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July 1, 1972Circulation ResearchOpen Access

Alterations in Preload and Myocardial Mechanics in the Dog and in Man

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Why the study?

Does an increase in preload affect myocardial contractility indexes measured using total pressure versus developed pressure in the intact heart?

Population

7 dogs and 8 patients undergoing cardiac catheterization

Comparison

Increase in left ventricular end-diastolic… vs Baseline state prior to preload alteration

Design

Other

Authors

WGWilliam GrossmanFHFlorence W. HaynesJPJohn A Paraskos

Discussion

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Overview

Caution using total-pressure contractility indexes with varying preload; challenges consensus and leaves open developed-pressure validation.

Key Points

  • The aim is to evaluate which indexes of myocardial mechanics are independent of preload in the left ventricle.
  • Infusion of dextran or whole blood to increase left ventricular end-diastolic pressure in seven dogs.
  • Elevation of legs during cardiac catheterization in eight patients to enhance left ventricular end-diastolic pressure.
  • Measurement of Vmax and (dP/dt)/P metrics under varying preload conditions.
  • In dogs, increased left ventricular end-diastolic pressure resulted in significant declines in Vmax and (dP/dt)/P using total pressure (P < 0.01).
  • Vmax measured using developed pressure remained stable despite changes in left ventricular end-diastolic pressures.
  • In patients, similar preload increases led to reductions in (dP/dt)/P using total pressure, but did not affect developed pressure Vmax.

Structured PICO

Does an increase in preload affect myocardial contractility indexes measured using total pressure versus developed pressure in the intact heart?

P
Population
7 dogs and 8 patients undergoing cardiac catheterization
I
Intervention
Increase in left ventricular end-diastolic pressure (preload) via infusion of dextran or whole blood (dogs) or sudden elevation of the legs (patients)
C
Comparator
Baseline state prior to preload alteration
O
Outcome
Changes in myocardial contractility indexes (Vmax and [(dP/dt)/P]max) measured using total pressure versus developed pressuresurrogate

Myocardial mechanics measurements using developed pressure are independent of preload, whereas those using total pressure are inversely dependent, questioning the validity of total pressure measurements as indexes of myocardial contractility.

Cite This Study

Grossman et al. (1972) studied this question.

synapsesocial.com/papers/6a15785a5347fbb1739fd536https://doi.org/10.1161/01.res.31.1.83
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