64 research outputs found
Mechanisms of Intradialytic Hypertension
No full textIntradialytic Hypertension and Its Association with Endothelial Cell Dysfunction
BACKGROUND: Intradialytic hypertension is associated with adverse outcomes, yet the mechanism is uncertain. Patients with intradialytic hypertension exhibit imbalances in endothelial-derived vasoregulators nitric oxide and endothelin-1, indirectly suggesting endothelial cell dysfunction. We hypothesized that intradialytic hypertension is associated in vivo with endothelial cell dysfunction, a novel predictor of adverse cardiovascular outcomes.
DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS: We performed a case-control cohort study including 25 hemodialysis (HD) subjects without (controls) and 25 with intradialytic hypertension (an increase in systolic BP pre- to postdialysis greater than or equal to 10 mmHg greater than or equal to 4/6 consecutive HD sessions). The primary outcome was peripheral blood endothelial progenitor cells (EPCs) assessed by aldehyde dehydrogenase activity (ALDHbr) and cell surface marker expression (CD34+CD133+). We also assessed endothelial function by ultrasonographic measurement of brachial artery flow-mediated vasodilation (FMD) normalized for shear stress. Parametric and nonparametric t tests were used to compare EPCs, FMD, and BP.
RESULTS: Baseline characteristics and comorbidities were similar between groups. Compared with controls, 2-week average predialysis systolic BP was lower among subjects with intradialytic hypertension (144.0 versus 155.5 mmHg), but postdialysis systolic BP was significantly higher (159.0 versus 128.1 mmHg). Endothelial cell function was impaired among subjects with intradialytic hypertension as measured by decreased median ALDHbr cells and decreased CD34+CD133+ cells (ALDHbr, 0.034% versus 0.053%; CD34+CD133+, 0.033% versus 0.059%). FMD was lower among subjects with intradialytic hypertension (1.03% versus 1.67%).
CONCLUSIONS: Intradialytic hypertension is associated with endothelial cell dysfunction. We propose that endothelial cell dysfunction may partially explain the higher event rates observed in these patients.
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Probing the Mechanisms of Intradialytic Hypertension: a Pilot Study Targeting Endothelial Cell Dysfunction
BACKGROUND: Intradialytic hypertension may be caused by an impaired endothelial cell response to hemodialysis. Carvedilol has been shown to improve endothelial cell function in vivo and in vitro to block endothelin-1 release. Among patients with intradialytic hypertension, we hypothesized that carvedilol would improve endothelial cell function and reduce the occurrence of intradialytic hypertension.
DESIGN, SETTINGS, PARTICIPANTS & MEASUREMENTS: We performed a prospective 12-week pilot study of carvedilol titrated to 50 mg twice daily among 25 hemodialysis participants with intradialytic hypertension. Each patient served as their own control. Changes in endothelial cell function (assessed by flow-mediated vasodilation, endothelial progenitor cells (EPCs by aldehyde dehydrogenase activity and CD34+CD133+), asymmetric dimethylarginine (ADMA) and endothelin-1) and blood pressure (BP) from baseline to study-end were analyzed by paired tests.
RESULTS: Flow-mediated vasodilation was significantly improved with carvedilol (from 1.03% to 1.40%, p=0.02). There was no significant change in EPCs, endothelin-1 or ADMA. At baseline, participants exhibited a significant increase in endothelin-1 pre to postdialysis that resolved by study-end. While pre-hemodialysis systolic BP was unchanged (144 to 146 mmHg, p=0.5), post-hemodialysis systolic BP, 44-hour ambulatory systolic BP, and the frequency of intradialytic hypertension decreased with carvedilol (159 to 142 mmHg, p<0.0001; 155 to 148 mmHg, p=0.05; 77% (4.6/6) to 28% (1.7/6), p<0.0001, respectively).
CONCLUSIONS: Among hemodialysis participants with intradialytic hypertension, targeting endothelial cell dysfunction with carvedilol was associated with modest improvements in endothelial cell function, improved intra and interdialytic BP, and reduced frequency of intradialytic hypertension. Randomized controlled trials are required to confirm these findings.
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The Role of Dialysate Exposure in Intradialytic Hypertension
BACKGROUND: Intradialytic hypertension is associated with endothelial dysfunction, but the cause of vascular impairment is unknown. Exposure to high concentration sodium has been shown in vitro to promote endothelial stiffness and imbalances in markers of vascular function. We hypothesized that, among patients with intradialytic hypertension, exposure to dialysate sodium would lead to increases in endothelin-1, decreases in nitric oxide, and an intradialytic increase in systolic blood pressure.
DESIGN, SETTINGS, PARTICIPANTS & MEASUREMENTS: We performed a 6-week crossover study of 10 hemodialysis patients with intradialytic hypertension. Changes in blood pressure, endothelin-1, and nitric oxide levels were measured during three different, midweek dialysis treatments consisting of: 1) regular hemodialysis with standard dialysate sodium (140 mEq/L); 2) ultrafiltration only without dialysate exposure; and 3) hemodialysis (Na 140 mEq/L) without ultrafiltration. These changes were analyzed using mixed model analyses.
RESULTS: Serum sodium levels rose with dialysate exposure during regular HD and HD without UF sessions (+1.6 and +3 mEq/L, respectively), and fell during UF only session (-0.9 mEq/L). Endothelin-1 level also rose with dialysate exposure during regular HD and HD without UF (+0.15 and +0.25pg/mL, respectively), but fell during UF only session (-0.02 pg/mL). Plasma nitrite levels fell with all treatment types, most significantly with regular HD (-123.25 nM), then HD without UF (-52.77 nM), with lowest decrease seen during UF only session without dialysate exposure (-48.48 nM). Systolic BP rose during all treatments, most significantly with HD without UF (13.3%), followed by regular dialysis (6.9%), and UF only (5.7%).
CONCLUSIONS: Among hemodialysis patients prone to intradialytic hypertension, there was an association between dialysate exposure and increases in endothelin-1, decreases in nitric oxide, and increases in systolic blood pressure during dialysis. We propose that high dialysate to plasma sodium gradient may contribute to intradialytic hypertension
Acute Effect of High vs Low Dialysate Sodium on Endothelial Cell Function During Hemodialysis
No full textThe 51st Annual Medical Student Research Forum at UT Southwestern Medical Center (Tuesday, January 22, 2013, 3-6 p.m., D1.602)BACKGROUND: Intradialytic hypertension (HTN), a rise in blood pressure that occurs during hemodialysis (HD) treatments in up to 15% of patients, is associated with higher morbidity and mortality. The cause of intradialytic HTN is unknown but may be due to endothelial cell (EC) dysfunction. In vitro exposure of ECs to high sodium (Na+) concentration promotes EC stiffness and imbalances in vasoconstrictors (endothelin-1 [ET-1]) and vasodilators (nitric oxide [NO]). We hypothesized that, among patients with intradialytic HTN, exposure to high dialysate Na+ would lead to a decrease in NO and increase in ET-1 during HD.
METHODS: We performed a 3-week, 2-arm, randomized crossover study among 16 HD patients with intradialytic HTN and compared the effects of high dialysate-to-serum Na+ gradients (5 mEq/L above participants' baseline Na+) vs low dialysate-to-serum Na+ gradients (5 mEq/L below baseline Na+ with lower limit of 134 mEq/L) on intradialytic changes in nitrite and ET-1. Differences between treatments were compared with repeated measures mixed linear regression and included randomization arm (high - low Na+ vs low - high Na+), treatment effect (high vs low Na+), subject, time and session.
RESULTS: Study participants (N=16) had an average age of 58.8 years, 38% were black, 56% were Hispanic, and 94% were male. Intradialytic changes in NO and ET-1 with high and low dialysate-to-plasma Na+ gradients are shown in Figure 1. In the primary comparison of high vs low dialysate-to-serum Na+ gradient, there were no significant differences in intradialytic levels of NO or ET-1 (Table 1). However, when compared by randomization arm, participants who received the low dialysate-to-serum Na+ gradient followed by high compared to those who received the high dialysate-to-serum Na+ gradient followed by low had a significant decrease in ET-1 (parameter estimate -0.49 pg/mL, p=0.04) and significant increase in nitrite during hemodialysis (parameter estimate +0.16 nM, p=0.02) (Table 1).
CONCLUSIONS: Patients who received the low dialysate-to-serum Na+ gradient before the high dialysate-to-serum Na+ gradient had higher levels of nitrite and lower levels of ET-1 throughout the three week study period compared to patients who received the high dialysate-to-serum Na+ gradient before the low dialysate-to-serum Na+ gradient. This suggests that the dialysate Na+ concentration may have longer-term effects on endothelial cell function.Southwestern Medical Foundatio
In Reply To ‘“Malignant” Intradialytic Hypertension: A Severe Form of Intradialytic Hypertension’
No full textHypertension in dialysis: what you don't know can hurt your patients
No full textDetailed formal protocol with illustrations and extensive bibliography.UT Southwestern--Internal Medicin
Intradialytic Hypertension: A Less-Recognized Cardiovascular Complication of Hemodialysis
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Hypertension and hemodialysis: pathophysiology and outcomes in adult and pediatric populations
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