Chronic hemodialysis: high risk patients for arrhythmias?

Performance Evaluation and Fouling Propensity of Forward Osmosis (FO) Membrane for Reuse of Spent Dialysate

The number of chronic renal disease patients has shown a significant increase in recent decades over the globe. Hemodialysis is the most commonly used treatment for renal replacement therapy (RRT) and dominates the global dialysis market. As one of the most water-consuming treatments in medical procedures, hemodialysis has room for improvement in reducing wastewater effluent. In this study, we investigated the technological feasibility of introducing the forward osmosis (FO) process for spent dialysate reuse. A 30 LMH of average water flux has been achieved using a commercial TFC membrane with high water permeability and salt removal. The water flux increased up to 23% with increasing flowrate from 100 mL/min to 500 mL/min. During 1 h spent dialysate treatment, the active layer facing feed solution (AL-FS) mode showed relatively higher flux stability with a 4–6 LMH of water flux reduction while the water flux decreased significantly at the active layer facing draw solution (AL-DS) mode with a 10–12 LMH reduction. In the pressure-assisted forward osmosis (PAFO) condition, high reverse salt flux was observed due to membrane deformation. During the membrane filtration process, scaling occurred due to the influence of polyvalent ions remaining on the membrane surface. Membrane fouling exacerbated the flux and was mainly caused by organic substances such as urea and creatinine. The results of this experiment provide an important basis for future research as a preliminary experiment for the introduction of the FO technique to hemodialysis.

Fluctuations in plasma potassium in patients on dialysis

Plasma potassium concentration is maintained in a narrow range to avoid deleterious electrophysiologic consequences of both abnormally low and high levels. This is achieved by redundant physiologic mechanisms, with the kidneys playing a central role in maintaining both short-term plasma potassium stability and long-term total body potassium balance. In patients with end-stage renal disease, the lack of kidney function reduces the body’s ability to maintain normal physiologic potassium balance. Routine thrice-weekly dialysis therapy achieves long-term total body potassium mass balance, but the intermittent nature of dialytic therapy can result in wide fluctuations in plasma potassium concentration and consequently contribute to an increased risk of arrhythmogenicity. Various dialytic and nondialytic interventions can reduce the magnitude of these fluctuations, but the impact of such interventions on clinical outcomes remains unclear.

Arrhythmias in Patients on Maintenance Dialysis: A Cross-sectional Study

RATIONALE & OBJECTIVE

Patients with kidney failure treated with maintenance dialysis experience a high rate of mortality, in part due to sudden cardiac death caused by arrhythmias. The prevalence of arrhythmias, including the subset that are clinically significant, is not well known. This study sought to estimate the prevalence of arrhythmias, characterize the pattern of arrhythmic events in relation to dialysis treatments, and identify associated clinical characteristics.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

152 patients with kidney failure treated with maintenance dialysis in Denmark.

EXPOSURES

Dialysis treatment; clinical characteristics; cardiac output and preload defined using echocardiography.

OUTCOMES

Prevalence and pattern of arrhythmias on 48-hour Holter monitoring; odds ratios for arrhythmias.

ANALYTICAL APPROACH

Descriptive analysis of the prevalence of arrhythmias. Pattern of arrhythmias described using a repeated-measures negative binomial regression model. Associations between clinical characteristics and echocardiographic findings with arrhythmias were assessed using logistic regression.

RESULTS

Among the 152 patients studied, 83.6% were treated with in-center dialysis; 10.5%, with home hemodialysis; and 5.9%, with peritoneal dialysis. Premature atrial and ventricular complexes were seen in nearly all patients and 41% had paroxysmal supraventricular tachycardia. Clinically significant arrhythmias included persistent atrial fibrillation observed among 8.6% of patients, paroxysmal atrial fibrillation among 3.9%, nonsustained ventricular tachycardia among 19.7%, bradycardia among 4.6%, advanced second-degree atrioventricular block among 1.3%, and third-degree atrioventricular block among 2.6%. Premature ventricular complexes were more common on dialysis days, while tachyarrhythmias were more often observed during dialysis and in the immediate postdialytic period. Older age (OR per 10 years older, 1.53; 95% CI, 1.15-2.03; P=0.003), elevated preload (OR, 4.02; 95% CI, 1.05-15.35; P=0.04), and lower cardiac output (OR per 1L/min greater, 0.66; 95% CI, 0.44-1.00; P=0.05) were independently associated with clinically significant arrhythmias.

LIMITATIONS

Arrhythmia monitoring limited to 48 hours; small sample size; heterogeneous nature of the population, risk for residual confounding.

CONCLUSIONS

Arrhythmias, including clinically significant abnormal rhythms, were common. Tachyarrhythmias were more frequent during dialysis and the immediate postdialytic period. The relevance of these findings to clinical outcomes requires additional study.

Serum-to-dialysate potassium gradient and its association with short-term outcomes in hemodialysis patients

Background

A high serum-to-dialysate potassium (K+) gradient at the start of dialysis leads to rapid lowering of serum K+ and may confer a greater risk of adverse events. Here, we examined the near-term association of K+ gradient with clinical outcomes.

Methods

This retrospective (2010-11) event-based study considered 830 741 patient-intervals, each defined by a pre-dialysis measurement of serum K+ made among adult Medicare Parts A and B enrollees who received in-center hemodialysis on a Monday/Wednesday/Friday schedule at a large US dialysis organization. K+ gradient was considered based on the difference in K+ concentration (serum-dialysate) on the date of measurement; analyses accounted for multiple observations per patient. Outcomes considered were: all-cause and cardiovascular hospital admissions, emergency department (ED) visits and deaths.

Results

Higher K+ gradient was associated with younger age, greater fistula use, lower comorbidity scores and better nutritional indices. Adjusting for patient differences, there was a dose-response relationship between higher K+ gradient and greater risks of all-cause hospitalization and ED visit. A similar trend was seen for cardiovascular hospitalization but did not achieve statistical significance. No associations were observed with mortality, potentially due to a low number of events.

Conclusions

Higher K+ gradient is independently associated with greater risk of all-cause hospitalizations and ED visits. Further research is needed to determine whether interventions that reduce the K+ gradient ameliorate this risk.

Predictors of Arrhythmic Events Detected by Implantable Loop Recorders in Renal Transplant Candidates

BACKGROUND

The recording of arrhythmic events (AE) in renal transplant candidates (RTCs) undergoing dialysis is limited by conventional electrocardiography. However, continuous cardiac rhythm monitoring seems to be more appropriate due to automatic detection of arrhythmia, but this method has not been used.

OBJECTIVE

We aimed to investigate the incidence and predictors of AE in RTCs using an implantable loop recorder (ILR).

METHODS

A prospective observational study conducted from June 2009 to January 2011 included 100 consecutive ambulatory RTCs who underwent ILR and were followed-up for at least 1 year. Multivariate logistic regression was applied to define predictors of AE.

RESULTS

During a mean follow-up of 424 ± 127 days, AE could be detected in 98% of patients, and 92% had more than one type of arrhythmia, with most considered potentially not serious. Sustained atrial tachycardia and atrial fibrillation occurred in 7% and 13% of patients, respectively, and bradyarrhythmia and non-sustained or sustained ventricular tachycardia (VT) occurred in 25% and 57%, respectively. There were 18 deaths, of which 7 were sudden cardiac events: 3 bradyarrhythmias, 1 ventricular fibrillation, 1 myocardial infarction, and 2 undetermined. The presence of a long QTc (odds ratio [OR] = 7.28; 95% confidence interval [CI], 2.01-26.35; p = 0.002), and the duration of the PR interval (OR = 1.05; 95% CI, 1.02-1.08; p < 0.001) were independently associated with bradyarrhythmias. Left ventricular dilatation (LVD) was independently associated with non-sustained VT (OR = 2.83; 95% CI, 1.01-7.96; p = 0.041).

CONCLUSIONS

In medium-term follow-up of RTCs, ILR helped detect a high incidence of AE, most of which did not have clinical relevance. The PR interval and presence of long QTc were predictive of bradyarrhythmias, whereas LVD was predictive of non-sustained VT.

Prevalence and Predictors of Arrhythmia in End Stage Renal Disease Patients on Hemodialysis

BACKGROUND

Sudden death is common in end-stage renal disease (ESRD). Cardiac arrhythmia is observed frequently in patients with ESRD and is thought to be responsible for this high rate of sudden death. This study investigated the prevalence and the predictors of arrhythmia in patients on maintenance dialysis.

METHODS

Ninety-four patients on hemodialysis program were enrolled in the study. Routine laboratory results were noted. Arrhythmia, periods of silent ischemia, and heart-rate variability analyses were obtained from 24-hour Holter monitor recordings. Corrected QT (QTc) dispersion was calculated from 12-lead surface EKG. Echocardiographic and tissue Doppler examinations were performed on interdialytic days as well. Ventricular arrhythmia was classified according to Lown classification; classes 3 and above were accepted as complex ventricular arrhythmia (CVA).

RESULTS

The mean age was 52.5+/-13.2 years; 44 (46.8%) were women. Ventricular premature contractions were detected in 80 (85.1%) patients, of whom 35 (37.2%) were classified as complex ventricular arrhythmia (CVA). Coronary artery disease, hypertension, and QTc dispersion appeared as independent factors predictive of CVA development. Atrial premature contractions (APC) were detected in 53 patients (56.4%) and supraventricular arrhythmia in 15 (16%) patients; all were identified as atrial fibrillation. Duration of dialysis therapy was found as an independent predictor of APC.

CONCLUSION

Arrhythmia is frequently observed in ESRD patients receiving hemodialysis and may be responsible for the high rate of sudden mortality. Hypertension, CAD, and QTc dispersion are independent predictors of CVA, and duration of dialysis therapy is an independent factor affecting APC development in these patients.

Hemodialysis-induced left ventricular dysfunction is associated with an increase in ventricular arrhythmias

Conventional hemodialysis results in intradialytic cardiac ischemia in a significant proportion of patients. Segmental myocardial ischemia results in the development of left ventricular regional wall motion abnormalities. Sudden death is the most common cause of mortality in hemodialysis patients. This study looked to examine any association between the development of left ventricular regional wall motion and cardiac arrhythmias. Forty established hemodialysis patients had 24-hour Holter recordings, which commenced immediately before a dialysis session. Frequency of isolated ectopy was classified as a percentage of the total beats on the Holter monitor record. Ventricular arrhythmias were stratified according to the Lown classification. Classes 3 and above were taken as complex ventricular arrhythmias. Patients also underwent baseline and intradialytic echocardiography to assess the development of concurrent regional wall motion abnormalities. Premature ventricular complexes and complex ventricular arrhythmias were both more common during hemodialysis than in the subsequent monitored period. Patients who developed regional wall motion abnormalities (n = 27) had significantly more premature ventricular complexes during hemodialysis than afterward (p < 0.001). Patients with ischemic heart disease and left ventricular hypertrophy both had a higher frequency of premature ventricular complexes during hemodialysis than those without (p < 0.03 and p < 0.02, respectively). Cardiac arrhythmias are common in hemodialysis patients. The frequency of premature ventricular complexes is significantly higher during hemodialysis in patients who develop regional wall motion abnormalities and may be related to factors associated with demand ischemia.

The Acute Cardiac Effects of Dialysis

It is well recognized that the procedure of hemodialysis is associated with significant changes in blood pressure and systemic hemodynamics; 20-30% of treatments are complicated by intradialytic hypotension (IDH). There are now an increasing number of studies using electrocardiographic, isotopic and echocardiographic techniques that show that subclinical myocardial ischemia occurs during dialysis. This concept is supported by some studies showing that dialysis can induce acute rises in troponins and creatinine kinase MB, although this has not been found by all authors. Some of this controversy may at least in part be due to the collection of blood samples immediately postdialysis, which is likely to be too early to reliably detect dialysis-induced elevations of cardiac enzymes. Cardiovascular death is the biggest single cause of mortality in dialysis patients and of this sudden death comprises the largest proportion. As such, there is a large body of evidence examining whether dialysis is pro-arrhythmogenic. It is clear that dialysis can increase QTc interval and QT dispersion and is capable of inducing arrhythmias on Holter monitoring, likely due to the interaction of multiple factors, some of which prime for the development of arrhythmias (particularly the presence of preexisting cardiac disease), and some of which act as triggers. However, the link between these electrocardiographic alterations and sudden death is relatively poorly studied. This review summarizes the available literature regarding the acute cardiac effects of dialysis in relation to the above, and discusses how these acute changes may contribute to the genesis of uremic cardiomyopathy and longer term cardiac outcomes.

Severe coronary stenosis is an important factor for induction and lengthy persistence of ventricular arrhythmias during and after hemodialysis

BACKGROUND

Ventricular arrhythmias have been shown to be the major cause of sudden cardiac death in hemodialysis (HD) patients. We investigated whether angiographic coronary stenosis was responsible for the induction of ventricular arrhythmias in HD patients.

METHODS

HD patients (n = 150) showing ischemic signs in exercise electrocardiography or echocardiography were divided into 2 groups: the stenotic group (n = 61), with significant coronary stenosis (> or =75% in diameter), and the nonstenotic group (n = 89), without significant coronary stenosis on coronary angiography. Severity of ventricular arrhythmias was evaluated by means of ambulatory 24-hour Holter monitoring in HD patients with and without significant coronary stenosis.

RESULTS

The frequency of ventricular premature contractions and prevalence of patients with Lown class 4 ventricular arrhythmias were significantly greater in the stenotic than nonstenotic group during HD and for 12 hours after HD (P < 0.03). In the stenotic group, a significantly greater frequency of ventricular premature contractions and prevalence of patients with complex arrhythmias were observed during HD (1.33% and 31.1%, respectively) compared with before HD (0.50% and 11.5%, respectively), and the high incidence persisted for 6 hours after HD. In the nonstenotic group, a slightly increased incidence was observed only during HD compared with before HD. Multivariate analysis showed only coronary stenosis (odds ratio, 5.69; P = 0.041) as an independent and significant factor for the induction of complex arrhythmias.

CONCLUSION

These data clearly indicate that severe coronary stenosis, which may cause myocardial ischemia, is an important factor for the induction and lengthy persistence of ventricular arrhythmias during and after HD.

Hyperkalemia in dialysis patients

Serious hyperkalemia is common in patients with end-stage renal disease (ESRD) and accounts for considerable morbidity and death. Mechanisms of extrarenal disposal of potassium (gastrointestinal excretion and cellular uptake) play a crucial role in the defense against hyperkalemia in this population. In this article we review extrarenal potassium homeostasis and its alteration in patients with ESRD. We pay particular attention to the factors that influence the movement of potassium across cell membranes. With that background we discuss the emergency treatment of hyperkalemia in patients with ESRD. We conclude with a review of strategies to reduce the risk of hyperkalemia in this population of patients.

Cardiac arrhythmias and silent myocardial ischemia during hemodialysis

Cardiac arrhythmias are noted in a significant proportion of chronic renal failure (CRF) patients on hemodialysis (HD), and may contribute to cardiovascular mortality. A number of factors have been implicated in the genesis of these arrhythmias. The role of silent myocardial ischemia (SMI), however, has not been evaluated systematically. We prospectively studied 38 unselected CRF patients on regular HD by continuous Holter monitoring starting 24 hours before HD, lasting through the dialysis session and continued for 20 hours thereafter. The recordings were analyzed for frequency, timing and severity of supraventricular and ventricular arrhythmias and SMI as identified by ST-segment depression. Ventricular arrhythmias during HD were noted in 11 (29%) patients (group I), and were potentially life-threatening (Lown Class III and IVa) in 13%. The remaining 27 patients (group II) had no ventricular arrhythmias during HD. There was no difference in the age, sex ratio, duration of HD, blood pressure, fluctuations in weight, hematocrit, predialysis creatinine, sodium, potassium, calcium or inorganic phosphate levels between patients in the two groups. The number of patients with clinical ischemic heart disease was significantly greater in group I. SMI was noted in 72% and 33% of group I and II patients respectively (p = 0.026). 46% of those with and 25% of those without ST changes during HD developed ventricular arrhythmias during HD. Both SMI and ventricular arrhythmias were noted most frequently during the last hour of dialysis. Hypertension, diabetes mellitus and ischemic heart disease were observed more frequently amongst patients with SMI. Ventricular arrhythmias are detected in a significant proportion of CRF patients on HD. These are probably related to coronary artery disease since silent myocardial ischemia is also noted more frequently during HD in these patients. Further studies incorporating coronary angiography are needed in a larger number of patients to establish a definite causal relationship.

Effect of hemodialysis on the signal-averaged electrocardiogram

The presence of late potentials (LPs) on signal-averaged electrocardiography (SAECG) is predictive of ventricular tachycardia. The effect of hemodialysis (HD) on SAECG has not been well studied. SAECG was evaluated in 28 patients with chronic renal failure immediately before and after HD. In each SAECG, QRS duration, low-amplitude signal duration (LASd), and root-mean-square voltage of the terminal 40 milliseconds of the QRS (RMS40) were measured. To evaluate the effect of fluid removal on SAECG, the last 12 patients were studied during two different HD sessions, one with and one without fluid removal. Two-dimensional echocardiography was performed before and after HD on these 12 patients. At baseline, four patients met the criteria for LPs on SAECG. Only one patient met the criteria for LPs on SAECG after HD. After HD, the mean LASd decreased (28.3 +/- 12.9 to 24.9 +/- 10.1 milliseconds; P = 0.041) and RMS40 increased (63.0 +/- 56.9 to 79.0 +/- 59.2 microV; P = 0. 006). Among the 12 patients who underwent HD with and without fluid removal, left ventricular end-diastolic dimension decreased with (5. 4 +/- 0.6 to 5.1 +/- 0.6 cm; P = 0.024) but not without fluid removal (5.2 +/- 0.3 to 5.1 +/- 0.4 cm; P = not significant [NS]). RMS40 improved with (43.8 +/- 23.1 to 53.2 +/- 22.6 microV; P = 0. 03) but not without fluid removal (51.0 +/- 26.5 to 51.5 +/- 24.2 microV; P = NS). A significant negative correlation was found between change in body weight and change in RMS40 parameter (r = 0. 456; P = 0.0381). SAECG parameters are abnormal in a significant proportion of patients with chronic renal failure and improve with HD despite electrolyte and other proarrhythmic changes. Decreased left ventricular dimension because of fluid removal during HD is one possible explanation for this improvement.

QT/corrected QT (QTc) intervals and QT/QTc dispersions in children with chronic renal failure

We aimed to examine QT/corrected QT (QTc) intervals, QT/QTc dispersions (QTD/QTcD) and also the effect of different clinical and laboratory variables on these parameters in children with chronic renal failure. Serum biochemistry, 12-lead electrocardiogram, telecardiogram, and echocardiography were performed in 50 children with chronic renal failure (23 female and 27 male; aged 12.3+/-3.6 years, range 5 to 20 years). None of them had symptoms related to arrhythmias. When compared with a control group (372 children, aged 7 to 18 years, mean 12.4+/-2.6) patients with chronic renal failure had greater QT/QTc intervals and QT/QTc dispersion values (Patient: QT = 360.9+/-53.3; QTc = 438.5+/-33.2; QTD = 42.4+/-20.8; QTcD = 57.5+/-23.8;

CONTROL

QT = 325.9+/-24.1; QTc = 398.7+/-19.7; QTD = 29.9+/-10.2; QTcD = 47.3+/-16.6; P<0.01). QT, QTc, and QTcD values were significantly greater in patients who had renal failure duration longer than 2 years. Patients who had impaired left ventricular systolic function on echocardiogram had greater QTc, QTD, and QTcD values. It was found that sex, cardiomegaly on chest X-ray, and left ventricular hypertrophy on echocardiogram were not related to these parameters. It is concluded that, impaired cardiac systolic function and longer renal failure duration are related to an increase in QT, QTc, QTD, and QTcD values and hence these variables may be risk factors for ventricular arrhythmias in uremic patients.

Effect of a new model of hemodialysis potassium removal on the control of ventricular arrhythmias

The primary aim of this multicenter, prospective, randomized cross-over study was to clarify whether a new model of hemodialysis (HD) potassium (K) removal using a decreasing intra-HD dialysate K concentration and a constant plasma-dialysate K gradient (treatment B) is capable of reducing the arrhythmogenic effect of standard HD, which has a constant dialysate K concentration and decreasing plasma-dialysate K gradient (treatment A). The secondary aim was to verify whether this new model is clinically safe. In treatment B, the initial dialysate K concentration had to be 1.5 mEq/liter less than the plasma K concentration, and exponentially decrease to 2.5 mEq/liter at the end of HD. Forty-two chronic HD patients with an increase in premature ventricular complexes (PVC) during dialysis were enrolled from 18 participating centers, and randomly assigned to either sequence 1 (ABA) or sequence 2 (BAB). A pool of 333 of 378 expected ECG Holter recordings were checked for signal quality; 269 (71%) from 36 patients (86%) had a satisfactory signal quality and 108 were selected for analysis (1 per patient per period). There was a difference in the natural logarithm of the increase in PVC/hr and PVC couplets/hr during HD between treatments A and B (1.70 +/- 1.59 vs. 1.09 +/- 1.76 and 0.94 +/- 0.86 vs. 0.64 +/- 1.01, a reduction of 36% and 32%, P = 0.011 and 0.047, respectively) without any carry over effect (P = 0.61 and 0.24, respectively). The fact that this decrease of one third is due to a lower plasma-dialysate K gradient is supported by the observation that it was more evident during the first than the last two hours of HD (a reduction in the natural logarithm of the increase in PVC/hr and PVC couplets/hr of 60% and 60%, P 0.002 and 0.009, vs. 26% and 17%, P = 0.098 and 0.332, respectively): the initial plasma-dialysate K gradient was 2.3 times lower during treatment B than during treatment A, without adversely affecting pre-HD plasma K levels. These results could have a considerably clinical impact not only because of the possibility of physiologically decreasing the arrhythmogenic effect of HD, but also because this effect can be considered a "marker" of the electrophysiological derangement induced by the administration of standard HD three times a week for years ("electric disequilibrium syndrome").

Blood pressure influences the occurrence of complex ventricular arrhythmia in hemodialysis patients

We investigated the relationship between blood pressure and the occurrence of complex ventricular arrhythmias (multiform, couplets, or runs) as assessed by 48-hour Holter monitoring in 74 stable long-term hemodialysis patients (44.5 +/- 12 years old; 54% men; 74% whites; dialysis duration, 51.3 +/- 36.1 months; systolic pressure, 146.6 +/- 19.3 mm Hg; diastolic pressure, 89.2 +/- 12.1 mm Hg; prevalence of arterial hypertension, 33.8%). Systolic and diastolic pressures represented the average of all predialysis determinations during the 3 months preceding the tests. Hemodialysis was performed midway through the Holter monitoring period. M-mode and bidimensional echocardiograms and myocardial perfusion tests were also obtained from all patients. Complex arrhythmias were observed in 37 individuals (50%). Univariate analysis showed that systolic pressure (P < .001), diastolic pressure (P < .05), age (P < .001), left ventricular posterior wall thickness (P < .01), left ventricular mass index (P < .05), and ischemic alterations on myocardial perfusion tests (P < .005) were significantly associated with complex arrhythmias. With the use of a multivariate model (stepwise logistic regression analysis) only systolic pressure (P < .01) and age (P < .05) were independently associated with complex arrhythmias. Sex; angina; dialysis duration; New York Heart Association functional class; use of digitalis; plasma levels of creatinine, sodium, potassium, calcium, and phosphate; hematocrit; left ventricular fractional shortening; left ventricular diastolic diameter; and ST segment deviation were not correlated with complex arrhythmias. The severity and frequency of complex arrhythmias were not influenced by hemodialysis. At follow-up (5 to 80 months) 5 patients had died of sudden death, 4 of whom were hypertensive and older than 45 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodialysis using a Constant Potassium Gradient: Rationale of a Multicenter Study

The aim of this study is to evaluate the relationship between two different procedures for potassium removal during hemodialysis (HD) and cardiac arrhythmias. Cell excitability and the transmission of impulses may be influenced by variations of resting membrane potential (RMP). The rapid decrease of plasma potassium during the first two hours of standard HD causes a membrane hyperpolarization. A different K+ kinetic, with a gradual and constant elimination of K+ during HD, may reduce this further unphysiological aspect and its clinical consequences. This can be obtained keeping blood-dialysate K+ gradient as constant as possible with the use of a dialysate K+ concentration (Kd) decreasing during HD. Our experimental studies on various K+ intradialytic gradients seem to indicate as optimal to this purpose K+ gradients of 1.5 mEq/l at the beginning of dialysis, esponentially decreasing during treatment to Kd values of 2.5 mEq/l at the end of dialysis (variable Kd). Patients included in the trial will be submitted to two different methods of treatment with Kd 2 mEq/l and variable Kd, and to a 24 hours ECG the day of dialysis. We will compare the number of intra and interdialytic premature ventricular complexes to evaluate the impact of two different models of potassium removal on arrhythmias.

ECG changes and cardiac arrhythmias in chronic renal failure patients on hemodialysis

Serial 12-lead electrocardiogram (ECG) recordings and 24-hour Holter monitoring were carried out in 39 patients with chronic renal failure, starting just before a routine dialysis session. In an attempt to identify risk factors for cardiac arrhythmias, the results obtained from each patient were correlated with a variety of clinical, hematological, and biochemical data. All patients exhibited ECG changes, which were most pronounced during the first 2 hours of dialysis. The most frequent of these changes were a decrease in T wave amplitude and increase in Tmax time (all patients), an increase of QRS amplitude (61% of patients), shortened or prolonged QTc interval (61%) and ischemic-like ST-T changes (22% and 39%, respectively). Potentially clinically significant arrhythmias occurred in 12 patients (31%) of which 8 were supraventricular, 3 were combined ventricular and supraventricular, and 1 was pure ventricular. The only clinically identified risk factor for complex ventricular and supraventricular arrhythmia was advanced age. The arrhythmia and nonarrhythmia groups differed significantly in their predialysis hematocrit, O2 content, serum urea, and osmolarity, and in their postdialysis serum phosphorus and osmolarity. The results indicate that patients with chronic renal failure frequently exhibit ECG changes and a high incidence of ventricular and supraventricular arrhythmias, which may be prognostically significant, during and after hemodialysis.

Serum calcium increases the incidence of arrhythmias during acetate hemodialysis

We investigated the occurrence of arrhythmias during maintenance acetate hemodialysis (HD) using a 24-hour continuous electrocardiogram recording system. Three of 22 patients showed augmented increases in both ventricular premature beats and supraventricular premature beats during HD. When we changed the dialysate from one with a Ca2+ concentration of 1.75 mmol/L (3.5 mEq/L), to one with a Ca2+ concentration of 1.25 mmol/L (2.5 mEq/L), the elevation of serum Ca2+ concentration during HD was abolished and the increases in both ventricular premature beats and supraventricular premature beats were significantly decreased. The elevation of serum Ca2+ concentration during HD might induce either extracellular or intracellular increase in Ca2+ concentration in the heart and elicit either reentry- or triggered-activity types of arrhythmias during HD. The present results indicate that the dialysate with a lower Ca2+ concentration is advisable to use in patients with underlying cardiac diseases.

Electrocardiographic monitoring in children with chronic renal failure

Continuous electrocardiographic (ECG) monitoring was performed over 24 h in 44 children at various stages of chronic renal failure in order to determine the incidence and nature of cardiac dysrhythmias. In addition the ECG was followed during haemodialysis sessions and during dialysate exchanges in continuous ambulatory peritoneal dialysis (CAPD) patients. In contrast to adult patients on haemodialysis life-threatening dysrhythmias were not observed. The proportion of children with premature ventricular complexes (41%) was at the upper limit of that in healthy children. A relatively high heart rate was found in children on CAPD, which varied during the exchange procedure. In 57% of all patients a transient marked prolongation of the QT interval up to 40% greater than normal was observed without obvious changes in the serum electrolyte levels. Continuous ECG monitoring is a useful tool for detecting alterations of cardiac rhythm and conduction in at-risk children with renal failure.

Safety and efficacy of low-potassium dialysate

To evaluate the safety and efficacy of low-potassium dialysate, 11 patients with stable end-stage renal disease and with no history of arrhythmia or digitalis use were studied. All were treated with hemodialysis three times per week. Dialysates with potassium concentrations of 2 mEq/L, 1 mEq/L, or 0 mEq/L were compared. Each patient (exceptions noted in text) was studied once at each bath potassium concentration. Cardiac rhythm was recorded by Holter monitor during and for six hours following dialysis. Single PVCs and APCs were common with all potassium concentrations. Only one patient had high-grade ventricular ectopy. It was seen with each of the three potassium concentrations, but was most severe with the potassium-free dialysate. The potassium-free dialysate removed significantly more potassium (78.5 +/- 2.6 mEq) than the 1-K dialysate (62.9 +/- 5.1 mEq) or the 2-K dialysate (50.6 +/- 6 mEq), and the 1-K dialysate removed significantly more potassium than the 2-K dialysate. There were small but significant differences in serum potassium concentrations with the three different dialysates. It was concluded that (1) in all but one of our patients potassium-free dialysate did not produce new ectopy; (2) potassium-free dialysate was 24% more effective than 1-K dialysate and 50% more effective than 2-K dialysate in removing body potassium; and (3) 1-K dialysate was 20% more effective than 2-K dialysate in removing body potassium.

Effect of digitoxin on cardiac arrhythmias in hemodialysis patients

Digitoxin is considered a risk factor for ventricular arrhythmias in hemodialysis patients. In a randomized, crossover controlled study, 55 hemodialysis outpatients with sinus rhythm were prospectively investigated in two 48-h periods of electrocardiographic monitoring, one on and one off digitoxin or vice versa. The frequency of ventricular ectopic beats (mean +/- SD) which were found in 31 of 55 patients (56%), was slightly higher on hemodialysis (10 +/- 28 beats/h) than in the following 20 h (5.4 +/- 10 beats/h) and the next day off hemodialysis (3.6 +/- 6.6 beats/h); however, no difference was seen in patients on digitoxin during hemodialysis (10 +/- 29 beats/h), in the following 20 h (4.8 +/- 15 beats/h) and on the next day off hemodialysis (1.2 +/- 6.6 beats/h). The frequency of ventricular bigemini, polymorphous ectopies, couplets, more than 30 ectopies/h, salvos and tachycardias (10 vs 9 patients) on and off digitoxin was about the same (n.s., Fisher test). Supraventricular bigemini, salvos, tachycardias, and atrial fibrillation, however, occurred in significantly fewer patients on digitoxin (3 vs 13) than in those off digitoxin (P = 0.01, Fisher test). It is concluded that digitoxin does not increase the risk of ventricular arrhythmias in hemodialysis patients. Digitoxin, however, may have a beneficial effect on the supraventricular arrhythmias frequently observed in these patients.