What does this research mean for the field?

The inner half of the left ventricular free wall contributes significantly more to systolic wall thickening than the outer half at rest, and its thickening is more sensitive to increases in afterload and changes in inotropic state. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To examine how increasing afterload and modifying inotropic states alter systolic wall thickening in the inner versus outer halves of the left ventricular free wall.

July 1, 1992AJP Heart and Circulatory Physiology

Effect of changing afterload and inotropic states on inner and outer ventricular wall thickening

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Why the study?

Does changing afterload and inotropic states affect inner and outer ventricular wall thickening in anesthetized dogs?

Key Points

To examine how increasing afterload and modifying inotropic states alter systolic wall thickening in the inner versus outer halves of the left ventricular free wall.
Measured left ventricular pressure and inner and outer wall thickness using sonomicrometry in 11 anesthetized dogs.
Assessed percent systolic wall thickening and fractional contribution under baseline conditions, aortic constriction alone, and aortic constriction combined with either dobutamine (3 µg·kg⁻¹·min⁻¹) or propranolol (2 mg iv bolus).
At rest, inner half thickening and fractional contribution were significantly greater than outer half values (% delta WT: 33 ± 3% vs. 13 ± 2%, P < 0.01; FC: 74 ± 5% vs. 29 ± 4%, P < 0.01).
Aortic constriction alone reduced inner half thickening to 22 ± 2% while outer half thickening remained unchanged at 12 ± 3%, whereas dobutamine maintained resting thickening and fractional contribution in both layers.
Propranolol during aortic constriction markedly decreased inner half thickening from 29 ± 4% to 15 ± 6% (P < 0.01) with little change in the outer half (11 ± 2% to 10 ± 3%), eliminating the significant difference in fractional contribution between layers (56 ± 16% vs. 40 ± 13%, P > 0.1).

Structured PICO

Does changing afterload and inotropic states affect inner and outer ventricular wall thickening in anesthetized dogs?

Population

11 anesthetized dogs

Intervention

Increasing afterload by aortic constriction (AC) alone, with dobutamine infusion (3 micrograms/kg/min), or with propranolol (2 mg bolus IV)

Comparator

Resting values (baseline)

Outcome

Percent systolic wall thickening (% delta WT) and fractional contribution (FC) of inner and outer halves of the left ventricular free wall measured by sonomicrometrysurrogate

In an anesthetized dog model, increasing afterload combined with beta-blockade disproportionately reduces systolic wall thickening in the inner half of the left ventricle compared to the outer half.

Discussion

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Implication

Disproportionate inner-wall effects in this canine model warrant caution extrapolating to patients; leaves open mechanisms of transmural heterogeneity under hemodynamic stress.

Cite This Study

Matsuzaki et al. (1992) studied this question.

synapsesocial.com/papers/6a154b5779ff98d0de4e6581 https://doi.org/10.1152/ajpheart.1992.263.1.h109

Topics

Echocardiography

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Implication

Disproportionate inner-wall effects in this canine model warrant caution extrapolating to patients; leaves open mechanisms of transmural heterogeneity under hemodynamic stress.

Effect of changing afterload and inotropic states on inner and outer ventricular wall thickening

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Topics

Effect of changing afterload and inotropic states on inner and outer ventricular wall thickening

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Topics

Also Consider