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Biomedical subjects

Alan G Fraser

Publications and source records attributed to Alan G Fraser.

32 records · Page 2Linked to original sources
PubMed2004

Gender differences in management after acute myocardial infarction: not 'sexism' but a reflection of age at presentation.

OBJECTIVE: To test whether women receive less intensive treatment and fewer risk stratification tests following acute myocardial infarction (MI), than men. METHODS: A retrospective study of medical records in all district general hospitals and tertiary referral centres for cardiology in Wales was performed. Patients (n = 1595, of which 989 were men) admitted to hospital over 4 months with a diagnosis of acute MI had their case notes reviewed for treatment, stratification of risk factors and secondary prevention. Data were analysed for differences in treatment between men and women and whether these could be attributed to age at presentation. RESULTS: Women were older than men at presentation [mean age 75 (SD 11) versus 66 (12) years, p < 0.01]; fewer women received thrombolysis (34 versus 44 per cent) and low molecular weight heparin (63 versus 71 per cent) (both p < 0.001); and women had higher 30 day mortality (28 versus 17 per cent, p < 0.001). Fewer women received cardiac catheterization, investigations to identify high risk, drugs for secondary prevention on discharge and referral to cardiac rehabilitation. However, intensities of treatment, investigation and secondary prevention were strongly related to age and, after adjusting for age, gender differences remained only for thrombolysis and exercise testing. CONCLUSION: Although women receive fewer investigations and treatments than men, this potential gender bias can be explained by age. The lower use of treatment and investigation among older patients draws attention to the lack of direct evidence of effectiveness for these patients. Further studies are needed to confirm effectiveness of investigations and treatments in older patients.

Adult↗
PubMed2004

Tissue Doppler imaging for the evaluation of patients with hypertrophic cardiomyopathy.

PURPOSE OF REVIEW: To discuss the role of tissue Doppler imaging for assessing regional myocardial function in patients with proven or suspected hypertrophic cardiomyopathy and review its application in clinical practice for diagnosis, estimation of filling pressures, and monitoring of treatment. RECENT FINDINGS: Patients with hypertrophic cardiomyopathy have very abnormal systolic and diastolic myocardial function, even if global systolic function of the left ventricle appears normal. Regional function is most abnormal in walls that are markedly hypertrophied, but it is also abnormal in segments that are not affected by hypertrophy, and it is depressed in patients who have a mutation for hypertrophic cardiomyopathy but have not yet developed clear phenotypic changes. Genetic diagnosis remains difficult especially in sporadic cases, due to the very large number of mutations that have been identified; the hypertrophy may represent a nonspecific compensatory response to any mutation that impairs myofibrillar function. Subclinical changes especially affect long-axis ventricular function, and tissue Doppler imaging is the most sensitive test to identify reduced velocities of long-axis shortening and early diastolic lengthening of the left ventricle, prolonged contraction and relaxation times, and reduced strain in affected segments, both in patients with hypertrophy and in asymptomatic subjects with mutations. It can also discriminate well between hypertrophic cardiomyopathy and athlete's heart, and can be used with standard echocardiographic measurements to estimate left ventricular filling pressure or to monitor treatment. SUMMARY: Tissue Doppler imaging can now be usefully incorporated into the routine echocardiographic study of patients with proven or suspected hypertrophic cardiomyopathy.

Blood Flow Velocity↗
PubMed2003

A new scoring system to determine thromboembolic risk after heart valve replacement.

OBJECTIVE: To determine the most important inflammatory and hematologic predictors of thromboembolism (TE) in patients undergoing valve replacement (VR) to be used in conjunction with clinical risk factors for preoperative risk profiling. METHODS AND RESULTS: Preoperative and immediately postoperative clinical, echocardiographic, hematologic, biochemical and microbiological parameters were examined prospectively in 370 patients undergoing VR (249 AVR, 93 MVR, 28 DVR). Mean follow-up was 4.4 years (max 6.6 years; total 1566 pt/yrs), and 96 TE events were documented (28 major and 68 minor). INR data were collected on all patients. Laboratory values were considered elevated if they exceeded the 80th percentile of those of 70 controls with the same distribution of age and gender. IgA antibody to Chlamydia pneumoniae (CP)>or=1:64 was considered indicative of significant infection. Predictors of TE on multivariate analysis following AVR were (hazard ratios): CP infection (2.6), previous TE (2.5), raised eosinophils (2.4), cancer history (2.1), postoperative infection (2.0), hypertension (2.0), CABG x 3/4 (2.0), and diabetes (1.9). Predictors of TE following MVR/DVR were raised mean platelet volume (4.0), raised factor VII (3.1), CP infection (2.7), previous mitral valvotomy (2.5), raised fibrinogen (2.2), and raised reticulocytes (2.0). These risk factors were additive when present in the same patient, enabling a scoring system to be developed that accurately predicted risk of TE based on number of risk factors. CONCLUSIONS: Selected blood tests and clinical risk factors provide a scoring system that accurately predicts TE risk and may guide prosthesis choice and antithrombotic management.

Aged↗
PubMed2003

Wave intensity analysis from the common carotid artery: a new noninvasive index of cerebral vasomotor tone.

Cerebral vasomotor tone is difficult to assess in patients. Wave intensity analysis has been applied to resolve complex upstream and downstream events within the vascular system. We hypothesized that the backward-traveling wave measured in the common carotid artery was caused by reflection from the cerebrovascular "beach", and that the magnitude of this reflected wave would be altered by changes in cerebral vasomotor tone. We measured common carotid arterial diameter and velocity of flow to calculate wave intensity in ten healthy male volunteers (age mean 31 +/- 3 years). Applying a rebreathing technique, we were able to increase the inspired carbon dioxide concentration to a mean of 5.9% +/- 1.7% and to compare baseline wave intensity readings to those recorded during hypercapnia. The magnitude of the reflected wave decreased significantly after CO(2) rebreathing, from -43.0 +/- 27.1 to -25.0 +/- 16.9 mmHg m s(-2), P = 0.02. This reduction in negative wave reflections in mid-systole during hypercapnia remained significant when it was analyzed as the reflection coefficient (the magnitude of the reflected wave normalized for the magnitude of the initiating forward wave, which fell from -2.8 +/- 1.5 to -1.6 +/- 1.4 ms (P = 0.01). Carotid wave reflection was significantly decreased during cerebral vasodilatation induced by increased arterial pCO(2). Wave intensity may provide a simple noninvasive means of assessing changes in cerebral vasomotor tone in vivo.

Adult↗
PubMed2003

Can regional strain and strain rate measurement be performed during both dobutamine and exercise echocardiography, and do regional deformation responses differ with different forms of stress testing?

BACKGROUND: Regional strain (epsilon) and strain rate (SR) measurement could be the optimal approach to quantifying stress echocardiography images. However, signal noise could preclude their use. Study aims Our aim was to compare the feasibility of regional peak systolic (p) velocity (Vel), pSR/epsilon measurement, and their normal responses during upright (group 1, n = 10) and supine (group 2, n = 10) bicycle exercise and (group 3, n = 10) dobutamine stress. METHODS: For each type of stress study, pVel/pSR/epsilon data were acquired at baseline, low (100-120 bpm), and peak (140-160 bpm) heart rate (HR); and during recovery. RESULTS: During dobutamine pVel/pSR/epsilon were interpretable in >95% of segments at every stress stage, whereas in groups 1 and 2 pSR/epsilon responses were noninterpretable in >36% of segments (P <.0002). The highest proportions of data exclusions were from the lateral and anterior walls. In all groups, regional systolic pVel and SR values increased linearly and reached maximal value at peak HR (P <.0006 vs baseline). Pepsilon showed a biphasic response, initially increasing at low HR, and then remaining constant or falling at peak HR. CONCLUSION: PSR/pepsilon quantification of stress echocardiography may currently be restricted to dobutamine as increased signal noise precludes adequate data acquisition during exercise. For all forms of stress both pSR and pVel increased linearly, whereas pepsilon response was biphasic as a result of the reduced filling at higher HRs.

Adult↗
PubMed2003

Subclinical left ventricular dysfunction in asymptomatic patients with Type II diabetes mellitus, related to serum lipids and glycated haemoglobin.

The aim of the present study was to measure regional ventricular function at rest and during stress in order to assess if patients with Type II diabetes have subclinical myocardial dysfunction and if it is related to risk factors. Seventy subjects (35 patients with Type II diabetes with no symptoms, signs or history of heart disease, and 35 age- and sex-matched healthy controls) had echocardiography at rest and during dobutamine stress. Myocardial velocities were measured off-line from digital loops of colour tissue Doppler. Subendocardial function was assessed from the mean longitudinal velocities of four basal segments (apical views) and radial function from the velocities of the basal posterior wall (parasternal view). Systolic functional reserve was calculated as the increase in velocity from baseline. Longitudinal peak systolic velocity was lower in patients with diabetes, at rest (5.6 +/- 1.4 compared with 6.5 +/- 1.1 cm/s) and at peak stress (10.9 +/- 2.8 compared with 14.3 +/- 2.1 cm/s) (both P <0.01). Functional reserve was impaired in patients with diabetes (+5.4 +/- 2.0 compared with +7.7 +/- 1.7 cm/s; P <0.01). Radial systolic velocity was higher in patients with diabetes (5.4 +/- 1.3 compared with 4.7 +/- 1.4 cm/s; P <0.05). Resting longitudinal systolic function correlated inversely with low-density lipoprotein-cholesterol ( r =-0.53), glycated haemoglobin ( r =-0.48), age ( r =-0.41) and diastolic blood pressure ( r =-0.38) (all P < 0.05). Peak stress systolic velocity correlated inversely with glycated haemoglobin ( r =-0.46) and age ( r =-0.44) (both P < 0.01). In conclusion, patients with Type II diabetes and no clinical heart disease have impaired subendocardial function of the left ventricle at rest and peak stress, which is related to glycated haemoglobin and serum low-density lipoprotein-cholesterol.

Aged↗
PubMed2003

Abnormal myocardial strain rate in noncompaction of the left ventricle.

A 28-year-old woman presented in the second trimester of pregnancy with palpitations and left heart failure. Transthoracic echocardiography showed features consistent with isolated noncompaction of the left ventricle. Doppler tissue echocardiography with strain-rate imaging revealed unique appearances of paradoxical alternating bands of compression and expansion throughout systole and diastole. These features may be pathognomonic for this disease.

Adult↗
PubMed2003

Methotrexate: first-line or second-line immunomodulator?

Methotrexate is established as an effective treatment for inducing remission or preventing relapse in Crohn's disease. This review discusses the mechanisms of action, pharmacokinetics and clinical trials as well as considering the comparative efficacy between thiopurines and methotrexate. Comparisons are made with the treatment of rheumatoid arthritis. Its role in ulcerative colitis and potential toxicity are addressed. At present, the role of methotrexate is in the treatment of active or relapsing Crohn's disease for patients who are refractory to, or intolerant of, azathioprine or 6-mercaptopurine.

Arthritis, Rheumatoid↗
PubMed2002

Left ventricular long-axis diastolic function is augmented in the hearts of endurance-trained compared with strength-trained athletes.

In order to determine left ventricular global and regional myocardial functional reserve in endurance-trained and strength-trained athletes, and to identify predictors of exercise capacity, we studied 18 endurance-trained and 11 strength-trained athletes with left ventricular hypertrophy (172+/-27 and 188+/-39 g/m(2) respectively), and compared them with 14 sedentary controls. Global systolic (ejection fraction) and diastolic (transmitral flow) function, and regional longitudinal and transverse myocardial velocities [tissue Doppler echocardiography (TDE)], were measured at rest and immediately after exercise. In endurance-trained compared with strength-trained athletes, resting heart rate was lower (59+/-11 and 76+/-9 beats/min respectively; P<0.001), and the increase at peak exercise was greater (+211% and +139% respectively; P<0.001). In addition, exercise duration, workload, maximal oxygen consumption and global systolic functional reserve (but not peak ejection fraction) were higher in the endurance-trained athletes, and resting global diastolic function (E/A ratio 1.62+/-0.40 compared with 1.18+/-0.23; P<0.01) (where E-wave is peak velocity of early-diastolic mitral inflow and A-wave is peak velocity of mitral inflow during atrial contraction) and long-axis diastolic velocities (E(TDE)/A(TDE) ratio 2.2+/-1.2 compared with 1.1+/-0.3; P<0.01) (where E(TDE) and A(TDE) represent peak early- and late-diastolic myocardial or tissue velocity respectively) were augmented. Systolic velocities were similar. Exercise capacity was best predicted from end-diastolic diameter index and E/A ratio at rest, and end-diastolic volume index and diastolic longitudinal velocity during exercise (r=0.74, n=43, P<0.001). In conclusion, endurance-trained athletes had higher left ventricular long-axis diastolic velocities, augmented global early diastolic filling, and greater chronotropic and global systolic functional reserve. Maximal oxygen consumption was determined by diastolic loading and early relaxation rather than by systolic function, suggesting that dynamic exercise training improves cardiac performance by an effect on diastolic filling.

Adult↗
PubMed2002

Estimation of global left ventricular function from the velocity of longitudinal shortening.

AIMS: To determine if global ventricular function can be assessed from the long-axis contraction of the left ventricle, we compared pulsed-wave Doppler myocardial imaging of mitral annular motion to radionuclide ventriculography. METHODS AND RESULTS: We studied 51 patients (56 +/- 10 years, 11 women) with a radionuclide ejection fraction of 52 +/- 13% (15%-70%). Peak systolic velocities of medial and lateral mitral annular motion correlated with ejection fraction (0.55 and 0.54, respectively; P < 0.001), as did the time-velocity integrals (0.57 and 0.58, respectively; P < 0.001). Correlations were higher in normal ventricles (0.62-0.69) than in patients with previous myocardial infarction (0.39-0.64). Patients with anterior myocardial infarction had the lowest correlations (0.39-0.46). The best differentiation of normal (> or = 50%) from abnormal (< 50%) ejection fraction was provided by peak systolic velocity > or = 8 cm/sec for the medial (sensitivity 80%, specificity 89%) or lateral (sensitivity 80%, specificity 92%) mitral annulus. CONCLUSION: Global left ventricular function can be estimated by recording mitral annular velocity. The implementation of a cutoff limit of 8 cm/sec gave a simple guide for differentiating between normal and abnormal left ventricular systolic function that might be useful clinically in patients without regional wall-motion abnormalities. However, in patients with important segmental wall-motion abnormalities during systole, left ventricular longitudinal shortening is an imperfect surrogate for ejection fraction.

Echocardiography, Doppler, Pulsed↗
PubMed2002

Perioperative tissue Doppler echocardiography and bypass graft flowmetry in patients undergoing coronary revascularization: predictive power for late recovery of regional myocardial function.

To assess if recovery of regional myocardial function can be predicted by perioperative Doppler tissue echocariography, 20 patients undergoing coronary artery bypass graft surgery (mean 4.1 grafts) had serial transthoracic and transesophageal echocardiography. Systolic velocities were lower in basal posterior and anterior segments, and higher in the midanterior septum, at intraoperative transesophageal echocardiography compared with preoperative transthoracic echocardiography (-45%, -30%, +18%, respectively), but comparable elsewhere. After bypass, velocities were increased in midposterior, basal lateral, basal anterior, and midanterior septal segments (+41%, 25%, 27%, 44%, respectively, P <.05). Increased velocities in circumflex segments at 6 weeks (midposterior, basal lateral, and midlateral +54%, 45%, 39%, respectively, P <.05) were not predicted by perioperative changes or related to graft flow (transit-time flowmetry; R -0.09, -0.14, and -0.32, respectively, not significant). Myocardial velocities measured by transthoracic and transesophageal echocardiography are not comparable in segments with different angles of insonation. Perioperative changes in resting myocardial systolic velocity are highly variable and do not predict late recovery.

Aged↗
PubMed2002

Epicardial colour-Doppler scanning of coronary artery stenoses and graft anastomoses.

OBJECTIVE: Epicardial ultrasound scanning was applied during coronary surgery to assess coronary artery stenoses and quality of distal graft anastomoses, with special emphasis to the left anterior descending artery (LAD). DESIGN: Twenty-three patients with coronary artery disease (M:F 19:4, mean age 65.0 +/- 9.5 years) had coronary artery bypass grafting (CABG) on cardiopulmonary bypass. Intraoperative scanning of coronary artery stenoses and graft anastomoses was performed with a new 10 MHz linear array Vingmed transducer connected to a GE Vingmed System FiVe echocardiography unit. Coronary stenoses detected by ultrasound were compared with preoperative angiograms. Intraoperatively, coronary graft flow was assessed with a Medi-Stim transit-time flowmeter. RESULTS: Twenty LADs were investigated. In 17 LADs (85%) stenoses were clearly identified. In three LADs (15%) stenoses were not identified because LADs were deeply intramyocardial or the stenosis was very proximal. There was a significant correlation between LAD stenoses detected by ultrasound and angiogram (R = 0.7; p < 0.01). Mean number of grafts was 3.8 +/- 0.9. Of 26 LAD anastomoses assessed, good images were obtained in 22 cases (84.4%); the mean LAD diameter measured 1 cm below the anastomosis was 1.6 +/- 0.2 mm. In two LADs images were rated fair and in two LADs images were poor because of intramyocardial LAD. No technical error of the anastomoses was detected. All grafts had good flows as ascertained by flow measurements. CONCLUSION: Epicardial ultrasound scanning with the new 10 MHz transducer allowed satisfactory imaging of coronary stenoses and graft anastomoses. Factors limiting the quality of imaging are proximal lesions, intramyocardial vessel, vessel tortuosity, and extensive calcifications. Epicardial ultrasound scanning with updated technology should become a further advancement to graft assessment during off-pump coronary surgery.

Aged↗
PubMedDate not supplied

Systolic dysfunction in heart failure with a normal ejection fraction: echo-Doppler measurements.

Heart failure with a normal ejection fraction, also called heart failure with preserved ejection fraction or diastolic heart failure, is thought to be characterized by normal systolic function and disturbed diastolic function only. However, studies using newer Doppler-echocardiographic techniques have shown that ventricular function is not normal particularly in the long axis. Ejection is relatively preserved because of increased radial function. Similar findings are seen with normal ageing and the typical precursors of heart failure with a normal ejection fraction such as hypertension, diabetes, and ischemia. There appears to be a spectrum of abnormalities of systolic function from the truly normal to systolic heart failure with heart failure with a normal ejection fraction occupying an intermediate position. The use of ejection fraction, which has a normal distribution, to dichotomize patients with heart failure is not supported on theoretical or experimental grounds, and any cutoff is arbitrary. Patients with heart failure have a mixture of systolic and diastolic abnormalities and variable degrees of remodeling. It is more important to correctly identify these in the individual patient.

Diastole↗