Hypertension in chronic renal disease

Hypertension in chronic kidney disease: What lies behind the scene

Hypertension is a frequent condition encountered during kidney disease development and a leading cause in its progression. Hallmark factors contributing to hypertension constitute a complexity of events that progress chronic kidney disease (CKD) into end-stage renal disease (ESRD). Multiple crosstalk mechanisms are involved in sustaining the inevitable high blood pressure (BP) state in CKD, and these play an important role in the pathogenesis of increased cardiovascular (CV) events associated with CKD. The present review discusses relevant contributory mechanisms underpinning the promotion of hypertension and their consequent eventuation to renal damage and CV disease. In particular, salt and volume expansion, sympathetic nervous system (SNS) hyperactivity, upregulated renin–angiotensin–aldosterone system (RAAS), oxidative stress, vascular remodeling, endothelial dysfunction, and a range of mediators and signaling molecules which are thought to play a role in this concert of events are emphasized. As the control of high BP via therapeutic interventions can represent the key strategy to not only reduce BP but also the CV burden in kidney disease, evidence for major strategic pathways that can alleviate the progression of hypertensive kidney disease are highlighted. This review provides a particular focus on the impact of RAAS antagonists, renal nerve denervation, baroreflex stimulation, and other modalities affecting BP in the context of CKD, to provide interesting perspectives on the management of hypertensive nephropathy and associated CV comorbidities.

Insomnia is Associated with Systolic Hypertension in Uremic Patients on Hemodialysis

A newly developed questionnaire was administered to 140 hemodialyzed patients (82 M and 58 F) who have achieved adequate anemia correction according to the best guidelines with the aim: to evaluate the prevalence of clinical/subclinical dyssomnias in these patients; to study the influence of the dialytic shift (morning versus afternoon schedules) on sleep duration and disturbancies; and to evaluate the relationship between clinical sleep disorders and blood pressure values in uremic patients. Results indicated that 85% of uremic patients undergoing hemodialysis complain of clinical insomnia (frequent, persistent and associated with daytime consequences) or subclinical sleep disorders; patients dialyzing in the morning sleep significantly less during the night preceding the treatment, than those dialyzing in the afternoon; older patients complaining of clinical insomnia have a higher risk of failure to achieve target-optimal values in systolic blood pressure.

Daily ultrafiltration results in improved blood pressure control and more efficient removal of small molecules during hemodialysis

BACKGROUND

Although prior studies have shown that frequent hemodialysis (HD) can lead to improved control of dry weight in end-stage renal disease patients, there are no clinical studies examining whether this can improve blood pressure (BP) control and can also shorten the dialysis time needed to achieve satisfactory removal of small molecules. Several models of wearable dialysis systems are now under various stages of development. These devices present the possibility of hemodialyzing patients to their dry weights. We have built a prototype of a wearable ultrafiltration (UF) device that can provide daily UF. Apart from better fluid control, we hypothesize that separating HD from UF will result in better BP control, and adequate weekly small molecule removal could be achieved with a decreased duration of dialysis. We tested the hypothesis in current HD patients using conventional dialysis equipment.

METHODS

Thirteen patients were selected from a large urban HD center. The experimental period consisted of 4 weeks of daily UF (4 days/week of UF alone and 2 days/week of HD with UF). The duration of the HD sessions was increased by 15-30 min to maintain weekly standard Kt/V >2.0. The patients were then returned to their conventional 3 days/week of HD with UF and studied for 4 weeks. Predialysis BPs, interdialytic weight gains, and Kt/V results of the experimental and return periods were compared with those of the 3-month control period. No changes were made in antihypertensive or other medication during the study.

RESULTS

During the experimental period, mean arterial pressure decreased from 110 to 95 mm Hg (p < 0.001), systolic BP from 158 to 136 mm Hg (p < 0.001), while interdialytic weight gains were reduced from 3.25 to 1.21 liters (p < 0.0001). During the experimental period, weekly standard Kt/V of 2.16 was achieved in 8.24 h/week of HD, as compared to 11.14 h/week.

CONCLUSIONS

Volume control with daily UF results in improved BP control and, by separating the UF function from HD, adequate weekly standard Kt/V >2 can be achieved with twice weekly HD.

Management of hypertension in hemodialysis patients

Hypertension is very common in patients with chronic kidney disease and is present in most patients with end-stage renal disease (ESRD). Hypertension is largely responsible for premature cardiovascular disease in dialysis patients. The pathophysiology of hypertension in ESRD is complex, and multiple mechanisms are likely involved in blood pressure dysregulation in patients on hemodialysis. Some of these patients demonstrate resistant hypertension. Aggressive control of hypertension in ESRD/dialysis is mandatory. Generally, nonpharmacologic treatments are not enough to achieve the goal blood pressure levels in dialysis patients. Multiple antihypertensive drugs are often necessary. Drugs that block the renin-angiotensin system offer a number of advantages for patients with chronic kidney disease or ESRD, but additional drug classes are often needed to achieve effective blood pressure control in dialysis patients. Physicians treating hypertension in dialysis patients should be familiar with the pharmacokinetic properties of antihypertensive drugs in renal failure and choose the dosages accordingly. Vigorous control of hypertension is recommended to reduce the disease burden in patients with ESRD.

The general picture of uremia

The clinical presentation and manifestations of uremia that constitute the uremic syndrome are presented. The first descriptions of patients with advanced or "terminal" renal failure who were treated with hemodialysis are evoked to illustrate the wide range of signs and symptoms that are associated even to a moderate decrease in renal function, presently referred to as chronic kidney disease (CKD) stages 3-4. The kidney is a central organ guaranteeing the maintenance of the "milieu intérieur," where all the cells of the body are generated, develop, proliferate, and die. Chronic kidney disease, by altering the "milieu intérieur," may alter the metabolism of every type of cell or organ, leading to a wide scope of symptoms. The most frequently observed signs in daily clinical practice are summarized and put into the perspective of the renal physician. Disturbances of ion and water metabolism, hypertension, cardiovascular disease, anemia, mineral and bone disorders, endocrine, inmmunologic and neurologic syndromes are described. The addition of these clinical manifestations defines and describes each uremic patient as a specific individual. The pathophysiologic mechanisms by which each of these signs and symptoms appears and the particular compounds responsible for their occurrence, are described in depth in subsequent chapters of this issue.

Are traditional risk factors valid for assessing cardiovascular risk in end-stage renal failure patients?

AIM

Cardiovascular diseases (CVD) are the major cause of morbidity and mortality in end-stage renal failure (ESRF). Establishing whether traditional risk factors are valid predictors of CVD in ESRF is important in order to devise preventive and interventional strategies for the ESRF populations.

METHODS

In this retrospective cohort study, a cohort of patients on dialysis were examined between September 2000 and February 2001. Only those without previous CVD events at baseline were included. For each individual, 5 year CVD risk was calculated using the New Zealand 5 year CVD risk prediction charts based on the Framingham Heart Study prognostic algorithm. The subsequent 5 year CVD outcome for each patient was determined and the observed rate of first CVD events was compared to the predicted risk. Relation of individual risk factors with the CVD outcome was also assessed.

RESULTS

Of the patients, 274 were without previous CVD events at baseline and 27% experienced CVD events during the subsequent 5 years. Observed CVD risk was more than twofold that of predicted risk although there was a linear correlation between the two. Among individual risk factors, increasing age, diabetes and smoking were significantly related to the incidence of the CVD events but, unlike in the general population, systolic blood pressure, total cholesterol/high-density lipoprotein ratio and body mass index were not significantly related to CVD events.

CONCLUSION

The very high incidence of CVD in ESRF patients suggest that non-traditional risk factors present in the uraemic state are independent risk factors for CVD in ESRF patients. Nevertheless, the application of traditional cardiovascular risk profiles does allow risk stratification of the ESRF population.

Associations between sympathetic activity, plasma concentrations of renin, aldosterone, and parathyroid hormone, and the degree of intractability of blood pressure control in modialysis patients

This study was designed to examine how such factors as hemodialysis parameters, body mass index, renin and aldosterone concentrations, sympathetic nervous activity, and parathyroid hormone concentrations are associated with the control of hypertension in hemodialysis patients. Hemodialysis patients (n=114) were grouped into four categories. Group 1 had normal BP without antihypertensive medication. Group 2 needed one antihypertensive drug, Group 3 needed combination of two or three categories of antihypertensive drugs without minoxidil. Group 4 needed more than three categories of antihypertensive drugs including minoxidil. Parathyroid hormone, beta2-microglobulin, renin and aldosterone, epinephrine, norepinephrine, and hemodialysis parameters were measured. The fractional clearance of urea as Kt/V urea was significantly lower in Group 3 and Group 4 than in Group 2 (p<0.01). Concentrations of parathyroid hormone were significantly higher in Group 4 than the other groups (p<0.01). Pre-hemodialysis norepinephrine concentrations were significantly higher in Group 4 than the other groups (p<0.05). Traditional factors associated with hypertension did not seem to be relevant to the degree of hypertension in hemodialysis patients in the present study. In conclusion, poor Kt/V urea, elevated parathyroid hormone concentrations, and elevated concentrations of plasma norepinephrine seemed to be the factors that might be associated with control of hypertension in hemodialysis patients.

Fluid balance, dry weight, and blood pressure in dialysis

The total amount of sodium present in the body controls the extracellular volume. In advanced renal failure, sodium balance becomes positive and the extracellular volume expands. This leads to hypertension, and vascular changes that lead to adverse cardiovascular consequences in dialysis patients. Controlling the body sodium content and the extracellular volume allows one to better control hypertension and its consequences. This can be achieved by reducing the sodium input (sodium dietary restriction and reasonably low sodium dialysate) and/or by increasing the sodium output (ultrafiltration by convection). The discontinuous nature of hemodialysis causes saw-tooth volume fluctuations. This has led to the concept of dry weight (DW), a crucial component of dialysis adequacy. Assessment and achievement of DW is feasible on pure clinical grounds. But its relative lack of accuracy (and the physicians' progressive lack of interest in bedside examination) has led to several nonclinical methods of assessing DW in an effort to improve the assessment of fluid status in dialysis patients.

Anaemia correction in predialysis elderly patients: influence of the antihypertensive therapy on darbepoietin dose

Anaemia and hypertension are common in patients with chronic renal insufficiency. The correction of anaemia with erythropoiesis stimulating agents (ESA) can improve survival and decrease the decline of renal function. Angiotensin converting-enzyme inhibitors (ACEI) and angiotensin II receptor blockers (AIIRA) can also slow the progression of renal failure, but the blockade of the renin-angiotensin system can worsen anaemia. The aim of our study was to assess the impact of antihypertensive therapy (ACEI plus AIIRA) in the requirements of darbepoietin in a group of elderly predialysis patients. We included 71 patients (m = 39, f = 32), mean age of 76.3 years with a mean creatinine clearance of 17.5 ml/min. Patients were divided in two groups according to their antihypertensive therapy: G-I patients under ACEI or AIIRA therapy and G-II normotensive patients or hypertensive patients under antihypertensive drugs other than ACEI or AIIRA. The groups were compared regarding demographic, nutritional, biochemical and inflammatory parameters. We also compared the mean darbepoietin dose. In GI the mean dose of darbepoietin was higher than in GII (0.543 vs. 0.325 microg/kg/week, P = 0.032). We did not find any difference regarding other parameters analysed. We conclude that ACEI and AIIRA can increase the needs of darbepoietin in predialysis elderly patients. However, when formally indicated to treat hypertension in a specific patient, they should not be switched to another antihypertensive agent. Instead, in such cases, higher doses of ESA should be used, if necessary.

Angiographical severity of coronary atherosclerosis predicts death in the first year of hemodialysis

BACKGROUND

Cardiac deaths and events tend to cluster within the early-phase after starting dialysis. Our goal is to clarify the influence of severity of coronary atherosclerosis on early-phase death after starting hemodialysis (HD) therapy.

PATIENTS AND METHODS

Eighty-three consecutive patients [mean age 62 years; male/female 64/19; diabetic nephropathy in 50 (54%)] with end-stage renal disease who admitted to our hospital to initiate regular HD treatment, and then received coronary angiography within 3 months after first dialysis therapy, were eligible for this study. Angiographical severity of coronary atherosclerosis was scored by numerically using Gensini scoring system. The patients who died within one year from starting HD were compared with those who survived as control by means of logistic regression analysis.

RESULTS

Of 83 patients, 12 (14%) died less than one year after starting dialysis therapy. Of these 12 patients, nine died for cardiac causes. Confirmed predictors of death from cardiac cause were older age (>70 years), lower mean blood pressure (<100 mmHg), presence of ischemic heart disease (IHD), myocardial infarction (MI), angina pectoris (AP), chronic heart failure (CHF), poor cardiac function, abnormal wall motion of left ventricule (LV) and angiographical severity of coronary atherosclerosis by univariate model. Adjusting for confounding variables by multivariate model, only severity of coronary atherosclerosis (Gensini score >40 points) had a powerful influence, increasing risk for cardiac cause of early-phase death by about 17 times.

CONCLUSIONS

Severity of coronary atherosclerosis predicts death in the first year of HD. These findings suggest that the strategy for prevention of coronary atherosclerosis should be instituted during the early phase of chronic renal failure.

Atherosclerotic cardiovascular disease risks in chronic hemodialysis patients

BACKGROUND

Cardiovascular diseases are the most common causes of death among chronic hemodialysis patients, yet the risk factors for these events have not been well established.

METHODS

In this cross-sectional study, we examined the relationship between several traditional cardiovascular disease risk factors and the presence or history of cardiovascular events in 936 hemodialysis patients enrolled in the baseline phase of the Hemodialysis Study sponsored by the U.S. National Institutes of Health. The adjusted odds ratios for each of the selected risk factors were estimated using a multivariable logistic regression model, controlling for the remaining risk factors, clinical center, and years on dialysis.

RESULTS

Forty percent of the patients had coronary heart disease. Nineteen percent had cerebrovascular disease, and 23% had peripheral vascular disease. As expected, diabetes and smoking were strongly associated with cardiovascular diseases. Increasing age was also an important contributor, especially in the group less than 55 years and in nondiabetic patients. Black race was associated with a lower risk of cardiovascular diseases than non-blacks. Interestingly, neither serum total cholesterol nor predialysis systolic blood pressure was associated with coronary heart disease, cerebrovascular disease, or peripheral vascular disease. Further estimation of the coronary risks in our cohort using the Framingham coronary point score suggests that traditional risk factors are inadequate predictors of coronary heart disease in hemodialysis patients.

CONCLUSIONS

Some of the traditional coronary risk factors in the general population appear to be also applicable to the hemodialysis population, while other factors did not correlate with atherosclerotic cardiovascular diseases in this cross-sectional study. Nontraditional risk factors, including the uremic milieu and perhaps the hemodialysis procedure itself, are likely to be contributory. Further studies are necessary to define the cardiovascular risk factors in order to devise preventive and interventional strategies for the chronic hemodialysis population.

Cardiopulmonary events during hemodialysis: effects of dialysis membranes and dialysate buffers

Adverse cardiac and pulmonary events are frequently observed during hemodialysis and contribute to significant morbidity and mortality. The temporal relationship between these events during the intradialytic period has not been well defined. To examine the event rate and timing of silent ischemia, cardiac ectopy, and hypoxemia, we conducted a prospective, single-blind, randomized study of 10 subjects undergoing maintenance hemodialysis with four contiguous combinations of dialysis membranes (cuprammonium or polysulfone) and dialysates (acetate or bicarbonate). The frequency of oxygen desaturation events peaked during the first 2 hours, whereas silent myocardial ischemia and supraventricular ectopies occurred more often in the later hours. Ventricular ectopy occurred steadily throughout the intradialytic period. The combination of acetate dialysis and cuprammonium membrane is associated with the most frequent events. We conclude that cardiopulmonary events can occur frequently during hemodialysis, and the frequency is dependent on the type of dialysis membrane and dialysate buffer used.

Treatment of hypertension in dialysis patients by ultrafiltration: role of cardiac dilatation and time factor

We retrospectively analyzed the blood pressure (BP) and cardiothoracic index (CTi) of 67 hemodialysis patients with hypertension who could be followed up for at least 8 months. A new treatment policy was adopted, aimed at strict volume control. Dietary salt restriction was strongly emphasized. Ultrafiltration (UF) was applied during regular dialysis sessions and sometimes in additional sessions, as long as BP and CTi remained at greater than normal values. All antihypertensive drugs were discontinued at the beginning of treatment. Average BP decreased from 173 +/- 17/102 +/- 9 to 139 +/- 18/86 +/- 11 mm Hg after 6 months and to 118 +/- 12/73 +/- 6 mm Hg after 36 months. Corresponding values for CTi were 52% +/- 4%, 47% +/- 3%, and 42% +/- 4%, respectively. Conventional relatively short dialysis (three times weekly for at least 4 hours) can achieve normal BPs with prolonged effort in most patients, whereas improvement in heart condition facilitates this.

"U" curve association of blood pressure and mortality in hemodialysis patients. Medical Directors of Dialysis Clinic, Inc

BACKGROUND

Hypertension may play an important role in the pathogenesis of the excess cardiovascular and cerebrovascular (CV) morbidity observed in hemodialysis patients (HD). However, the optimal blood pressure (BP) range for HD patients has not been defined. We postulated that there is a "U" curve relationship between BP and CV mortality. To explore this hypothesis we studied 5,433 HD patients in Dialysis Clinic Inc., a large not-for-profit chain, over a five year period.

METHODS

Cox regression, with fixed and time-varying covariates, was used to assess the effect of systolic blood pressure (SBP) and diastolic blood pressure (DBP), pre- and post-dialysis, on CV mortality, while adjusting for age, gender, ethnicity, primary cause of end-stage renal disease, Kt/V, serum albumin, and antihypertensive medications.

RESULTS

The overall impact of BP on CV mortality was modest. Pre-dialysis, neither systolic nor diastolic hypertension were associated with an increase in CV mortality. Post-dialysis, SBP > or = 180 mm Hg (RR = 1.96, P < 0.015) and DBP > or = 90 mm Hg (RR = 1.73, P < 0.05) were associated with increased CV mortality. Low SBP (SBP < 110 mm Hg) was associated with increased CV mortality, pre- and post-dialysis.

CONCLUSIONS

The results suggest the presence of a "U" curve relationship between SBP post-dialysis and CV mortality in HD patients.

Systemic hypertension and its management

The pathophysiology of hypertension in dogs and cats, the methods available to monitor blood pressure, and the signs and treatment of hypertension are reviewed. Clinical signs of hypertension are usually referable to target organ damage, most notably in ophthalmic, renal, and cardiovascular tissues, which have a rich arteriolar supply. Blood pressure should be measured in any animal with renal disease, hyperthyroidism, hyperadrenocorticism, retinal detachment or hemorrhage, hyphema, or echocardiographically determined cardiac hypertrophy. All cats with acquired cardiac murmur should also be evaluated for hypertension. Antihypertensive medication should be administered if the indirect blood pressure in cats is consistently over 170/100 mmHg, or if the indirect blood pressure in dogs is greater than 180/100 mmHg.

Low diastolic blood pressure, hypoalbuminemia, and risk of death in a cohort of chronic hemodialysis patients

In a previous report, we showed that nutritional status and especially serum albumin had great predictive value for death in chronic hemodialysis patients, whereas blood pressure did not. In the present study, we analyzed the causes of death in consideration of the relationship between serum albumin and blood pressure. A total of 1,243 Okinawan patients (719 males, 524 females) undergoing hemodialysis in January 1991 were followed up through the end of 1995. Three hundred forty-two of the patients died, 45 received transplants, and 12 were transferred by the end of the follow-up period. The total duration of observation was 5,110.3 patient-years. Blood pressure as well as clinical and laboratory variables were determined immediately prior to the first dialysis session in January 1991. The crude death rate was 40.0% when the diastolic blood pressure (DBP) <70 mm Hg, 35.0% at 70 to 79 mm Hg, 25.0% at 80 to 89 mm Hg, 25.0% at 90 to 99 mm Hg, and 13.0% at >100 mm Hg. The death rate showed an inverse correlation with DBP. DBP showed a significant positive correlation with serum albumin (r = 0.137, P < 0.001) and age (r = -0.325, P < 0.0001). The adjusted odds ratio (95% confidence interval) of death was 0.84 (0.71 to 0.99) with 10 mm Hg increments in DBP when the reference DBP was less than 69 mm Hg. Low DBP may be a manifestation of malnutrition and/or cardiovascular disease in chronic hemodialysis patients. Target DBP levels may be higher levels in chronic hemodialysis patients than the general population.

Cardiovascular risk factors in chronic renal failure and hemodialysis populations

Cardiovascular disease is the leading cause of death in patients with end-stage renal disease (ESRD). Risk factors for cardiovascular disease, including hypertension, lipid abnormalities, left ventricular hypertrophy (LVH), and glucose intolerance, are present more frequently in patients with chronic renal failure than in the general population, even before the onset of replacement therapy. The prevalence, pathogenesis, and significance of these factors in the uremic population are examined, and the potential roles of intervention are reviewed. Evidence suggests, but is not conclusive, that these factors are of predictive value for cardiovascular complications in patients with chronic renal failure. The effect of modification of these factors on cardiovascular morbidity and mortality in this population, especially in the early stages of renal failure, is an important area for further study.

Is parathormone a cardiac toxin in uremia?

In uremia, parathormone (PTH) has been associated with inadequate left ventricular hypertrophy, cardiomyopathy, and mitral anular calcification (MAC). We related levels of serum PTH, calcium, phosphate, magnesium, calcium-phosphate product, and systolic blood pressure to average left ventricular wall thickness, left ventricular mass index, ejection fraction, and presence and extent of MAC by echocardiography in 44 patients before and after renal transplantation. Pre-transplant, 18 patients (41%) had MAC; these and the 26 others had similar values for serum PTH, calcium-phosphate product, systolic blood pressure, age, and years of hemodialysis. The patients with PTH levels greater than 1000 mcl eq/ml had higher systolic blood pressures pre-transplant (157 +/- 21 vs 147 +/- 17 mm Hg, p less than 0.05), but not post-transplant as PTH levels normalized. Post-transplant, there were significant decreases in left ventricular mass index (140 +/- 35 to 103 +/- 25 g/m2) and average diastolic left ventricular wall thickness (1.4 +/- 0.2 to 1.2 +/- 0.2 cm, both p less than 0.05); however, ejection fraction and extent of MAC did not change. Left ventricular mass index, average diastolic left ventricular wall thickness, and ejection fraction did not correlate with serum PTH or electrolyte levels before or after renal transplantation. MAC is present in more than one third of uremic pts and does not resolve after renal transplantation. Although PTH does not correlate with left ventricular hypertrophy, cardiac function, or MAC before or after transplantation, elevated levels pre-transplant are associated with a slightly greater degree of hypertension. Thus PTH may be a mild vasoactive pressor in some patients with end-stage renal failure.

Erythrocyte Na,K pump activity and arterial hypertension in uremic dialyzed patients

We have evaluated in 26 uremic patients [21 on hemodialysis, 5 on continuous ambulatory peritoneal dialysis (CAPD)], 11 normotensive, and 15 hypertensive (MAP greater than 110 mm Hg) patients the following properties: a) erythrocyte (RBC) Na concentration [Nai] and ouabain-sensitive and -resistant Na effluxes; b) the effect of uremic sera on ouabain-sensitive Na efflux in normal RBC; c) serum digoxin-like immunoreactivity; d) cardiac index and total peripheral resistance. In 19 healthy subjects a) and c) were also evaluated. RBC Na,K pump activity was lower in uremic patients than in normal subjects (P less than 0.0005), and lower in hypertensive (P less than 0.02) than in normotensive patients. Serum from uremic patients inhibited ouabain-sensitive Na efflux in normal RBC, the inhibition being correlated with both the rate constant for ouabain-sensitive Na efflux (r = -0.67; P less than 0.005) and [Nai] (r = 0.43; P less than 0.05) of RBC of patients from whom the serum was obtained. Inhibition of ouabain-sensitive Na efflux was significantly higher with serum from hypertensive than from normotensive patients (P less than 0.05). Serum digoxin-like immunoreactivity was present in all uremic patients (0.402 +/- 0.054 ng/ml in normotensive and 0.428 +/- 0.040 ng/ml in hypertensive, P = ns), while it was not detectable in normal subjects. Hypertensive patients had peripheral resistance significantly higher than normotensive (P less than 0.05), while cardiac index was similar in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac consequences of renal transplantation: changes in left ventricular morphology and function

To characterize changes in left ventricular morphology and function associated with renal transplantation, noninvasive cardiac evaluations were performed in 41 adults at the time of surgery and at follow-up. At the time of transplantation, 36 patients had undergone hemodialysis through a fistula for 2.3 +/- 2.5 years (mean +/- SD); their hematocrit level was 26 +/- 6% and systolic blood pressure was 151 +/- 19 mm Hg. Perioperatively, left ventricular hypertrophy was present in 93% of patients by echocardiography, but in only 37% by electrocardiography. Abnormal left ventricular diastolic function was present in 67% of patients and indicated a high risk for perioperative pulmonary edema. At follow-up (1.5 +/- 1.4 years), mean hematocrit level increased to 39 +/- 7%, systolic blood pressure decreased to 132 +/- 14 mm Hg and spontaneous closure of the fistula occurred in 13 patients. Left ventricular mass by echocardiography decreased from 237 +/- 66 to 182 +/- 47 g (p less than 0.001), a decrease of 23%. Left ventricular volumes and cardiac index also decreased significantly, reflecting the rapid resolution of a pretransplant high output state. Despite proportionate regression of left ventricular hypertrophy within months of transplantation, diastolic function did not improve. The significant regression of left ventricular hypertrophy that occurs after renal transplantation may help explain the improved cardiovascular survival of patients with a renal transplant over that of patients on long-term dialysis.

Immunohistochemical localization of renin in end-stage kidneys

Hypertension in chronic renal failure is usually due to excessive accumulation of salt and water. In some cases, sodium and volume depletion by dialysis fail to reduce the high BP, and plasma renin activity tends to be higher. We performed a semiquantitative analysis of the immunohistochemical distribution of renin in the kidneys of ten patients with end-stage renal disease and hypertension using a specific antihuman renin antibody and a peroxidase-antiperoxidase technique on paraffin sections of nephrectomy and/or autopsy specimens. In five cases with severe, dialysis-resistant hypertension, the degree of immunoreactivity was most striking, exceeding that found in renovascular hypertension and present in arterioles at a distance from the glomeruli. Three cases of advanced diabetic glomerulosclerosis consistently showed minimal immunoreactivity. We conclude that renin often can be detected immunologically in the kidney of patients with chronic renal failure and hypertension, but its pathophysiological role will require further study.

Captopril slows the progression of chronic renal disease in partially nephrectomized rats

The effect of captopril, an angiotensin-converting enzyme inhibitor, on the progression of chronic renal disease was studied in rats subjected to partial nephrectomy. Following ablation of approximately 70% of their renal mass, rats were divided into three treatment groups: group I received a placebo treatment; group II received daily po administrations of captopril; group III received captopril at the same dosage schedule as group II, but the drug was not given for 4 weeks in the middle of the treatment period. Measurements of renal function were performed at 4-week intervals, and light microscopic evaluation of the remnant kidneys was performed following 19 weeks of treatment. Deterioration of renal function, as measured by endogenous creatinine clearance, plasma creatinine, and plasma urea nitrogen, progressed more rapidly in group I than the other two groups. Twenty-four-hour urinary protein excretion was higher in group I than the others, except in group III following the 4-week period when captopril was not administered. Morphologic damage in the remnant kidney was significantly greater in group I than group II (p = 0.007). The renal lesions in the rats of group III were intermediate in severity. Histopathologic ranking of the remnant kidneys was correlated with antemortem laboratory parameters (r greater than or equal to 0.50; p less than 0.05). In a second experiment, similarly nephrectomized rats receiving po captopril daily had significantly longer survival, at 260 days, postnephrectomy than rats receiving a placebo (p = 0.0045). We conclude that captopril retards the progression of renal damage and increases survival time in this model of chronic renal disease. The mechanism may involve the alteration of potentially harmful intraglomerular hemodynamic changes which occur in the remnant kidney model.