Hemodialysis with high-calcium dialysate impairs cardiac relaxation

Background. During hemodialysis (HD), serum ionized calcium is directly related to the dialysate calcium concentration. We have recently shown an acute induction of hypercalcemia to impair left ventricular (LV) relaxation. In the current study we sought to establish whether changes in serum Ca++ also affect LV function during HD. Methods. We echocardiographically examined the LV relaxation and systolic function of 12 patients with end-stage renal disease before and after three HD treatments with dialysate Ca++ concentrations of 1.25 mmol/liter (dCa(++)1.25), 1.5 mmol/ liter (dCa(++)1.50), and 1.75 mmol/liter (dCa(++)1.75), respec tively. Age- and sex-matched healthy controls were also examined echocardiographically. Results. The LV posterior wall thickness and the interventricular septum thickness, and the LV end-diastolic dimension and the end-systolic dimensions were significantly greater in the patients when compared with the controls, and the LV fractional shortening, the ratio of peak early to peak late diastolic velocities (E/A(max)), and the isovolumic relaxation time (IVRT) showed impairment of LV relaxation and systolic function in the patients. Serum ionized calcium increased significantly during the dCa(++) 1.5 HD (1.24 +/- 0.10 vs. 1.34 +/- 0.06 mmol/liter, P = 0.004) and dCa(++)1.75 KD (1.19 +/- 0.10 vs. 1.47 +/- 0.06 mmol/liter, P = 0.002), and plasma intact parathyroid hormone decreased significantly during the dCa(++) 1.75 HD (medians 8.2 vs. 2.7 pmol/liter, P = 0.002). LV systolic function was not altered during any of the treatments. The changes in E/A(max) and IVRT suggested impairment of relaxation during all sessions, but only during the dCa(++) 1.75 HD was the impairment statistically significant (E/A(max) 1.153 +/- 0.437 vs. 0.943 +/- 0.352, P < 0.05; IVRT 147 +/- 29 vs. 175 +/- 50 msecond, P < 0.05). Conclusion. HD with high-calcium (dCa(++) 1.75 mmol/liter) dialysate impairs LV relaxation when compared with lower calcium dialysate (dCa(++)1.25 and dCa(++)1.5 mmol/liter) treatments.