Saturday, April 16, 2011

TOPIC DISCUSSIONS: Glomerular Disease following congenital cyanotic Heart disease

Glomerular Disease following congenital cyanotic Heart disease (CCHD) is not uncommon. There is fair amount on this in the literature.  What do you see on biopsy?

1.       Glomerulomegaly
2.       Capillary dilatation
3.       Thickened capillary walls
4.       Focal and diffuse proliferation of mesangial cells
5.       Segmental and global glomerular sclerosis
6.       Podocyte hypertrophy
7.       Proteinuria usually presenting symptom following age 20 or so.

Cause of the damage that has been proposed: increased viscosity, elevated hemotocrit, chronic hypoxia, increased venous pressures, and glomerular hyperfiltration. 
Mechanisms:  In one study( listed below) , Glomeruli from both kidneys were studied with light microscopy in 13 necropsied cyanotic patients and in 8 controls. The vascular changes were:  hilar arteriolar dilatation, capillary diameter, glomerular diameter, and capillary engorgement with red blood cells.  The nonvascular changes were :  juxtaglomerular cellularity, mesangeal cellularity, mesangeal matrix, focal interstitial fibrosis. There was a significant increase in each of the above vascular and nonvascular items of interest relative to controls. Electron microscopy identified whole megakaryocytes with their cytoplasm in glomeruli. The vascular abnormality is believed to result from intraglomerular release of nitric oxide. The nonvascular abnormality is believed to result from platelet derived growth factor and transforming growth factor beta.  
In summary, one sees a FSGS like picture with significant vascular and non vascular changes. Perhaps chronic hypoxia leads to increased Hypoxia induced factor production that might lead to increased VEGF and ultimately FSGS.  Not yet studied in these cases. Collapse hasn’t been described in such cases either.  Smoking related FSGS might have similar findings and similar findings of glomerulomegaly are also seen in Obesity related FSGS.

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