M.Sc. (Med. (Paediatric Cardiology)), Faculty of Health Sciences, University of the Witwatersrand, 2008 / Left ventricular (LV) noncompaction is characterized by the presence of an
extensive trabecular myocardial layer within the luminal aspect of the compact
myocardium of the ventricular wall. The trabeculae are both excessive in number and
more prominent than normal. Noncompaction may occur in isolation usually with
clinical features of dilated cardiomyopathy, or it may be associated with congenital or
acquired heart diseases. Echocardiography is the reference standard for diagnosis,
where a ratio of thickness of trabecular-to-compact myocardium (compaction ratio) of
>2 is a major diagnostic criterion. Noncompaction is usually considered to result from
persistence of the highly trabeculated myocardium found in early cardiogenesis of
the human embryo. If persistence of excess trabeculae is the only determinant of the
compaction ratio it would be expected that it would remain a consistent measurement
in postnatal life. However, temporal changes in the degree of noncompaction in
individual case reports have raised the question as to whether the compaction ratio
might be sensitive to haemodynamic or other factors.
In the present dissertation, I assessed echocardiographically whether the
compaction ratio is associated with increases in indices of LV volume preload in 100
children or adolescents with ventricular septal defects (VSD), and 36 with chronic
rheumatic heart disease (RHD). Compared to 79 normal controls (compaction
ratio=1.4±0.07), patients with VSDs (compaction ratio=2.0±0.2, p<0.0001) and RHD
(compaction ratio = 2.0±0.3, p< 0.0001) had a marked increase in the compaction
ratio. A compaction ratio>2 was found in 42% of patients with VSDs and 47% with
RHD. In VSDs, independent of age and gender, the compaction ratio was positively
associated with LV mass index (LVMI) (partial r=0.44, p<0.0001), VSD size (partial
r=0.4, p<0.0001), LV end diastolic diameter indexed (LVEDD) (partial r=0.24, p=
0.01), and the presence of additional shunts (partial r=0.21, p=0.02). In RHD,
independent of age and gender, the compaction ratio was positively
associated with LVEDD (partial r=0.62, p=0.0001), and LVMI (partial r=0.48,
p=0.005), and negatively with LV ejection fraction (partial r=0.31, p=0.03).
The strong association of indices of LV volume load and the compaction ratio
would suggest that haemodynamic influences are contributing to the compaction ratio
both in congenital and acquired cardiac disease in childhood. Thus an increased
compaction ratio may be the consequence of an increased volume preload, and
therefore may not necessarily occur only as a result of persistence of embryonic
patterns.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/7451 |
| Date | 17 November 2009 |
| Creators | Hunter, Vivienne Isla |
| Source Sets | South African National ETD Portal |
| Language | Spanish |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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