Is there a connection between postprandial hyperglycemia and IGT related sensory nerve dysfunction?

BACKGROUND AND AIMS

To assess the risk factors for sensory nerve dysfunction in subjects with isolated impaired glucose tolerance (IGT).

METHODS AND RESULTS

Seventy-two people with isolated IGT (WHO 1999 criteria) and 39 gender and age-matched healthy volunteers underwent detailed clinical and neurological assessment including quantitative sensory testing using the Neurometer device (current perception threshold measurement on four limbs at three different frequencies). Sensory nerve dysfunction was defined as at least two abnormalities on any frequencies on the upper or lower limbs. Sensory nerve dysfunction was more prevalent among subjects with IGT compared to controls (58.3 vs. 10.3%, OR: 11.23, 95%CI: 3.57-35.35). This association was not influenced by BMI, systolic and diastolic blood pressure, heart rate and autonomic neuropathy (multiple adjusted OR: 13.87, 95%CI: 3.18-60.58), but further adjustment for glycaemic measures abolished the association (OR: 1.58, 95%CI: 0.07-35.68). Assessing the components of glycaemic measures separately, the association between sensory nerve dysfunction and IGT was not affected by HbA1c (OR: 13.94, 95%CI: 1.84-105.5). It was, however, substantially attenuated by fasting plasma glucose (OR: 6.75, 95%CI: 1.33-34.27) while the significance was lost after adjustment for 120 min postload glucose level (OR: 3.76, 95%CI: 0.26-54.10). In the pooled population assessed, independent determinants of sensory nerve dysfunction were older age, 120 min glucose, higher height and cardiovascular autonomic neuropathy at near significance.

CONCLUSIONS

Sensory nerve dysfunction amongst subjects with IGT was not explained by cardiovascular covariates, only by glycaemic measures. In addition to 120 min glucose, cardiovascular autonomic neuropathy at borderline significance, age, and height were the independent determinants of sensory nerve dysfunction.

Small-Fiber Neuropathy: A Diabetic Microvascular Complication of Special Clinical, Diagnostic, and Prognostic Importance

Damage of small nerve fibers may lead to a large variety of clinical symptoms. Small-fiber neuropathy underlies the symptoms of painful diabetic neuropathy, which may decrease quality of life. It also contributes to the poor prognosis of diabetic neuropathy because it plays a key role in the pathogenesis of foot ulceration and autonomic neuropathy. Impairment of small nerve fibers is considered the earliest alteration in the course of diabetic neuropathy. Therefore, assessment of functional and morphological abnormalities of small nerve fibers may enable timely diagnosis. The definition, symptoms, and clinical significance of small-fiber neuropathy are considered in the present review. An apparently more complex interaction between small-fiber impairment and microcirculation is extensively discussed. Diagnostic modalities include morphometric and functional methods. Corneal confocal microscopy and punch skin biopsy are considered gold standards, but noninvasive functional tests are also diagnostically useful. However, in routine clinical practice, small-fiber neuropathy is diagnosed by its typical clinical presentation. Finally, prompt treatment should be initiated following diagnosis.

A simple new non-invasive sweat indicator test for the diagnosis of diabetic neuropathy

A simple non-invasive indicator test (Neuropad(®)) has been developed for the assessment of sweating and, hence, cholinergic innervation in the diabetic foot. The present review summarizes current knowledge on this diagnostic test. The diagnostic ability of this test is based on a colour change from blue to pink at 10 min, with excellent reproducibility, which lends itself to patient self-examination. It has a high sensitivity (65.1-100%) and negative predictive value (63-100%), with moderate specificity (32-78.5%) and positive predictive value (23.3-93.2%) for the diagnosis of diabetic peripheral neuropathy. It also has moderate to high sensitivity (59.1-89%) and negative predictive value (64.7-91%), but low to moderate specificity (27-78%) and positive predictive value (24-48.6%) for the diagnosis of diabetic cardiac autonomic neuropathy. There are some data to suggest that Neuropad can detect early diabetic neuropathy, but this needs further evaluation. It remains to be established whether this test can predict foot ulceration and amputation, thereby contributing to the identification of high-risk patients.

Autonomic dysfunction and circadian blood pressure variations in people with impaired glucose tolerance

AIMS

To assess circadian blood pressure variability in people with impaired glucose tolerance and a healthy control population.

METHODS

Seventy-five people with impaired glucose tolerance and 40 healthy volunteers (frequency matched on 10-year age bands and sex) underwent a detailed neurological assessment. Autonomic neuropathy was detected by the five standard cardiovascular autonomic tests and heart rate variability was characterized by the triangle index. Diurnal indices were assessed by 24-h ambulatory blood pressure monitoring. Systolic and diastolic diurnal indices were defined as: (mean daytime blood pressure - mean night-time blood pressure) × 100/mean daytime blood pressure.

RESULTS

Mean 24-h systolic and diastolic blood pressure was significantly higher in the group with impaired glucose tolerance compared with the control group [126 ± 12 (mean ± SD) vs. 117 ± 10, 75 ± 7 vs. 71 ± 6 mmHg, both P < 0.05). Systolic and diastolic diurnal indices and heart rate variability triangular index were significantly lower in people with impaired glucose tolerance compared with control subjects (9.1 ± 7.8 vs. 13.2 ± 5.4, 14.5 ± 9.7 vs. 18.4 ± 7.1 mmHg, 28.0 ± 8.4 vs. 39.5 ± 9.3, all P < 0.05). Differences in mean diastolic blood pressure, heart rate variability triangular index and the frequency of non-dippers between those with impaired glucose tolerance and control subjects seemed to be independent of BMI and the presence of cardiovascular autonomic neuropathy, as simultaneous adjustment for BMI and cardiovascular autonomic neuropathy had no major effect on the results.

CONCLUSION

Our data suggest that people with impaired glucose tolerance have increased diastolic blood pressure and abnormal circadian blood pressure regulation, independent of obesity and the presence of cardiovascular autonomic neuropathy.

Management strategies for gastrointestinal, erectile, bladder, and sudomotor dysfunction in patients with diabetes

There are substantial advances in understanding disordered gastrointestinal autonomic dysfunction in diabetes. It occurs frequently. The underlying pathogenesis is complex involving defects in multiple interacting cell types of the myenteric plexus as well. These defects may be irreversible or reversible. Gastrointestinal symptoms represent a major and generally underestimated source of morbidity for escalating health care costs in diabetes. Acute changes in glycaemia are both determinants and consequences of altered gastrointestinal motility. 35-90% of diabetic men have moderate-to-severe erectile dysfunction (ED). ED shares common risk factors with CVD. Diagnosis is based on medical/sexual history, including validated questionnaires. Physical examination and laboratory testing must be tailored to patient's complaints and risk factors. Treatment is based on PDE5-inhibitors (PDE5-I). Other explorations may be useful in patients who do not respond to PDE5-I. Patients at high cardiovascular risk should be stabilized by their cardiologists before sexual activity is considered or ED treatment is recommended. Estimates on bladder dysfunction prevalence are 43-87% of type 1 and 25% of type 2 diabetic patients, respectively. Common symptoms include dysuria, frequency, urgency, nocturia and incomplete bladder emptying. Diagnosis should use validated questionnaire for lower urinary tract symptoms. The type of bladder dysfunction is readily characterized with complete urodynamic testing. Sudomotor dysfunction is a cause of dry skin and is associated with foot ulcerations. Sudomotor function can be assessed by thermoregulatory sweat testing, quantitative sudomotor axon reflex test, sympathetic skin response, quantitative direct/indirect axon reflex testing and the indicator plaster.

Relationship between autonomic neuropathy and hypertension--are we underestimating the problem?

BACKGROUND

Cardiac autonomic neuropathy (CAN) is associated with significant morbidity and mortality in diabetes and the risk is even greater in those with hypertension.

AIMS

The aim of our study was to investigate the relationship between CAN and 24-h blood pressure profile in normoalbuminuric patients with Type 2 diabetes mellitus.

METHODS

Seventy patients with Type 2 diabetes (31 without CAN, 39 with CAN), who had no history of hypertension, and 29 healthy volunteers underwent five standard cardiovascular reflex tests to assess autonomic function and 24-h ambulatory blood pressure monitoring.

RESULTS

Twenty-four-hour mean systolic blood pressure, blood pressure load and hyperbaric impact values were significantly higher in diabetic patients with CAN compared with control subjects and diabetic patients without CAN (P < 0.05). In spite of normal clinic blood pressures, 54% of diabetic subjects with CAN and 29% without CAN were hypertensive (systolic blood pressure load > 20%, P < 0.05). In the diabetes group as a whole, Valsalva ratio, postural systolic blood pressure changes and diastolic blood pressure responses during sustained handgrip correlated significantly and negatively with 24-h mean systolic blood pressure (P < 0.01, P < 0.001, P < 0.05) and blood pressure load (P < 0.05, P < 0.001, P < 0.05).

CONCLUSIONS

Cardiovascular autonomic neuropathy is independently associated with hypertension in normoalbuminuric Type 2 diabetic patients with no history of hypertension. Relying on clinic blood pressures in subjects with CAN could lead to a failure to diagnose hypertension in over half of cases. All normotensive patients with CAN should be screened for hypertension using ambulatory blood pressure monitoring in order to institute early aggressive interventions to improve their long-term outlook.

Coronary flow reserve, insulin resistance and blood pressure response to standing in patients with normoglycaemia: is there a relationship?

AIMS

To establish the relationships between coronary flow reserve, cardiovascular autonomic function, and insulin resistance characterized by the homeostasis model assessment insulin resistance score in patients with normal carbohydrate metabolism according to the World Health Organization (WHO) and American Diabetes Association (ADA) criteria, and with morphologically normal epicardial coronary arteries.

METHODS

Twenty-five patients [12 women and 13 men, mean (sd) age: 53 +/- 11 years] with normal coronary angiography were enrolled into the study. Coronary flow reserve was measured during stress transoesophageal echocardiography. Autonomic dysfunction was assessed by means of five standard cardiovascular reflex tests. The fasting serum glucose and insulin levels were determined and the homeostasis assessment model insulin resistance score was calculated.

RESULTS

In patients with normal carbohydrate metabolism, negative correlations were observed between the coronary flow reserve and both the serum insulin level (r = -0.445, P = 0.026) and the homeostasis assessment model insulin resistance score (r = -0.449, P = 0.024). The systolic blood pressure response to standing also correlated with the coronary flow reserve (r = -0.519, P = 0.011). The heart rate response to deep breathing, the Valsalva ratio, the 30/15 ratio and the sustained handgrip test results were not correlated with the coronary flow reserve.

CONCLUSIONS

Our data suggest the possible role of insulin resistance and early sympathetic nerve dysfunction in the development of decreased coronary flow reserve in patients without diabetes mellitus or impaired glucose tolerance.

Risk factors for cardiac autonomic neuropathy in type 1 diabetes mellitus

AIMS/HYPOTHESIS

Cardiac autonomic neuropathy (CAN) is associated with increased morbidity and mortality in type 1 diabetes. Apart from glycaemic control, risk factors for CAN have not been extensively studied.

METHODS

As part of the EURODIAB Prospective Complications Study, CAN--defined as either a loss of heart rate variability or postural hypotension on standing--was assessed at baseline and follow-up (7.3+/-0.6 years from baseline) in patients with type 1 diabetes.

RESULTS

Follow-up measurements were available for 956 participants without CAN at baseline (age at baseline 31.3+/-8.9 years, duration of diabetes 13.5+/-8.3 years). During follow-up, 163 (17%) subjects developed CAN, yielding an incidence of 23.4 per 1,000 person-years. Blood pressure, weight, the presence of cardiovascular disease, albuminuria, distal symmetrical polyneuropathy (DSP) and retinopathy at baseline were associated with the incidence of CAN after adjustment for sex, duration of diabetes and HbA(1)c. In a multivariate regression model, baseline factors associated with an increased risk of developing CAN were age [odds ratio (OR)=1.3 per decade, 95% CI 1.1-1.7], HbA(1)c (OR=1.2 per percentage point, 95% CI 1.1-1.4), systolic blood pressure (OR=1.1 per 10 mmHg, 95% CI 1.0-1.3), feeling faint on standing (OR=2.0, 95% CI 1.2-3.2), DSP (OR=1.9, 95% CI 1.2-3.0) and retinopathy (OR=1.7, 95% CI 1.1-2.6).

CONCLUSION/INTERPRETATION

This study confirms the importance of exposure to hyperglycaemia as a risk factor for CAN. A small set of variables, including HbA(1)c, hypertension, DSP and retinopathy, predict the risk of CAN. Clinical trials are needed to address the impact of intensive antihypertensive treatment on CAN in type 1 diabetes.

GUIDE study: double-blind comparison of once-daily gliclazide MR and glimepiride in type 2 diabetic patients

BACKGROUND

Progressive beta-cell failure is a characteristic feature of type 2 diabetes; consequently, beta-cell secretagogues are useful for achieving sufficient glycaemic control. The European GUIDE study is the first large-scale head-to-head comparison of two sulphonylureas designed for once-daily administration used under conditions of everyday clinical practice.

DESIGN

Eight hundred and forty-five type 2 diabetic patients were randomized to either gliclazide modified release (MR) 30-120 mg daily or glimepiride 1-6 mg daily as monotherapy or in combination with their current treatment (metformin or an alpha-glucosidase inhibitor) according to a double-blind, 27-week, parallel-group design. Efficacy was evaluated by HbA1c and safety by hypoglycaemic episodes using the European Agency definition.

RESULTS

HbA1c decreased similarly in both groups from 8.4% to 7.2% on gliclazide MR and from 8.2% to 7.2% on glimepiride. Approximately 50% of the patients achieved HbA1c levels less than 7%, and 25% less than 6.5%. The mean difference between groups of the final HbA1c was -0.06% (noninferiority test P < 0.0001). No hypoglycaemia requiring external assistance occurred. Hypoglycaemia with blood glucose level < 3 mmol L(-1) occurred significantly less frequently (P = 0.003) with gliclazide MR (3.7% of patients) compared with glimepiride (8.9% of patients). The distribution of the sulphonylurea doses was similar in both groups.

CONCLUSIONS

This study provides new insights into therapeutic strategies using sulphonylureas. It shows that gliclazide MR is at least as effective as glimepiride, either as monotherapy or in combination. The safety of gliclazide MR was significantly better, demonstrating approximately 50% fewer confirmed hypoglycaemic episodes in comparison with glimepiride.

Treatment of symptomatic diabetic polyneuropathy with the antioxidant alpha-lipoic acid: a meta-analysis

AIMS

To determine the efficacy and safety of 600 mg of alpha-lipoic acid given intravenously over 3 weeks in diabetic patients with symptomatic polyneuropathy.

METHODS

We searched the database of VIATRIS GmbH, Frankfurt, Germany, for clinical trials of alpha-lipoic acid according to the following prerequisites: randomized, double-masked, placebo-controlled, parallel-group trial using alpha-lipoic acid infusions of 600 mg i.v. per day for 3 weeks, except for weekends, in diabetic patients with positive sensory symptoms of polyneuropathy which were scored by the Total Symptom Score (TSS) in the feet on a daily basis. Four trials (ALADIN I, ALADIN III, SYDNEY, NATHAN II) comprised n=1258 patients (alpha-lipoic acid n=716; placebo n=542) met these eligibility criteria and were included in a meta-analysis based on the intention-to-treat principle. Primary analysis involved a comparison of the differences in TSS from baseline to the end of i.v. Treatment between the groups treated with alpha-lipoic acid or placebo. Secondary analyses included daily changes in TSS, responder rates (> or =50% improvement in TSS), individual TSS components, Neuropathy Impairment Score (NIS), NIS of the lower limbs (NIS-LL), individual NIS-LL components, and the rates of adverse events.

RESULTS

After 3 weeks the relative difference in favour of alpha-lipoic acid vs. placebo was 24.1% (13.5, 33.4) (geometric mean with 95% confidence interval) for TSS and 16.0% (5.7, 25.2) for NIS-LL. The responder rates were 52.7% in patients treated with alpha-lipoic acid and 36.9% in those on placebo (P<0.05). On a daily basis there was a continuous increase in the magnitude of TSS improvement in favour of alpha-lipoic acid vs. placebo which was noted first after 8 days of treatment. Among the individual components of the TSS, pain, burning, and numbness decreased in favour of alpha-lipoic acid compared with placebo, while among the NIS-LL components pin-prick and touch-pressure sensation as well as ankle reflexes were improved in favour of alpha-lipoic acid after 3 weeks. The rates of adverse events did not differ between the groups.

CONCLUSIONS

The results of this meta-analysis provide evidence that treatment with alpha-lipoic acid (600 mg/day i.v.) over 3 weeks is safe and significantly improves both positive neuropathic symptoms and neuropathic deficits to a clinically meaningful degree in diabetic patients with symptomatic polyneuropathy.

Autonomic neuropathy is associated with increased cardiovascular risk factors: the EURODIAB IDDM Complications Study

AIMS

To assess the prevalence of and risk factors for autonomic neuropathy in the EURODIAB IDDM Complications Study.

METHODS

The study involved the examination of randomly selected Type I (insulin-dependent) diabetic patients from 31 centres in 16 European countries. Neuropathic symptoms and two tests of autonomic function (changes in heart rate and blood pressure from lying to standing) were assessed and data from 3007 patients were available for the present analysis. Autonomic neuropathy was defined as an abnormality of at least one of the tests.

RESULTS

The prevalence of autonomic neuropathy was 36% with no sex differences. The frequency of one and two abnormal reflex tests was 30% and 6%, respectively. The R-R ratio was abnormal in 24% of patients while 18% had orthostatic hypotension defined as a fall in systolic blood pressure > 20 mmHg on standing. Significant correlations were observed between autonomic neuropathy and age (P < 0.01), duration of diabetes (P < 0.0001), HbA1c (P < 0.0001), diastolic blood pressure (P < 0.05), lower HDL-cholesterol (P < 0.01), the presence of retinopathy (P < 0.0001) and albuminuria (P < 0.0001). New associations have been identified from the study: the strong relationship of autonomic neuropathy to cigarette smoking (P < 0.01), total cholesterol/HDL-cholesterol ratio (P < 0.05) and fasting triglyceride (P < 0.0001). As a key finding, autonomic neuropathy was related to the presence of cardiovascular disease (P < 0.0001). All analyses were adjusted for age, duration of diabetes and HbA1c. However, data have been only partly confirmed by logistic regression analyses. Frequency of dizziness on standing up was 18%, while only 4% of patients had nocturnal diarrhoea and 5% had problems with bladder control.

CONCLUSION

Cardiovascular reflex tests, even in the form of the two tests applied, rather than a questionnaire, seem to be appropriate for the diagnosis of autonomic neuropathy. The study has identified previously known and new potential risk factors for the development of autonomic neuropathy, which may be important for the development of risk reduction strategies. Our results may support the role of vascular factors in the pathogenesis of autonomic neuropathy.

Gallbladder hypomotility in diabetic polyneuropathy

This study was performed to evaluate the gallbladder motility in long-standing diabetes mellitus. The gallbladder function of diabetic patients was measured by means of quantitative hepatobiliary scintigraphy, and the severity of the associated autonomic and sensory polyneuropathy was determined. The presence of a marked gallbladder hypomotility was established, and a positive correlation was observed between the severity of the autonomic disturbance and the contractile disorder. This study underlines the important role of the neuropathy in the development of gallbladder hypomotility accompanying long-term diabetes mellitus.

[The pathogenesis of diabetic and hepatic neuropathies]

The pathomechanism of neuropathies associated with diabetes and chronic liver diseases are poorly understood. Both metabolic and vascular factors are involved in the pathogenesis of diabetic neuropathy. It seems likely, that microangiopathy on the one hand and changes of various metabolic pathways due to hyperglycaemia on the other hand are much more related to each other than it was suggested previously. Nitric oxide may be the link between the metabolic and vascular hypotheses of diabetic neuropathy. Both reduced endoneurinal blood flow and increased oxidative stress leads to reduced nitric oxide synthetase activity. There are widespread inter-relationships between the most relevant metabolic changes included polyol pathway hyperactivity, reduced myoinosit concentration, advanced glycation end products formation, increased oxidative stress and lipid peroxidation. Changes of hemorheological conditions and primary hemostasis leeds to hyperviscosity just as to increased activity of the coagulation system. Among patients with chronic alcoholic liver diseases the direct toxic effect of alcohol is of particular relevance, however, malabsorption, impairment of axoplasmatic transport, changes of intermedier metabolism as well as thiamine and pyridoxine deficiency are of importance as well. The role of decreased insulin sensitivity and various degrees of glucose intolerance related to chronic liver diseases are still underestimated. Impairment of proteoglycan metabolism as well as increased oxydative stress are thought to be important factors in the pathogenesis of both diabetic and hepatic neuropathies. Glucose autooxidation and enhanced lipid peroxidation contribute to increased oxidative stress in patients with diabetes and chronic liver diseases as well. Vitamin E deficiency, autoimmun processes, circulating immune complexes, cryoglobulinemia, just as changes of vascular responsiveness associated with nitric oxide activity plays a role in the development of neural damage of hepatic origin. Most likely, similarly to diabetes mellitus, vascular changes contribute to the development of neuropathy in patients with chronic liver diseases.

Blood pressure response to standing in the diagnosis of autonomic neuropathy: the EURODIAB IDDM Complications Study

Autonomic neuropathy is associated with poor prognosis. Cardiovascular reflexes are essential for the diagnosis of autonomic nerve dysfunction. Blood pressure response to standing is the most simple test for the evaluation of sympathetic integrity, however it is still discussed which diagnostic criteria of abnormal response should be considered as optimal. The EURODIAB IDDM Complications Study involved the examination of randomly selected Type 1 diabetic patients from 31 centres in 16 European counties. Data from 3007 patients were available for the present evaluation. Two tests of autonomic function (response of heart rate /R-R ratio/ and blood pressure from lying to standing) just as the frequency of feeling faint on standing up were assessed. R-R ratio was abnormal in 24% of patients. According to different diagnostic criteria of abnormal BP response to standing (>30 mmHg, >20 mmHg, and >10 mmHg fall in systolic BP), the frequency of abnormal results was 5.9%, 18% and 32%, respectively (p < 0.001). The frequency of feeling faint on standing was 18%, thus, it was identical with the prevalence of abnormal blood pressure response to standing when >20 mmHg fall in systolic blood pressure was considered as abnormal. Feeling faint on standing correlated significantly with both autonomic test results (p < 0.001). A fall >20 mmHg in systolic blood pressure after standing up seems to be the most reliable criterion for the assessment of orthostatic hypotension in the diagnosis of autonomic neuropathy in patients with Type 1 diabetes mellitus.

Angiotensin II type 1 receptor gene polymorphism and mitral valve prolapse syndrome

BACKGROUND

Mitral valve prolapse syndrome (MVPS), a term applied to patients who have a variety of symptoms, has been associated with autonomic or neuroendocrine dysfunction. Recent evidence suggests that effects of angiotensin II mediated by the angiotensin II type 1 (AT(1)) receptor are involved in modulation of cardiovascular autonomic control in human beings. Association of a genetic polymorphism (A-C(1166)) of the AT(1) gene with abnormal vasomotion and low blood pressure related to autonomic control has been reported recently. Because the role of this genetic variant in MVPS has not been studied, we performed a case-control study of the A-C(1166) variant in a group of 76 white subjects with MVPS.

METHODS AND RESULTS

All patients were genotyped by use of a mismatch polymerase chain reaction/Afl II restriction fragment length polymorphism analysis. Frequency of the C(1166) allele was 0.4 in patients with MVPS and 0.26 in control patients. The difference in genotype (chi square = 6.5; P <.05) and allele (chi square = 5.9; P =.02) frequencies between the groups was significant. The odds ratio in favor of carrying the C allele was 4 times greater for patients with MVP than for control patients (95% confidence interval 1.4 to 12.1).

CONCLUSIONS

The current results indicate that the A-C(1166) polymorphism of the angiotensin II type 1 receptor gene is associated with MVPS in the white population.

Effectiveness of different benfotiamine dosage regimens in the treatment of painful diabetic neuropathy

The therapeutic effectiveness of a benfotiamine (CAS 22457-89-2)-vitamin B combination (Milgamma-N), administered in high (4 x 2 capsules/day, = 320 mg benfotiamine/day) and medium doses (3 x 1 capsules/day), was compared to a monotherapy with benfotiamine (Benfogamma) (3 x 1 tablets/day, = 150 mg benfotiamine/day) in diabetic patients suffering from painful peripheral diabetic neuropathy (DNP). In a 6-week open clinical trial, 36 patients (aged 40 to 70 yrs) having acceptable metabolic control (HbA1c < 8.0%) were randomly assigned to three groups, each of them comprising 12 participants. Neuropathy was assessed by five parameters: the pain sensation (evaluated by a modified analogue visual scale), the vibration sensation (measured with a tuning fork using the Riedel-Seyfert method) and the current perception threshold (CPT) on the peroneal nerve at 3 frequencies: 5, 250 and 2000 Hz). Parameters were registered at the beginning of the study and at the end of the 3rd and 6th week of therapy. An overall bneneficial therapeutic effect on the neuropathy status was observed in all three groups during the study, and a significant improvement in most of the parameters studied appeared already at the 3rd week of therapy (p < 0.01). The greatest change occurred in the group of patients receiving the high dose of benfotiamine (p < 0.01 and 0.05, resp., compared to the othr groups). Metabolic control did not change over the study. It is concluded that benfotiamine is most effective in large doses, although even in smaller daily dosages, either in combination or in monotherapy, it is effective.

Prevalence and management of hypertension in type 1 diabetes mellitus in Europe: the EURODIAB IDDM Complications Study

AIM

To examine the prevalence of hypertension and the rates of hypertension awareness by investigating treatment and control among respondents to the EURODIAB IDDM Complications Study, and to explore the variation in hypertension management by age, sex and end-organ damage.

METHODS

A cross-sectional study, examining 3250 randomly selected Type 1 diabetic patients from 31 diabetes clinics in 16 European countries between 1989 and 1990. Mean age was 32.7 years (SD= 10.0) and mean duration of diabetes mellitus (DM) was 14.7 years (SD=9.3). Subjects were asked about a history of high blood pressure (BP) and current prescribed medications were recorded by the subject's physician. Hypertension was defined as having a systolic BP > or = 140 mmHg or diastolic BP > or = 90 mmHg or current use of antihypertensives. Control was defined as a BP < 130/85 mmHg.

RESULTS

Twenty-four per cent of subjects had hypertension, among whom fewer than one-half (48.5%) were aware of a previous diagnosis and a similar proportion (42.2%) were on treatment. Only 11.3% of those with hypertension were both treated and controlled. The majority (81%) of those receiving drug therapy for hypertension were on a single drug, most commonly an angiotensin-converting enzyme inhibitor (47%).

CONCLUSION

These data show the extent of undermanagement of hypertension in Type 1 DM across Europe prior to the publication of the St. Vincent Declaration and provide a useful baseline against which future improvements in the management of hypertension can be monitored.

Neuropathy as an extrahepatic manifestation of chronic liver diseases

Gastrointestinal motor disturbances and various cardiovascular symptoms are the characteristic features of autonomic neuropathy. Autonomic and sensory neuropathy has been described in chronic alcoholic liver diseases. Cardiovascular autonomic reflex tests as the gold standard for autonomic neuropathy and measuring of thresholds for constant current electric sine wave stimulation by neurometer were used for measuring sensory neuropathy in patients with chronic liver diseases of different etiology. Autonomic and sensory neuropathy was also observed in non-alcoholic liver diseases. We proved that there is a correlation between autonomic neuropathy and prolongation of corrected QT interval in chronic liver diseases. We claim that autonomic neuropathy may have a role to play in the development of hyperdynamic circulation and portal hypertension in chronic liver diseases.

Peripheral sensory nerve dysfunction in children and adolescents with type 1 diabetes mellitus

The aim of the present study was to investigate peripheral sensory nerve function in diabetic children and adolescents without neurological symptoms. Ninety-two children and adolescents with Type 1 (insulin-dependent) diabetes mellitus (mean +/- SD age: 14.2 +/- 2.1 years, diabetes duration: 5.8 +/- 3.0 years) and 80 healthy control subjects (age: 13.8 +/- 2.2 years) matched for age, sex, body mass index, and height standard deviation score were involved in the study. Using a sine-wave transcutaneous stimulator, current perception threshold (CPT) testing at 2000, 250 and 5 Hz was performed on the left median and peroneal nerves. Diabetic children had increased CPT at 2000 Hz on both nerves as compared to the control group (median (interquartile range), median nerve: 2.43 (2.20-3.43) vs 1.80 (1.51-2.60) mA, p = 0.02; peroneal nerve: 3.51 (2.81-4.82) vs 2.70 (2.04-3.70) mA, p = 0.01). Twenty-one (23%) of patients had CPT values higher than that of any healthy individual. Of these, elevated CPT was observed in 9 (9.8%) patients on the median nerve, in 8 (8.7%) patients on the peroneal nerve, and in 4 (4.3%) patients on both median and peroneal nerves. Using multiple logistic regression analysis, worse long-term metabolic control and advanced puberty were independently predictive of peripheral sensory nerve dysfunction as the dependent variable (adjusted OR (95% CI): 3.4 (1.2-6.2), p = 0.01, and 2.8 (1.1-5.6), p = 0.03, respectively). In conclusion, evidence of peripheral sensory nerve dysfunction is not rare in children and adolescents with diabetes and can be demonstrated by CPT testing in asymptomatic patients. Poor metabolic control is a risk factor for such subclinical neuropathy, and pubertal development may be involved in the pathogenesis of diabetic peripheral neuropathy.

[The place of enalapril in the management of hypertension]

In Hungary the use of angiotensin converting enzyme inhibitor enalapril has emerged as one of the most important drugs in the treatment of hypertension. The aim of our study was to evaluate the antihypertensive effect of enalapril of Hungarian production in combination therapy and alone, according to sexes, to the body mass index, among smokers and non smokers as well as non diabetic and in patients with diabetes (IDDM and NIDDM). The diurnal blood pressure values were registered by a 24 hour ambulatory blood pressure monitor. During the 6 weeks of the enalapril therapy (n = 28) both the daytime (141/84 vs. 135/80 mmHg) and the night-time (130/78 vs. 124/72 mmHg) blood pressure values decreased; the increase of diurnal indices during the therapy (SI/DI 6/8% vs. 8/10) reflect the 24 hour long lasting effect of the drug. The body mass index had no influence on the efficacy of treatment. Our results indicate that enalapril manufactured in Hungary is an effective antihypertensive drug both in monotherapy and in combination, in both sexes (especially in men), irrespective of the body weight, in non-smokers and especially in smokers, in insulin dependent and in non-insulin dependent diabetes mellitus alike.

[Gallbladder hypomotility in diabetic polyneuropathy]

A study was made of the pathogenic role of gallbladder hypomotility, which is presumably responsible for the high incidence of gallstone disease in long-standing diabetes mellitus. The gallbladder motility of diabetic patients (n = 10) was measured by means of quantitative hepatobiliary scintigraphy, and the severity of concomitant autonomic and sensory polyneuropathy was determined. The presence of marked gallbladder hypomotility was proven, and a positive correlation was observed between the severity of autonomic neuropathy and the contractile disorder. In this group of diabetic patients, a hypaesthetic sensory polyneuropathy too was recognized, the degree of which exhibited a positive correlation with the autonomic neuropathy score. This study underlines the important role of the autonomic neural dysfunction in the development of gallbladder hypomotility accompanying long-term diabetes mellitus.

Is autonomic neuropathy a risk factor for severe hypoglycaemia? The EURODIAB IDDM Complications Study

The hypothesis that diabetic patients with autonomic neuropathy are at increased risk of severe hypoglycaemia was examined in an epidemiological study of over 3000 IDDM patients in Europe (EURODIAB IDDM Complications Study). Autonomic function was assessed by two standard cardiovascular tests: change in heart rate and systolic blood pressure on standing. Severe hypoglycaemia was defined as an attack serious enough to require the help of another person. Compared to patients (68%) reporting no attacks in the last year, those reporting one or more attacks were older (34.0 +/- 10.7 vs 32.1 +/- 9.9 years, mean +/- SD, p < 0.0001), had had diabetes for a longer period (16.6 +/- 9.5 vs 13.8 +/- 9.1 years, p < 0.0001), had better glycaemic control (HbA1c 6.4 +/- 1.8 vs 6.9 +/- 1.9%, p < 0.0001) and were more likely (p = 0.002) to have abnormal responses to both autonomic tests (13.0 vs 7.7%). A single abnormal autonomic response was not associated with an increased risk of severe hypoglycaemia. The odds ratio for severe hypoglycaemia in people with abnormal responses to both autonomic tests, compared to those with normal responses, was 1.7 (95% confidence interval 1.3, 2.2) after controlling for age, duration of diabetes, glycaemic control and study centre. In conclusion, a combined autonomic deficit in heart rate and blood pressure responses to standing is associated with only a modest increase in the risk of severe spontaneous hypoglycaemia. Although the increase in risk is not large, severe hypoglycaemia was a frequently reported event in this study. IDDM patients with deficient autonomic responses who strive for tight glycaemic control may therefore be at particular risk of severe hypoglycaemia.

Aminophylline fails to improve the outcome of cardiopulmonary resuscitation from prolonged ventricular fibrillation: a placebo-controlled, randomized, blinded experimental study

OBJECTIVES

The purpose of this study was to evaluate systematically the effects of the adenosine antagonist aminophylline on resuscitation outcome in a canine model of postcardioversion nonperfusing rhythm.

BACKGROUND

Theoretic considerations and experimental studies indicate that myocardial adenosine accumulation during prolonged ventricular fibrillation might play a significant role in postcardioversion asystole and electromechanical dissociation. A recent uncontrolled clinical trial has suggested that the adenosine antagonist aminophylline might improve the outcome of cardiopulmonary resuscitation from refractory bradyasystolic cardiac arrest.

METHODS

Two placebo-controlled, randomized, blinded experimental studies were performed. In protocol 1 (20 dogs), ventricular fibrillation was induced and maintained for 7.5 min. Sixty seconds before cardioversion, dogs received 1 mg of epinephrine followed by 250 mg of aminophylline or placebo. In protocol 2 (20 dogs), dogs were cardioverted to electromechanical dissociation after 5 min of unsupported ventricular fibrillation. Sixty seconds later, all dogs received 1 mg of epinephrine followed by 250 mg of aminophylline or placebo. In both experiments, resuscitation efforts were continued until return of spontaneous circulation, or up to 30 min. The primary end point was survival to 1 h.

RESULTS

In protocol 1, 4 of 10 dogs survived in the aminophylline group, whereas 7 of 10 dogs survived in the placebo group, a nonsignificant trend toward unfavorable outcome from aminophylline. Pretreatment with aminophylline increased the number of cardioversion applications required to terminate ventricular fibrillation. In protocol 2, 5 of 10 and 6 of 10 dogs survived in the aminophylline and placebo groups, respectively.

CONCLUSIONS

The results of this study suggest that aminophylline fails to improve the outcome of resuscitation from prolonged ventricular fibrillation. It does not reverse established electromechanical dissociation and may in fact increase the number of cardioversion applications required to terminate ventricular fibrillation. The rationale for conducting clinical trials with aminophylline during cardiopulmonary resuscitation is questionable.

[Autonomic neuropathy in chronic liver diseases]

Autonomic neuropathy has been evaluated by various cardiovascular bedside tests in 172 patients with chronic alcoholism (36 alcoholics without liver disease, 50 patients with fatty liver and 86 with cirrhosis), in 21 patients with HBsAg-positive chronic liver disease, in 14 patients with primary biliary cirrhosis, in 14 patients with cirrhosis of other origin and in 86 healthy controls. Parasympathetic integrity was evaluated by beat-to-beat variation during deep breathing, Valsalva manoeuvre and standing up, sympathetic function by blood pressure response to standing and to sustained handgrip test. Autonomic reflex damage was found in all groups examined. Patients with alcoholic cirrhosis exhibited the most severe alterations. Our results suggest, that chronic hepatopathy itself presents a pathogenetic factor of autonomic neuropathy. Autonomic failure has to be considered as a possible cause of symptoms in liver diseases with all its prognostic consequences.

Catheterization technique for laser photoablation of atrioventricular conduction from the aortic root in dogs

A simple catheterization technique for producing suppression or block of atrioventricular (AV) conduction in dogs by neodymium:YAG (Nd:YAG) laser photocoagulation from the aortic root is described. In 14 canines, electrode catheters were percutaneously advanced to the high right atrium, to the His bundle area at the tricuspid valve (right His [RH]), and the noncoronary cusp of the aortic valve (left His [LH]). A 400 microns optical fiber was fed into the lumen of the LH catheter. Continuous wave Nd:YAG lasing at lambda = 1,064 nm at 15-20 watts was performed at the site of the largest recorded LH deflection, opposite to the RH catheter, until complete AV block (CAVB, group I, eight dogs) or persistent A-H prolongation (AHPr, group II, four dogs) occurred; in two animals, laser photoablation was unsuccessful. CAVB and AHPr were achieved in < 140 seconds of lasing. Mean lasing time was 51 +/- 41 seconds, total energy delivered, 776 +/- 601 J. There were no complications. Dogs were followed for up to 120 days. In group I, 6/6 dogs followed for at least 1 week continued to have CAVB (three AV nodal, five infra-His). In group II, 1/4 dog progressed to infra-His CAVB; 3/4 had depressed AV nodal function. AV block was not reversed by isoproterenol. Aortic root angiograms revealed intact valve function in all. Histology showed various degrees of damage and repair of AV junctional tissue. There were no valvular perforations. Transcatheter Nd:YAG laser photocoagulation of the AV junction from the aortic root is a fast, simple, and safe method for creating AV conduction block in dogs.

Prolongation of the QTc-interval reflects the severity of autonomic neuropathy in primary biliary cirrhosis and in other non-alcoholic liver diseases

It was the aim of our study to prove a potential correlation (a) between laboratory findings of cholestasis and autonomic neuropathy (AN) and (b) between the severity of AN and the prolongation of the corrected QT-time (QTc). The five standard tests of autonomic cardiac neuropathy were investigated. QTc was calculated according to Bazett's formula. 12 out of 14 patients with primary biliary cirrhosis, 18 out of 21 patients with HBsAg positive liver diseases and 11 out of 14 patients with cirrhosis of other origin had AN. No significant correlation between the laboratory parameters of cholestasis and AN was found. Abnormal QTc values (> 440 m/sec) were observed significantly more often (p < 0.002) in patients with AN than in patients without AN. Significant linear regression (p < 0.01) could be confirmed between the prolongation of the QTc-time and the severity of AN. Besides the non-invasive investigation of the cardiovascular reflexes the evaluation of the QT-time might be an additional diagnostic means to identify patients with an increased cardiovascular risk in chronic non-alcoholic liver diseases.

Selective elimination of retrograde conduction by intraoperative neodymium: YAG laser photocoagulation in dogs

OBJECTIVES

The purpose of this study was to test the feasibility of selective elimination of ventriculoatrial (VA) conduction by limited laser photocoagulation of the atrioventricular (AV) node, and to analyze the histologic substrate of unidirectional retrograde block.

BACKGROUND

Atrioventricular node reentry requires intact retrograde conduction.

METHODS

Neodymium:yttrium-aluminum-garnet laser photocoagulation was performed during cardiopulmonary bypass through a right atriotomy in 15 dogs that had intact retrograde conduction before operation. Short laser pulses were delivered to an area between the coronary sinus orifice and the proximal His bundle. The end point of lasing was second-degree AV node block at a paced atrial cycle length of 250 ms.

RESULTS

Complete retrograde block developed immediately in 11 of the 15 dogs (group I), while AV conduction persisted in all 11. In 4 of the 15 dogs (group II), both AV and VA conduction remained intact. During a 3-month follow-up period, retrograde conduction remained absent in all group I dogs. Retrograde block was not reversed by isoproterenol. Anterograde AV node characteristics (Wenckebach cycle length, functional refractory period, ventricular rate during atrial fibrillation) were unchanged in five dogs and modified in six. Complete AV block did not develop. In four control dogs (group III, sham operation), anterograde and retrograde AV node characteristics were unchanged. The anterograde Wenckebach cycle lengths in groups I, II and III at 3 months measured 192 +/- 15 ms, 195 +/- 6 ms and 170 +/- 22 ms, respectively, whereas the retrograde Wenckebach cycle lengths in groups II and III measured 345 +/- 62 ms and 278 +/- 25 ms, respectively. Histologic study at 3 months in cases with unidirectional VA block showed the compact part of the AV node intact with destruction of the atrial approaches and the superficial layers of the proximal end of the node on the right side.

CONCLUSIONS

1) With limited laser photocoagulation of the proximal AV node area, VA conduction can be eliminated and anterograde AV node transmission maintained. 2) Destruction of the atrial approaches on the right side with preservation of the compact part of the AV node may result in unidirectional retrograde block.

Neodymium:YAG contact laser photocoagulation of the in vivo canine epicardium: dosimetry, effects of various lasing modes, and histology

Neodymium:YAG laser photocoagulation (LPC) is an investigational technique for the treatment of drug-resistant postinfarction ventricular tachycardia that requires cardiopulmonary bypass and open heart surgery. The purpose of this experimental study was to evaluate the feasibility of contact epicardial LPC to reach subepicardial, deep myocardial, and subendocardial regions without ventriculotomy and to analyze the dose-response relationships of this new technology. In 24 open-chest, closed heart dogs, a total of 219 epicardial laser lesions were generated under sterile conditions. Laser source was a continuous wave 1064 nm Nd:YAG; the delivery system consisted of a 400 mu bare quartz fiber fed into an 8F electrode catheter in direct contact with the epicardial surface. Laser variables were power at 10-15-20 W; lasing time, 6-12-18-24 s; lasing mode, continuous and pulse-pause; fiber mode, optical fiber tip inside and extending out from the electrode catheter. Hearts were harvested at 1 week. Histologic measurements included lesion surface diameter, internal diameter, and depth.

RESULTS

Significant linear correlation was found between the total delivered energy and all measured lesion parameters. Transmural lesions were found at energy levels of 270-480 J. Maximum depth measured up to 1.68 cm; at high energies, it was limited by myocardial thickness only. At constant energy levels, power and lasing time did not independently affect lesion dimensions; lasing mode and fiber mode had statistically significant but minor effects. Laser lesions were homogeneous and sharply demarcated without epicardial crater or endocardial thrombus formation. Endocardial surface cooling by circulating blood and the presence of epicardial vessels resulted in modifications in lesion morphology. In 29 out of 74 grossly transmural lesions, there was a 0.082 +/- 0.127 cm thin surviving subendocardium. Forty-five coagulation lesions were truly transmural with no surviving myocardial strands. In conclusion, contact epicardial LPC can result in deep, transmural myocardial coagulation lesions. Lesion dimensions can be adequately controlled by total delivered energy. Closed heart epicardial Nd:YAG laser photocoagulation could become a new, less invasive surgical technique for the treatment of drug-resistant ventricular tachycardia.

Severe symptomatic atrioventricular block induced by pilocarpine eye drops

An 89-year-old man with chronic glaucoma received hourly pilocarpine eye drops for seven hours, when he developed third-degree atrioventricular block with a slow idioventricular escape rate. After discontinuing the pilocarpine, the atrioventricular block gradually disappeared. The site of pilocarpine-related block was most likely within the His-Purkinje system.