Dilated cardiomyopathy in dialysis patients--beneficial effects of carvedilol: a double-blind, placebo-controlled trial

OBJECTIVES

The aim of this study was to investigate in dialysis patients with symptomatic heart failure New York Heart Association (NYHA) functional class II or III whether the addition of carvedilol to conventional therapy is associated with beneficial effects on cardiac architecture, function and clinical status.

BACKGROUND

Congestive heart failure (CHF) in chronic hemodialyzed patients, particularly when associated with dilated cardiomyopathy, represents an ominous complication and is an independent risk factor for cardiac mortality.

METHODS

We enrolled 114 dialysis patients with dilated cardiomyopathy. All patients were treated with carvedilol for 12 months in a double-blind, placebo-controlled, randomized trial. The patients underwent M-mode and two-dimensional echocardiography at baseline, 1, 6 and 12 months after the randomization. Each patient's clinical status was assessed using an NYHA functional classification that was determined after 6 and 12 months of treatment.

RESULTS

Carvedilol treatment improved left ventricular (LV) function. In the active-treatment group, the increase in LV ejection fraction (from 26.3% to 34.8%, p < 0.05 vs. basal and placebo group) and the reduction of both LV end-diastolic volume (from 100 ml/m2 to 94 ml/m2, p < 0.05 vs. basal and placebo group) and end-systolic volume (from 74 ml/m2 to 62 ml/m2, p < 0.05 vs. basal and placebo group) reached statistical significance after six months of therapy, compared with baseline and corresponding placebo values, and they remained constant at one year of treatment (p < 0.05 vs. basal and placebo group). The clinical status of patients, assessed by NYHA functional classification, improved during the treatment period. Moreover, at the end of the trial, there were no patients in NYHA functional class IV in the carvedilol group, compared with 5.9% of the patients in the placebo arm.

CONCLUSIONS

One year of therapy with carvedilol in dialysis patients with CHF and dilated cardiomyopathy reduces LV volumes and improves LV function and clinical status.

Insulin, renin-aldosterone system and blood pressure in obese people

OBJECTIVE

To evaluate the relationship between insulin, the renin-aldosterone system and blood pressure in obese subjects.

DESIGN AND METHODS

A cross sectional study of a group of severely obese normotensive subjects who were surgical candidates (n=39; mean BMI: 47.8+/-1.4) and a group of hypertensive patients (n=57; mean BMI: 28.0+/-0.7) twenty-nine of whom had BMI>27. All subjects were studied after 15 days on a balanced diet. Insulin, plasma renin activity and aldosterone were measured.

RESULTS

Fasting insulin, plasma renin activity and aldosterone were higher in severely obese normotensive subjects than in hypertensive subjects (respectively 32.3+/-3.0 vs 13.1+/-1.0 mU/l, P=0.0001; 1.34+/-0.22 vs 0.88+/-0.12 ng/ml/h, P=0.04; 137.2+/-16.2 vs 87.9+/-12.1 pg/ml, P=0.015). Insulin was related to BMI and to aldosterone both in normotensive and in hypertensive patients.

CONCLUSION

Hyperinsulinemia itself does not determine hypertension; in some people it could play a vasodilator role in opposition to the renin-aldosterone system.

Helicobacter pylori eradication can induce platelet recovery in idiopathic thrombocytopenic purpura

Recent reports have suggested an association between Helicobacter pylori infection and idiopathic thrombocytopenic purpura (ITP). The prevalence of H pylori infection and the effect of its eradication in a series of 30 ITP patients were investigated. H pylori infection has been documented in 13 patients (43.33%) by 13C urea breath test and confirmed by histologic examination. Bacterium eradication with antibiotics, obtained in 12 of 13 infected patients (92.3%), led to a complete response in 4 (33.33%) and to a partial response (platelets 90 x 10(9)/L-120 x 10(9)/L) in 2 (16.66%). The response was maintained for a median of 8.33 months, but 1 patient relapsed 7 months after eradication. Search for H pylori infection seems appropriate in ITP patients at diagnosis. Bacterium eradication provides a new good option for a nonimmunosuppressive treatment in some ITP patients.

Cloning, post-translational modifications, heterologous expression and ligand-binding of boar salivary lipocalin

Boar submaxillary glands produce the sex-specific salivary lipocalin (SAL), which binds steroidal sex pheromones as endogenous ligands. The cDNA encoding SAL was cloned and sequenced. From a single individual, two protein isoforms, differing in three amino acid residues, were purified and structurally characterized by a combined Edman degradation/MS approach. These experiments ascertained that the mature polypeptide is composed of 168 amino acid residues, that one of the three putative glycosylation sites is post-translationally modified and the structure of the bound glycosidic moieties. Two of the cysteine residues are paired together in a disulphide bridge, whereas the remaining two occur as free thiols. SAL bears sequence similarity to other lipocalins; on this basis, a three-dimensional model of the protein has been built. A SAL isoform was expressed in Escherichia coli in good yields. Protein chemistry and CD experiments verified that the recombinant product shows the same redox state at the cysteine residues and that the same conformation is observed as in the natural protein, thus suggesting similar folding. Binding experiments on natural and recombinant SAL were performed with the fluorescent probe 1-aminoanthracene, which was efficiently displaced by the steroidal sex pheromone, as well as by several odorants.

Comparative FISH-mapping of the prion protein gene (PRNP) on cattle, river buffalo, sheep and goat chromosomes

Comparative FISH-mapping of the prion protein gene (PRNP) was performed on cattle (BTA), river buffalo (BBU), sheep (OAR) and goat (CHI) chromosomes using a PCR-product as a probe and R-banding. PRNP was mapped to BTA13q17, BBU14q15, OAR13q15 and CHI13q15 according to standard nomenclatures. These chromosomes and bands were homoeologous among the four species, confirming the high degree of gene and chromosome banding conservation among bovids. Furthermore, the assignment of PRNP to river buffalo and goat chromosomes allowed us to indirectly assign the bovine syntenic group U11 to specific chromosomes, since it is the first in situ localization on BBU14 and CHI13.

Antibacterial and allelopathic activity of extract from Castanea sativa leaves

Following the extraction of Castanea sativa with an aqueous solution of sulfuric acid (pH 3.0), the ethyl acetate soluble fraction was tested for its antibacterial and allelopathic activity. The extract was shown to have pronounced antibacterial effects against seven of the eight strains of Gram-positive and Gram-negative bacteria used (MIC in the range of 64-256 microg/ml and MBC in the range of 256-512 microg/ml). The active fraction was analyzed by TLC and HPLC showing the presence of rutin, hesperidin, quercetin, apigenin, morin, naringin, galangin and kaempferol. Standards of the identified flavonoids were tested against the same bacterial strains. The highest activity was shown by quercetin, rutin and apigenin. The allelopathic effect was tested against Raphanus sativus seed germination. The extract, quercetin, rutin and apigenin caused a decrease in the percentage of seed germination and root and epicotyl growth.

Efficacy of carvedilol on complex ventricular arrhythmias in dilated cardiomyopathy: double-blind, randomized, placebo-controlled study

AIMS

The aim of the present study was to investigate whether the addition of carvedilol to conventional therapy in dilated cardiomyopathy patients is associated with further benefits in the treatment of complex non-sustained ventricular arrhythmias (Lown class III, IV or V).

METHODS AND RESULTS

We recruited 168 patients with ischaemic or idiopathic dilated cardiomyopathy, with complex ventricular arrhythmias. Patients able to tolerate low doses of carvedilol were randomized to treatment with carvedilol or placebo for 6 months. Carvedilol treatment improved ventricular function and reduced the incidence of arrhythmic episodes. Notably, by the end of the first month of treatment, the antiarrhythmic efficacy of the drug was significantly greater in patients with ischaemic than in those with idiopathic dilated cardiomyopathy, an effect that could probably be attributed to the anti-ischaemic properties of carvedilol. After 3 months, at a time when ejection fraction was significantly improved in all treated patients, the antiarrhythmic efficacy of carvedilol was similar in the two study groups.

CONCLUSIONS

Carvedilol antiarrhythmic efficacy was paralleled by the improvement in ejection fraction, independent of the aetiology of heart failure. The possibility of adding to an already 'optimized' conventional therapy a drug able to reduce the incidence of complex non-sustained ventricular arrhythmias is a therapeutic option that should be considered in the treatment of these patients.

Ventricular tachyarrhythmias following coronary surgery: predisposing factors

The perioperative factors potentially associated with post-coronary artery bypass grafting (CABG) ventricular tachyarrhythmias (VT) onset have not been deeply investigated. Monomorphic or polymorphic ventricular tachycardia and ventricular fibrillation represent the most dreadful arrhythmic events that can complicate the postoperative course of CABG. As a consequence, the aim of our paper was to identify which perioperative variables might predict post-CABG VT occurrence. One hundred and fifty-two consecutive patients who underwent CABG surgery at our Institution were included in the study. Post-CABG VT occurred in 13 out of 152 patients (8.5%, six cases of monomorphic ventricular tachycardia and seven cases of ventricular fibrillation). At univariate analysis, VT patients were significantly younger (54.8+/-6.6 vs. 60.1+/-8.8, P=0.038), exhibited a more severe coronary artery disease (CAD) (number of diseased vessels 2.92+/-0.3 vs. 2.45+/-0.7, P=0.023, and percentage of patients with three-vessel CAD 91.7% vs. 57.3%, P=0.043) and received a greater number of CABGs than those remaining in sinus rhythm (SR) (percentage of patients receiving three or more CABGs 76. 9% vs. 38.8%, P1000 76.9% vs. 38%, Pnormal range 72.7% vs. 30.7%, P=0.014), electrolyte derangement (84.6% vs. 45.6%, P=0.017) and a severe haemodynamic impairment (need for IABP 23% vs. 2.9%, P1000, postoperative electrolyte imbalance, the need for three or more CABGs and of IABP all were independent correlates for VT. In conclusion, post-CABG VT seem to be related to the preexistence of a severe underlying coronary artery disease along with perioperative triggering factors such as acute ischemia, electrolytic disorders and a sudden haemodynamic impairment.

Perioperative correlates of malignant ventricular tachyarrhythmias complicating coronary surgery

Sustained ventricular tachyarrhythmias (VT), such as monomorphic or polymorphic ventricular tachycardia, and ventricular fibrillation, represent the most serious arrhythmic events that can complicate the postoperative course of coronary artery bypass grafting (CABG). The perioperative factors potentially associated with post-CABG sustained VT onset have not been thoroughly investigated. As a consequence, the aim of our study was to identify which perioperative variables might predict post-CABG VT occurrence. One hundred and fifty-two consecutive patients who underwent CABG surgery at our Institute were included in the study. Post-CABG VT occurred in 13 out of 152 patients (8.5%, six cases of monomorphic ventricular tachycardia and seven cases of ventricular fibrillation). Univariate analysis revealed that VT patients were significantly younger (54.8 +/- 6.6 vs 60.1 +/- 8.8, P = 0.038), exhibited more severe coronary artery disease (CAD) (no. of diseased vessels, 2.92 +/- 0.3 vs 2.45 +/- 0.7, P = 0.023; and percentage of patients with three-vessel CAD, 91.7 vs 57.3%, P = 0.043), and received a greater number of CABGs than those remaining in sinus rhythm (SR) (percentage of patients receiving three or more CABGs, 76.9 vs 38.8%, P = 0.018) Moreover, VT patients more frequently developed intra- or postoperative myocardial infarction (total CK > 1,000, 76.9 vs 38%, P = 0.016; and MB-CK > normal range, 72.7 vs 30.7%, P = 0.014), electrolyte derangement (84.6 vs 45.6%, P = 0.017), and a severe hemodynamic impairment (need for intra-aortic balloon pump (IABP), 23 vs 2.9%, P = 0.009). On multivariate analysis, total CK > 1,000, postoperative electrolyte imbalance, the need for three or more CABGs, and for IABP all were independent correlates for VT. In conclusion, post-CABG VT seem to be related to the preexistence of a severe underlying coronary artery disease along with perioperative triggering factors, such as acute ischemia, electrolytic disorders, and sudden hemodynamic impairment.

Sister chromatid exchange in chromosomes of sheep (Ovis aries)

Blood lymphocyte cultures from 32 Comisana and Laticauda sheep breeds (15 males and 17 females) raised in Southern Italy were studied using sister chromatid exchange (SCE) test. Of the 932 cells studied, the SCE-mean value was 7.20 +/- 2.5 per cell for both breeds. Indeed, the SCE mean values were 7.12 +/- 2.45 and 7.28 +/- 2.55 in Comisana and Laticauda breeds, respectively, and the differences were not significant. No statistical differences were noticed between male and female cells (7.25 +/- 2.39 and 7.16 +/- 2.60, respectively). The SCE frequency distribution did not follow a Poisson distribution. The number of SCE were significantly higher than expected in chromosomes 1, 2 and 3 (p < 0.001) and significantly lower than expected in the X and remaining chromosomes (p < 0.001) on the basis of relative chromosome lengths.

Bone mineral density and body composition in underweight and normal elderly subjects

The importance of malnutrition as a risk factor in osteoporosis is emphasized by the evidence that patients with fractures of the proximal femur are often undernourished. In this study, nutritional status, bone mineral mass and its association with body composition were investigated in underweight and normal weight elderly subjects. Moreover the hypothesis that malnutrition in elderly is associated with a higher risk of osteoporosis was tested. The participants were 111 elderly subjects divided into two groups according to body mass index (BMI): 51 patients were underweight (BMI < 22 kg/m2) while in 60 subjects BMI ranged from 22 to 30 kg/m2. In all patients anthropometric parameters and blood indices of malnutrition and of bone turnover were measured. Fat-free soft mass (FFSM), fat mass (FM), bone mineral content (BMC) and bone mineral density (BMD) 'total body' and at the hip were obtained by dual-energy X-ray densitometry. Dietary intake was evaluated with the diet history method, while resting energy expenditure (REE) was measured by indirect calorimetry. Underweight subjects had other signs of malnutrition, such as low visceral proteins, sarcopenia, and an inadequate energy intake. Moreover they showed a significant reduction of BMC and BMD compared with normal subjects. In men with BMI <22 kg/m2, T-score was below -2.5 (-3 at femoral neck and -2.7 at total hip) while men in the control group had normal bone mineral parameters. T-score at different sites was lower in underweight women than in underweight men, always showing values under -3.5, with clear osteoporosis and a high fracture risk. In healthy women the T-score values indicated the presence of mild osteoporosis. In underweight subjects, low levels of albumin (< 35 g/l) were associated with higher femoral bone loss. Using a partial correlation model, BMC, adjusted for age, bone area, knee height and albumin showed a significant association with FM in women (r = 0.48; p < 0.01) and with FFSM in men (r = 0.48; p < 0.05). Albumin, when adjusted for other variables, was significantly correlated (r = 0.52; p < 0.05) with femoral neck BMC only in women. In conclusion, the underweight state in the elderly is associated with malnutrition and osteoporosis; other factors occurring in malnutrition, besides body composition changes, such as protein deficiency, could be involved in the association between underweight and osteoporosis. Moreover bone mineral status seems to be related to fat-free soft mass tissue in men while in women it is much more closely associated with total body fat.

[Angiotensin-II receptor inhibitors in hemodialysed uremia patients with arterial hypertension: candesartan cilexitil versus losartan]

BACKGROUND

The aim of this study was to evaluate, in patients with chronic renal failure in hemodialysis and arterial hypertension, the effectiveness of a new angiotensin II receptor antagonist, the candesartan cilexitil, comparing it with losartan, the first of this new class of drugs.

METHODS

We have selected 128 patients with chronic renal failure (92 males and 36 females, mean age 56 +/- 6 years) and arterial hypertension, subjected to hemodialysis 3 times a week, with hemodialytic seniority of 90 +/- 10 months. The inclusion criteria in the study were given from the presence, after 15 days of pharmacological wash-out, of values of diastolic blood pressure (DBP) > or = 95 mmHg and systolic blood pressure (SBP) > or = 150 mmHg, despite a hemodialysis correctly performed. Patients were divided into two groups whether they received single blind randomized candesartan cilexitil 16 mg or losartan 50 mg at hour 8.00 for a period of 8 weeks at the end of which, after a period of pharmacological wash-out of 15 days, the drugs were administered to inverted groups for other 8 weeks. After 4 and 8 weeks of treatment an evaluation of the anti-hypertensive effectiveness by means of medical complete visit and measurement of blood pressure were made. The statistical analysis was made by means of Student's t test for paired data.

RESULTS

All the patients concluded the study. After 4 weeks of treatment SBP and DBP were reduced in the group with candesartan cilexitil with regard to baseline values (SBP 151.8 +/- 6.3 vs 159.8 +/- 5.1 mmHg, p < 0.05; DBP 93.6 +/- 4.5 vs 98.1 +/- 3.7 mmHg, p < 0.05). In the losartan group (SBP 151.8 +/- 6.3 vs 158.7 +/- 5.5 mmHg, p < 0.05; DBP 93.6 +/- 4.5 vs 97.5 +/- 3.8 mmHg, p < 0.05) no significant reduction in blood pressure values was observed compared with baseline values (SBP 158.7 +/- 5.5 vs 159.8 +/- 5.1 mmHg, NS; DBP 97.5 +/- 3.8 vs 98.1 +/- 3.7 mmHg, NS). After 8 weeks of treatment in the candesartan cilexitil group (SBP 128.3 +/- 5.9 vs 159.8 +/- 5.1 mmHg, p < 0.05; DBP 81.5 +/- 4.1 vs 98.1 +/- 3.7 mmHg, p < 0.05) and in the losartan group (SBP 151.7 +/- 5.1 vs 159.8 +/- 5.1 mmHg, p < 0.05; DBP 92.7 +/- 3.9 vs 98.1 +/- 3.7 mmHg, p < 0.05) blood pressure values were reduced in the same manner as at baseline. By comparing the two drugs, candesartan cilexitil proved to have a better antihypertensive effectiveness (SBP 128.3 +/- 5.9 vs 151.7 +/- 5.1 mmHg, p < 0.05; DBP 81.5 +/- 4.1 vs 92.7 +/- 3.9 mmHg, p < 0.05).

CONCLUSIONS

Our experience suggests that angiotensin II receptor antagonists may be a therapeutic remarkable option in patients with chronic renal failure in hemodialysis and arterial hypertension; the antihypertensive effect seems to be class-specific. Nevertheless, at least for our data, a better and more rapid antihypertensive results was obtained with candesartan cilexitil.

The diagnostic value of motor evoked potentials

OBJECTIVE

To assess the diagnostic usefulness of motor evoked potentials (MEPs) and to identify the optimal method for calculating the central conduction time. The test results were evaluated in a prospective study of 1023 neurological patients.

METHODS

We evaluated the correlation between clinical and electrophysiological findings, the accuracy, the sensitivity, the percentage of subclinical abnormalities and the false negative rates of MEPs in different neurological disorders. In patients with lower motor neuron involvement, we compared the central conduction time calculated as the difference between the latency of the cortical and magnetic root stimulation responses with that calculated using the F-wave method.

RESULTS

The agreement index between electrophysiological and clinical findings was 87%. The overall accuracy of the test was 0.97. The higher sensitivity values were demonstrated in spinal cord disorders (0.85), hereditary spastic paraplegia (0.80) and motor neuron diseases (0.74). The higher percentages of subclinical abnormalities were found in motor neuron disorders (26%) muscular diseases (24%), multiple sclerosis (13.5%) and spinal cord diseases (12.5%). The higher false negative rates were found in sylvian stroke (0.36) and hereditary spastic paraplegia (0.16). Central conduction study using magnetic paravertebral stimulation but not using the F-wave method, resulted in 12% and 10% of false positive values in lower limb multiradiculopathies and in neuropathies, respectively.

CONCLUSIONS

MEPs represent a highly accurate diagnostic test. MEP clinical value is maximum in motor neuron, muscle and spinal cord diseases. In patients with lower motor neuron involvement, the gold standard for central conduction determination is the F-wave method.

[Efficacy of diltiazem in uremic hemodialyzed patients with isolated diastolic dysfunction and dialysis hypotensive crisis]

The aim of our study was to assess the effects of diltiazem on diastolic function, left ventricular mass and intradialytic hypotension, in uremic patients on maintenance hemodialysis. Forty-eight uremic patients on maintenance hemodialysis (mean age 46 +/- 5 years) with diastolic heart failure and normal systolic function (ejection fraction > 40%), although hemodialysis had been correctly performed, were included in the study. All patients had left ventricular hypertrophy. Diltiazem was given at the dosage of 60 mg, twice a day, for 3 months. At the end of this period, significant improvement of Doppler echocardiographic filling pattern and clinical symptomatology were observed, but left ventricular mass index was unchanged. Episodes of intradialytic hypotension were significantly reduced. We conclude that diltiazem improves symptoms and left ventricular diastolic filling in uremic patients with diastolic heart failure, without modifying left ventricular mass index; impaired diastolic function has an important role in recurrent dialysis hypotension.

Antimicrobial peptides from the Brazilian frog Phyllomedusa distincta

Different peptides were purified by chromatographic procedures from the skin-secretory glands of the frog Phyllomedusa distincta. These are the first peptides reported from this frog species. Their primary structure was determined by a combination of automated Edman degradation and mass spectrometry. Peptide Q2 contains 25 amino acid residues, peptide Q1 and L have 28 each, peptide M contains 31, and peptide K has 33 amino acid residues. They all showed potent antimicrobial activity against Gram-negative and Gram-positive bacteria, presenting minimal inhibitory concentrations from 0.6 to 40 microM, when tested against Enterococcus faecalis, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Peptides K, L, and Q1 were chemically synthesized and shown to be active.

[Ultrasonic monitoring as a method of preventing risks of ovarian hyperstimulation during drug therapy]

BACKGROUND AND AIMS

Ultrasonographic monitoring represents the most immediate method for an early confirmation of the onset of the worst complication of the pharmacological induction of ovulation: ovarian hyperstimulation. The aim of this study was to evaluate the incidence of this complication in a sample group of anovulatory patients receiving pharmacological treatment and undergoing repeated ultrasonographic monitoring.

METHODS

The authors analysed the controls performed during 1996-1997 in which a total of 413 cycles were stimulated. The patients included in the study group (mean age 28.5 years) were treated using clomiphene, oestradiol, FSH, LH and GnRH, and in 5 cases stimulation was preceded by suppression of the menstrual cycle using tryptorelin. Each patient was monitored with 3 scans, except for those treated with tryptorelin or GnRH who were more closely monitored.

RESULTS

In 413 patients included in this study the authors noted the onset of slight hyperstimulation in 6 cases (1.45%) which then resolved spontaneously without the need for hospitalisation.

CONCLUSIONS

The authors affirm that ultrasonographic monitoring represents a valid means of controlling and preventing the risks of ovarian hyperstimulation.

Essential hypertension: leukocyte rheology and polymorphonuclear cytosolic Ca2+ content at baseline and after activation

In 24 hypertensives we evaluated, at baseline, the leukocyte filtration parameters (using the St. George's Filtrometer), polymorphonuclear (PMN) membrane fluidity (with the fluorescent probe 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene [TMA-DPH]) and PMN cytosolic Ca2+ content (with the fluorescent probe Fura 2-AM). In a subgroup of hypertensives (n = 17) the PMN filtration parameters, PMN membrane fluidity and cytosolic Ca2+ content were evaluated after in vitro chemotactic activation (prolonged for 5 and 15 min) with two stimulating agents (4-phorbol 12-myristate 13-acetate [PMA] and N-formyl-methionyl-leucyl-phenylalanine [fMLP]). It was evident, from the baseline data, that there was a significant difference in the mononuclear (MN) initial relative flow rate (IRFR), clogging rate (CR) and clogging particles (CP), and in PMN cytosolic Ca2+ content. There were, however, no differences in the filtration parameters of unfractionated leukocytes and PMNs or in PMN membrane fluidity. After activation, in normals and in hypertensives, a significant variation in PMN filtration parameters was evident. In normals no variation was present in PMN membrane fluidity or cytosolic Ca2+ content after activation. In hypertensives, however, we found an increase solely in PMN cytosolic Ca2+ content after fMLP activation. After PMN activation (at 15 min) one parameter (IRFR) of PMN filtration distinguished normal subjects from hypertensives. No difference between the two groups was found in PMN membrane fluidity or PMN cytosolic Ca2+ content after PMN activation.

[Incremental doses of diltiazem in patients with coronary artery disease in end-stage renal failure maintained on hemodialysis: which is the optimal dose?]

End-stage renal disease patients on maintenance hemodialysis suffering from coronary artery disease probably receive too low doses of calcium-antagonists, because the attempt to avoid adverse effects prevails the well-documented antianginal activity of the drug. The aim of our study was to assess the safety and efficacy of incremental doses of diltiazem in treating angina pectoris in hemodialyzed patients with coronary artery disease, to identify the optimal dose. Ninety-four chronic hemodialyzed patients (59 males and 35 females; mean age 55.2 +/- 3.3 years; on periodic dialysis for 80.3 +/- 25.6 months) with coronary artery disease and more than 5 min of transient myocardial ischemia during 48 hours of Holter monitoring were included in the study. A double-blind, randomized, placebo-controlled trial design was used. Incremental doses of diltiazem (from 120 to 240 mg/day) were administered in 4 months. At doses of 120 and 180 mg/day it was observed a statistically significant reduction in the number and duration of total and symptomatic ischemic episodes in 48 hours, compared with baseline (p < 0.001). Instead, the number and the duration of silent ischemic episodes did not significantly change (NS). The efficacy on silent myocardial ischemia was obtained only with the dosage of 240 mg/day (p < 0.001). If this dosage was obtained with a sustained-release formulation (120 mg twice a day), the efficacy was similar to the administration of 4 tablets/day of 60 mg, but the tolerability was better, especially during dialysis. The circadian variations of transient ischemic episodes showed two peaks in the 24 hours, one from 6.00 to 9.00 a.m. and another from 4.00 to 8.00 p.m., just during the dialysis. Both peaks were reduced only with 240 mg/day. In conclusion, this study demonstrates that sustained-release diltiazem (120 mg twice a day) is greatly useful in patients with coronary artery disease on maintenance dialysis because it reduces the frequency of silent ischemic episodes, has a good tolerability, and modifies the circadian pattern of ischemic episodes, reducing both peaks during the day.

[Syndrome X and microvascular angina]

The term X syndrome is used to indicate a group of patients who present anginous symptoms and ischemic-type electrocardiographic alterations which appear during exercise tolerance tests, dipiridamol tests or Holter's dynamic monitoring where coronary ultrasonography reveals no evident coronary lesions, vasospastic angina, arterial hypertension and/or diabetes mellitus, block of the left branch when resting or exercising, cardiomyopathy or valvulopathy. The highest incidence is in females with a mean age of around 50. A reduced reserve of coronary flow, highlighted both in response to vasodilatators or rapid stimulation and by positron emission tomography (PET), underlies this syndrome. It is thought to be caused by a dysfunction of the coronary microcirculation which consists in a deficit of the endothelium-dependent vasodilatory mechanisms, probably also owing to the accumulation of vasoconstrictive type substances, like endothelin-1. In addition to a dysfunction of the coronary microcirculation, one widely backed hypothesis concerns the existence of an altered perception of painful symptoms in patients with X syndrome: the anomalous constriction of prearteries might cause an increased release of adenosine, able to provoke angina despite the scarce signs of myocardial ischemia in terms of the metabolic or functional profile. From a therapeutic point of view, treatment of these patients is often ineffective: treatment should be based on the use of nitrates, calcium-antagonists or beta-blockers, if necessary moving on to other forms of therapy (aceinhibitors, xanthine methylate, estrogens, alphablockers, imipramine); the simultaneous use of tranquillizers may be useful in view of the anxious personality often characteristic of these patients.

[Complex ventricular arrhythmias and carvedilol: efficacy in hemodialyzed uremic patients]

Carvedilol has been shown to be effective in systemic hypertension and coronary artery disease in patients with end-stage renal disease, on maintenance hemodialysis. The aim of our study was to assess the effects of carvedilol on ventricular arrhythmias in these patients. Ninety-eight uremic patients maintained on hemodialysis, with complex ventricular arrhythmias (class III, IV and V of Lown's classification), not only during dialysis, were included in the study. They were divided into two groups, with mild-to-moderate hypertension or coronary artery disease. The efficacy and safety of carvedilol (50 mg/day) was compared to placebo in a 6-week randomized, double-blind study. Carvedilol significantly reduced, in both hypertensive and ischemic patients, total ventricular premature contractions (82.7 +/- 11.3 vs 358.1 +/- 73.9, p < 0.001; 88.3 +/- 24.4 vs 369.9 +/- 77.8, p < 0.001), repetitive ventricular premature contractions (1.3 +/- 1.3 vs 6.3 +/- 3.5, p < 0.001; 1.2 +/- 0.7 vs 6.9 +/- 2.6, p < 0.001) and episodes of ventricular tachycardia (1.1 +/- 1.2 vs 11.8 +/- 7.5, p < 0.001; 1.4 +/- 1.2 vs 14.0 +/- 8.3, p < 0.001). In placebo-treated patients, instead, these parameters were not significantly changed (329.1 +/- 76.5 vs 361.7 +/- 71.7, NS, and 324.6 +/- 79.7 vs 359.3 +/- 58.1, NS; 6.2 +/- 3.7 vs 7.3 +/- 3.7, NS, and 4.9 +/- 2.2 vs 6.1 +/- 3.2, NS; 9.8 +/- 6.3 vs 13.3 +/- 8.0, NS, and 9.0 +/- 6.2 vs 12.4 +/- 7.8, NS). Carvedilol confirmed a significant effect on myocardial ischemia and systemic hypertension. No significant side effects were reported. Ventricular arrhythmias are frequent in patients with end-stage renal disease maintained on hemodialysis. They are often due to an underlying cardiac disease, namely systemic hypertension with left ventricular hypertrophy and coronary artery disease. The results of our study show that the antiarrhythmic effect of carvedilol is linked, at least partly, to an improvement of the underlying cardiac disease. Uremic patients have a chronic increase in adrenergic tone, with a direct correlation between norepinephrine plasmatic concentration and frequence of premature ventricular contractions. Beta-blockers are very important in these patients because of their modulation on the adrenergic system. They also reduce potassium flow, from extracellular to intracellular fluid. Therefore carvedilol can affect the sudden hypokalemia occurring in the first phase of hemodialysis treatment, that may be an important cause of intradialytic arrhythmias.

Effects of voluntary contraction on descending volleys evoked by transcranial stimulation in conscious humans

1. The spinal volleys evoked by single transcranial magnetic or electric stimulation over the cerebral motor cortex were recorded from a bipolar electrode inserted into the cervical epidural space of three conscious human subjects. These volleys were termed direct (D) and indirect (I) waves according to their latency. 2. We measured the size and number of volleys elicited by magnetic stimulation at various intensities with subjects at rest and during 20 or 100 % maximum contraction of the contralateral first dorsal interosseous muscle (FDI). Surface EMG activity was also recorded. 3. Electrical stimulation evoked a D-wave volley. Magnetic stimulation at intensities up to about 15 % of stimulator output above threshold evoked only I-waves. At higher intensities, a D-wave could be seen in two of the three subjects. 4. At all intensities tested, voluntary contraction increased the number and size of the I-waves, particularly during maximum contractions. However, there was only a small effect on the threshold for evoking descending activity. Voluntary contraction produced large changes in the size of EMG responses recorded from FDI. 5. Because the recorded epidural activity is destined for muscles other than the FDI, it is impossible to say to what extent increased activity contributes to voluntary facilitation of EMG responses. Indeed, our results suggest that the main factor responsible for enhancing EMG responses in the transition from rest to activity is likely to be increased excitability of spinal motoneurones, rather than increases in the corticospinal volley. The latter may be more important in producing EMG facilitation at different levels of voluntary contraction.