Increased ionized calcium and left ventricular contractility during hemodialysis

Area of Science:

• Nephrology
• Cardiology
• Physiology

Background:

• Hemodialysis is known to increase left ventricular contractility.
• The underlying mechanisms for this improvement remain unclear.
• Potential factors include uremic toxin removal, increased ionized calcium, and increased bicarbonate.

Purpose of the Study:

• To investigate the specific roles of ionized calcium and bicarbonate in hemodialysis-induced left ventricular contractility changes.
• To determine the primary driver of improved cardiac function during dialysis.

Main Methods:

• Eight stable hemodialysis patients participated.
• Left ventricular contractility was assessed using two-dimensional echocardiography.
• Three dialysate protocols were employed, manipulating ionized calcium and bicarbonate levels.

Main Results:

• Contractility did not improve when neither ionized calcium nor bicarbonate increased.
• Left ventricular contractility significantly increased when ionized calcium rose, while bicarbonate remained constant.
• Increasing bicarbonate alone did not enhance contractility.

Conclusions:

• The rise in plasma ionized calcium concentration during hemodialysis is a key factor responsible for the observed improvement in left ventricular contractility.
• This highlights the importance of calcium balance in cardiac function for patients undergoing dialysis.