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Integrated wall stress: a new methodological approach to assess ventricular workload and myocardial contractile reserve.

Dong H, Mosca H, Gao E, Akins RE, Gidding SS, Tsuda T - J Transl Med (2013)

Bottom Line: IWS was calculated over one minute through simultaneous measurement of LV internal diameter and wall thickness by echocardiography and LV pressure by LV catheterization.At rest, the MI group showed concentric LV hypertrophy pattern with preserved LV cavity size, LV systolic function, and IWS comparable with the sham group.IWS showed good correlation with a product of peak-systolic wall stress and heart rate.

View Article: PubMed Central - HTML - PubMed

Affiliation: Nemours Cardiac Center and Nemours Biomedical Research, Alfred I, duPont Hospital for Children, 1600 Rockland Rd, Wilmington, DE 19103, USA.

ABSTRACT

Background: Wall stress is a useful concept to understand the progression of ventricular remodeling. We measured cumulative LV wall stress throughout the cardiac cycle over unit time and tested whether this "integrated wall stress (IWS)" would provide a reliable marker of total ventricular workload.

Methods and results: We applied IWS to mice after experimental myocardial infarction (MI) and sham-operated mice, both at rest and under dobutamine stimulation. Small infarcts were created so as not to cause subsequent overt hemodynamic decompensation. IWS was calculated over one minute through simultaneous measurement of LV internal diameter and wall thickness by echocardiography and LV pressure by LV catheterization. At rest, the MI group showed concentric LV hypertrophy pattern with preserved LV cavity size, LV systolic function, and IWS comparable with the sham group. Dobutamine stimulation induced a dose-dependent increase in IWS in MI mice, but not in sham mice; MI mice mainly increased heart rate, whereas sham mice increased LV systolic and diastolic function. IWS showed good correlation with a product of peak-systolic wall stress and heart rate. We postulate that this increase in IWS in post-MI mice represents limited myocardial contractile reserve.

Conclusion: We hereby propose that IWS provides a useful estimate of total ventricular workload in the mouse model and that increased IWS indicates limited LV myocardial contractile reserve.

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Related in: MedlinePlus

Continuous wall stress measurement in the mouse model. A. Simultaneous M-mode echocardiogram and LVP monitoring in obtaining continuous wall stress (CWS). The CWS curve was obtained from direct simultaneous measurement of LVID, LVPW, and LVP every 1 msec. Blue line outlines LV endocardial surfaces (a and b) and epicardial surface (c). Red line and green line indicate electrocardiogram (ECG) and LVP measurement, respectively. When calculating wall stress, LVID and LVPW were used as inner diameter and wall thickness, respectively. B: CWS curve obtained from the formula (see text) with dobutamine stimulation (baseline, 5, and 10 μg/kg/min) in the normal control mouse. IWS was calculated as an area below CWS curve over unit time.
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Figure 1: Continuous wall stress measurement in the mouse model. A. Simultaneous M-mode echocardiogram and LVP monitoring in obtaining continuous wall stress (CWS). The CWS curve was obtained from direct simultaneous measurement of LVID, LVPW, and LVP every 1 msec. Blue line outlines LV endocardial surfaces (a and b) and epicardial surface (c). Red line and green line indicate electrocardiogram (ECG) and LVP measurement, respectively. When calculating wall stress, LVID and LVPW were used as inner diameter and wall thickness, respectively. B: CWS curve obtained from the formula (see text) with dobutamine stimulation (baseline, 5, and 10 μg/kg/min) in the normal control mouse. IWS was calculated as an area below CWS curve over unit time.

Mentions: CWS curves were obtained via the simultaneous measurement of LVID and LVPW by M-mode echocardiogram and LV pressure by cardiac catheterization (Figure 1A). LV wall stress (σ) was calculated as follows [12,15]:


Integrated wall stress: a new methodological approach to assess ventricular workload and myocardial contractile reserve.

Dong H, Mosca H, Gao E, Akins RE, Gidding SS, Tsuda T - J Transl Med (2013)

Continuous wall stress measurement in the mouse model. A. Simultaneous M-mode echocardiogram and LVP monitoring in obtaining continuous wall stress (CWS). The CWS curve was obtained from direct simultaneous measurement of LVID, LVPW, and LVP every 1 msec. Blue line outlines LV endocardial surfaces (a and b) and epicardial surface (c). Red line and green line indicate electrocardiogram (ECG) and LVP measurement, respectively. When calculating wall stress, LVID and LVPW were used as inner diameter and wall thickness, respectively. B: CWS curve obtained from the formula (see text) with dobutamine stimulation (baseline, 5, and 10 μg/kg/min) in the normal control mouse. IWS was calculated as an area below CWS curve over unit time.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750700&req=5

Figure 1: Continuous wall stress measurement in the mouse model. A. Simultaneous M-mode echocardiogram and LVP monitoring in obtaining continuous wall stress (CWS). The CWS curve was obtained from direct simultaneous measurement of LVID, LVPW, and LVP every 1 msec. Blue line outlines LV endocardial surfaces (a and b) and epicardial surface (c). Red line and green line indicate electrocardiogram (ECG) and LVP measurement, respectively. When calculating wall stress, LVID and LVPW were used as inner diameter and wall thickness, respectively. B: CWS curve obtained from the formula (see text) with dobutamine stimulation (baseline, 5, and 10 μg/kg/min) in the normal control mouse. IWS was calculated as an area below CWS curve over unit time.
Mentions: CWS curves were obtained via the simultaneous measurement of LVID and LVPW by M-mode echocardiogram and LV pressure by cardiac catheterization (Figure 1A). LV wall stress (σ) was calculated as follows [12,15]:

Bottom Line: IWS was calculated over one minute through simultaneous measurement of LV internal diameter and wall thickness by echocardiography and LV pressure by LV catheterization.At rest, the MI group showed concentric LV hypertrophy pattern with preserved LV cavity size, LV systolic function, and IWS comparable with the sham group.IWS showed good correlation with a product of peak-systolic wall stress and heart rate.

View Article: PubMed Central - HTML - PubMed

Affiliation: Nemours Cardiac Center and Nemours Biomedical Research, Alfred I, duPont Hospital for Children, 1600 Rockland Rd, Wilmington, DE 19103, USA.

ABSTRACT

Background: Wall stress is a useful concept to understand the progression of ventricular remodeling. We measured cumulative LV wall stress throughout the cardiac cycle over unit time and tested whether this "integrated wall stress (IWS)" would provide a reliable marker of total ventricular workload.

Methods and results: We applied IWS to mice after experimental myocardial infarction (MI) and sham-operated mice, both at rest and under dobutamine stimulation. Small infarcts were created so as not to cause subsequent overt hemodynamic decompensation. IWS was calculated over one minute through simultaneous measurement of LV internal diameter and wall thickness by echocardiography and LV pressure by LV catheterization. At rest, the MI group showed concentric LV hypertrophy pattern with preserved LV cavity size, LV systolic function, and IWS comparable with the sham group. Dobutamine stimulation induced a dose-dependent increase in IWS in MI mice, but not in sham mice; MI mice mainly increased heart rate, whereas sham mice increased LV systolic and diastolic function. IWS showed good correlation with a product of peak-systolic wall stress and heart rate. We postulate that this increase in IWS in post-MI mice represents limited myocardial contractile reserve.

Conclusion: We hereby propose that IWS provides a useful estimate of total ventricular workload in the mouse model and that increased IWS indicates limited LV myocardial contractile reserve.

Show MeSH
Related in: MedlinePlus