Intervention in patients with renovascular hypertension and renal insufficiency

We report on 21 severely hypertensive patients with renal artery stenosis and renal insufficiency in whom percutaneous transluminal angioplasty and/or renal artery surgery was done in an effort to lower blood pressure and to preserve renal function. Of 12 patients who underwent angioplasty renal function and blood pressure improved in 3. Of the 9 patients without improvement 4 suffered permanent oliguric renal failure. An operation was performed in 12 patients, 4 after having failed angioplasty (1 was treated at another institution before referral for surgery). Two patients died postoperatively but 10 improved, with followup in 6 exceeding 3 years. This retrospective experience suggests that percutaneous transluminal angioplasty is not likely to supplant an operation in the treatment of patients with atherosclerotic renovascular hypertension and renal insufficiency.     

Reproductive function in patients with renal insufficiency

Hypogonadism is prevalent in patients with renal insufficiency and is manifested as sexual dysfunction and infertility in males and as anovulation and amenorrhea in females. Although many investigators believe that the defect represents primary gonadal damage by uremic toxins, we propose the coexistence of central neuroendocrine disorders in the regulation of gonadotropin secretion. Evidence supporting such a hypothesis is discussed.     

Beneficial effect of aspirin on renal function in patients with renal insufficiency postcardiac surgery

AIM: Renal function is one of the most important prognostic factors following cardiac surgery. Whether aspirin affects cardiopulmonary bypass related renal injury is investigated in this study. METHODS: Ninety-four patients with impaired renal function (creatinine = or >1.5 mg/dl) undergoing coronary artery bypass grafting (CABG) were categorized into 2 groups according to aspirin administration before surgery. Serum creatinine, urinary output and creatinine clearance along with other perioperative factors were compared between the 2 groups prior to surgery, 24 hours and 48 hours following cardiopulmonary bypass. RESULTS: Creatinine levels increased significantly in the second postoperative day only in the non-aspirin (control) group (3.7+/-1.6 vs 2.9+/-1.7 mg/dl, p=0.03). Aspirin (study) group had lower creatinine levels in day 1 (p=0.03) and day 2 (p=0.001). Furthermore, in the study group creatinine clearance was higher in day 1 (34.3+/-14.3 vs 30.9+/-13.1 ml/min, p=0.01) and in day 2 (32.6+/-13.8 vs 26.4+/-9.8 ml, p<0.0001). Creatinine levels at discharge were elevated compared to the preoperative levels in the control group (p=0.01). However, the study group had lower creatinine levels at discharge (2.6+/-1.4 vs 3.8+/-1.6 mg/dl, p<0.0001). Urinary output was higher in the study group in the first postoperative day compared to the control group (p=0.01). Postoperative bleeding was slightly increased in the study group compared to the control group (760+/-230 ml vs 530+/-210 ml, p=0.01). CONCLUSIONS: Continuation of aspirin administration until the day of surgery may have a protective effect against renal injury resulting from cardiopulmonary bypass, with only a negligible increase in bleeding. Possible explanations for this effect are antiplatelet activity of aspirin during cardiopulmonary bypass causing inhibition of vasoconstrictive agents like thromboxane, and improvement of renal perfusion by reducing blood viscosity.     

Plasma and urinary catecholamines as related to renal function in man

To assess the relationship between renal plasma flow (ERPF) or glomerular filtration rate (GFR) and the levels of norepinephrine (NE) or epinephrine (E) in plasma or urine in the presence of progressive degrees of non-oliguric renal functional impairment, these variables were assessed simultaneously in 18 normal subjects, 72 with parenchymal kidney disease and 14 with essential hypertension. ERPF and GFR were lower (P less than 0.01 to 0.001) in the groups with renal disease (mean +/- SD, 340 +/- 230 and 68 +/- 43 ml/min/1.73 m2, respectively) or essential hypertension (434 +/- 101 and 97 +/- 25 ml/min/1.73 m2) than normal subjects (597 +/- 133 and 118 +/- 14 ml/min/1.73 m2). Plasma and urinary NE and E did not differ significantly among groups and were unrelated with ERPF or GFR (range 4 to 160 ml/min/1.73 m2), except for reduced (P less than 0.001) urinary NE and E excretion in the presence of a GFR less than 20 ml/min. Subgroups with renal disease and a normal (N = 39) or high blood pressure (N = 33) also were comparable in their plasma and urinary NE and E, while ERPF and GFR tended to be lower in hypertensive patients. It is concluded that a chronic reduction in excretory kidney function may have no relevant impact on circulating levels of NE and E per se, although their urinary excretion falls distinctly at the stage of advanced renal failure. These aspects deserve consideration when pathogenetic or diagnostic studies of catecholamines are performed in normotensive or hypertensive patients with impaired kidney function.     

Treatment of arterial hypertension with nifedipine in patients with chronic renal insufficiency

The acute and chronic antihypertensive effects of nifedipine were investigated in patients with chronic renal insufficiency (CRI). The acute effects were assessed after the administration either of a fast-release nifedipine capsule or a slow-release nifedipine tablet in 10 and 15 patients respectively. Both the preparations induced prompt and marked reduction of systolic and of diastolic blood pressure, but the capsules showed a shorter antihypertensive effect (2 hours) than tablets (more than 6 hours). The chronic effects of nifedipine tablets given in addition to the previous therapy was assessed in 25 patients with CRI and resistant hypertension. Both systolic and diastolic blood pressure values promptly fell and maintained within the normal range over the whole period of the study (12 months).     

Tonicity of autonomic nervous system in patients with complicated gastroduodenal ulcer

Investigation of autonomic nervous system tonicity has been undertaken in 34 healthy persons (control group I), in 30 patients with non-complicated duodenal ulcer (control group 2), 38 patients with complicated gastroduodenal ulcer (10--with perforation, 13--with bleeding, 15--with stenosis) and 32 patients in the long-term period. The patients age was from 17 to 75 years. 72 patients were males and 28--females. Results of the study showed, that among the patients with complicated gastroduodenal ulcer there were eutonics and sympathicotonics, among those with non-complicated ulcer disease sympathotonics prevailed. To predict occurrence of complicated ulcer, determination of the tone of vegetative nervous system in patients with non-complicated ulcer in period between attacks is recommended. Identification of phenotype characteristics of vegetative nervous system tone allows to predict development of possible postoperative complications in patients with gastroduodenal ulcer.     

Cardiac baroreflex during the postoperative period in patients with hypertension: effect of clonidine

BACKGROUND: Patients with essential hypertension show altered baroreflex control of heart rate, and during the perioperative period they demonstrate increased circulatory instability. Clonidine has been shown to reduce perioperative circulatory instability. This study documents changes in measures of heart rate control after surgery in patients with essential hypertension and determines the effects of clonidine on postoperative heart rate control in these patients. METHODS: Using a randomized double-blind placebo-controlled design, 20 patients with essential hypertension (systolic pressure >160 mm Hg or diastolic pressure >95 mm Hg for > or =1 yr) were assigned to receive clonidine (or placebo), 6 microg/kg orally 120 min before anesthesia and 3 microg/kg intravenously over 60 min before the end of surgery. The spontaneous baroreflex ("sequence") technique and analysis of heart rate variability were used to quantify control of heart rate at baseline, before induction of anesthesia, and 1 and 3 h postoperatively. RESULTS: Baroreflex slope and heart rate variability were reduced postoperatively in patients given placebo but not those given clonidine. Clonidine resulted in greater postoperative baroreflex slope and power at all frequency ranges compared with placebo (4.9+/-2.9 vs. 2.2+/-2.1 ms/mm Hg for baroreflex slope, 354+/-685 vs. 30+/-37 ms2/Hz for high frequency variability). Clonidine also resulted in lower concentrations of catecholamine, decreased mean heart rate and blood pressure, and decreased perioperative tachycardia and hypertension. CONCLUSIONS: Patients with hypertension exhibit reduced heart rate control during the recovery period after elective surgery. Clonidine prevents this reduction in heart rate control. This may represent a basis for the improved circulatory stability seen with perioperative administration of clonidine.     

Localization of autonomic nervous system dysfunction in dialysis patients

Autonomic nervous system dysfunction has been described frequently in uremic patients. The purpose of this study is to determine the localization of this abnormality and to study the possible relationship between autonomic dysfunction and the occurrence of dialysis hypotension. Sixteen consecutive patients participated in the study, 5 of whom had a history of dialysis-induced hypotension. These 5 patients were compared to the other 11 as regards the cardiovascular response to isoproterenol infusion, tilt test and arteriovenous (AV) fistula occlusion. None of the responses to the above mentioned stimuli was significantly different between the 2 groups. In the whole study population, an index of parasympathetic control of heart rate (variation of heart period, VHP) was reduced (31 +/- 5 vs. 59 +/- 9 ms in age-matched controls; p less than 0.025). Heart rate and diastolic blood pressure response to isoproterenol infusion was normal (+23 +/- 2 beats/min and -9 +/- 3 mm Hg; p less than 0.005 for both), indicating normal response of effector organs to beta-adrenergic agonist stimulation. Similarly, plasma norepinephrine increased significantly (+294 +/- 51 pg/ml; p = NS from normal laboratory values) in response to head-up tilt, and heart rate increased simultaneously in all but 5 patients. Blood pressure response was within normal after 10 min of head-up tilt at 60 degrees in all but 3 patients; only 1 of these 3 patients was in the group of dialysis hypotension. However, during AV fistula occlusion, heart rate did not change markedly, despite the significant increase in systolic blood pressure, suggesting an altered sensitivity of baroreceptor reflex arc.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of diuretics on systemic and renal hemodynamics in patients with renal insufficiency

Diuretics have been used in acute renal failure in an attempt to increase urine flow and ameliorate the reduction in glomerular filtrate rate. A beneficial response occurs in some experimental models of acute renal failure when diuretics are administered prophylactically or very early in the course of renal failure and may require a renal vascular bed capable of responding partially, at least, to vasodilating stimuli. In chronic renal insufficiency the most important indications for diuretic use are for the treatment of systemic hypertension and for the correction of the congested state. However, the precise effect of diuretic therapy under these conditions is unpredictable and dependent on the functional state of the renal vessels. Diuretic administration may at times prove detrimental, resulting in a deterioration of glomerular filtration rate. In hemodynamically unstable conditions the slow removal of extracellular fluid by continuous arteriovenous hemofiltration may prove preferable to diuretic administration or standard forms of dialysis.     

The role of renal catecholamines in hypertension

We have found increased renal alpha 2-adrenoceptor density and a defect in prostaglandin and parathyroid stimulated adenylate cyclase in two genetic forms of rat hypertension. Changes in serum calcium and parathyroid hormone (PTH) levels suggest biologic significance to this defective adenylate cyclase response. Our hypothesis is that one or more of these defects contribute to excess renal retention of sodium and increase vascular resistance of genetically hypertensive rats and humans with essential hypertension who have similar abnormalities of calcium and PTH.     

Gastric secretory function in patients with chronic renal insufficiency and gastroduodenal hemorrhage

Gastric hypersecretion occurrence in patients, suffering chronic renal insufficiency (CHRI), creates conditions for acido-peptic gastroduodenal zone affection with possible formation of erosive-ulcerative defects, complicated by hemorrhage. In 116 patients, suffering CHRI, the state of gastric mucosa secretory function was studied up. In patients with an acute gastrointestinal hemorrhage and CHRI in conservative and terminal stages the analysis of acidity was conducted.     

QT dispersion and autonomic function in diabetic and non-diabetic patients with renal failure

We have studied 13 patients with diabetic nephropathy and 13patients with uraemia of other origin undergoing renal transplantation,and 12 control patients undergoing general surgery. QTc dispersionand maximum QTc interval were calculated from the 12-lead ECG,and cardiovascular autonomic function tests were performed.QTc dispersion was significantly greater in diabetic (mean 100(SD 37) ms) and non-diabetic (51 (17) ms) uraemic patients thanin control patients (29 (10) ms), and it differentiated thegroups better than maximum QTc. In diabetic patients, severeautonomic neuropathy was common. In other uraemic patients lesssevere disturbances in autonomic function were found. In diabeticuraemic patients, increased QTc dispersion and severe autonomicneuropathy may indicate high risk for cardiac arrhythmias. Inour opinion, QTc dispersion and autonomic function tests maygive valuable information on perioperative risks.