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Biomedical subjects

C Rajkumar

Publications and source records attributed to C Rajkumar.

At least 19 recordsLinked to original sources

Takayasu's arteritis: a cause of prolonged arterial stiffness.

OBJECTIVES: Cardiovascular disease is a major cause of mortality and morbidity in patients with Takayasu's arteritis (TA). Increased arterial stiffness is an independent risk factor and predictor of cardiovascular mortality in a variety of diseases. Pulse wave velocity (PWV) and the augmentation index (AI) are used as clinical measurements of arterial stiffness. METHODS: Data are presented from 10 patients with TA and 11 normal controls obtained between 2000 and 2004. Arterial compliance was assessed non-invasively by measurement of PWV, using the Complior system, and calculation of the aortic AI. RESULTS: TA patients (mean age 40.8+/-13.2 yr) were compared with a control group of healthy women from a parallel study (mean age 32.3+/-5.5 yr). The mean carotid-femoral PWV (PWV-CF) was higher in TA patients (P = 0.03). In addition, both aortic AI derived from the radial artery (P = 0.002) and carotid AI (P = 0.03) were higher in TA patients compared with controls. PWV-CF did not correlate with CRP (r = - 0.23, P = 0.23) or ESR (r = - 0.19, P = 0.27). Similar results were obtained for the correlation of carotid-radial PWV with CRP (r = 0.15, P = 0.32) and ESR (r = 0.33, P = 0.14). CONCLUSIONS: Our data show that TA is associated with elevated arterial stiffness in the central aorta, which may persist when the disease is quiescent. These data suggest that PWV represents a means by which cardiovascular risk can be detected and monitored in TA, and highlights the importance of effective management of cardiovascular risk factors in these patients.

Adult↗

Ageing and vascular ageing.

There is an age related decline in various physiological processes. Vascular ageing is associated with changes in the mechanical and the structural properties of the vascular wall, which leads to the loss of arterial elasticity and reduced arterial compliance. Arterial compliance can be measured by different parameters like pulse wave velocity, augmentation index, and systemic arterial compliance. There is evidence that arterial compliance is reduced in disease states such as hypertension, diabetes, and end stage renal failure. Changes in arterial compliance can be present before the clinical manifestation of cardiovascular disease. Pharmacological and non-pharmacological measures have been shown to improve arterial compliance. Arterial compliance may constitute an early cardiovascular risk marker and may be useful in assessing the effects of drugs on the cardiovascular system. Pharmacogenetics and genetics of arterial compliance in the future will improve our knowledge and understanding about vascular ageing.

Aging↗

Differences in the association between type 2 diabetes and impaired microvascular function among Europeans and African Caribbeans.

AIMS/HYPOTHESIS: Diabetes is associated with microvascular damage in all populations, but diabetic patients of Black African descent (African Caribbeans) have a greater risk of vascular target organ damage than would be anticipated for any given blood pressure level. We investigated whether this may be due to differences in the microvasculature. MATERIALS AND METHODS: To assess the maximum hyperaemic response to heating and the post-ischaemic response, Laser Doppler fluximetry was performed on 51 and 100 Europeans, and on 66 and 88 African Caribbeans with and without diabetes, respectively. Subjects were aged between 40 and 65 years and recruited from the general population. Echocardiographic interventricular septal thickness (IVST) was measured as a proxy for vascular target organ damage. RESULTS: In diabetic subjects of both ethnic groups, the maximum hyperaemic response and peak response to ischaemia were attenuated as compared to the corresponding non-diabetic subjects (p=0.08 for diabetic and 0.03 for non-diabetic Europeans; p=0.03 and 0.1 for African Caribbeans). Adjustment for cardiovascular risk factors, in particular insulin and blood pressure, abolished these differences in Europeans (p=0.8 for diabetic and 0.2 for non-diabetic Europeans), but not in African Caribbeans (p=0.03 and 0.05). CONCLUSIONS/INTERPRETATION: Persisting microvascular dysfunction in African Caribbeans may contribute to the increased risk of target organ damage observed in diabetes in this population. The weak contribution of conventional cardiovascular risk factors to these disturbances indicates that conventional therapeutic interventions may be less beneficial in these patients. There was a risk-factor-independent, inverse association between IVST and maximal hyperaemia. These ethnic differences in microvascular responses to temperature and arterial occlusion could account for increased target organ damage in African Caribbeans.

Aged↗

Testosterone suppression in men with prostate cancer is associated with increased arterial stiffness.

Low androgen levels in men are associated with increased cardiovascular risk, through unclear mechanisms. We measured arterial stiffness ('compliance') in 21 men receiving complete testosterone suppression therapy for prostate cancer, and in 25 controls. Systemic arterial compliance (SAC), which assesses proximal aortic stiffness, was calculated by simultaneous recording of aortic flow and carotid artery pressure (the 'area method'). Aorto-femoral (A-F), aorto-radial (A-R) and femoral-dorsalis pedis (F-DP) pulse-wave velocities (PWVs) were recorded using the 'Complior' system. SAC was significantly lower in the androgen-depleted men compared to controls (0.81 +/- 0.53 vs. 1.18 +/- 0.43 arbitrary compliance units, p = 0.01, mean +/- SD). Correspondingly, their A-F PWV was higher (14.1 (10.1-21.8) vs. 12.4 (9.6-17.4) m/s, p = 0.03, median (range)). Cases tended to be older (75 +/- 7 vs. 71 +/- 6 years, p = 0.07), and to have higher systolic blood pressure (148 +/- 22 vs. 143 +/- 17 mmHg, p = 0.40); however, SAC was still significantly lower (p = 0.03) after adjustment for age and stratification for central systolic pressure (< or = or > the median). Adjustment of A-F PWV for age and central systolic pressure reduced significance to p = 0.07. There was no significant difference in peripheral PWVs between groups. In conclusion, testosterone suppression is associated with increased aortic stiffness, only partly explained by age and blood pressure. Loss of androgens in men might therefore adversely affect cardiovascular risk.

Age Factors↗

The effect of reminder calls in reducing non-attendance rates at care of the elderly clinics.

BACKGROUND: DNA ("did not attend") at outpatient clinics is an important problem costing the NHS an estimated pound266 million annually. The national DNA rate for 1996-1997 for all clinics was 12%. The DNA rate at Hammersmith Hospital for the same year in the care of the elderly specialty was 21%. The aim of this study was to establish why this was so, and to test the efficacy of a reminder call in increasing attendance rates at care of the elderly clinics. METHODS: 23 DNAs from seven clinics were contacted to ascertain the reasons for non-attendance (group I). For seven further clinics, 84 patients were contacted in advance to reconfirm their appointment (group II). RESULTS: From group II 12 patients were identified who were unaware of their appointment (14%), six of whom agreed to attend; thus six potential DNAs were prevented. Eleven vacant appointments were identified in advance. The unexpected DNA rate was reduced to 5% from a potential 21% as a result of this exercise. The DNA rate for all patients with dementia (both groups) was 44%, whereas the DNA rate for all patients without this diagnosis (both groups) was 16% (p < 0.001). CONCLUSIONS: A preclinic phone call reminder to elderly patients is feasible, increases attendance rates, and identifies vacant appointments. Patients with dementia are more likely to miss clinic appointments; therefore they and their carers need specific reminders about appointment dates.

Aged↗

Prevention of cardiac disease in the elderly.

There is much evidence for identifying and altering certain risk factors, such as hypertension, diabetes, raised cholesterol levels, smoking, obesity, hormone changes and exercise to reduce the incidence of cardiovascular disease; certain drugs have also been shown to be of benefit. Although the elderly population is most likely to suffer cardiovascular disease, very little of the trial evidence has looked at this patient group. It is important that the interventions we recommend for young patients have a comparable risk/benefit profile in the elderly so that we can offer them the most appropriate treatment.

Aged↗

Postprandial silent ischaemia following a fatty meal in patients with recently diagnosed coronary artery disease.

Silent myocardial ischaemia (SI) is recognised as an important prognostic factor in patients with coronary artery disease (CAD). Postprandial angina is related to severity of CAD. The effect of postprandial metabolic changes in the pathogenesis of SI is unclear. We studied the postprandial changes in glucose, insulin and triglyceride, and non-esterified fatty acids (NEFA) in relation to postprandial SI and exercise capacity, in patients with CAD. Forty elderly volunteers (63 +/- 1 years) mean age +/- s.e.m., with a history of angina were selected on the basis of a Rose questionnaire and a positive exercise stress test (modified Bruce protocol). The test meal contained 45% fat. The meal was consumed at 9.00 am and hourly blood samples were taken for glucose, insulin, triglyceride and NEFA. Continuous Holter monitoring for SI was conducted using a Spacelabs 2000 monitor. Twenty-five percent of the subjects had episodes of silent ischaemia. Postprandial glucose, insulin, triglyceride, and NEFA were not significantly different in the patients with SI (group 1, n = 10) compared with those without SI (group 2, n = 30). The mean exercise time was 6.1 +/- 0.8 min in group 1 compared with 6.8 +/- 0.5 minutes in group 2 (P = 0.48). The time to onset of ST depression during exercise test was also not significantly different in the two groups. The occurrence of postprandial SI cannot be related to changes in plasma levels of glucose, triglyceride, insulin, and NEFA. The explanation is not apparent from this study but may relate to a haemodynamic changes such as mesenteric steal. Journal of Human Hypertension (2000) 14, 391-394

Aged↗

Androgen deprivation in males is associated with decreased central arterial compliance and reduced central systolic blood pressure.

The higher incidence of coronary artery disease in men is often attributed to androgens. Arterial compliance or 'stiffness' is increasingly regarded as a modifiable risk factor for cardiovascular disease. We wanted to look at the effects of complete androgen withdrawal, on arterial compliance in men. We performed arterial compliance studies on 12 men with complete androgen deprivation as treatment for prostate cancer, and on 12 age-matched healthy controls. Central pulse wave velocities were significantly higher in the androgen-deprived men (14.2 +/- 2.7 vs 11.8 +/- 1.6 m/sec, P = 0. 02). The cases tended to have higher brachial systolic pressures than controls though this difference was not significant (P = 0.2). We conclude that androgen withdrawal is associated with a reduction in central arterial compliance. Conversely androgen withdrawal does not affect peripheral arterial compliance. It is unlikely that the presence of normal concentrations of androgens can explain the sex difference in mortality rates. Longitudinal studies are needed for further evaluation. Journal of Human Hypertension (2000) 14, 395-397

Aged↗

The effect of age on vascular compliance in man: which are the appropriate measures?

Vascular compliance declines rapidly with age and measures of arterial compliance may help understanding of the aging process. Of the different measures of vascular compliance, those more closely related to chronological age need to be identified. These measures may help in the estimation of 'biological age'. We measured pulse wave velocity as the carotid-finger interval, carotid-toe interval and QKD interval (time between the Q wave and the arrival of the diastolic Korotkoff sound (K) over the brachial artery in diastoly (D)); central aortic compliance (CAC) and SV/PP (the stroke volume divided by pulse pressure in the brachial artery). Thirty-six volunteers were studied (30 men), ages 20 to 84, mean 49 years, to give the relationship of these measurements with age. CAC, the QKD interval and the carotid-toe interval were most closely related to age (r = - 0.51, -0.60 and -0.58 respectively). After adjustment for age, the only measure related to blood pressure was the carotid-finger interval; b for diastolic blood pressure = -0.83 (P = 0.01), the higher the pressure the shorter the interval. Measurements of CAC, QKD interval and carotid-toe interval may be employed to assess the impact of age on vascular compliance. Measures of peripheral vascular compliance, such as the carotid-finger interval, may prove useful in assessing the relationship between blood pressure and vascular compliance.

Adult↗

Peripheral arterial compliance is lower in Afro-Caribbeans compared to white Caucasians with type 2 diabetes after adjustment for blood pressure.

Arterial compliance declines with age. However this decline occurs more rapidly in both the hypertensive and diabetic states. Afro-Caribbeans have a higher prevalence of hypertension and other complications of diabetes than the indigenous white Caucasian population. We hypothesise that accelerated decline in arterial compliance may account for this racial difference. Forty-one volunteers, age 62.5 +/- 6.8 years (mean +/- s.d., range 48-75), were selected from diabetic clinics. Twenty-one were Caucasian and 20 were Afro-Caribbean. Pulse wave velocity (PWV) was measured using non-invasive techniques: the 'Complior' system was used to record PWV in the carotid-to-radial (C-R) and carotid-to-femoral (C-F) regions. Central arterial compliance (CAC) was measured by simultaneous aortic flow velocimetry and carotid artery applanation tonometry. The duration of diabetes was taken as the time from clinical diagnosis. Baseline characteristics in the two racial groups were comparable for age, BMI, cholesterol, HbA1c, blood pressure and duration of diabetes. Comparing the PWV in the C-F region showed that the mean PWV was 13.84 +/- 0.28 m/sec in the Caucasians and 13.97 +/- 0.34 m/sec in the Afro-Caribbeans (P = 0. 86) whereas in the C-R region the mean PWV was 11.13 +/- 0.28 m/sec in Caucasians and 12.10 +/- 0.34 m/sec in the Afro-Caribbeans (P = 0. 03). In agreement with the C-F findings there was no statistical difference in CAC between the two races. Adjustment of PWV in the carotid-radial (C-R) region for systolic and diastolic blood pressure, confirmed that the racial differences were independent of blood pressure (difference 0.91 m/sec, P = 0.046 after adjustment for diastolic pressure and 0.89 m/sec, P = 0.056 after adjustment for both systolic and diastolic blood pressure). Accelerated decline in peripheral arterial compliance may account for the increased stroke rate with diabetes in Afro-Caribbeans.

Adaptation, Physiological↗

Withdrawal of hormonal therapy for 4 weeks decreases arterial compliance in postmenopausal women.

BACKGROUND: We demonstrated in a previous cross-sectional study that arterial compliance is elevated in postmenopausal women taking estrogen-containing hormonal therapy, which may partially account for the reduction in cardiovascular risk observed. OBJECTIVE: To investigate the effects of withdrawal and recommencement of hormonal therapy, each for 4 weeks, on arterial compliance. METHODS: Seventeen postmenopausal women [aged 56 +/- 4 years (mean +/- SD)] taking long-term hormonal therapy (+HT group) were studied at baseline, 4 weeks after withdrawal of hormonal therapy and again 4 weeks after recommencement. Systemic arterial compliance (SAC), pulse wave velocity (PWV) in the aorto-femoral and femoral-dorsalis pedis regions, and hemodynamic variables were measured at baseline, and at the end of each study intervention. As a time-control, seventeen postmenopausal women (aged 63 +/- 7 years) not taking hormonal therapy (-HT group) were also investigated. RESULTS: SAC significantly decreased from 0.47 +/- 0.06 to 0.40 +/- 0.05 arbitrary compliance units (mean +/- SEM; P < 0.05) after 4 weeks withdrawal from hormonal therapy. PWV in the femoral-dorsalis pedis region was elevated significantly by the withdrawal of hormonal therapy (8.4 +/- 0.4 to 9.4 +/- 0.5 m/s; P < 0.05), but PWV in the aortofemoral region did not change. After therapy had been recommenced for 4 weeks, SAC and PWV in the femoral-dorsalis pedis region were restored to baseline values. The -HT group showed no difference in SAC or PWV, and mean arterial pressure did not change in either group throughout the study period. CONCLUSION: These data suggest that hormonal modulation of distal arterial vascular tone may account for short-term changes in arterial compliance associated with estrogen-containing hormonal therapy.

Aorta, Thoracic↗

Higher systemic arterial compliance is associated with greater exercise time and lower blood pressure in a young older population.

OBJECTIVES: Arterial compliance is an important therapeutic target in older individuals in whom stiffening of the proximal arterial circulation is thought to underlie systolic hypertension and increased cardiac work. We have shown previously that arterial compliance is related to aerobic fitness and that it is increased in young (20 to 35 years old), previously sedentary individuals by a 4-week period of moderate aerobic training. The extent to which compliance relates to exercise performance in a random selection of young older patients has not been reported previously. Therefore, we examined the interrelationship between systemic arterial compliance (SAC) and time to cessation of exercise during a standard treadmill exercise test in an older population. DESIGN: A cross-sectional survey. METHODS: SAC was estimated at rest using simultaneous recordings of ascending aortic flow and carotid applanation tonometry in 43 subjects aged 67 +/- 7 years (mean +/- SD; 24 men and 19 women). Treadmill exercise testing was performed using a modified Bruce protocol. Aerobic capacity was assessed as Heart Rate-Blood Pressure product and exercise tolerance as total treadmill time. RESULTS: SAC and exercise tolerance were related to gender, with men exhibiting greater exercise reserve and higher SAC than women. There was a significant positive correlation between SAC and time to cessation of exercise (r = .34; P = .03), with a negative correlation between SAC and resting heart rate-blood pressure product (r = -.66; P < .001). SAC was correlated with height and blood pressure. Exercise tolerance was related to height (P < .02). CONCLUSIONS: These data indicate a positive association between SAC and fitness level in healthy older people and an inverse association between SAC and systolic blood pressure. Our findings are consistent with either (1) acquisition of a more compliant circulation and lower blood pressure through more physical activity or (2) that a more compliant arterial circulation and lower blood pressure permit greater athletic performance.

Aged↗

Vascular compliance as a measure of biological age.

OBJECTIVES: To determine the measure of vascular compliance most closely related to age. DESIGN: A review of 22 studies relating aortic compliance to age and a discussion of other factors related to vascular compliance. MEASUREMENTS: Aortic compliance, elastic modulus, postmortem aortic changes, pulse wave velocity in the aorta, common carotid, lower limb and upper limb. RESULTS: 1. Aortic compliance and carotid artery compliance is closely related to age; 2. Compliance in the peripheral arteries, in 16 reports, appears less closely related to age; 3. There is evidence that aortic compliance is related to hypertension, cardiac function, and left ventricular hypertrophy and can be increased by exercise, hormonal therapy, antioxidant and antihypertensive treatment; and 4. Vascular compliance is more closely related to chronological age than other measures such as skin inelasticity, greying of hair, baldness etc. CONCLUSIONS: Because of the close relationship between aortic and carotid compliance and chronological age, deviation from the age-predicted norm (biological age) may prove to be a good predictor of cardiovascular pathology.

Aging↗

Blood pressure lowering for the primary and secondary prevention of stroke: treatment of hypertension reduces the risk of stroke.

Hypertension is the most important risk factor in the development of stroke. It is also the risk factor most amenable to treatment. The results from 18 controlled trials show a reduction in relative risk of stroke of 25-47% among treated hypertensive patients. This reduction applies both to the elderly and to younger patients, but the absolute reductions are greater among the elderly and the number of patients with hypertension that need to be treated to prevent a stroke is lower in the elderly because they have a higher risk of stroke. The reductions in relative but not absolute risk appear to be similar for both isolated systolic hypertension and combined systolic and diastolic hypertension in the elderly. The case for antihypertensive treatment in the secondary prevention of stroke is less clear but the results of four clinical trials of antihypertensive treatment among patients with and without hypertension and a history of cerebrovascular disease point to a probable benefit. The results of the PROGRESS trial will elucidate this further.

Antihypertensive Agents↗