This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Olsen, C. O. Articles by Rankin, J. S. Search for Related Content PubMed PubMed Citation Articles by Olsen, C. O. Articles by Rankin, J. S.

Circulation, Vol 72, 668-679, Copyright © 1985 by American Heart Association

ARTICLES

Diminished stroke volume during inspiration: a reverse thoracic pump

CO Olsen, GS Tyson, GW Maier, JW Davis and JS Rankin

In 12 conscious dogs, a three-dimensional array of pulse-transit ultrasonic transducers was used to measure left ventricular anterior- posterior minor, septal-free wall minor, and basal-apical major diameters. Matched micromanometers measured left ventricular, right ventricular, and intrapleural pressures. Electromagnetic ascending aortic blood flow and right ventricular transverse diameter were measured in five of the dogs. A major cause of the inspiratory decline in stroke volume in this preparation appeared to be reflex tachycardia and autonomic changes associated with inspiration. However, when heart rate was controlled by atrial pacing or pharmacologic autonomic attenuation (propranolol and atropine), stroke volume still decreased around 10%, with an inspiratory decrease in pleural pressure of 10 mm Hg. Based on the measurements of ventricular dimension, venous return to the right ventricle appeared to be augmented significantly during inspiration and the transient increase in right ventricular volume was associated with leftward interventricular septal shifting and altered diastolic left ventricular geometry. However, left ventricular end- diastolic volume was changed minimally, implying that alterations in preload were not important. Moreover, transmural left ventricular ejection pressure, calculated as intracavitary minus pleural pressure, was not significantly changed, and it seemed that neither pressure nor geometric components of afterload were altered significantly by inspiration. The inspiratory fall in left ventricular stroke volume correlated best with the decline in intracavitary left ventricular ejection pressure referenced to atmospheric pressure. It is hypothesized that during ejection, left ventricular pressure referenced to atmospheric pressure is the hydraulic force effecting stroke volume and that the decline in this effective left ventricular ejection pressure is responsible for the inspiratory fall in stroke volume through a reverse thoracic pump mechanism.

This article has been cited by other articles:

				S. L. Munns, L. K. Hartzler, A. F. Bennett, and J. W. Hicks Terrestrial locomotion does not constrain venous return in the American alligator, Alligator mississippiensis J. Exp. Biol., September 1, 2005; 208(17): 3331 - 3339. [Abstract] [Full Text] [PDF]

				K. Lu, J. W. Clark Jr., F. H. Ghorbel, D. L. Ware, and A. Bidani A human cardiopulmonary system model applied to the analysis of the Valsalva maneuver Am J Physiol Heart Circ Physiol, December 1, 2001; 281(6): H2661 - H2679. [Abstract] [Full Text] [PDF]

				O. P. Mathew Effects of transient intrathoracic pressure changes (hiccups) on systemic arterial pressure J Appl Physiol, August 1, 1997; 83(2): 371 - 375. [Abstract] [Full Text] [PDF]