Related Experiment Videos
Myocyte/capillary mismatch in the heart of uremic patients
1Department of Pathology, University of Heidelberg, Germany.
Insights
Uremic patients have significantly reduced heart capillary density, increasing hypoxia risk. This study provides the first human data on myocardial capillary supply in renal failure.
Area of Science:
- Cardiovascular Science
- Nephrology
- Pathology
Background:
- Capillary density is reduced in the hypertrophied left ventricle of rats with subtotal nephrectomy, suggesting cardiomyocytes outgrow their capillary supply in uremia.
- No data exists on myocardial capillary supply in human uremic hearts.
Purpose of the Study:
- To investigate myocardial capillary supply in dialyzed patients with renal failure.
- To compare capillary density in uremic patients to those with essential hypertension and healthy controls.
Main Methods:
- Postmortem hearts from nine dialyzed patients, nine with essential hypertension, and 10 controls were analyzed.
- Stereologic techniques and ulex lectin staining were used to determine myocardial capillary length density (Lv).
- Exclusion criteria included stenosing coronary lesions and left ventricular pump failure.
Main Results:
- Dialyzed patients showed significantly lower Lv (1483 +/- 238 mm/mm3) compared to essential hypertension (1872 +/- 243 mm/mm3) and control groups (2898 +/- 456 mm/mm3).
- Uremic patients exhibited increased myocyte diameter and interstitial tissue volume density.
- A significant reduction in capillary length density was observed in dialyzed patients (P < 0.001).
Conclusions:
- Renal failure is associated with diminished left ventricular capillary supply in humans.
- Reduced capillary density increases oxygen diffusion distance, potentially leading to cardiomyocyte hypoxia.
- Further research is needed to determine if anemia reversal can improve myocardial oxygen supply.
Abstract:
Experiments indicate that capillary density is reduced in the hypertrophied left ventricle of rats with subtotal nephrectomy compared to control rats with similar BP and left ventricular hypertrophy, suggesting that in uremia, hypertrophying cardiomyocytes outgrow their capillary supply. No information on myocardial capillary supply in humans is currently available. The hearts of nine dialyzed patients, nine patients with essential hypertension, and 10 normotensive control subjects at postmortem were obtained. Subjects with stenosing coronary lesions and left ventricular pump failure were excluded. Special sampling procedures were used to exclude stereologic artefacts. Capillaries were specifically stained with ulex lectin and analyzed by stereologic techniques. Length density of myocardial capillaries (Lv; mm/mm3) was significantly (P < 0.001) lower in dialyzed patients (1483 +/- 238) than in patients with essential hypertension (1872 +/- 243) or in normotensive control patients (2898 +/- 456). In parallel, myocyte diameter and volume density of myocardial interstitial tissue were significantly (P < 0.001) increased in uremic patients compared to patients with essential hypertension and control patients, respectively. Diminished left ventricular capillary supply in renal failure must increase critical oxygen diffusion distance in the myocardium, thus exposing cardiomyocytes to the risk of hypoxia. It is unknown whether such reduced ischemia tolerance can be reversed by increasing oxygen supply (e.g., by reversing anemia).