Congestive Heart Failure (CHF) is a major fatal disease today in the United
States. The heart's function is a mechanical one. To diagnose and treat CHF effectively
there is a need to understand at the microstructural level, the differences in
the response of the myocardium to a change in its mechanical environment. Hence to
assess growth and remodeling processes in the myocardium, the fiber and myolaminar
structure of two groups of Dahl salt-sensitive rats were compared: low salt (LS)
normal controls and a high salt (HS) group with hearts in "transitional eutrophy"
defined by normal size and shape but in transition from pressure overload hypertrophy
to dilated hypertrophy. To create the HS group with transitional eutrophy, we
fed Dahl salt-sensitive rats, a sustained high salt diet from age 6 wks till sacrifice
at age 11-13 wks. Such rats have a heart that transitions from too thick (pressure
overload hypertrophy at about age 9 wks) to too thin (dilated hypertrophy at about
age 15 wks to death) with a transitional period (age 11-13 wks) having normal size
and shape. Fiber angles, sheet angles, number and thickness of sheets were measured
in the septum at four transmural quarters (TQ1 to TQ4 with TQ1 being closest to
LV and TQ4 closest to RV). A uniformity index was defined to characterize sheet
angle dispersion. Upon comparison to LS controls, the HS group had normal size hearts with normal shape. However, there was a significant increase in the number
of sheets, which corresponded with a significant decrease in the thickness of sheets in
all quarters in HS group. Differences in fiber angles were significant in TQ1, TQ2,
and TQ4 with fiber angles more positive in HS group. Differences in sheet angles
and uniformity index were not significant. Despite having a normal size and shape,
we found that hearts in a state of transitional eutrophy have a significantly different
fiber and sheet morphology.
The experimental data was used to develop a model that represents the path to
failure that may be taken by the myolaminae when the heart is subjected to excessive
pressure overload.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1740 |
| Date | 02 June 2009 |
| Creators | Hegde, Bharati Krishna |
| Contributors | Criscione, John C. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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