ABSTRACT
Technological innovations in haemodialysis [HD] have improved its quality and safety but cardiovascular morbidity and mortality still poses a great risk. Proper fluid removal is a critical component of HD, as both under and over hydration are associated with deleterious consequences. However, there is no single accurate measure for adequacy of dialytic fluid removal and assessment of dry weight is largely empirical. This may rely on clinical assessment, biochemical markers as natriuretic peptides, dilution methods, measurement of inferior vena cava diameter [IVCD], blood volume monitoring and bioimpedance analysis [BIA]. Plasma BNP was recently reported to be a sensitive marker both for volume overload and ventricular hypertrophy and/or dysfunction. We aimed to study some pathogenetic factors and diagnostic parameters of left ventricular hypertrophy and/or dysfunction in end- stage renal disease [ESRD] patients on maintenance HD. Emphasis was made on the utility of echocardiographic and BIA measurements in monitoring the development and assessment of volume overload during the inter- dialytic interval. Two groups of subjects were studied: 50 patients with ESRD on maintenance HD for >/= 6 months, and 15 age and sex matching controls. Patients were subjected to full clinical assessment, ECG, predialysis measurement of serum fasting blood sugar, creatinine, calcium, phosphorus, intact parathyroid hormone, lipid profile, uric acid, haemoglobin concentration and haematocrit value. Dialysis dose was assessed by urea reduction ratio and Kt/V. Plasma BNP, echocardiographic studies [for presence and geometric pattern of left ventricular hypertrophy, systolic and diastolic dysfunction and measurement of IVCD and right atrial pressure] and BIA were all done on two occasions 3 days apart: after termination of the end- of- the week HD session and before the start of the first session in the next week. Controls were subjected to assessment of clinical state, plasma BNP, and BIA. Both post- and pre- dialysis plasma BNP levels in patients were significantly higher when compared with the single plasma BNP reading in controls. Extracellular water [ECW] and its percent to total body water [ECW%] were higher in patients [both post- and pre- dialysis] compared to controls. The differences were statistically significant, except for post- dialysis ECW. The pre- dialysis values of mean velocity of circumferential fiber shortening, stroke volume, cardiac output, E/A ratio, Right atrial pressure, IVCD, ECW and ECW% were all significantly higher compared with the post- dialysis values. Left ventricular hypertrophy [LVH] was found in 47 [94%] patients, concentric LVH being the most frequent pattern [in 60%]. Pre- dialysis left ventricular mass index [LVMI] showed a statistically significant positive correlation with serum phosphorus, calcium phosphorus product, and plasma BNP. Pre- dialysis plasma BNP had a statistically significant negative correlation with pre- dialysis ejection fraction and fractional shortening. Volume overload plays a key role in the pathogenesis of LV hypertrophy and/or dysfunction in HD patients. BIA and IVCD are useful adjunctive measures for assessment of hydration status, keeping their limitations in mind. Plasma BNP concentrations have limited potential for the assessment of hydration status in HD patients, but it may be useful to have a baseline measure when the patient is at dry weight. Whether BNP can be used as a bedside test in the dialysis unit to measure adequacy of volume removal remains to be determined