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February 1, 1985AJP Heart and Circulatory Physiology

Effects of reduced resistive afterload on left ventricular pressure-volume relationship

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Population

13 anesthetized, beta-blocked dogs (7 for LV pressure/volume measurement, 6 for aortic flow measurement)

Comparison

Reduction in systemic vascular resistance by… vs Base-line condition

Design

Preclinical

Authors

JDJohn DucasUniversity of ManitobaUSUsha SchickHealth Sciences CentreLGLinda GirlingUniversity of Manitoba

Discussion

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Implication

Reducing afterload may augment ventricular emptying at fixed pressure; leaves open translation to human HF management.

Key Points

  • To examine how acute reductions in systemic vascular resistance alter left ventricular systolic mechanics and pressure-volume relationships when end-systolic pressure is held constant.
  • Evaluated anesthetized, beta-blocked dogs (N=7 for volume/pressure metrics, N=6 for aortic flow) at baseline and after opening one and two arteriovenous fistulas to reduce systemic vascular resistance.
  • Infused volume to maintain left ventricular end-systolic pressure while measuring pressure, aortic flow, and scintigraphic volumes.
  • Decreasing systemic vascular resistance from 81 to 48 units (P < 0.0025) reduced left ventricular end-systolic volume from 42 to 31 ml (P < 0.025), and further resistance reduction to 30 units (P < 0.025) lowered volume to 24 ml (P < 0.0025).
  • Instantaneous aortic flow increased and pressure-volume trajectories shifted leftward toward the end of ejection without significant changes in end-diastolic volume.

Structured PICO

P
Population
13 anesthetized, beta-blocked dogs (7 for LV pressure/volume measurement, 6 for aortic flow measurement)
I
Intervention
Reduction in systemic vascular resistance (SVR) by opening one and then two arteriovenous fistulas (AVF), with volume infusion to maintain LV end-systolic pressure
C
Comparator
Base-line condition
O
Outcome
Left ventricular systolic mechanics (LV end-systolic volume, instantaneous flow, LV pressure-volume trajectories)surrogate

Demonstrates that at a given contractile state and ventricular pressure, alterations in resistive load directly affect the rate and extent of ventricular shortening.

Cite This Study

Ducas et al. (1985) studied this question.

synapsesocial.com/papers/6a70abdefe4101aa97e0442bhttps://doi.org/10.1152/ajpheart.1985.248.2.h163
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Also Consider

Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:

  1. 1Effect of Altered Resistive Load on Left Ventricular Systolic Mechanics in Dogs1982 · 18 citations
  2. 2Sensitivity of left ventricular end-systolic pressure-volume relation to type of loading intervention in dogs.1988 · 133 citations
  3. 3Effects of increased afterload on left ventricular function in closed-chest dogs1990 · 28 citations
  4. 4The effect of vasoactive agents on the left ventricular end-systolic pressure-volume relation in closed-chest dogs.1986 · 93 citations
  5. 5Respiratory phasic effects of inspiratory loading on left ventricular hemodynamics in vagotomized dogs1992 · 21 citations