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Hypocalcemia and myocardial function in uremia
Insights
Acute calcium replacement improved cardiac contractility in dialysis patients with hypocalcemia. However, long-term therapy did not enhance resting or exercise cardiac performance, indicating differing responses to short-term versus sustained correction.
Area of Science:
- Nephrology
- Cardiology
- Clinical Medicine
Background:
- Uremia is associated with hypocalcemia, which can impact cardiovascular function.
- Cardiac performance abnormalities are common in patients undergoing dialysis.
Purpose of the Study:
- To evaluate the effects of short- and long-term hypocalcemia correction on cardiac performance in uremic patients on dialysis.
- To investigate hemodynamic changes in response to acute and sustained calcium level increases.
Main Methods:
- A study involving 4 uremic patients on dialysis.
- Continuous wave Doppler echocardiography was used to assess hemodynamic parameters.
- Measurements were taken at rest and during exercise testing before and after calcium infusion/replacement.
Main Results:
- Acute intravenous calcium infusion (1 hour) significantly increased serum calcium levels and cardiac output (minute distance) at rest.
- Peak velocity and acceleration of ascending aortic blood flow also increased during acute calcium infusion.
- Long-term calcium replacement normalized serum calcium levels but did not improve resting hemodynamics or peak exercise parameters, although exercise duration increased.
- Hemodynamic parameters at peak exercise remained similar despite long-term calcium therapy.
Conclusions:
- Acute calcium replacement can enhance cardiac contractility in uremic patients with hypocalcemia.
- Long-term calcium therapy does not appear to improve resting or exercise cardiac performance in this population.
- The cardiac response to calcium correction differs between acute and chronic interventions in uremic patients.
Abstract:
To investigate whether hypocalcemia affects cardiac performance in uremic patients, we studied the hemodynamic changes with short- and long-term correction of hypocalcemia in 4 uremic patients on dialysis using continuous wave Doppler study. At rest, 1 h of intravenous calcium infusion increased calcium level from 1.74 +/- 0.17 to 1.92 +/- 0.16 mmol/l (p less than 0.05). Cardiac output represented by minute distance increased from 10.5 +/- 2.0 to 12.1 +/- 2.5 m (p less than 0.05), but heart rate and blood pressure were unchanged. The peak velocity and acceleration of ascending aortic blood flow increased during calcium infusion. With long-term replacement, calcium level increased from 1.74 +/- 0.17 to 1.94 +/- 0.15 mmol/l (p less than 0.05), but resting hemodynamics were unchanged. On exercise testing, exercise duration increased from 10.6 +/- 1.6 min to 12.9 +/- 1.5 min (p less than 0.01), but hemodynamic parameters at peak exercise were similar. We conclude that acute calcium replacement enhanced cardiac contractility in uremic patients, but cardiac performance at rest and peak exercise was not improved with long-term therapy. This reflects different cardiac responses to acute versus chronic calcium replacement.