Background: Left ventricular hypertrophy (LVH) is an independent risk factor for mortality in the dialysis population. LVH has been attributed to several factors, including hypertension, excess extracellular fluid (ECF) volume, anemia and uremia. Nocturnal hemodialysis is a novel renal replacement therapy that appears to improve blood pressure control.
Methods: This observational cohort study assessed the impact on LVH of conversion from conventional hemodialysis (CHD) to nocturnal hemodialysis (NHD). In 28 patients (mean age 44 +/- 7 years) receiving NHD for at least two years (mean duration 3.4 +/- 1.2 years), blood pressure (BP), hemoglobin (Hb), ECF volume (single-frequency bioelectrical impedance) and left ventricular mass index (LVMI) were determined before and after conversion. For comparison, 13 control patients (mean age 52 +/- 15 years) who remained on self-care home CHD for one year or more (mean duration 2.8 +/- 1.8 years) were studied also. Serial measurements of BP, Hb and LVMI were also obtained in this control group.
Results: There were no significant differences between the two cohorts with respect to age, use of antihypertensive medications, Hb, BP or LVMI at baseline. After transfer from CHD to NHD, there were significant reductions in systolic, diastolic and pulse pressure (from 145 +/- 20 to 122 +/- 13 mm Hg, P < 0.001; from 84 +/- 15 to 74 +/- 12 mm Hg, P = 0.02; from 61 +/- 12 to 49 +/- 12 mm Hg, P = 0.002, respectively) and LVMI (from 147 +/- 42 to 114 +/- 40 g/m2, P = 0.004). There was also a significant reduction in the number of prescribed antihypertensive medications (from 1.8 to 0.3, P < 0.001) and an increase in Hb in the NHD cohort. Post-dialysis ECF volume did not change. LVMI correlated with systolic blood pressure (r = 0.6, P = 0.001) during nocturnal hemodialysis. There was no relationship between changes in LVMI and changes in BP or Hb. In contrast, there were no changes in BP, Hb or LVMI in the CHD cohort over the same time period.
Conclusions: Reductions in BP with NHD are accompanied by regression of LVH.