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Biomedical subjects

J B Chambers

Publications and source records attributed to J B Chambers.

At least 37 records · Page 2Linked to original sources
PubMed1999

Plasma sialic acid and coronary artery atheromatous load in patients with stable chest pain.

Serum or plasma sialic acid and C-reactive protein have recently been shown to be cardiovascular risk factors. Our aim was to determine whether plasma sialic acid or C-reactive protein concentration correlate with atheromatous load on coronary angiography. Plasma sialic acid concentration and plasma C-reactive protein concentration were determined in 128 consecutive patients attending day case coronary angiography. Patients were excluded for previous coronary angioplasty, coronary artery bypass grafting, recent myocardial infarction, acute or chronic inflammatory disease and proximal occlusions precluding analysis of distal coronary anatomy. Total cholesterol, triglyceride, HDL cholesterol and glucose concentrations were assayed on fasting samples of venous blood. Angiograms were graded according to a semisubjective scoring system. There was no significant correlation between plasma sialic acid (r = 0.19, P = 0.07), or C-reactive protein concentration (r = 0.17, P = 0.13) and atheromatous load. There was no significant correlation between sialic acid (P = 0.13), or C-reactive protein concentration (P = 0.32) and the number of diseased coronary vessels. The difference in plasma sialic acid concentration between those with normal coronary angiograms and those with coronary artery disease did not reach significance (P = 0.08). Plasma sialic acid concentration correlated with C-reactive protein (r = 0.58, P = 0.0001), serum triglyceride (r = 0.32, P = 0.002), and blood cholesterol concentration (r = 0.22, P = 0.04). Plasma sialic acid concentration does not correlate with atheromatous load on coronary angiography in patients with stable angina.

Adult↗
PubMed1999

Gender differences in the treatment of patients with acute myocardial ischemia and infarction in England.

We conducted a retrospective cohort study based on a case note review to determine whether there are differences in the treatment pathways followed for men and women admitted with acute myocardial ischemia and infarction after adjusting for differences in case mix. Women were as likely as men to receive thrombolysis, but were less likely subsequently to undergo exercise testing (adjusted odds ratio, 0.58; 95% CI, 0.40-0.84) or angiography (adjusted odds ratio, 0.62; 95% CI, 0.39-0.99). Coronary anatomy was the strongest predictor of revascularization regardless of sex. Women with diagnosed cardiac pain are less likely than men to be placed on the investigative pathways that lead to revascularization. Those women who are investigated are as likely as men to undergo revascularization. These findings are independent of the effects of age, angina grade, comorbidity, or cardiac risk factors. Clinicians' and patients' beliefs and preferences about treatment require investigation.

Acute Disease↗
PubMed1998

A prospective study of oesophageal function in patients with normal coronary angiograms and controls with angina.

AIMS: To compare the incidence of oesophageal abnormalities and their correlation with chest pain in patients with normal coronary angiograms, and in controls with angina. PATIENTS: Sixty one patients with normal coronary angiograms (NCA group) referred to a single cardiac centre between March 1990 and April 1991; 25 matched controls with confirmed coronary artery disease (CAD group). SETTING: Cardiac referral centre and oesophageal function testing laboratory. MAIN OUTCOME MEASURES: Oesophageal manometry, provocation tests, and 24 hour ambulatory pH monitoring. RESULTS: Simultaneous contractions were more common (6.7% versus 0.8%, p < 0.01), and the duration of peristaltic contractions was longer (2.9 versus 2.4 seconds, p < 0.01) in the NCA group than in the CAD group. There were no group differences in the amplitude of peristaltic contractions, and none had nutcracker oesophagus. Ten (16%) patients with NCA and no patients with CAD had diffuse spasm (p = 0.03). Twenty one (34%) patients with NCA, and five (20%) patients with CAD had abnormal gastro-oesophageal reflux (p > 0.05). There was no significant difference between the groups in the number of patients whose pain was temporally related to pH events. Particular chest pain characteristics, or the presence of additional oesophageal symptoms, were not predictive of an oesophageal abnormality. CONCLUSION: Oesophageal function tests commonly implicate the oesophagus as a source of pain in patients with normal coronary angiograms. With the exception of simultaneous contractions during manometry however, the incidence of abnormalities and in particular the correlation of pH events with chest pain are as common in patients with normal coronary angiograms as in controls with angina. The oesophagus may often be an unrecognised source of pain in both groups of patients.

Angina Pectoris↗
PubMed1997

Haemodynamic changes during dobutamine stress echocardiography in patients with and without ischaemia.

We studied haemodynamic changes during dobutamine stress echocardiography in 69 patients (mean age 58 years, 6 female, 63 male) referred for investigation of chest pain. We used a standard protocol of 3 min stages using infusion rates of 5, 10, 20, 30 and 40 micrograms/kg/min. Heart rate rose from 74 (13) to 123 (21) beats per min with the major increment occurring during the high dose phase of the study (> 20 micrograms/kg/min). Stroke volume was calculated as the product of left ventricular outflow tract cross-sectional area and the velocity integral of the continuous wave aortic signal. Mean stroke volume increased from 67.5 (22) ml pre-test to 82 (22) ml at 20 micrograms/kg/min dose (P < 0.0001) and 85 (21) ml at 40 micrograms/kg/min (P < 0.00001). Only 15 patients (26%) reached their maximal stroke volume by 10 micrograms/kg/min, 38 patients (65%) reached maximal stroke volume by 20 micrograms/kg/min. Patients with ischaemic responses tended to have a blunted rise in stroke volume from 67 (22) ml to 85 (22) ml at maximum compared with a rise from 69 (23) to 92 (19) ml in those without ischaemic (P = 0.09). In conclusion, the early rise in cardiac output during dobutamine stress was mainly due to a rise in stroke volume and the later due to an increase in heart rate. Individual increases in stroke volume did not adequately differentiate between ischaemic and non-ischaemic results.

Adult↗
PubMed1997

Clinical and echocardiographic survey of the Ehlers-Danlos syndrome.

Cardiac abnormalities such as mitral valve prolapse (MVP) are reported to be common features of the Ehlers Danlos syndrome (EDS), and it has been suggested that the majority of patients with type IV EDS will have cardiac involvement and vascular aneurysms. However, the evidence for valve lesions is inconsistent and often based on early clinical studies using mainly M-mode echo. We studied 33 patients (six male, 27 female; median age 35 yr) with EDS (30 type I, II or III, three type IV) and 30 age- and sex-matched controls. The study assessed skin stretch and joint hypermobility using Beighton and Contompasis scores. Echocardiographic examination included standard two-dimensional views from the parasternal and apical windows, and measurement of the aorta at four sites (annulus, sinotubular junction, arch and abdominal aorta). Echocardiographic abnormalities were found in four patients (12.1%) (one atrial septal aneurysm, one tricuspid prolapse, two MVP) and two controls (6.7%). MVP was found in 6.1% of EDS patients and 7% of controls. Seven patients had previously been diagnosed as having MVP; only two were shown to have true MVP using current criteria. None of those with type IV EDS had any echocardiographic abnormality. No patients with EDS had mean aortic dimensions outside the normal range at any of the points tested. Cardiac symptoms were more frequent amongst the patients than controls (atypical chest pain 48%, P = 0.0001; palpitation 39%, P = 0.001; exertional dyspnoea 30%). A wide range of rheumatological complaints were reported (current arthralgia 75%; recent back pain 72%, P = 0.005; recurrent dislocation 72%). Contrary to earlier published observations, we have not found an increased incidence of cardiac abnormalities in EDS. This syndrome may be relatively more benign, from the cardiac point of view, than was previously thought.

Adolescent↗
PubMed1997

Comparative study of chest pain characteristics in patients with normal and abnormal coronary angiograms.

OBJECTIVE: To improve the characterisation of chest pain by comparing symptoms in patients with normal and abnormal coronary angiograms. STUDY DESIGN: Prospective case-control study. SETTING: Single tertiary cardiac referral centre. PATIENTS: 65 consecutive patients with chest pain and completely normal coronary angiograms recruited over a period of one year, and 65 sex matched patients with significant stenoses at angiography. MAIN OUTCOME MEASURES: Standardised chest pain questionnaires. RESULTS: 61 of 65 patients (94%) and every control reported chest pain on exertion. There were no important differences in the site, quality, and radiation of pain but three symptoms had discriminatory value expressed in binary fashion ("typical" v "atypical"): the consistency with which pain was reproduced by exercise (typical, score index 10/10), the duration of pain episodes (typical, five minutes), and the frequency of pain at rest (typical, 10% all pain episodes). All three symptoms were atypical in 21 (32%) patients with normal coronary angiograms, but only one patient with an abnormal coronary angiogram. Patients with no typical features had a 2% chance of an abnormal coronary angiogram if aged under 55 years or 12% if aged 55 years or more. The additional impact of exercise stress testing was low. CONCLUSIONS: Chest pain characteristics which separate patients with normal coronary angiograms from patients with obstructive coronary heart disease can be defined objectively. This may allow improvements in referral patterns for specialist opinion or angiography, and in characterisation of patients in research studies.

Age Factors↗
PubMed1997

The role of transesophageal echocardiography in patients with chronic renal failure at low and high risk of endocarditis.

BACKGROUND AND AIMS OF THE STUDY: The benefits of transesophageal echocardiography (TEE) may depend on the clinical likelihood of infective endocarditis, but little data exist on patients at low risk. METHODS AND RESULTS: We studied 32 patients with renal failure with either a low (n = 21) or high (n = 11) level of clinical suspicion for infective endocarditis. In the low-risk cases, TEE provided no new information whether the transthoracic echo was normal or abnormal, although it did confirm that an echogenic mass was more likely to be a calcific deposit than a vegetation. In the high-risk cases, transthoracic echocardiography was always abnormal but TEE added new information in seven out of 11 cases-positively in six, and by exclusion in one. TEE detected signs of complications of infective endocarditis in one case. CONCLUSIONS: We conclude that, when the clinical suspicion of endocarditis is low, TEE is rarely necessary.

Echocardiography↗
PubMed1996

Extra-articular features of benign joint hypermobility syndrome.

To define the phenotype of patients with benign joint hypermobility syndrome (BJHS), we studied 58 consecutive patients (mean age 37 yr) presenting to a rheumatology clinic and 30 controls. Patients underwent rheumatological and ophthalmic examination, hypermobility scoring, echocardiography, measurement of bone mineral density (BMD), and skin thickness, elasticity and light transmissibility. The median hypermobility score was 5/9 Beighton and 31/56 Contompasis. Eighteen (31%) patients complained of significant arthralgia. Six (10%) patients and two (7%) controls had mitral valve prolapse (MVP) (chi(2) = 0.27, P = NS). Neither MVP nor aortic diameters showed a correlation with hypermobility score. There was no significant reduction in BMD. There was a significant correlation between hypermobility and light transmissibility of the skin (r = 0.71, P < 0.0001 Contompasis; r = 0.47, P < 0.05 Beighton) and skin stretchiness (r = 0.49, P < 0.05 Contompasis; r = 0.39, P < 0.05 Beighton). On ophthalmic examination, 14 (41%) patients had upper eyelid laxity. Thus, patients with BJHS do not have an increased prevalence of significant cardiac, bone, skin or eye abnormalities, helping differentiate BJHS from other more serious hereditary disorders of connective tissue.

Adolescent↗
PubMed1996

Hyperventilation and esophageal dysmotility in patients with noncardiac chest pain.

OBJECTIVES: Hyperventilation is known to cause esophageal spasm, but the importance of this interaction in clinical practice is unknown. In the present study, we report the effects of hyperventilation provocation on esophageal motility in a consecutive series of patients with noncardiac chest pain. METHODS: In a prospective observational study design, 46 consecutive patients with normal coronary angiograms were studied. Esophageal motility was recorded at rest and after voluntary over-breathing at 40 breaths/min for 3 min. RESULTS: Hyperventilation was associated with a significant fall in mean distal peristaltic amplitude [66 (SD 28) to 55 (SD 24) mm Hg, p <0.001] and mean duration [2.9 (SD 0.7) to 2.6 (SD 0.9) s,p = 0.02]. It induced diffuse spasm in two (4%) patients, and nonspecific motility disorders in 10 (22%). Chest pain was reproduced in seven (15%) patients, but in none did this coincide with an important change in peristaltic amplitude, duration, or frequency. CONCLUSION: Hyperventilation has important effects on esophageal motility, and manometrists should be aware of these before recommending that anxious patients overbreathe to help relaxation during clinical studies. Although overbreathing is a common source of dysmotility, it rarely produces chest pain via its effects on the esophagus.

Breath Tests↗
PubMed1996

A comparison of valve resistance, the continuity equation, and the Gorlin formula against directly observed orifice area in bioprosthetic valves in the mitral position: an in vitro study.

BACKGROUND AND AIMS OF THE STUDY: There is no consensus over how to describe forward flow through valves in the mitral position. There are three main candidate hydraulic formulae; resistance, the Gorlin formula and the continuity equation. However, virtually no work has been performed to validate resistance and the continuity equation for valves in the mitral position. The aim of this study, therefore, was to compare the three formulae against an independent standard provided by directly observed orifice areas. MATERIALS AND METHODS: Five bioprosthetic valves with orifice areas between 0.14 cm2 and 2.33 cm2 were studied in a pulse simulator at up to 20 different stroke volume/rate combinations using quasi-physiologic flow curves. Orifice areas were measured using a video camera, pressure difference using strain gauge transducers and Doppler signals using a 1.9 MHz Pedoff probe with a Vingmed SD50 system. RESULTS: The Gorlin ratio (flow/square root of mean delta P) had a direct curvilinear relationship with the orifice area (log(y) = 0.31 + 0.36x; r = 0.94, SEE 0.08 cm2, p < 0.0001). Resistance (mean delta P/flow) had an indirect curvilinear relationship (log(y) = 0.19 - 0.55x, r = -0.93, SEE 0.13 cm2, p < 0.0001). The continuity equation was directly related to observed orifice area although with high scatter (y = 1.13 + 0.79x; r = 0.90, SEE 0.23 cm2, p < 0.0001). Although both the Gorlin ratio and resistance changed with flow, there was also a tendency for observed orifice areas to increase with flow. Empirical effective orifice areas calculated using the regression equations closely resembled observed orifice areas and agreement was reasonable, with 95% limits of -0.33 cm2 to +0.33 cm2 (Gorlin), -0.41 cm2 to +0.42 cm2 (resistance) and -0.40 cm2 to +0.48 cm2 (continuity). CONCLUSION: In conclusion, no single formula adequately predicted all observed orifice areas although resistance and the Gorlin formula gave useful predictions after empirical correction.

Bioprosthesis↗
PubMed1995

How should we describe forward flow through replacement mitral valves using echocardiography?

Pressure half-time is no longer thought to reflect orifice area in normally-functioning mitral valves, but no satisfactory alternative method has been validated. Effective orifice area by the continuity equation is theoretically justified. However, we have shown no correlation against manufacturer's area in a clinical study of 40 bileaflet mechanical valves. Valve resistance is useful in native mitral stenosis, but virtually no work exists for replacement valves. We have shown no correlation against manufacturer's area in the same 40 mechanical valves. The proximal isovelocity surface area method based on the continuity equation can only be applied using the transesophageal approach; it is therefore not practical. Imaging and colour flow provide good qualitative or semiquantitative information, and together with continuous wave Doppler allow detection of obstruction for clinical diagnosis. An adequate quantitative method for research use has not yet been established.

Algorithms↗
PubMed1994

Noonan's cardiomyopathy: a non-hypertrophic variant.

OBJECTIVE: To describe the association of the Noonan's phenotype and a primary, familial non-hypertrophic cardiomyopathy with restrictive pathophysiology. DESIGN: Observational study. SETTING: Tertiary cardiac referral centre. PATIENTS: Affected family members. METHODS: Two generations of a single family were examined and a description of the clinical characteristics and electrocardiographic, echocardiographic, and haemodynamic data of those affected is given. RESULTS: Three family members have classic Noonan's phenotype and all have a non-dilated, non-hypertrophic cardiomyopathy. Inheritance is autosomal dominant but with variable penetrance. The electrocardiograms show increased left ventricular voltages in two patients. On echocardiography left ventricular wall and internal end diastolic dimensions are normal, and there is considerable bilateral atrial enlargement. Systolic function is moderately impaired in one patient and mildly impaired in another. Doppler echocardiography showed restrictive pathophysiology as an early end of left ventricular filling and considerable reversal of flow in the superior vena cava during atrial systole. CONCLUSION: Hypertrophic cardiomyopathy is well described in Noonan's syndrome. This is the first report of a non-hypertrophic cardiomyopathy with echocardiographic and haemodynamic features of restrictive pathophysiology.

Adult↗
PubMed1994

QT interval in anorexia nervosa.

OBJECTIVES: To determine the incidence of a long QT interval as a marker for sudden death in patients with anorexia nervosa and to assess the effect of refeeding. To define a long QT interval by linear regression analysis and estimation of the upper limit of the confidence interval (95% CI) and to compare this with the commonly used Bazett rate correction formula. DESIGN: Prospective case control study. SETTING: Tertiary referral unit for eating disorders. SUBJECTS: 41 consecutive patients with anorexia nervosa admitted over an 18 month period. 28 age and sex matched normal controls. MAIN OUTCOME MEASURES: maximum QT interval measured on 12 lead electrocardiograms. RESULTS: 43.6% of the variability in the QT interval was explained by heart rate alone (p < 0.00001) and group analysis contributed a further 5.9% (p = 0.004). In 6 (15%) patients the QT interval was above the upper limit of the 95% CI for the prediction based on the control equation (NS). Two patients died suddenly; both had a QT interval at or above the upper limit of the 95% CI. In patients who reached their target weights the QT interval was significantly shorter (median 9.8 ms; p = 0.04) relative to the upper limit of the 60% CI of the control regression line, which best discriminated between patients and controls. The median Bazett rate corrected QT interval (QTc) in patients and controls was 435 v 405 ms.s-1/2 (p = 0.0004), and before and after refeeding it was 435 v 432 ms.s1/2 (NS). In 14(34%) patients and three (11%) controls the QTc was > 440 ms.s-1/2 (p = 0.053). CONCLUSIONS: The QT interval was longer in patients with anorexia nervosa than in age and sex matched controls, and there was a significant tendency to reversion to normal after refeeding. The Bazett rate correction formula overestimated the number of patients with QT prolongation and also did not show an improvement with refeeding.

Adolescent↗
PubMed1994

Gastroesophageal reflux in patients with angiographically normal coronary arteries: an uncommon cause of exertional chest pain.

OBJECTIVES: To investigate the association between exertional chest pain and gastroesophageal reflux in patients with normal coronary angiograms and in controls by measuring oesophageal pH during treadmill exercise tests and to compare the results with routine ambulatory monitoring. DESIGN: Case control study. SETTING: Tertiary referral cardiac unit. PATIENTS: 50 consecutive patients with chest pain and completely normal coronary angiograms and 16 controls with coronary artery stenoses. MAIN OUTCOME MEASURES: Episodes of acid reflux and chest pain during treadmill exercise; a symptom index expressing the percentage of episodes of pain related to acid reflux during ambulatory monitoring. RESULTS: Four (8%) patients and two (12%) controls had reflux during treadmill exercise (NS). 32 (64%) and 16 (100%) reported chest pain, but only three (6%) and two (12%) had coincident reflux (NS). Reflux was as frequent before, during, and after treadmill exercise (five (8%) v six (9%) v two (3%)) in the 66 subjects; (NS). 19 (38%) patients and three (19%) controls had abnormal reflux on ambulatory monitoring (NS). Eight (16%) and three (19%) had a symptom index > 50%, but six and two of these reported pain without coincident reflux during treadmill exercise. CONCLUSION: There are many potential causes of chest pain in patients with angiographically normal coronary arteries. Although gastroesophageal reflux is commonly implicated and many patients have a high incidence of spontaneous reflux during ambulatory monitoring, it rarely occurs during exertion and the association with chest pain is poor.

Adult↗