Biomedical subjects
Publications and source records attributed to D B Rowlands.
Patients with cyanotic congenital heart disease who have obstruction proximal to the pulmonary arteries and, hence, do not develop pulmonary hypertension, can go through pregnancy successfully, if the pregnancy and delivery are adequately cared for, with possible complications in mind. We report a successful pregnancy in a woman with congenital tricuspid stenosis and a patent oval foramen.
Ambulatory blood pressure variability and forearm haemodynamics were measured in 23 untreated hypertensive patients with a mean casual blood pressure of 162/102(11/9) mmHg (without target organ damage). There was a good inverse correlation between blood pressure variability and the ability of the forearm resistance vessels to dilate after a period of venous occlusion. Previous work has shown that this vasodilatory component of the response to forearm venous occlusion is significantly reduced in hypertensive patients compared with normotensive controls and is probably an indicator of the compliance properties of these vessels. The present results suggest that blood pressure variability is greater when resistance vessels are stiffer and emphasise the need to account for this vascular factor in studies of blood pressure behaviour.
We examined the effect of three antihypertensive agents with differing modes of action on blood pressure, heart rate, plasma catecholamines, plasma renin activity, and echocardiographic left ventricular mass. Twenty-six patients were studied; nine were treated with nifedipine, a calcium antagonist, nine were treated with timolol, a nonselective beta-blocker, and eight were treated with indapamide, a diuretic with some probable calcium antagonist properties. All drugs reduced blood pressure satisfactorily; the reduction of systolic blood pressure was not significantly different among the three drugs, but timolol reduced diastolic blood pressure by a greater amount than did either indapamide or nifedipine. Left ventricular (LV) mass was reduced equally by all three drugs. However, there were markedly different effects on the other parameters measured. Heart rate was reduced to a greater extent by timolol than by the other two drugs. Plasma renin activity was reduced by timolol, unchanged by nifedipine, and increased by indapamide. There were no significant changes in either adrenaline or noradrenaline with any of the three drugs. We conclude that these data do not support the hypothesis that the sympathetic nervous system is primarily responsible for left ventricular hypertrophy, and suggest that reduction of left ventricular mass with antihypertensive agents is not the property of any one class of drug.
Nine elderly and 11 young hypertensives underwent continuous ambulatory monitoring of blood pressure (BP), assessment of cardiovascular reflexes and M-mode echocardiography as hospital in-patients prior to treatment with once-daily indapamide (2.5 mg). They were followed as out-patients for 4 months during which time casual BP was measured at monthly intervals. The patients were then readmitted to hospital and studied using the same protocol under similar standardised conditions. The results showed that indapamide reduced casual and ambulatory BP in both young and elderly although the most marked effect was seen on systolic BP. Assessment of cardiovascular reflexes indicates that at least part of the hypotensive action of indapamide is due to a diuretic effect. Treatment with indapamide has comparable results on both young and elderly.
Thirty-three elderly subjects--9 hypertensives, 15 with a history of unexplained falls and 9 asymptomatic volunteers, underwent 24 h continuous intra-arterial ambulatory blood pressure (BP) monitoring under controlled conditions. During this time their response to standardized exercise and baroreflex activity were assessed. The casual BP of the hypertensives was significantly higher than that of the other groups, but during ambulatory BP monitoring, the BP of all 3 groups fell and indeed diastolic BP (DBP) of the hypertensives and fallers was similar during the awake period of monitoring whilst all 3 groups had similar DBP during sleep. Variability of awake and sleep BP was similar. During exercise all 3 groups sustained similar increases in systolic BP (SBP) but the increase in DBP was lower in the volunteers. Baroreflex activity was similar in all groups. The results show little difference between the groups other than those pre-selected by casual BP measurement, and the parameters recorded reflect the process of ageing rather than specific abnormalities associated with the elderly hypertensives or fallers.
Thirteen elderly hypertensives underwent continuous ambulatory blood pressure (BP) monitoring and measurement of cardiovascular reflexes. The results were compared with elderly normotensives and young hypertensives studied using the same protocol. There was a greater disparity between casual systolic BP (SBP) and ambulatory awake SBP in the elderly hypertensives than either the elderly normotensives or young hypertensives. Variability of SBP was greater in the elderly than the young, whilst baroreflex activity was reduced in the elderly, and more markedly so in the elderly hypertensives. Response to tilt and pressor tests was similar for the elderly. The elderly hypertensives showed a greater fall of SBP in response to tilt and a greater rise of SBP during dynamic exercise than the young hypertensives. Stimulation of plasma renin activity (PRA) in response to upright tilt was less in the elderly hypertensives than the young hypertensives. Resting plasma noradrenaline (PNA) increased with age.
Prophylactic antibiotics are frequently prescribed for patients undergoing permanent pacemaker implantation even though data confirming their effectiveness are limited. Five hundred patients requiring elective permanent pacemaker implantation or generator replacement were prospectively randomized either to receive or not receive prophylactic antibiotic treatment at the time of implantation. The implantation site was treated with 10% povidone-iodine solution and 0.5% alcoholic chlorhexidine preoperatively. The wound were inspected for evidence of infection at 3 days and 1, 3, 6 and 12 months postimplantation. Three patients (two receiving prophylactic antibiotics and one no antibiotics) developed pacemaker pocket infection; Staphylococcus aureus was the pathogenic organism in each case (P = 0.56). Eighteen patients developed clinical evidence of superficial wound inflammation requiring antibiotic treatment but not pacemaker removal. Six had received prophylactic antibiotics and 12 had not (P = 0.27). We conclude that pacemaker pocket infection is unusual with careful preoperative skin preparation and close postoperative follow-up. Under these circumstances prophylactic antibiotic treatment is of no practical value.
The effect of environment on blood pressure was studied by recording intra-arterial pressure continuously in nine patients with essential hypertension during controlled periods of activity and rest at home and in hospital. Mean systolic pressure was higher at home (152 +/- 16 mm Hg) than in hospital (138 +/- 11 mm Hg, p less than 0.01), the difference being greatest during the period of activity (165 +/- 21 v 142 +/- 13 mm Hg, p less than 0.001); heart rates and diastolic pressures did not differ significantly at these times. Systolic pressure recorded by conventional sphygmomanometry was also higher at home (173 +/- 23 v 159 +/- 23 mm Hg, p less than 0.01), as was diastolic pressure (98 +/- 10 v 89 +/- 11 mm Hg, p less than 0.02). Systolic pressure was consistently higher at home, and this effect was independent of the pressure of an observer. This must be taken into consideration when assessing blood pressure and efficacy of treatment in hospital.
Thirteen elderly hypertensives (EH) underwent ambulatory blood pressure (BP) monitoring and measurement of cardiovascular reflexes. The results were compared with elderly normotensives (EN) and young hypertensives (YH) in studies using the same protocol. There was a greater disparity between casual systolic BP (SBP) and ambulatory awake SBP in EH than EN or YH. Variability of SBP was greater in the elderly than in the young, whilst baroreflex activity was reduced in the elderly, more markedly so in EH. Response to tilt and pressor tests were similar in EH and EN. EH showed greater changes in response to tilt and dynamic exercise than YH. The results suggest an exaggerated response to casual BP measurement in EH. The reduced baroreflex activity in EH could be associated with greater degenerative changes. The EH are exposed to greater peaks of BP than EN in response to pressor stimuli.
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50 patients with mild to moderate essential hypertension underwent M-mode echocardiography and continuous intra-arterial ambulatory monitoring of blood pressure. Indices of left-ventricular (LV) mass were derived from echocardiographic data by standard formulae. 43 of the patients were followed up for 12+/-7 months with repeat M-mode echocardiography, and casual blood-pressure measurements. 25 of these patients received antihypertensive therapy and 18 were untreated. Mean 24 h systolic blood pressure was significantly correlated with echocardiographic LV mass; mean 24 h diastolic blood pressure was also correlated, but the relation was weaker. In the treated group there was a significantly greater fall in blood pressure and LV mass index than in the untreated group, and there was a significant correlation between the fall in systolic blood pressure and the fall in LV mass index in the treated group. Systolic blood pressure appears to be an important factor in the pathogenesis of LV hypertrophy, and in hypertensive patients changes in LV mass assessed by echocardiography correlate with changes in blood pressure.
1 Ten untreated hypertensive patients underwent 24 h continuous intra-arterial ambulatory monitoring of blood pressure (BP) and M-mode echocardiography. 2 They were treated with once-daily timolol and followed up at 2, 4, 8 and 12 weeks when dosage was titrated against BP control (indirect measurement) and degree of beta-adrenoceptor antagonism (submaximal bicycle ergometry and sub-lingual GTN). 3 Sixteen weeks after commencing therapy, nine patients underwent repeat continuous ambulatory monitoring of BP and M-mode echocardiography. 4 Casual BP was significantly reduced during the follow-up period at 2, 4, 8 and 12 weeks. 5 A reduction of BP was seen throughout the 24 h although this did not achieve statistical significance when sympathetic activity was low. 6 Echocardiographic measurement of left ventricular mass was significantly reduced after 16 weeks treatment.
1. Continuous intra-arterial ambulatory monitoring of blood pressure was recorded in 46 patients with mild to moderate hypertension under standardized conditions. M-mode echocardiography was performed after recording and left ventricular mass index calculated by standard formulae. 2. Systolic blood pressure from continuous recording was significantly correlated with left ventricular mass index (mean 24 h: r = 0.543, n = 45, P less than 0.001). Diastolic blood pressure exhibited a weaker but still significant correlation with left ventricular mass index (mean 24 h: r = 0.318, n = 45, P less than 0.05). Casual systolic blood pressure was significantly correlated with left ventricular mass index (r = 0.476, n = 46, P less than 0.001) but casual diastolic blood pressure did not correlate with left ventricular mass index (r = 0.245, n = 46). Awake blood pressure variability, age, resting plasma renin activity and resting plasma noradrenaline levels did not have a significant correlation with left ventricular mass index. 3. Nine patients were treated for 16 weeks with once-daily timolol and repeat ambulatory monitoring and M-mode echocardiography was performed with the same protocol. 4. Once-daily timolol provided good 24 h control of blood pressure and repeat echocardiography showed a reduction in left ventricular mass index in that group of patients (t = 2.59, P less than 0.05).
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1. Ambulatory blood pressure recordings were made over a 48 h period on six hypertensive patients. The conditions of study were standardized, particularly with regard to physical activity, and during one period of each day the patients were randomly allocated to be active or inactive. 2. Results show that blood pressure was highest during physical activity and lowest during sleep. There was no significant difference between the arterial pressures measured during the same physical activities carried out at the same time each day. However, during the same time on consecutive days when activity was randomized, there was a significant difference between the pressure recordings during physical activity compared with those during inactivity. Heart rate changes showed a similar trend during the randomized period. 3. Physical activity and sleep have a profound effect on continuous arterial blood pressure recordings and these are independent of time alone. These observations should be taken into account when using this ambulatory system to assess hypotensive therapy.
Sixteen untreated black patients with mild-to-moderate hypertension and no evidence of target organ damage were matched for age, sex, casual blood pressure (BP), and socioeconomic status with 16 white hypertensives. All patients were studied under standardized conditions in the hospital where they underwent continuous intraarterial ambulatory monitoring of BP and assessment of BP control mechanisms. BP characteristics over prolonged periods of recording were similar for both groups, as were sinoaortic baroreflex activity and pressor response to isometric and dynamic exercise and to cold. Fasting cholesterol and triglyceride levels in both groups were similar. Resting plasma renin activity (PRA) was significantly lower in blacks, but no difference was observed in resting plasma norepinephrine levels. Urinary excretion of NA+ and K+ was also similar in both groups. Thus, results showed that casual BPs matched for black and whites, and recorded over a prolonged period, were similar in pattern, variability, and response to pressor stimuli. It appears that, if BP contributes to the different patterns of morbidity in blacks and whites, it is more likely to be the actual level of BP rather than differences in BP characteristics.