Background: Pathologic changes that are associated with the cardiorenal syndrome (CRS) are seldom described. The two theories that address renal physiology in CRS include chronic indolent ischemia from renal vasoconstriction and chronic glomerular venous congestion from increased venous pressures. We report on the glomerular histologic changes that occur with long standing heart failure.
Objective: To examine whether CRS causes renal ischemia that manifests as glomerular size reduction.
Methods: We performed a case-control study where we measured total glomerular areas in 16 adult cases with end-stage heart disease and compared them with matched controls. Control biopsy samples were obtained from renal tissue included in nephrectomies. Glomerular size was measured using the BioQuant Image Analysis program. Cases and controls were matched on the following variables: age (within 10 years), race, body mass index (BMI), diabetes mellitus (DM), glomerular filtration rate (GFR) (within 10 mL/min/1.73 m2), and history of tobacco use.
Results: The age range of all patients at the time of biopsy was 40 - 73 years. Nine of the case patients had DM. Estimated GFR ranged from 29 to 55 mL/min/1.73 m2. Mean BMI was 30.8 (SD 4.7) kg/m2. The average median glomerular area in the case patients was 23,944 pixels (1 pixel = 1 μm2), (IQR 22,549 - 27,990) vs. in controls 38,566 pixels (IQR 31, 227 - 45,938) (p = 0.004).
Conclusions: This case-controlled cohort study demonstrates that patients with long standing heart failure have smaller glomerular size as compared with controls matched for relevant clinical variables but not for heart failure.