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. 2013 Nov 19;8(11):e80591.
doi: 10.1371/journal.pone.0080591. eCollection 2013.

Impact of acute changes of left ventricular contractility on the transvalvular impedance: validation study by pressure-volume loop analysis in healthy pigs

Vincenzo Lionetti  1 , Simone Lorenzo Romano, Giacomo Bianchi, Fabio Bernini, Anar Dushpanova, Giuseppe Mascia, Martina Nesti, Franco Di Gregorio, Alberto Barbetta, Luigi Padeletti
Affiliations

Impact of acute changes of left ventricular contractility on the transvalvular impedance: validation study by pressure-volume loop analysis in healthy pigs

Vincenzo Lionetti et al. PLoS One. .

Abstract

Background: The real-time and continuous assessment of left ventricular (LV) myocardial contractility through an implanted device is a clinically relevant goal. Transvalvular impedance (TVI) is an impedentiometric signal detected in the right cardiac chambers that changes during stroke volume fluctuations in patients. However, the relationship between TVI signals and LV contractility has not been proven. We investigated whether TVI signals predict changes of LV inotropic state during clinically relevant loading and inotropic conditions in swine normal heart.

Methods: The assessment of RVTVI signals was performed in anesthetized adult healthy anesthetized pigs (n = 6) instrumented for measurement of aortic and LV pressure, dP/dtmax and LV volumes. Myocardial contractility was assessed with the slope (Ees) of the LV end systolic pressure-volume relationship. Effective arterial elastance (Ea) and stroke work (SW) were determined from the LV pressure-volume loops. Pigs were studied at rest (baseline), after transient mechanical preload reduction and afterload increase, after 10-min of low dose dobutamine infusion (LDDS, 10 ug/kg/min, i.v), and esmolol administration (ESMO, bolus of 500 µg and continuous infusion of 100 µg·kg-1·min-1).

Results: We detected a significant relationship between ESTVI and dP/dtmax during LDDS and ESMO administration. In addition, the fluctuations of ESTVI were significantly related to changes of the Ees during afterload increase, LDDS and ESMO infusion.

Conclusions: ESTVI signal detected in right cardiac chamber is significantly affected by acute changes in cardiac mechanical activity and is able to predict acute changes of LV inotropic state in normal heart.

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Conflict of interest statement

Competing Interests: VLS is a PLOS ONE Editorial Board member and this does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials. In addition, AB and FDG are employees of Medico Spa. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.

Figures

Figure 1
Figure 1. ESTVI (A), EDTVI (B) and pk-pk TVI (C) changes during different loading and inotropic conditions. * p<0.05 vs baseline; # p<0.05 vs LDDS.
Figure 2
Figure 2. RV ESTVI-LV contractility relationship during changes in different loading conditions.
Correlations between changes in RV end systolic TVI (ESTVI) and in left ventricular (LV) stroke volume (SV) or maximum of the first derivative of LV pressure (dP/dtmax) during preload reduction (A,B) and increase of LV afterload (C, D). Changes normalized to baseline values.
Figure 3
Figure 3. RV ESTVI-LV contractility relationship during changes in different inotropic conditions.
Correlations between changes in RV end systolic TVI (ESTVI) and in left ventricular (LV) stroke volume (SV) or in maximum of the first derivative of LV pressure (dP/dtmax) during low dose dobutamine stress (LDDS) (A,B) and following esmolol infusion (C, D). Changes normalized to baseline values.
Figure 4
Figure 4. RV ESTVI- LV Ees relationship during changes in different loading and inotropic conditions.
Correlation between changes in RV end-systolic TVI (ESTVI) and left ventricular Ees during preload reduction (A), increase of afterload (B), low dose dobutamine stress (C) and following esmolol infusion (D). Changes normalized to baseline values.
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