Thalamic deep-brain stimulation for movement disorders due to multiple sclerosis.
Explore the source record for details and available documents.
Electric Stimulation Therapy↗
Biomedical subjects
J Hooper
Publications and source records attributed to J Hooper.
Treatment of milrinone-associated tachycardia with beta-blockers.
PURPOSE: To describe a case of milrinone-associated tachycardia that was successfully treated with two beta-blockers. CLINICAL FEATURES: A 74-yr-old male patient underwent elective abdominal aortic aneurysm repair under combined epidural/general anaesthesia. He had a history of alcohol abuse, controlled hypertension and ischaemic heart disease. Postoperatively, the patient had persistent sinus tachycardia that was initially unsuccessfully treated with metoprolol. Subsequently, the patient's blood pressure and cardiac index decreased with an associated increase in pulmonary artery pressure. Analysis of the ST-segment revealed no evidence of myocardial ischaemia or infarction. These haemodynamic changes were treated with milrinone which exacerbated the baseline tachycardia without adverse blood pressure response. The subsequent administration of beta-blockers (esmolol and metoprolol) was successful in controlling the heart rate response to milrinone without adversely affecting the patient's haemodynamic profile. CONCLUSION: This report demonstrates the efficacy of esmolol and metoprolol for the treatment of milrinone-associated tachycardia, without compromising the haemodynamic effects of milrinone.
Adrenergic beta-Antagonists↗
Advances in mechanical ventilation.
Explore the source record for details and available documents.
Animals↗
Dopamine clearance in critically ill patients.
OBJECTIVE: To examine the validity of the low-dose "renal" dopamine regimen in critically ill patients by investigating the steady-state clearance of dopamine. DESIGN: A prospective clinical study. SETTING: Teaching hospital intensive care unit. PATIENTS: 48 haemodynamically stable patients receiving a dopamine infusion. INTERVENTIONS: Sampling of arterial blood and dopamine infusates. MEASUREMENT AND RESULTS: Plasma and infusate dopamine levels were measured by liquid chromatography with electrochemical detection. Steady-state clearance was determined by dividing the actual infusion rate by the steady-state plasma concentration. Dopamine clearance for the whole group was 46.4 +/- 35.9 ml/kg per min (mean +/- SD), which is significantly lower than 70 +/- 15.2 ml/kg per min reported for elective surgical patients (p = 0.01). Twelve patients with renal dysfunction had significantly lower dopamine clearances (36 +/- 16.6 ml/kg per min) than the remaining 36 patients (61 +/- 38.5 ml/kg per min, p = 0.022). There was a very poor correlation between plasma dopamine level and infusion rate for the group as a whole (r = 0.47), and this worsened (r = 0.31) when only those patients on a "renal" dose of 2-5 microg/kg per min were considered (n = 30). CONCLUSION: Plasma dopamine clearance is lower in critically ill patients and there is a large interindividual variation. It is therefore impossible to predict the plasma level from the infusion rate. Consequently, the concept of a selective renovascular low-dose dopamine infusion is invalid in critically ill patients.
Adult↗
Rater reliability of Fahn's tremor rating scale in patients with multiple sclerosis.
OBJECTIVE: Assessment of movement disorders in patients with multiple sclerosis (MS) is difficult because of the complex nature of the movement disorders. The aim of this study was to determine the reliability of Fahn's Tremor Rating Scale (FTRS) in assessing movement disorders in patients with MS. METHOD: Videos were made of 10 patients with MS showing their rest, postural, action/intention, and goal-related movement disorders as well as their performance of spirometry, a volumetric task, and timed functional tasks. Ratings of tremor were carried out by one rater on two occasions 3 months apart and by 8 raters on one occasion using FTRS. RESULTS: Intrarater reliability was generally very good, with no significant "drift" in ratings over time. Interrater reliability was generally good, with some variation in interpretation of scoring criteria that may reflect raters' backgrounds. CONCLUSION: The FTRS is a reliable and potentially useful tool with which to assess movement disorders in patients with MS.
Activities of Daily Living↗
Deficient insulin-like growth factor I in chronic heart failure predicts altered body composition, anabolic deficiency, cytokine and neurohormonal activation.
BACKGROUND: Recent studies of growth hormone supplementation in chronic heart failure have been associated with variable results. Acquired abnormalities of biochemical parameters of the growth hormone insulin-like growth factor I axis have been associated with severe chronic heart failure. There are suggestions of an acquired growth hormone resistance with deficient insulin-like growth factor I in some patients. OBJECTIVES: Therefore, we set out to investigate the clinical and functional status and the degree of cytokine and neurohormonal alteration of chronic heart failure patients with deficient insulin-like growth factor I responses. METHODS: Patients with chronic heart failure were divided into two groups according to their insulin-like growth factor I levels (classified according to the manufacturer's assay range in normal controls): low insulin-like growth factor I <104 (n = 20; 89 +/- 9.6 ng/ml), and normal/high >104 ng/ml (n = 32; 169 +/- 52 ng/ml). Between groups there was no difference in age (low versus high: 65.3 +/- 12.1 versus 61.6 +/- 9.1 years, p = 0.21), body mass index, aerobic capacity (peak oxygen consumption: low versus high: 15.5 +/- 5.2 versus 17.3 +/- 6.3 mL/kg/min, p = 0.23), left ventricular ejection fraction, New York Heart Association classification. RESULTS: During quadriceps strength testing, patients with low insulin-like growth factor I had reduced absolute strength (-24%), and strength per unit area muscle (- 14%) than patients with normal/high insulin-like growth factor I. Leg muscle cross-sectional area was lower in the low insulin-like growth factor I group (-12% and -13% for right and left legs, respectively). These alterations were accompanied by increased levels of growth hormone (+145%), tumor necrosis factor-alpha (+46%), cortisol/ dehydroepiandrosterone ratio (+60%), noradrenaline (+49%) and adrenaline (+136%) (all at least p < 0.05). CONCLUSIONS: Patients with low insulin-like growth factor I levels show signs of altered body composition, cytokine and neuroendocrine activation, to a greater extent than patients with normal/high levels.
Adrenergic alpha-Agonists↗
Gastro-intestinal protein loss in late survivors of Fontan surgery and other congenital heart disease.
AIMS: Protein losing enteropathy is a serious complication of Fontan surgery. The aim of this study was to investigate gastro-intestinal protein loss in adults with congenital heart disease, both with and without Fontan surgery, and to correlate findings with systemic venous pressure. METHODS AND RESULTS: Forty eight patients were studied. The first group included adult survivors of Fontan surgery. The second and third groups were control patients with congenital heart disease who had not had Fontan surgery and had either normal or chronically elevated systemic venous pressure. Gastro-intestinal protein loss was assessed by measurement of faecal alpha-1-antitrypsin. Faecal alpha-1-antitrypsin levels were significantly higher in the Fontan group (0.55 +/- 0.15 mg. g-1 faeces, P = 0.002) and the control group with chronically elevated venous pressure (0.60 +/- 0.30 mg. g-1 faeces, P < 0.001) compared to the controls with normal venous pressure (0.29 = 0.12 mg. g-1 faeces). Of the 15 subjects who were found to have increased gastro-intestinal protein loss, only four had clinical protein-losing enteropathy. The degree of gastro-intestinal protein loss correlated significantly with venous pressure (P = 0.01) and with serum aspartate transaminase (P = 0.04). CONCLUSION: Increased gastro-intestinal protein loss is common in this select group of late survivors of Fontan surgery and in other subjects with congenital heart disease and chronic elevation of systemic venous pressure, and was present in patients who did not have protein-losing enteropathy. Increased faecal alpha-1-antitrypsin is an important finding in these patients as intervention at this stage, before the onset of florid protein-losing enteropathy, might prevent the development of further complications.
Adult↗
Intraoperative release of troponin T in coronary venous and arterial blood and its relation to recovery of left ventricular function and oxidative metabolism following coronary artery surgery.
OBJECTIVE: To investigate the intraoperative release of troponin T during uncomplicated coronary artery surgery and to determine its relation to ischaemic time and to recovery of left ventricular function and oxidative metabolism. DESIGN: A prospective observational study. SETTING: Cardiac surgical unit in a tertiary referral centre. METHODS: Troponin T, creatine kinase, and lactate were analysed from arterial and coronary sinus samples taken before operation, and 1, 4, 6, 10, 20, 35, and 45 minutes after cross clamp release. Net myocardial troponin T release and lactate extraction were derived from their respective arteriovenous differences. Haemodynamic measurements were made using a thermodilution pulmonary artery catheter. PATIENTS: 45 patients, mean (SD) age 62 (9) years, with two or three vessel coronary artery disease and chronic stable angina undergoing routine coronary artery surgery. RESULTS: Before operation, troponin T concentrations were not raised, but within one minute of cross clamp release they increased progressively in both coronary sinus and arterial blood for the entire 45 minutes of reperfusion studied. Coronary sinus troponin T concentrations were consistently higher than arterial concentrations at all time points (p < 0.001), indicating net troponin T release by the myocardium. Peak net troponin T release and area under the curve of net troponin T release correlated closely with ischaemic time (r = 0.58 and r = 0.61, p < 0.0001 for both). Area under the curve of arterial troponin T concentration was also significantly correlated with ischaemic time (r = 0.44, p < 0.01). Patients with cross clamp times longer than 72 minutes (upper quartile for ischaemic time) had greater troponin T release, delayed reversion to lactate extraction, and lower left ventricular stroke work index three hours after surgery, compared with patients who had short (< 50 minutes, lower quartile) and intermediate (51-71 minutes, interquartile) cross clamp times. Peak net troponin T release and area under the curve of arterial troponin T concentration were inversely correlated with left ventricular stroke work index three hours after surgery (r = -0.57, r = -0.38, p < 0.01). CONCLUSIONS: Troponin T concentrations increased in every patient after cross clamp release, and were consistently higher in coronary sinus blood than in arterial blood, indicating net myocardial release of troponin T during the period of reperfusion. Intraoperative net troponin T release has functional significance, as it is closely related to ischaemic time and reflects delayed recovery of left ventricular function and oxidative metabolism; therefore, its measurement may contribute to the perioperative assessment of myocardial injury sustained during coronary artery surgery.
Biomarkers↗
Log-jam in acid-base education and investigation: why make it so difficult?
Medical students frequently have difficulty in interpreting acid-base data particularly when pH values are used. The difficulty persists when students qualify and has implications for the safe management of patients who require investigation of acid-base status. Simplification of tuition is required together with a change of practice in the reporting of acid-base data by the laboratories. To improve understanding, we recommend that the teaching and reporting of acid-base status should be changed to use [H+] instead of pH, and a greater emphasis placed on the logical interpretation of primary measurements--that is [H+] and PCO2--with less reliance on derived variables.
Acid-Base Equilibrium↗
Can C reactive protein or troponins T and I predict outcome in patients with intractable unstable angina?
OBJECTIVE: To determine whether a single blood test for the measurement of C reactive protein, or troponin I or T concentrations could be used to stratify patients with intractable unstable angina awaiting transfer for coronary angiography by correlating these values with coronary anatomy and transient myocardial ischaemia. DESIGN: Prospective study. SETTING: Tertiary cardiac unit. PATIENTS: All patients admitted to their local hospital with ischaemic chest pain, uncontrolled by medical treatment, in whom acute myocardial infarction had been excluded by serial measurement of creatine kinase and lack of Q waves on ECG. INTERVENTION: Coronary angiography and ST segment monitoring for 24 hours. MAIN OUTCOME MEASURES: Concentrations of C reactive protein, troponins T and I, coronary anatomy, presence of transient myocardial ischaemia. RESULTS: Median C reactive protein, troponin I, and troponin T concentrations were 17.1 mg/dl (4.8 to 203.9), 0.05 microgram/l (0 to 7.8), and 0.0 microgram/l (0 to 2.51), respectively. Seven patients (10%) had normal coronaries and 14, 20, and 31 had one, two, or three vessel coronary disease, respectively. Nineteen (26%) had transient myocardial ischaemia, 33 (46%) had complex lesion morphology, and six (8%) had intracoronary thrombus. Of the three markers, troponin T alone was higher in patients with multivessel disease (p < 0.05) and in those with transient myocardial ischaemia (p < 0.05), but there was no significant relation between C reactive protein, troponin T or I and lesion morphology or thrombus. CONCLUSIONS: In patients transferred to a tertiary centre with intractable chest pain, C reactive protein and troponin I are not predictive of transient myocardial ischaemia or lesion morphology, both of which are surrogate markers of outcome. Troponin T is, however, raised in patients with multivessel disease or transient myocardial ischaemia. These serum protein assays cannot be used to stratify the risk of patients with unstable angina who are awaiting transfer to the tertiary centre.
Adult↗
Random blood glucose alone in the diagnosis of cystic fibrosis related diabetes.
Explore the source record for details and available documents.
Adult↗
Effects of age and ischemic times on biochemical evidence of myocardial injury after pediatric cardiac operations.
INTRODUCTION: The vulnerability of pediatric myocardium to ischemia is poorly documented in the clinical setting. METHODS: Serial measurements of serum concentrations of myoglobin, the MB isoenzyme of creatine kinase, and cardiac troponins T and I and their respective areas under the curve were obtained, with particular reference to age and ischemic time, in 80 children undergoing cardiac operations. Sixteen (the control group) did not require cardiopulmonary bypass and 64 did. RESULTS: In the control group there were increases (p < 0.01) in myoglobin and creatine kinase MB isoenzyme but no increase in cardiac troponin T or I; by contrast, the group treated with cardiopulmonary bypass had significant increases in all four markers but with differing temporal patterns. Younger age (especially < 12 months) was a highly significant explanatory variable only for the release of cardiac troponins T and I, and ischemic time was a significant explanatory variable for the release of creatine kinase MB isoenzyme, cardiac troponins T and I, but not myoglobin. In comparison with previous studies in adults, creatine kinase MB and cardiac troponin T concentrations were three times greater in children than in adults. CONCLUSIONS: This study supports the specificity of cardiac troponins T and I as markers of myocardial injury after pediatric cardiac operations and defines the importance of age and ischemic time in determining their release. In comparison with previous data in adults, our results raise the possibility that the pediatric heart may be more vulnerable to the effects of ischemia and reperfusion. Cardiac troponins will permit comparison of new myocardial protective strategies or other potentially therapeutic myocardial interventions.
Adult↗
Ischaemic preconditioning reduces troponin T release in patients undergoing coronary artery bypass surgery.
OBJECTIVE: To investigate whether ischaemic preconditioning could reduce myocardial injury, as manifest by troponin T release, in patients undergoing elective coronary artery bypass surgery. DESIGN: Randomised controlled trial. SETTING: Cardiothoracic unit of a tertiary care centre. PATIENTS: Patients with three vessel coronary artery disease and stable angina admitted for first time elective coronary artery bypass surgery were invited to take part in the study; 33 patients were randomised into control or preconditioning groups. INTERVENTION: Patients in the preconditioning group were exposed to two additional three minute periods of myocardial ischaemia at the beginning of the revascularisation operation, before the ischaemic period used for the first coronary artery bypass graft distal anastomosis. MAIN OUTCOME MEASURE: Serum troponin T concentration at 72 hours after cardiopulmonary bypass. RESULTS: The troponin T assays were performed by blinded observers at a different hospital. All patients had undetectable serum troponin T (< 0.1 microgram/l) before cardiopulmonary bypass, and troponin T was raised postoperatively in all patients. At 72 hours, serum troponin T was lower (P = 0.05) in the preconditioned group (median 0.3 microgram/l) than in the control group (median 1.4 micrograms/l). CONCLUSIONS: The direct application of a preconditioning stimulus in clinical practice has been shown, for the first time, to protect patients against irreversible myocyte injury.
Adenosine Triphosphate↗
Plasma brain natriuretic peptide concentrations in patients with chronic mitral regurgitation.
BACKGROUND AND AIMS OF THE STUDY: Patients with chronic mitral regurgitation (MR) are often referred for surgery only after irreversible left ventricular (LV) dysfunction has developed. Our aim was to determine whether plasma brain natriuretic peptide (BNP) concentrations could serve as a marker for early LV dysfunction in this condition. METHODS: Twenty-two patients with isolated chronic MR and echocardiographic evidence of at least moderate regurgitation were studied. RESULTS: Plasma BNP concentrations were significantly higher in patients than in normal volunteers (20.85 +/- 16.9 versus 3.37 +/- 0.9 pmol/l; p = 0.007). Concentrations increased with increasing severity of symptoms and were highest in those in NYHA class IV, but did not correlate with LV dimensions, fractional shortening or left atrial size. Of note, two asymptomatic patients with high BNP concentrations were referred for surgery within the 12-month follow up period due to symptom progression. CONCLUSIONS: Plasma BNP concentrations are elevated in most patients with isolated chronic MR, including those who are asymptomatic with normal LV dimensions. The significance of these findings is uncertain, but they suggest that changes in ventricular physiology occur early in the disease process and before they can be detected echocardiographically. Longitudinal studies are required to determine if patients with high BNP levels have an adverse prognosis and if this can be altered by earlier surgical intervention.
Adult↗
Leg blood flow, metabolism and exercise capacity in chronic stable heart failure.
OBJECTIVES: To assess the metabolic state of skeletal muscle during exercise in patients with chronic heart failure (CHF) and relate this to exercise capacity. BACKGROUND: During exercise in CHF, there is little relation between exercise capacity and central haemodynamic function. Skeletal muscle and limb blood flow are abnormal in CHF. We investigated the relationship between leg blood flow, metabolism and exercise capacity and ventilation in 10 patients (average age 63.3 +/- 6.0 years; 3 female) with stable CHF. METHODS: Patients undertook maximal exercise testing. Peak oxygen consumption (VO2) and the slope of the relationship between ventilation and carbon dioxide production (VE/CO2 slope) were derived. During a supine cycle exercise test, cardiac output (CO) by Doppler echocardiography, femoral blood flow (FBF) by thermodilution, pulse and blood pressure were recorded, and radial arterial and femoral venous blood samples taken for catecholamine, lactate and potassium estimation every 3 min. RESULTS: The average peak VO2 was 19.7 (+/- 5.2; range 11.3-29.0) ml/kg/min. The proportion of CO to the right leg increased from 0.08 (+/- 0.03) to 0.22 (+/- 0.06) (P < 0.001) at 3 min, with no further significant change thereafter. There was a liner increase in leg VO2 reaching a plateau towards peak. At peak, femoral venous saturation was 22.79% +/- 7.20%. Venous lactate and potassium were higher than arterial (P < 0.001 for each comparison). There was no correlation between exercise performance and any of the measured metabolites either in absolute measurements, expressed as change from rest to peak exercise or as arterio-venous difference. The closest correlate of leg VO2 was leg hydrogen ion production, V[H+]. Change in femoral venous lactate from rest to peak exercise correlated with VE/VCO2 slope even when calculated from before the anaerobic threshold (r = -0.80; P = 0.025). CONCLUSIONS: In CHF, exercise capacity is not determined by individual haemodynamic events, and does not seem to be determined by the possible humoral signals we investigated. Ventilation is abnormal before anaerobic threshold, and predicts subsequent lactate rise, suggesting that skeletal muscle is the origin of excessive ventilation.
Aged↗
Learning clinical biochemistry using multimedia interactive clinical cases.
Explore the source record for details and available documents.
Biochemistry↗
Effects of short-term supplementation with coenzyme Q10 on myocardial protection during cardiac operations.
BACKGROUND: Coenzyme Q10 (CoQ10) is a naturally occurring vitamin-like substance that may have a beneficial role in ischemia-reperfusion injury. Coenzyme Q10 administered either as an additive to cardioplegia or as long-term preoperative oral supplementation has been reported to ameliorate myocardial injury after cardiac operations. METHODS: To determine whether short-term supplementation with large doses of CoQ10 (600 mg in divided doses 12 hours before operation) was effective in myocardial protection, 20 patients with well-preserved left ventricular function (ejection fraction greater than 0.50) undergoing elective coronary revascularization were enrolled in a prospective, double-blind, placebo-controlled randomized trial. Serial concentrations of CoQ10, myoglobin, creatine kinase MD fraction, and cardiac troponin T were measured preoperatively and 1, 6, 24, 72, and 120 hours postoperatively. Efficacy of myocardial protection was also assessed by clinical outcome and serial changes in electrocardiographic indices. RESULTS: The patient groups were similar with respect to preoperative and intraoperative characteristics. There was no significant difference in the preoperative plasma levels of CoQ10. These levels fell significantly in both groups after operation, although the magnitude of the decrease was less in the CoQ10-supplemented group (43% versus 60%). In both groups, there were significant postoperative increases in myoglobin, creatine kinase MB fraction, and cardiac troponin T. The magnitude of increases in cardiac troponin T was greater in the CoQ10-supplemented group, reaching marginal overall statistical significance (p = 0.06). CONCLUSIONS: Short-term supplementation with large doses of CoQ10 does not lead to improved myocardial protection in patients undergoing coronary revascularization with well-preserved ventricular function and relatively short ischemic times.
Coenzymes↗