Improved left ventricular contractility with cool temperature hemodialysis

Cool temperature dialysis (CTD) has been shown to sharply decrease the frequency of intradialytic hemodialysis hypotension, but the mechanism of this hemodynamic protection is unknown. Therefore, we performed two-dimensional echocardiographic studies of left ventricular contractility in six stable hemodialysis patients before and after hemodialysis at 37°C (RTD) and 35°C (CTD). Left ventricular function was assessed by plotting the rate-corrected velocity of circumferential fiber shortening (Vcf(c)) against end-systolic wall stress (σ(es)) at four different levels of afterload. Linear regression was used to calculate Vcf(c) at a common afterload of 50 g/cm². Changes in weight and dialysis parameters were similar following RTD and CTD. Mean arterial pressure and heart rate did not change significantly following RTD or CTD. The Vcf(c)-σ(es) relation was shifted upward in each patient after CTD, indicating increased contractility as compared to RTD or pre-dialysis baseline. Pre-dialysis Vcf(c) at an afterload of 50 g/cm² was similar during RTD and CTD (0.94 ± 0.24 circ/sec vs. 0.92 ± 0.22 circ/sec). Postdialysis Vcf(c) at an afterload of 50 g/cm² was significantly higher for CTD than for RTD (1.13 ± 0.29 circ/sec vs. 0.98 ± 0.30 circ/sec, P = 0.0004). Thus, cool temperature dialysis increases left ventricular contractility in hemodialysis patients, which may be a potential mechanism whereby hemodynamic tolerance to the dialysis procedure is improved.