Commentaries on viewpoint: is left ventricular volume during diastasis the real equilibrium volume, and what is its relationship to diastolic suction?

Commentaries on Viewpoint: Is left ventricular volume during diastasis the real equilibrium volume, and what is its relationship to diastolic suction? TO THE EDITOR: 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 intramyo-cardial 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 percu-taneous 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. REFERENCES 1. Kenner HM, Wood EH. Intrapericardial, intrapleural, and intracardiac pressures during acute heart failure in dogs studied without thoracotomy. Acute alterations in left ventricular diastolic chamber stiffness. Role of the " erectile " effect of coronary arterial pressure and flow in normal and damaged heart. Viewpoint: Is left ventricular volume during diastasis the real equilibrium volume, and what is its relationship to diastolic suction? J Appl Physiol; 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 …