E O'Brien

ECHOCARDIOGRAPHY IN DIAGNOSIS OF AORTIC DISSECTION

In a multicentre study the accuracy of echocardiography was measured in 164 consecutive patients with suspected aortic dissection. The diagnosis was subsequently proven (82 patients) on the basis of transthoracic and transoesophageal echocardiography and additional diagnostic procedures, including computed tomography (CT), aortic angiography, and surgery and/or necropsy. The sensitivity and specificity of echocardiography were 99% and 98%, respectively, with positive and negative predictive values of 98% and 99%. For CT sensitivity was 83%, specificity 100%, and positive and negative predictive values 100% and 86%, respectively. For aortography sensitivity and specificity were 88% and 94%, and the positive and negative predictive values 96% and 84%, respectively. Echocardiography, including the transoesophageal route, can provide accurate diagnosis of aortic dissection within 15 min. Diagnostic difficulties occur only in a few type II dissections, when complementary diagnostic procedures, including CT or angiography, may be needed. To clarify branch involvement angiography is required.

Diagnosis of White Coat Hypertension by Ambulatory Blood Pressure Monitoring

White coat hypertension (WCH) is common in referred hypertensive patients. Ambulatory blood pressure monitoring (ABPM) is not free from the white coat syndrome. We examined the use of the elevation of the first and last measurements of ABPM for diagnosis of WCH in a hypertensive population that had been referred to a hospital-based hypertension unit. Data were obtained on 1350 patients for clinic and ABPM parameters. WCH, as diagnosed by conventional clinic blood pressure (BP) measurement, was compared with a variety of alternative methods determined from ABPM. In all cases, mean daytime pressure was <135 mm Hg/85 mm Hg with an elevation of clinic BP >/=140 mm Hg systolic or 90 mm Hg diastolic. The definitions tested for this elevation were first hour mean pressure, first reading, maximum reading in first hour, last hour mean pressure, last reading, maximum reading in the last hour and maximum reading in first or last hour. Elevation of the maximum pressure in the first hour or last hour above 140 mm Hg systolic or 90 mm Hg diastolic showed a high level of agreement (kappa=0.91) with classical WCH for diagnosis of the white coat syndrome. Termed ambulatory white coat hypertension, patients with this finding were older than classic white coat patients and had higher daytime (127+/-6/78+/-5 mm Hg versus 121+/-5.5/74+/-6 mm Hg, P<0.005 for systolic and diastolic) and nighttime (114+/-11/67+/-8 mm Hg versus 106+/-9/61+/-6 mm Hg, P<0.005 for systolic and diastolic) pressures. They also had a significantly greater Sokolow-Lyon index (leads V(1)+V(5), 21+/-7 mV versus 18+/-6 mV). Elevation of BP above 140 mm Hg systolic or 90 mm Hg diastolic in the first or last hour of monitoring diagnoses patients with a white coat response in whom there is a higher BP profile than in patients with classic white coat response alone. We suggest, therefore, that this is a better measure of the white coat phenomenon.

Determinants of white-coat hypertension.

BackgroundThe prevalence of white-coat hypertension (WCH) is considerable in patients referred with elevated office blood pressure. Failure to recognise this phenomenon can lead to the inappropriate use of antihypertensive medications. We undertook this study to determine the profile of patients with WCH. MethodsBaseline clinic and daytime ambulatory blood pressures were available from 5716 patients referred over a 22-year period. Individuals were considered to have WCH if they had an elevated clinic blood pressure measurement greater than 140/90 mmHg and normal daytime mean ambulatory blood pressure. Mean age was 53.6 years and 53.2% were female. ResultsThe overall prevalence of white-coat hypertension was 15.4%. A higher prevalence was seen amongst older adults, females, and non-smokers. ConclusionMultivariate logistic regression analysis confirmed these characteristics as independent predictors of WCH.

Accuracy of the SpaceLabs 90207 ambulatory blood pressure measuring system in normotensive pregnant women determined by the British Hypertension Society protocol.

The SpaceLabs 90207 monitor (Redmond, Washington, USA) for ambulatory blood pr-nue measurement u-as evaluated according to the protocol of the British Hypertension Society (BHS) 111 in normotmsive pregnant women. We have previously evaluated the SpaceLabs 90207 in nonnotmsive and hypertensive men and non-pregnant women according to the BHS protocol (21, In this evaluation the device achieved B gnding for systolic and diasoiic pressure and fulfilled the criteria of the Association for the Advancement of Medical Instrumentarion W) 131. three sequential measurements were performed in the same arm with the Spacehbs 90207 and a standard mercury sphvgmomanometer using Korotkoff phase v (disappearance of sounds) for diastolic pressure. The mean and standard deviation of the first mercury sphygmomanometer measurements were (systoliddiastolic) 1121 1/6&12 mrn~g. The SpaceLabs 90207 =as grad4 A for systolic and C for diastolic pressure according to the BHS protocol (Table 1). ~pplying the AMlI accuracy criteria 141, the SpaceLabs 90207 W e d the requirement for systolic but not diastolic p m , mean differences being 524 for systolic and mmHg for phase V diastolic pressurr.

Thirty years of research on diagnostic and therapeutic thresholds for the self-measured blood pressure at home.

ObjectiveThe goal of this review study is to summarize 30 years of research on cut-off limits for the self-measured blood pressure. MethodsWe reviewed two meta-analyses, several prospective outcome studies in populations and hypertensive patients, studies in pregnant women, three clinical trials and the thresholds proposed in earlier and current hypertension guidelines. ResultsIn line with existing guidelines, prospective studies support that levels of the self-measured blood pressure at home of greater than or equal to 135 mmHg systolic or greater than or equal to 85 mmHg diastolic indicate hypertension. Circumstantial data suggest that levels of the self-measured blood pressure below 120/80 and 130/85 mmHg are optimal and normal, respectively. Therapeutic targets of the self-measured blood pressure to be attained on antihypertensive drug treatment are currently unknown, but should logically be lower (<135/85 mmHg) than those used to diagnose hypertension. Currently, there is no proof that therapeutic thresholds for the home blood pressure should be lower in high-risk compared with normal-risk patients. A large body of evidence, however, demonstrated that each millimetre of mercury of blood pressure lowering counts in the prevention of cardiovascular complications and that in high-risk patients even small decreases in blood pressure result in large absolute benefit. ConclusionThe thresholds to diagnose hypertension from self-measured blood pressure readings at home remain unaltered since the 2000 consensus conference, but are currently supported by outcome data. Further studies need to establish what values of the self-measured blood pressure are optimal and normal in terms of cardiovascular outcome.

Ambulatory pressure decreases on long-term placebo treatment in older patients with isolated systolic hypertension

Objective This long-term study investigated the widely accepted hypothesis that ambulatory pressure does not decrease in patients given placebo. Methods: One hundred and twelve older (±60 years) outpatients with isolated systolic hypertension were recruited. Treatment consisted of a placebo during a 3-month baseline period and long-term follow-up. Results: At baseline, on placebo treatment, clinic systolic/diastolic (SBP/DBP) blood pressure (±SD) averaged 176±12/86±7 mmHg and 24-h SBP/DBP 151 ± 15/81 ± 10mmHg. These pressures were unaltered in 51 patients in whom the baseline measurements were repeated after a further month on placebo. After the 112 patients had received placebo for 1 year (median), clinic SBP/DBP fell by 6.6±15.9 (P <0.001)/1.4±7.4 (P=0.06)mmHg and 24-h SBP by 2.4±10.7mmHg (P<0.05), whereas 24-h DBP did not change significantly. The 24-h SBP decreased more with higher baseline level and longer follow-up (5–21 months). Conclusions: These findings in older patients with isolated systolic hypertension suggest that in long-term studies the ambulatory pressure may slightly but significantly decrease on a placebo. Like those using conventional sphygmomano-metry, long-term studies using non-invasive ambulatory monitoring require a placebo-controlled design.

Ambulatory blood pressure monitoring and postprandial hypotension in elderly patients with isolated systolic hypertension

The present analysis was undertaken to evaluate postprandial (PP) changes in blood pressure (BP) assessed with ambulatory BP monitoring (ABPM) in elderly subjects with isolated systolic hypertension (ISH) on conventional measurement. A total of 530 patients (335 women and 195 men, aged 60–100 years, median 70 years) who performed an ABPM during the placebo run-in period of the Syst-Eur trial were included into the analysis. The PP changes in BP and heart rate (HR) were calculated by subtracting the mean systolic BP (SBP), diastolic BP (DBP) and HR in the 2 h preceding the main meal from the corresponding means covering the 2 h after the meal. The reproducibility of the postprandial fall in BP and heart rate (PPH) was assessed by contrasting the first and second ABPM in a subgroup of 147 patients who performed two ABPM’s during the placebo run-in period. The mean SBP and DBP decreased and reached the nadir 2 h after the main meal while HR did not change. When PPH was assessed by comparing BP in the 2 h before and after the meal, both SBP and DBP decreased significantly (respectively −6.6 mm Hg, −5.4 mm Hg; P < 0.001). in 67.6% of all patients a decrease in sbp was observed and in 24.1% it exceeded 16 mm hg. the corresponding values for dbp were 71.3% and 24.5% (dbp decreased more than 12 mm hg). a greater fall in dbp was associated with a greater decrease in hr (r = 0.20, P < 0.001), while changes in sbp and hr were not interrelated. regression analysis did not identify any significant covariate of pph. group means of pph could be reproduced without significant changes in their values, but the within-subject reproducibility of the pp changes was low. there were no differences in pph according to the place of residence of the patients. in conclusion, the descriptive analysis of the meal-induced changes in abpm in elderly subjects with ish showed that in every day circumstances most of them experience falls in both sbp and dbp within 2 h after the meal.

Clinical trials with ambulatory blood pressure monitoring: fewer patients needed?

We have tested the concept that fewer patients are needed in trials of antihypertensive treatment if blood pressure is measured by ambulatory monitoring rather than by conventional sphygmomanometry. 233 patients (> or = 60 years old) with isolated systolic hypertension were randomly allocated placebo (n = 119) or active treatment (n = 114). Blood pressure measurements were compared by Wilcoxons test and blood pressure profiles by ANOVA. With either method of measurement, the same number of patients (40 in each treatment group) was required to show a reduction after 1 year in clinic (13/8 mm Hg) or average blood pressure over 24 h (9/5 mm Hg). To detect that the decrease in systolic pressure was not steadily maintained through the day, 40 patients in each treatment group were needed for blood pressure profiles made up of 4-hourly or 2-hourly means and 60 for profiles of 1-hourly means. For diastolic pressure, the corresponding numbers were 80, 100, and more than the number of available patients, respectively. We conclude that parallel-group trials focusing on the average blood pressure over 24 h, rather than on conventionally measured blood pressure, cannot economise on sample size. Moreover, trials studying the full course of blood pressure throughout the day, require more--not fewer--patients than studies of only the conventional or average 24 h blood pressure.

Ambulatory blood pressure in the hypertensive population : patterns and prevalence of hypertensive subforms

Background A number of clinically identifiable patterns of blood pressure elevation are apparent using ambulatory measurement. Their prevalence and age and sex distribution have not been described. The purpose of this study was to describe the epidemiology of patterns of high blood pressure in a large population. Design Retrospective database analysis of referral hypertensive population. Patients Clinic and ambulatory blood pressure measurements were performed in 2092 patients with essential hypertension while they were not taking antihypertensive medication. Methods The patients were classified into six groups on the basis of their ambulatory blood pressure monitoring profiles: white-coat hypertensives, borderline hypertensives, isolated systolic hypertensives, isolated diastolic hypertensives, combined systolic and diastolic hypertensives and nocturnal hypertensives. The categories were examined for age and sex differences. Results All patients were categorized into one of the six groups. The majority (56.2%) were systolodiastolic hypertensives, 12.9% were borderline and 10.8% were white-coat hypertensives. Isolated systolic hypertensives comprised 6.2% of the population, isolated diastolic hypertensives 6.9% and nocturnal hypertensives 7.1%. The isolated systolic hypertensives showed the greatest change with age, with a prevalence of < 5% in patients below 40 years of age, rising to almost 20% in the 70 plus age group. White-coat, isolated diastolic and borderline hypertensives showed the opposite change in prevalence, falling from younger to older age groups. Apart from a greater prevalence of white-coat hypertension in females, the patterns were largely similar between sexes. Conclusions Ambulatory blood pressure monitoring allows the blood pressure pattern to be defined in hypertensive patients. The patterns identified here in a referral hypertensive cohort show changes in prevalence with age, and further study is required to determine the prognostic significance of hypertensive sub-forms.

Ambulatory Monitoring Uncorrected for Placebo Overestimates Long-term Antihypertensive Action

This study compares blood pressure (BP) changes during active antihypertensive treatment and placebo as assessed by conventional and ambulatory BP measurement. Older patients (> or = 60 years, n=337) with isolated systolic hypertension by conventional sphygmomanometry at the clinic were randomized to placebo or active treatment consisting of nitrendipine (10 to 40 mg/d), with the possible addition of enalapril (5 to 20 mg/d) and/or hydrochlorothiazide (12.5 to 25 mg/d). At baseline, clinic systolic/diastolic BP averaged 175/86 mm Hg and 24-hour and daytime ambulatory BPs averaged 148/80 and 154/85 mm Hg, respectively. After 13 months (median) of active treatment, clinic BP had dropped by 22.7/7.0 mm Hg and 24-hour and daytime BPs by 10.5/4.5 and 9.7/4.3 mm Hg, respectively (P<.001 for all). However, clinic (9.8/1.6 mm Hg), 24-hour (2.1/1.1 mm Hg), and daytime (2.9/1.0 mm Hg) BPs decreased also during placebo (P<.05, except for daytime diastolic BP); these decreases represented 43%/23%, 20%/24%, and 30%/23% of the corresponding BP fall during active treatment. After subtraction of placebo effects, the net BP reductions during active treatment averaged only 12.9/5.4, 8.3/3.4, and 6.8/3.2 mm Hg for clinic, 24-hour, and daytime BPs, respectively. The effect of active treatment was also subject to diurnal variation (P<.05). Changes during placebo in hourly systolic and diastolic BP means amounted to (median) 21% (range, -1% to 42%) and 25% (-3% to 72%), respectively, of the corresponding changes during active treatment. In conclusion, expressed in millimeters of mercury, the effect of antihypertensive treatment on BP is larger with conventional than with ambulatory measurement. Regardless of whether BP is measured by conventional sphygmomanometry or ambulatory monitoring, a substantial proportion of the long-term BP changes observed during active treatment may be attributed to placebo effects. Thus, ambulatory monitoring uncorrected for placebo or control observations, like conventional sphygmomanometry, overestimates BP responses in clinical trials of long duration.