡠PT embodies pressure augmentations along the flow (3) from both convective and local decelerations. Soon after the onset of E-wave downstroke, the adverse pressure causes flow separation and inception of recirculation with a vortex surrounding the central inflow, and facilitating filling by robbing kinetic energy that would otherwise contribute to a convective pressure rise (4). REFERENCES 1. Pasipoularides A. Clinical assessment of ventricular ejection dynamics with and without outflow obstruction. J Am Coll Cardiol 15: 859 – 882, 1990. 2. Pasipoularides AD, hu M, Womack MS, Shah A, von Ramm O, Glower DD. RV functional imaging: 3-D echo-derived dynamic geometry and flow field simulations. Am J Physiol Heart Circ Physiol 284: H56 –H65, 2003. 3. Pasipoularides A, Khandheria BK, KorineA, Shu M, Shah A, Tucconi A, Glower DD. RV instantaneous intraventricular diastolic pressure and velocity distributions in normal and volume overload awake dog disease models. Am J Physiol Heart Circ Physiol 285: H1956 –H1965, 2003. 4. Pasipoularides A, Khandheria BK, KorineA, Shu M, Shah A, Womack MS, Glower DD. Diastolic right ventricular filling vortex in normal and volume overload states. Am J Physiol Heart Circ Physiol 284: H1064–H1072, 2003. 5. Zhang W, Chung C, Shmuylovich L, Kovacs SJ. Viewpoint: Is left ventricular volume during diastasis the real equilibrium volume, and what is its relationship to diastolic suction? J Appl Physiol; doi:10.1152/ japplphysiol.00799.2007. Ares Pasipoularides, MD, PhD, FACC Emeritus Research Professor of Surgery Duke University DOES LEFT VENTRICULAR SUCTION EXIST? TO THE EDITOR: A vacuum chamber does not attract matter, but matter is pushed out of regions with high pressure (Wikipedia, item “suction”). Mitral flow is energized by the summed action of left atrium (LA) and left ventricle (LV). At initiation of mitral flow, the LA contributes energy by push (pLA-pPERI)䡠dVLV. Following the ideas of Nikolic, the LV sucks when during filling the cavity pressure (pLV) is below intrapericardial pressure (pPERI), which was atmospheric in his open chest preparations. The LV contributes energy by (pPERI-pLV)䡠dVLV, which value is practically always negative, i.e., the LV does not suck, but is weakly pushing. Why talking about suction? LV energy is the sum of elastic recoil by the passive matrix and active contraction. At initiation of mitral flow, passive recoil delivers energy to filling. The still partly activated myocardium however generates stress while being stretched, implying consumption of mechanical energy. Ap- 8750-7587/08 $8.00 Copyright © 2008 the American Physiological Society 1015 Downloaded from http://jap.physiology.org/ by 10.220.33.4 on May 3, 2017 The Viewpoint by W. Zhang et al. (3) advances our understanding of the age-old question about the meaning of end diastole of the left ventricle as well as its corollary, diastolic suction. The discussion omits several additional mechanisms that may also be contributing to left ventricular (LV) filling. One plausible explanation of the recoil generated by the myocardial muscle is the erectile effect of the intramyocardial microcirculation being distended as blood enters it again after the systolic “blanching” ceases (2). Another plausible mechanism is that the recoiling LV myocardium merely advances over the stationary blood in the ventricle and atrium— much like a sock pulled (or in this case pushed) over a foot. Given these multiple plausible mechanisms, the question arises as to how much of the ventricular filling is due to suction. Suction generated by the ventricle should be reflected by negative transmural pressure during early diastolic relaxation. That this is true only in the late systolic phase was suggested by Kenner and Wood (1) using simultaneous percutaneous measurement of pericardial and intracardiac pressures. Their data show that although pericardial pressure is transiently more negative during systole, that pressure is essentially constant at pleural pressure after the aortic valve closes, suggesting return to a positive transmural pressure during diastole. In summary, while I do not disagree with the observations and conclusions drawn from them as presented in this Viewpoint, I believe that these other mechanisms should also be considered as possible contributors to this elusive issue. Letters To The Editor 1016 LETTERS TO THE EDITOR parently, the weak passive suction component is overruled by the effect of stretching of still partly activated myocardium. A consistent definition of suction is supply of mechanical energy by the LV wall during filling, implying negative transmural pressure. If we would accept the proposed definition of suction by dpLV/dVLV ⬍ 0, with increasing LA pressure together with LV dilatation, suction would stay high, whereas a dilated LV is accepted to have less or no suction at all. In summary, the left ventricle can suck, but it never does. Doppler and ultrasonic digital particle imaging velocimetry. J Am Coll Cardiol 49: 899 –908, 2007. 4. Sengupta PP, Khandheria BK, Korinek J, Wang J, Jahangir A, Seward JB, Belohlavek M. Apex-to-base dispersion in regional timing of left ventricular shortening and lengthening. J Am Coll Cardiol 47: 163–172, 2006. 5. Zhang W, Chung CS, Shmuylovich L, Kovacs SJ. Viewpoint: Is left ventricular volume during diastasis the real equilibrium volume, and what is its relationship to diastolic suction? J Appl Physiol; doi:10.1152/ japplphysiol.00799.2007. Partho P. Sengupta, MBBS Bijoy K. Khandheria A. Jamil Tajik, MD Division of Cardiovascular Diseases Mayo Clinic Arizona Scottsdale, Arizona REFERENCE 1. Zhang W, Chung CS, Shmuylovich L, Kovacs SJ. Viewpoint: Is left ventricular volume during diastasis the real equilibrium volume and what is its relationship to diastolic suction? J Appl Physiol; doi:10.1152/ japplphysiol.00799.2007. IS DIASTASIS REALLY A PHASE OF HEMODYNAMIC STASIS? TO THE EDITOR: The Viewpoint by Zhang et al. (5) reiterates diastasis as a period of zero-motion (static) condition over a finite time interval where left ventricular (LV) wall mechanics and transmitral flow are both absent. The following observations, however, would suggest that diastasis may be more complex than just a period of equilibrium and stasis. 1) First, changes in LV volume and deformation during diastasis does not reveal a halted phase of mechanical relaxation, rather, LV continues relaxing and lengthening, attaining progressively higher volumes (1). 2) Volume change in diastasis result from large-scale intracavitary vortical motions that develop during the down stroke of E-wave (3). Large vortices never unwind smoothly. Rather, they break up into smaller eddies, dissipating and maintaining a steady outward force on the LV endocardial surface. This facilitates continued filling and an increase in LV volume. 3) Indeed filling mechanisms in diastasis are heightened in some failing hearts. Flow in diastasis may be augmented, leading to genesis of mid-diastolic filling wave, also referred to as “L-wave” (2). There are practical limitations, therefore, in separating early diastolic suction from diastasis because LV volume changes during both phases occur on a continuum. Recent studies have redefined suction as an active state wherein postsystolic regional shortening (beyond aortic valve closure) produces dynamic shortening-relaxation gradients within LV wall that hasten the process of diastolic restoration (4). The cross-over point of postsystolic shortening into relaxation may therefore better define the period in diastole when active LV suction ceases to operate. REFERENCES 1. Carlsson M, Cain P, Holmqvist C, Stahlberg F, Lundback S, Arheden H. Total heart volume variation throughout the cardiac cycle in humans. Am J Physiol Heart Circ Physiol 287: H243–H250, 2004. 2. Ha JW, Oh JK, Redfield MM, Ujino K, Seward JB, Tajik AJ. Triphasic mitral inflow velocity with middiastolic filling: clinical implications and associated echocardiographic findings. J Am Soc Echocardiogr 17: 428 – 431, 2004. 3. Sengupta PP, Khandheria BK, Korinek J, Jahangir A, Yoshifuku S, Milosevic I, Belohlavek M. Left ventricular isovolumic flow sequence during sinus and paced rhythms: new insights from use of high-resolution J Appl Physiol • VOL TO THE EDITOR: The definition of diastolic suction is most often based on intraventricular pressure and volume changes. In clinical echocardiography, Doppler indexes used to study diastolic function, reflect changes in the regional pressure gradients. The causal mechanism for diastolic suction is the conformational change occurring during diastole. During this period, the heart lengthens in the longitudinal direction, thins in the radial direction, and lengthens its circumference. In addition, torsion is observed between the base and apex. LV systolic torsional deformation (twisting) is one mechanism by which potential energy is stored during ejection, to be later released during diastole (untwisting) and contributes to the creation of suction. The diastasis volume summarizes the combination of all forces (trans-mural, between-cavities gradients, torsionnal) acting to adapt a chamber volume to its load (blood content). Recently, new ultrasonographic technologies such as strain echocardiography have been introduced to assess myocardial deformation. It has been demonstrated that global diastolic strain rate during the isovolumic relaxation period, is well related to hemodynamic indices of LV relaxation (2). Furthermore, Notomi et al. (1) highlighted that ventricular untwisting provided a temporal link between relaxation and diastolic suction. Consequently, and as underlined by Zhang et al. (3), the definition of the diastolic suction should not be limited to changes in pressure and volume, but should also integrate the heart deformations leading to the restoration of a nonstressed LV shape (equilibrium volume). REFERENCES 1. Notomi Y, Popovc ZB, Yamada H, Wallick DW, Martin MG, Oryszak SJ, Shiota T, Greenberg NL, Thomas JD. Ventricular untwisting: a temporal link between left ventricular relaxation and suction. Am J Physiol Heart Circ Physiol Heart Circ Physiol 294: H505–H513, 2008. 2. Wang J, Khoury DS, Thohan V, Torre-Amone G, Nagueh SF. Global diastolic strain rate for the assessment of left ventricular relaxation and filling pressures. Circulation 115: 1376 –1383, 2007. 3. Zhang W, Chung CS, Shmuylovich L, Kovacs SJ. Viewpoint: Is left ventricular volume during diastasis the real equilibrium volume, and what is its relationship to diastolic suction? J Appl Physiol; doi:10.1152/ japplphysiol.00799.2007. 105 • SEPTEMBER 2008 • Alain Boussuges,1 MD, PhD Jacques Regnard,2 MD, PhD 1 Université de la Méditerranée Marseille, France 2 Université de Franche Comté Besançon, France www.jap.org Downloaded from http://jap.physiology.org/ by 10.220.33.4 on May 3, 2017 Theo Arts, Professor Tammo Delhaas Cardiovascular Research Institute Maastricht Maastricht, The Netherlands