Tilt table testing for assessing syncope. American College of Cardiology.
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Adult↗
Biomedical subjects
R Sutton
Publications and source records attributed to R Sutton.
Possible discrimination of Gitelman's syndrome from Bartter's syndrome.
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Bartter Syndrome↗
Progressive disruption of acinar cell calcium signaling is an early feature of cerulein-induced pancreatitis in mice.
BACKGROUND & AIMS: Disruption of pancreatic exocrine secretion is an important feature of acute pancreatitis. Because cytosolic calcium is a key intracellular messenger controlling pancreatic secretion, this study examined patterns of calcium signaling during the early stages of cerulein-induced pancreatitis. METHODS: Mice were administered hourly intraperitoneal injections of cerulein (50 micrograms/kg), and paired controls were administered saline. Acini were isolated by collagenase from pancreatic tissue harvested after injections 1, 3, 5, and 7 and were loaded with Fura-2. Individual cellular calcium responses to acetylcholine and cholecystokinin were studied using digital imaging. RESULTS: The proportion of cells maintaining a normal oscillatory calcium response to physiological secretagogue stimulation diminished progressively after increasing cerulein injections. Also, the normal polarized spatial pattern of calcium Increase within individual acinar cells was progressively lost. A sustained response to high-dose stimulation was maintained but with diminishing amplitude. The characteristic calcium response to the Ca(2+)-adenosine triphosphatase inhibitor thapsigargin was maintained, implying that calcium reuptake and extrusion were not impaired. CONCLUSIONS: Progressive disruption of physiological patterns of pancreatic acinar cell calcium signaling, notably in the secretory pole of the cell, is an early feature of pancreatitis induced by cerulein hyperstimulation. These changes may be important in contributing to the disruption of exocrine secretion in acute pancreatitis.
Acetylcholine↗
Cost benefit analysis of single and dual chamber pacing for sick sinus syndrome and atrioventricular block. An economic sensitivity analysis of the literature.
The benefits of dual (DDD) over single chamber pacing (VVI) have been demonstrated in haemodynamics, exercise capacity, quality of life and reduced complications in atrioventricular block and sick sinus syndrome. The literature was reviewed to provide complication rates for dual and VVI pacing. Cost calculations were based on United Kingdom 1991 prices. Over a 10-year period, a computer model calculated the incidence and prevalence of atrial fibrillation, stroke, permanent disability, heart failure and mortality in six patient categories: sick sinus syndrome paced VVI, sick sinus syndrome upgraded to DDD, sick sinus syndrome paced DDD from outset, atrioventricular block paced VVI and those upgraded to DDD and atrioventricular block paced initially DDD. Calculations were based on intention to treat. The 10 year survival with DDD vs VVI pacing was 71% vs 57% in sick sinus syndrome and 61% vs 51%, respectively, in atrioventricular block. In both indications the prevalence of heart failure in the 10 year survivors was 60% lower with DDD pacing. In sick sinus syndrome patients paced VVI, 36% had severe disability while only 8% experienced this with DDD pacing. For atrioventricular block the figures were, respectively, 22% vs 3%. The difference in 10 year cumulative cost between VVI and DDD is 13 times the purchase price of a VVI pulse generator for sick sinus syndrome and 7 times for atrioventricular block. In the third year after implantation the cumulative costs of DDD were lower than for VVI for both indications. Dual chamber pacing for both indications, sick sinus syndrome and atrioventricular block, is both clinically and cost effective.
Atrial Fibrillation↗
Dual sensor pacing technology.
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Arrhythmias, Cardiac↗
Guidelines for pacemaker follow up. Report of a British Pacing and Electrophysiology Group (BPEG).
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Clinical Protocols↗
Octreotide in the control of post-sclerotherapy bleeding from oesophageal varices, ulcers and oesophagitis.
Bleeding from oesophageal varices, oesophageal ulcers or oesophagitis is occasionally massive and difficult to control. Octreotide, a synthetic analogue of somatostin lowers portal pressure and collateral blood flow including that through varices, increases lower oesophageal sphincter pressure, and inhibits the gastric secretion of acid as well as pepsin. Our current experience suggests it is effective in controlling acute variceal haemorrhage. Therefore we have examined the efficacy of octreotide in the control of post-sclerotherapy bleeding from oesophageal varices, oesophageal ulcers and oesophagitis. During the study period 77 patients experienced a significant gastrointestinal bleed (blood pressure < 100 mm Hg, pulse > 100 beats per min or the need to transfuse 2 or more units of blood to restore the hemoglobin level) following injection sclerotherapy of oesophageal varices. The source of bleeding was varices in 42 patients, oesophageal ulcers in 31 and oesophagitis in 4. All patients received a continuous intravenous infusion of octreotide (50 micrograms/h) for between 40-140h. If bleeding was not controlled in the first 12h after commencing octreotide hourly bolus doses (50 micrograms) for 24h were superimposed on the continuous infusion. Haemorrhage was successfully controlled by an infusion of octreotide in 38 of the 42 patients with bleeding from varices, in 30 of 31 patients with oesophageal ulceration, and all patients with oesophagitis. In the 1 patient with persistent bleeding from oesophageal ulceration and in 2 of the 4 with continued haemorrhage from varices, haemostasis was achieved by hourly boluses of 50 micrograms octreotide for 24h in addition to the continuous infusion. No major complications were associated with octreotide administration. The results of this study clearly indicate that octreotide is a safe and effective treatment for the control of severe haemorrhage after technically successful injection of sclerotherapy.
Adult↗
Abnormalities of gastric emptying in portal hypertension.
OBJECTIVES: To investigate: 1) the rate of gastric emptying of portal hypertensive patients and 2) whether alterations in gastric emptying play any role in the development of portal hypertensive gastropathy. METHODS: Fifty patients (37 with esophageal varices) with cirrhosis and seven with extrahepatic portal hypertension underwent upper GI endoscopy followed by radionuclide gastric emptying studies using a semi-solid meal. Twenty-six patients also under went corrected wedged hepatic venous pressure measurement. Sixteen normal subjects underwent gastric emptying studies only. RESULTS: Varices were completely obliterated by sclerotherapy in 17 patients and were patent in 27. Thirty-seven patients had portal hypertensive gastropathy, 25 of whom had mild changes and 12 severe. No significant difference in gastric emptying was observed between patients with mild and severe portal hypertensive gastropathy and between those with portal hypertensive gastropathy and a normal gastric mucosa. There was no significant difference in gastric emptying between normal subjects and portal hypertensive patients although the latter group showed a tendency for faster gastric emptying. No difference in the rate of gastric emptying was observed between portal hypertensive patients with intrahepatic and extrahepatic pathology. However, patients with esophageal varices (patent and obliterated) emptied their stomachs significantly faster than those without (p = 0.01). There was no correlation between the rate of gastric emptying and corrected wedged hepatic venous pressure. CONCLUSIONS: It would appear that, although alterations in gastric emptying are common in portal hypertension, gastric emptying does not appear to play a causative role in the mucosal changes characteristic of portal hypertensive gastropathy.
Analysis of Variance↗
Is there an effective pharmacological treatment in the prevention of vasovagal syncope?
Many studies have claimed successful pharmacological prevention of vasovagal syncope in open formats with a wide variety of drugs. However, when therapy has been subjected to clinical trial to date no drug has shown any real benefit but it is necessary to add that the means of assessment leave much to be desired. These are repeat tilt testing, reported symptoms, analysis of syncopal burden in a population and time to syncopal recurrence. The disadvantages of any parameter derived from tilt testing is that its reproducibility is open to question and other aspects such as tilt duration before syncope have been inadequately investigated. With respect to symptom recurrence there are limitations because of the well known occurrence of vasovagal syncope in clusters and the long trial time that it is necessary because of relatively infrequent attacks. Furthermore, there is a placebo effect of the investigation of syncope which may delay the first recurrence. The first large trial is now underway and it is hoped that it may offer a method of prevention of vasovagal syncope which is both effective and acceptable.
Drug Evaluation↗
Is an elevated concentration of acinar cytosolic free ionised calcium the trigger for acute pancreatitis?
The pathogenesis of acute pancreatitis is poorly understood, despite well-recognised precipitating factors. Current evidence suggests that the earliest abnormalities of acute pancreatitis arise within acinar cells, but the key intracellular trigger has yet to be identified. Within the pancreas, physiological concentrations of secretagogues bind to G-protein-linked cell-surface receptors on acinar cells, evoking short, oscillatory spikes of acinar cytosolic-free ionised calcium ([Ca2+]i), an ubiquitous intracellular messenger. Specific effects within acinar cells include initiation of enzyme release through the phosphorylation cascades of stimulus-secretion coupling. Low resting levels of [Ca2+]i are restored by Ca(2+)-ATPase, which pumps calcium into the endoplasmic reticulum and out of the cell. If high concentrations of [Ca2+]i persist, toxicity results, intracellular signalling is disrupted, and cell damage occurs. Sustained elevations in acinar [Ca2+]i result from exposure to high concentrations of secretagogues, high doses of which also induce acute pancreatitis. Similarly, sustained elevations of [Ca2+]i may result from ductal hypertension, alcohol, hypoxia, hypercalcaemia, hyperlipidaemia, viral infection, and various drugs--all factors known to precipitate acute pancreatitis. We suggest that these factors precipitate acute pancreatitis by causing either excessive release of acinar [Ca2+]i, or damage to the integrity of mechanisms that restore low resting levels of [Ca2+]i, and that the consequent calcium toxicity is the key trigger in the pathogenesis of acute pancreatitis.
Acute Disease↗
Cardiac pacing for prevention of recurrent vasovagal syncope.
PURPOSE: To review the status of cardiac pacing for the treatment of patients with recurrent vasovagal syncope. DATA SOURCES: A MEDLINE search for English- and French-language articles published between 1980 and 1994 about cardiac pacing for prevention or treatment of vasovagal syncope. The term cardiac pacing was used in conjunction with the terms vasovagal, neurally mediated, or neurocardiogenic syncope, but not with the term carotid sinus hypersensitivity. STUDY SELECTION: Case reports and series from peer-reviewed journals were selected if they documented the presence of vasovagal syncope and assessed pacing effectiveness using tilt-table testing, clinical follow-up, or both. Four case reports and four series met these criteria. DATA EXTRACTION: Findings were summarized individually. Statistical analysis of combined data was inappropriate given differences among studies in patient selection, testing, and follow-up. RESULTS: Pacing may be useful in selected patients with predominantly cardioinhibitory vasovagal responses. Pacing alone may eliminate symptoms in 25% of these patients and may prevent abrupt cardiovascular collapse in others (such as those in whom syncope occurs with minimal or no premonitory sensation). However, interpretation of most available reports has been limited both by the uncertainty associated with using the tilt-table technique to assess pacing effectiveness and by relatively short-term follow-up. CONCLUSIONS: The usefulness of cardiac pacing for patients with recurrent vasovagal syncope remains only partly understood. Randomized controlled trials are needed for this and other aspects of the treatment of this condition. Additionally, substantial room remains for innovation both in earlier recognition of imminent vasovagal syncope by implantable devices and in specifically designing cardiac pacing algorithms for treatment of this condition.
Algorithms↗
Growth factor expression in skin during wool follicle development.
A variety of growth factors are likely to be involved in initiation and morphogenesis of wool follicles. To enable direct comparisons of the expression of different growth factors, reverse transcriptase-polymerase chain reactions (RT-PCR) were developed for ovine and murine TGF alpha, TGF beta 1, TGF beta 2, TGF beta 3, IGF1, IGF2, and FGF-2, which could all be carried out on a single cDNA sample. These RT-PCR were used with 16 sheep RNA samples from different foetal stages, neonatal sheep and mouse skin. The mRNAs for these growth factors were detected throughout gestation in sheep skin, except for TGF beta 1 mRNA which was not expressed in 51-day-old skin, but was expressed in 54-day and older samples. Since the first microscopically visible changes of follicle initiation occur around 62 days gestation, these results suggest that TGF beta 1 expression may be a signal for follicle initiation.
Animals↗
Intrathecal baclofen--a multicentre clinical comparison of the Medtronics Programmable, Cordis Secor and Constant Infusion Infusaid drug delivery systems.
A retrospective review was carried out of 34 consecutive traumatic spinal cord damaged patients who have had the Medtronics Programmable, Cordis Secor or Constant Infusion Infusaid intrathecal baclofen drug delivery systems inserted between July 1987 and 1992. The results indicate that whilst this treatment has many benefits there is a significant risk of complications, some potentially fatal. It should only be provided by a skilled and experienced team. The Medtronics Programmable pump is an excellent pump. It is of particular benefit where the therapeutic window is small or fine-tuning required. The Constant Infusion Infusaid is adequate if less precise control and continuous infusion is sufficient. It is of particular benefit in financially disadvantaged countries. The Cordis Secor device is helpful when unpredictable intermittent relief of spasticity is required but is otherwise limited by its complication rate.
Adolescent↗
The clinical spectrum of neurocardiogenic syncope.
Neurocardiogenic syncope is a collective term used to describe the clinical syndromes of syncope that result from inappropriate, and often excessive, autonomic reflex activity, and manifest as abnormalities in the control of vascular tone and heart rate. These include carotid sinus syndrome, vasovagal syncope, and the syndromes of cough, deglutition, and micturition syncope. Orthostatic hypotension, which, in contrast, results from a failure of autonomic reflexes, is not considered part of this family of closely related syndromes. This review will focus on vasovagal and carotid sinus syndromes.
Cardiovascular Diseases↗
Oxygenator evaluation: Maxima 1380 versus Maxima Plus.
Continual improvement of oxygenators has been important in the growing demands of patient safety and support during cardiopulmonary bypass. The purpose of this study was to compare the Maxima 1380 oxygenator to the upgraded Maxima Plus oxygenator. Thirty-two adult patients were randomized to either the 1380 group or the Plus group. Information was recorded on the patients' weight, age, body surface area, esophageal temperature, arterial temperature, venous oxygen saturation, arterial pO2, arterial pCO2, blood flow, hematocrit, gas sweep, and FiO2. No significant difference was found between the two groups' mean weight, body surface area, arterial pO2 arterial pCO2, age, esophageal temperature, arterial temperature, venous oxygen saturation, and blood flow (p > 0.05). The Plus group demonstrated significantly lower mean gas sweep rates and FiO2 settings than the 1380 group. FiO2 of the 1380 was dependent on age, body surface area, blood flow, and esophageal temperature (r = 0.89, p < 0.001). FiO2 of the Plus was correlated with weight, esophageal temperature, arterial temperature, and arterial pO2 (r = 0.93, p < 0.001). Gas sweep rate of the 1380 was dependent on age, weight, esophageal temperature, blood flow, arterial temperature, and arterial pCO2 (r = 0.84, p < 0.001). The gas sweep rate of the Plus was dependent on weight and esophageal temperature (r = 0.55, p < 0.001). Based on these analyses, the new Maxima Plus oxygenator is more efficient in oxygen and carbon dioxide transport than the Maxima 1380.
Adult↗
Evaluation of five in-line hematocrit monitors.
Monitoring the hematocrit is essential during cardiopulmonary bypass for efficacious administration of blood products. The purpose of this study was to evaluate five cardiopulmonary bypass in-line monitors designed to display continuous hematocrit or hemoglobin values. The devices were evaluated for accuracy using an in vitro circuit primed with human blood while randomizing hematocrit, blood flow rate, and temperature. Hematocrits correlated significantly with the error in all the devices (p < 0.01). Over evaluation time, the error of the CDI, Gish, IBC, and MX2 increased significantly (p < 0.05). Temperature correlated significantly with the error of the Gish device (r = -0.49, p < 0.01). Blood flow correlated significantly with the Gish error (r = -0.24, p < 0.01). The Cobe device had a significantly smaller overall error than the other devices (p < 0.001). Device evaluation, based on a low mean error, a low percent error, a high correlation with the actual hematocrit, low correlations between mean error, blood flow, and temperature, and insignificant correlation between time and error, suggests that the Cobe device is more accurate for the continuous monitoring of hematocrit during cardiopulmonary bypass.
Blood Circulation↗
Psychogenic syncope diagnosed by prolonged head-up tilt testing.
Four patients with 'syncope' during prolonged head-up tilt testing despite normal blood pressure and heart-rate behaviour are described. They represent 5.5% of all positive tilt-test outcomes from a prospective study of 181 consecutive patients with unexplained syncope. All four patients were female, and were both younger and more symptomatic than patients with vasovagal syncope or orthostatic hypotension. In three of the patients, clinical episodes of syncope were observed which closely resembled those provoked during tilt. It is suggested that the tilt response is psychogenic and reveals a psychiatric cause for recurrent syncope.
Adolescent↗
Alcohol and oesophageal varices.
Oesophageal varices are abnormally dilated veins that develop beneath the mucosa of the lower oesophagus and upper stomach and cause profound gastrointestinal haemorrhage associated with a high mortality. Varices develop in the presence of protal hypertension, which, in Europe and the USA, is most commonly due to alcoholic cirrhosis of the liver. Alcoholic cirrhosis develops in 10-20% of chronic ethanol abusers as a result of prolonged hepatocyte damage, leading to centrilobular inflammation and fibrosis. The net effect on the portal venous system is an elevation of resistance, and/or increase of inflow, producing portal hypertension, and the development of collateral channels in the form of varices. Such parenchymal liver disease also causes ascites, clotting deficiencies, secondary malnutrition and hepatic encephalopathy, all of which contribute to the high mortality associated with variceal haemorrhage. Variceal bleeding is more likely to occur when the varices are large, long and numerous, with surface red markings, and may be precipitated to respiratory tract infection, non-steroidal anti-inflammatory drugs, alcohol, or may occur spontaneously. Once identified by endoscopy, the aims of management are to control the haemorrhage, to prevent recurrent haemorrhage, and to treat the underlying cause of portal hypertension. Attention to nutrition and long-term rehabilitation are particularly important in those alcoholic cirrhotic patients who survive.
Alcoholism↗