Chakravarthi Rajkumar

Estimation of central aortic pressure by SphygmoCor ® requires intra-arterial peripheral pressures

Central arterial pressure, measured close to the heart, may be of more patho-physiological importance than conventional non-invasive cuff blood pressure. The technique of applanation tonometry using SphygmoCor® has been proposed as a non-invasive method of estimating central pressure. This relies on mathematically derived generalized transfer functions, which have been previously validated using invasive peripheral pressure measurements. We compared simultaneous estimates of central aortic pressure using this technique with those measured directly during the routine diagnostic cardiac catheterization of 30 subjects (age range 27–84 years), half of whom were aged 65 years or more. This was done by applanating the left radial artery and recording the non-invasive brachial cuff blood pressure to generate a central aortic pressure estimate, using the SphygmoCor® radial transfer function. The comparative results were analysed using Bland—Altman plots of mean difference. SphygmoCor®, on average, underestimated systolic central arterial pressure by 13.3 mmHg and overestimated diastolic pressure by 11.5 mmHg. The results were similar in patients aged under and above 65 years. Furthermore, non-invasively measured brachial pressures were seen to give an overall closer estimate of the central arterial pressure than the SphygmoCor® system. The transfer function has been validated from invasively measured arterial pressures and the current use by the system of non-invasive measures may explain the discrepancies. However, age, drugs and arterial disease would also be expected to play a role.

Ethnic differences in vascular stiffness and relations to hypertensive target organ damage.

Objective People of Black African descent have greater risks of hypertensive target organ damage than would be anticipated for given levels of blood pressure. Arterial stiffness may further account for ethnic differences in risk. Design Cross-sectional study. Setting Population based, London, UK. Participants One hundred and three Europeans and 99 African Caribbeans aged 40–64 years. Methods We measured resting and ambulatory blood pressure, and pulse wave velocity (PWV) of elastic and muscular arteries. Echocardiography measured interventricular septal thickness (IVST). Main outcome measures PWV, IVST. Results Carotid–femoral PWV was 12.7 m/s [95% confidence interval (CI) 12.3, 13.1] in African Caribbeans and 11.2 m/s (10.9, 11.6) in Europeans (P < 0.0001). This difference persisted on adjustment for resting and ambulatory blood pressure, 12.4 versus 11.5 m/s (P = 0.003). The greater IVST in African Caribbeans (9.6 mm) compared to Europeans (9.1 mm, P = 0.0005), could only in part be accounted for by differences in carotid–femoral PWV. Stiffness in the muscular carotid–radial segment did not differ by ethnicity, but was positively associated with systolic pressure in Europeans (β regression coefficient 0.033, P = 0.04), and negatively associated in African Caribbeans (−0.036, P = 0.04, and P = 0.02 for interaction). Conclusions Aortic stiffness is increased in African Caribbeans compared to Europeans, even when higher blood pressures are accounted for. It is most closely related to IVST, but contributes little to explaining ethnic differences. Stiffness of the upper limb muscular arteries did not differ by ethnicity, but remained favourable in the presence of hypertension in African Caribbeans, while being increased in Europeans. We suggest that this is due to ethnic differences in vascular remodelling.

Views of elderly people on living wills: interview study

Editorial by Emanuel nnLiving wills or advance statements record peoples healthcare wishes in case they are unable to contribute to a decision concerning their health care in the future, either because of mental incapacity or because physical disability prevents communication.1 Elderly people are often in this position owing to illnesses such as dementia and strokes that cause dysphasia. The views of elderly North Americans on this subject are well documented, but there are no reports of the views of older people in England.2 3 This study aimed to determine the knowledge of elderly inpatients in the United Kingdom on living wills and their healthcare choices should they write such a will.nnSeventy four out of 76 medical inpatients approached answered a questionnaire administered by one interviewer (RS) at two hospitals in London. All participants were aged over 65 and had a normal score on the abbreviated mental test. Ethical approval had been obtained.nnThe …

Vascular Compliance as a Measure of Biological Age

OBJECTIVES: To determine the measure of vascular compliance most closely related to age.

The Relationship Between Androgens and Arterial Stiffness in Older Men

Objectives: To assess the relationship between endogenous androgen levels and arterial stiffness in older men.

Blood pressure measurement in patients with rate controlled atrial fibrillation using mercury sphygmomanometer and Omron HEM-750CP deice in the clinic setting

Blood pressure measurement in patients with rate controlled atrial fibrillation using mercury sphygmomanometer and Omron HEM-750CP deice in the clinic setting

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

Aims/hypothesisDiabetes 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 methodsTo 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.ResultsIn 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/interpretationPersisting 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.

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.

Estimation of central aortic pressure by SphygmoCor® requires intra-arterial peripheral pressures: authors' reply

Central arterial pressure, measured close to the heart, may be of more patho-physiological importance than conventional non-invasive cuff blood pressure. The technique of applanation tonometry using SphygmoCor has been proposed as a non-invasive method of estimating central pressure. This relies on mathematically derived generalized transfer functions, which have been previously validated using invasive peripheral pressure measurements. We compared simultaneous estimates of central aortic pressure using this technique with those measured directly during the routine diagnostic cardiac catheterization of 30 subjects (age range 27-84 years), half of whom were aged 65 years or more. This was done by applanating the left radial artery and recording the non-invasive brachial cuff blood pressure to generate a central aortic pressure estimate, using the SphygmoCor radial transfer function. The comparative results were analysed using Bland-Altman plots of mean difference. SphygmoCor, on average, underestimated systolic central arterial pressure by 13.3 mmHg and overestimated diastolic pressure by 11.5 mmHg. The results were similar in patients aged under and above 65 years. Furthermore, non-invasively measured brachial pressures were seen to give an overall closer estimate of the central arterial pressure than the SphygmoCor system. The transfer function has been validated from invasively measured arterial pressures and the current use by the system of non-invasive measures may explain the discrepancies. However, age, drugs and arterial disease would also be expected to play a role.