Effects of short daily hemodialysis and extended standard hemodialysis on blood pressure and cardiac hypertrophy: a comparative study.

BACKGROUND: Causes of hypertension and cardiac hypertrophy in hemodialysis (HD) patients are multiple, but the role of fluid overload appears to be crucial. Short daily HD (sDHD = 2 hr x 6/week) seems to allow reductions in left ventricular mass (LVM) through the reduction of extracellular water (ECW). Better cardiovascular stability during HD can be obtained with short, but more frequent HD sessions, but also by increasing the session length accompanied with a reduction in ultrafiltration (UF)/hr. Regardless of the method, the adequate reduction in extracellular volume should permit better control of hypertension and left ventricular hypertrophy (LVH). This study aimed to compare sDHD with an extended form of standard HD (eSHD = 4.5-5 hr x 3/week) on the reduction of fluid overload, blood pressure (BP) and LVM index (LVMi). PATIENTS AND METHODS: Twenty-four HD patients with hypertension and LVH were enrolled in a prospective non-randomized study. After a 3-month run-in period they were divided in two comparable groups: 12 patients treated with sDHD, and 12 patients treated with eSHD for 6 months. LVMi, 24 hr BP monitoring, ECW, determined with electrical bio-impedance, biochemical correlates and spKT/V were studied at the beginning of the study and 6 months later. RESULTS: The weekly session length was increased in eSHD from 722.9 +/- 7.5 to 877.3 +/- 35.5 min. ECW% was reduced similarly in the two groups (Delta ECW: eSHD = 4.6 +/- 2.4 L; sDHD = 4.1 +/- 2.3 L); 24 hr BP decreased significantly from 157/81 to 137/75 mmHg in eSHD, and from 149/79 to 128/72 mmHg in sDHD. The reduction in systolic BP was similar in the two groups (eSHD = 20.1 +/- 15.3 mmHg, sDHD = 21.2 +/- 16.7 mmHg). Finally, LVMi was similarly reduced (eSHD = 55 +/- 30.3 g/m(2), sDHD = 54.4 +/- 21.3 g/m(2). The number of antihypertensive drugs decreased significantly after ECW% reduction: only 2/10 patients on eSHD and 4/12 patients on sDHD were maintained on therapy (p = ns). Intra-dialysis hypotension episodes did not differentiate between SHD and DHD. The reduction in LVMi was significantly correlated to fluid volume changes when these were measured as phase angle (PA) with bio-impedance (r = -0.43, p < 0.05). CONCLUSIONS: In hypertensive HD patients with LVH, fluid overload is invariably present and its reduction allows the decrease of BP and LVM. These results can be obtained by forcing UF with eSHD and sDHD, but patients maintained on x 3/week schedules need longer dialysis sessions to avoid intra-dialysis symptoms.

Association between extracellular water, left ventricular mass and hypertension in haemodialysis patients.

BACKGROUND: Hypertension and left ventricular hypertrophy (LVH) are present in the majority of patients undergoing haemodialysis (HD). These two pathologies persist after dialysis onset, and pharmacological therapy is often required for adequate control of blood pressure (BP). Although fluid overload is a determinant of hypertension, clinical assessment of this parameter remains difficult and unsatisfactory. Bioimpedance analysis (BIA) spectroscopy and the relative determination of extracellular water (ECW%) may provide a simple and inexpensive tool for investigating fluid overload. We studied 110 patients on thrice-weekly HD to determine whether ECW body content correlates with hypertension and LVH in this patient population. METHODS: Hypertension was determined according to the WHO criteria (office BP >/= 140/90 and/or the use of antihypertensive therapy). Twenty-four hour BP monitoring and echocardiography were performed on midweek inter-HD days. Blood chemistries, dialysis dose (spKt/V) and bioimpedance were analysed on midweek HD days. RESULTS: Hypertension was present in 74.5% of patients. There were no differences for age, spKt/V, haemoglobin, serum creatinine and residual renal function between normotensive and hypertensive patients. Twenty-four hour systolic BP (SBP), 24 h diastolic BP and 24 h pulse pressure were higher in hypertensive patients, in spite of antihypertensive therapy. LVH was present in 61.8% of patients. BIA revealed that ECW% was increased in LVH+ patients (LVH+ = 47.5 +/- 7.9%, LVH- = 42.4 +/- 6.2%, P = 0.01) and in hypertensive patients compared with normotensives (46.5 +/- 7.7% vs 43 +/- 7.2%, P = 0.02). Dry body weights and inter-HD body weight increases did not differ between hypertensive and normotensive patients nor between patients with or without LVH. ECW was correlated with SBP (r = 0.35, P < 0.01) and with left ventricular mass index (LVMi(g/sqm)) (r = 0.49, P < 0.001). A stepwise multiple linear regression model revealed that LVMi(g/sqm) was significantly correlated with ECW%, SBP and male gender (r = 0.65, P < 0.001). CONCLUSIONS: LVH and hypertension are present in a majority of HD patients and they are closely correlated with one another. We found associations between fluid load, measured by BIA and expressed as ECW, and BP and LVM.

Blunted nocturnal blood pressure decrease and left-ventricular mass in hypertensive hemodialysis patients.

Left-ventricular hypertrophy (LVH) represents a frequent complication in hemodialysis (HD) patients. Hypertension is a well-known risk factor of cardiac morbidity which is present in 2 of 3 patients: among them about 60% have a blunted nocturnal decrease of blood pressure (BP). Although some large studies on essential hypertensives have documented that non-dipper patients have a higher number of cardiac events and a higher left ventricle (LV) mass than dipper ones, conflicting results have been reported for dialysis patients. Therefore, the aim of our study was to assess differences in LV mass between dipper and non-dipper hypertensive HD patients. We studied 66 patients with 24-hour ambulatory BP monitoring performed on HD and on inter-HD day. They were classified as dipper when a decrease of at least 10% of nocturnal systolic blood pressure on the inter-HD day was present. Echocardiography and bioimpedance were performed. 29% of the patients were classified as dippers and 71% as non-dippers. The 48-hour systolic and diastolic BP were not significantly different between the two groups (SBP: dipper = 144 +/- 12.9 mm Hg, non-dipper = 149 +/- 17.8 mm Hg; DBP: dipper = 80 +/- 9.9 mm Hg, non-dipper = 81 +/- 10.6 mm Hg). LV mass index (LVMi) did not differ between the two groups (dipper = 143.1 +/- 40.7 g/m(2); non-dipper = 159.4 +/- 46.3 g/m(2)). No differences were reported between dipper and non-dipper patients regarding extracellular water distribution (ECW: 48.1 +/- 7.7 vs. 49.8 +/- 10.8%). SBP night/day ratio and 48-hour SBP were not correlated to LVMi. A strong correlation was reported between ECW% and LVMi (r = 0.53, p < 0.001). In conclusion, 2 of 3 hypertensive HD patients are non-dipper, and this condition does not seem to be associated with significant differences in 48-hour blood pressure and LV mass. Volume overload appears to be the main independent determinant of LVH in these patients.