Vasorelaxant actions of enoximone, dobutamine, and the combination on human arterial coronary bypass grafts

Enoximone (a type III-selective phosphodiesterase inhibitor) and dobutamine (a beta-receptor agonist) are positive inotropic drugs frequently used in the postoperative management of coronary bypass surgery. The purpose of this study was to characterize their relaxant effects on the human internal mammary artery (IMA) and the gastroepiploic artery (GEA) and to test the hypothesis that their combination may have greater than additive relaxant effects. In organ baths, the relaxant effects of enoximone and dobutamine were tested on rings of IMA (n = 86) precontracted with U46619 (a thromboxane A2 mimetic), norepinephrine (NE), or KCl. The relaxant effects of dobutamine and enoximone also were tested on rings of GEA (n = 42) precontracted with U46619 and NE. The effect of the combination of enoximone and dobutamine were tested on rings of IMA (n = 24) precontracted with U46619 or NE. With respect to maximal relaxations induced by papaverine (10(-4) M), enoximone (< or =10(-3) M) caused full relaxations of IMA precontracted with NE, U46619, or KCI. Dobutamine (< or =10(-3) M) caused full relaxations of IMA precontracted with NE or KCI but only 46% (95% CI, 27-65) relaxation in the rings precontracted with U46619. Similar patterns of relaxation were observed in GEA rings, with dobutamine inducing partial relaxation in GEA precontracted with U46619. The pD2 values of enoximone and dobutamine were both significantly lower in segments precontracted with U46619. The in vitro threshold relaxant concentrations were in the upper limits or over the range of therapeutic plasma concentrations. The relaxant effect of the combination was significantly more important than the theoretic additive effect in IMA contracted with U46619 or NE. Enoximone and dobutamine are potent in vitro vasodilators but exert weak relaxant effects in IMA and GEA at concentrations in the therapeutic range. There is, however, a greater than additive vasorelaxant effect of the combination, suggesting that the vasorelaxant effect of the combination, in addition to the additive inotropic effect, may be beneficial to patients undergoing coronary bypass grafting.

[Pulmonary embolism and anaphylactic shock caused by rupture of a hepatic hydatid cyst]

A 44 year old man was admitted to hospital as an emergency for shock associated with giant urticaria and atrial fibrillation. Angiography showed pulmonary embolism, and an image suggesting a hydatid cyst of the liver was observed by echocardiography in the sub-costal view, confirmed by liver ultrasonic scan and serology. After treatment with Albendazole, the cyst was removed surgically and histology showed the characteristic appearances of hydatid disease. The final diagnosis was rupture of a hydatid cyst into a sub-hepatic vein with anaphylactic shock and pulmonary embolism.

[Evaluation of the ambulatory blood pressure monitor SAVE 33 model 2]

This work tests a new ambulatory blood pressure device: Save 33 II. The evaluation is conducted according to the phases II and IV of the British Hypertension Society (BHS) protocol: the phases I and III (before and after use) are not performed as this device has received the European quality label 'CE' that guarantees a +/- 3 mmHg accuracy before and after 10,000 simulated cycles. Two trained observers (hearing test and certification done according to the BHS recommendations) have performed 7 sequential BP measurements with conventional and automatic method, at the same arm, among 85 patients. The ranges of mean blood pressure are 78-203 mmHg, for SBP and 53-130 mmHg for DBP.

RESULTS

The Save 33 II monitor satisfies the grade B of BHS evaluation for both systolic and diastolic pressures. This device also satisfies the Association for the Advancement of Medical Instrumentation (AAMI) protocol: mean difference between methods and standard deviation less than 5 +/- 8 mmHg: -2.7 +/- 6.8 mmHg for SBP and -0.86 +/- 6.6 mmHg for DBP. The in-use assessment is conform to BHS criteria for 20 recordings (less than 20% invalid values during day and night); the 5 other recordings have not enough night values, due to batteries failure (2 cases), sleeping discomfort (2 cases) and a cuff withdraw.

CONCLUSION

This device, in the tested configuration, agrees the B grade of BHS and can be recommended for ambulatory blood pressure measurement.

[Kinetics of circadian variations in ambulatory arterial blood pressure and cardiovascular sequelae]

OBJECTIVE

To study the relationships between evolution of changes in blood pressure (BP) over the 24 hour cycle and their cardiac and vascular consequences in mild to moderate hypertensive (HT) subjects (WHO criteria).

MATERIAL AND METHODS

151 patients presenting with mild to moderate essential HT (Age 49 +/- 12 yrs, 63 M 44W)--ambulatory measurement of BP over 24 hours (Spacelabs 90207) automatic determination of the diurnal cycle by Fourier analysis (5 harmonics) and calculation of the slope of BP variation (mmHg/hr) at the point of transition from day to night (nocturnal dip slope (NDS)), and at the change from night to day (morning rise slope (MRS). Patients with inversion of the day-night cycle were excluded, day-night being arbitrarily defined as 7 to 22 h and 22 to 7 h. Echography of left ventricular mass index (LVMI)/Penn convention, formula of Devereux, and carotido-femoral distensibility by pulse wave velocity (PWV, Complior Colson France).

RESULTS

Ambulatory measures of BP and HR and of cardiovascular parameters were as follows. [table: see text] The slope of nocturnal fall (NDS) and morning rise in SBP (MRS) is significantly correlated with LVMI (NDP r = -0.02, p = 0.049, MPP r = 0.21, p = 0.029) and with PWV (MPP: r = 0.32, p = 0.005). No relationship was found with the DBP values. By multivariate analysis taking into account age, sex, 24 h SBP, MPP slope velocity was the only variable which was significantly related with the model of PWV and LVMI (p < 0.001).

CONCLUSION

Dipper and non-dipper studies have been performed to examine the consequences of day night variations in BP. The evolution of diurnal changes in BP seems to have an effect on the vessels and heart and may be a simple analysis tool for assessing prognosis and therapeutic effects.

High prevalence and persistence of sleep apnoea in patients referred for acute left ventricular failure and medically treated over 2 months

AIMS

Cardiac failure patients were studied systematically using polysomnography 1 month after recovering from acute pulmonary oedema, and again after 2 months of optimal medical treatment for cardiac failure.

METHODS AND RESULTS

This prospective study of consecutive patients was conducted in a cardiac care unit of a university hospital. V o(2)measurements and left ventricular ejection fraction were recorded. Thirty-four patients, initially recruited with pulmonary oedema, improved after 1 month of medical treatment to NYHA II or III. They were aged less than 75 years and had a left ventricular ejection fraction less than 45% at the time of inclusion. Age was 62 (9) years, body mass index= 27 (5) kg x m(-2)and an ejection fraction= 30 (10)%. Eighteen of the 34 patients (53%) had coronary artery disease. Twenty-eight of the 34 had sleep apnoea syndrome with an apnoea+hypopnoea index >15 x h(-1)of sleep. Thus, the prevalence of sleep apnoea in this population was 82%. Twenty-one of 28 (75%) patients had central sleep apnoea and seven of 28 (25%) had obstructive sleep apnoea. Patients with central sleep apnoea had a lower Pa co(2)than those with obstructive sleep apnoea (33 (5) vs 37 (5) mmHg, P<0.005). Significant correlations were found between apnoea+hypopnoea index and peak exercise oxygen consumption (r= -0.73, P<0.01), and apnoea+hypopnoea index and Pa co(2)(r= -0.42, P = 0.03). When only central sleep apnoea patients were considered, a correlation between apnoea+hypopnoea index and left ventricular ejection fraction was also demonstrated (r= -0.46, P<0.04). After 2 months of optimal medical treatment only two patients (both with central sleep apnoea) showed improvement (apnoea+hypopnoea index <15 x h(-1)).

CONCLUSIONS

We have demonstrated a high prevalence of sleep apnoea, which persisted after 2 months of medical treatment, in patients referred for acute left ventricular failure. Central sleep apnoea can be considered a marker of the severity of congestive heart failure.

[Effect of intensive antihypertensive treatment and of aspirin in a low dose in the hypertensive. The HOT (Hypertension Optimal Treatment) study]

The aim of the HOT Study (Hypertension Optimal Treatment) was to determine the optimal diastolic blood pressure decrease and to assess the effect of the acetyl salicylic acid as a primary prevention on the cardiovascular morbidity and mortality in hypertensive patients. The HOT Study is an open, prospective, randomised, international trial with blinded end points. This study included 18,790 patients, 50 to 80 years old (mean 61.5 years) in 26 countries (1,574 patients in France) with a primary hypertension (100 < or = PAD < or = 115 mmHg). The patients were randomised in 3 target diastolic blood pressure: < or = 80 mmHg (n = 6,262), < or = 85 mmHg (n = 6,264), < or = 90 mmHg (n = 6,264). The felodipine LP, a long acting dihydropyridine, was selected as a first line therapy, other hypertension drugs combined if necessary. The lowest incidence of cardiovascular events was observed at a diastolic blood pressure level of 82.6 mmHg. There was no increased risk below this level even in the hypertensive patients with medical history of coronary heart disease or stroke. In the diabetic population, the diastolic blood pressure decrease from 90 to 80 reduced the incidence of the major cardiovascular events by 51%. The acetyl salicylic acid reduced the myocardial infarction risk in the blood pressure well-controlled population.

[Evaluation of the activity of the autonomic nervous system in "dipper" and "non dipper" essential hypertensives. Gender differences]

OBJECTIVES

1) To compare the autonomic nervous system activity parameters obtained from a photoplethysmographic recording in dipper and non dipper hypertensive. 2) To look for an interaction between dipper/non dipper status and gender.

METHODS

Prospective study involving 245 untreated hypertensives (51 +/- 13 years, 146 men, 99 women). All of the patients underwent a 24-hour ambulatory blood pressure measurement (ABPM) as well as an echocardiography for left ventricular mass index determination (LVMI) and a photoplethysmographic recording of blood pressure (BP). Nondippers were defined as those whose nocturnal decrease in systolic BP (SBP) and/or diastolic BP (DBP) was < 10% of daytime BP. Spectral powers were obtained from the photoplethysmographic recording using a fast Fourier transform over the low frequency band (LF) and the high frequency band (HF). Baroreflex sensitivity (BRS) was evaluated by the sequences method.

RESULTS

Of the 245 patients, 159 were dippers (98 men, 61 women) and 86 were non dippers (48 men and 38 women). Clinic BP was significantly higher in non dippers than in dippers (168/101 vs 161/98 mmHg; p < 0.01 for SBP and p < 0.05 for DBP) whereas daytime ABPM and LVMI were not different, whatever the gender. LF spectral powers were significantly lower in non dippers than in dippers for SBP (respectively 25 +/- 11% vs 30 +/- 13%; p < 0.01) for DBP (respectively 35 +/- 14% vs 41 +/- 15%; p < 0.01) and for HR (respectively 34 +/- 15% vs 38 +/- 15%; p = 0.03). They showed a positive correlation with the nocturnal SBP fall (r = 0.21, p < 0.001 for SBP and DBP spectral powers, r = 0.19; p < 0.005 for HR spectral power) and with the nocturnal DBP fall, too (r = 0.19; p < 0.005 for SBP spectral power, r = 0.20; p < 0.002 for DBP spectral power, r = 0.19; p < 0.005 for HR spectral power). HF spectral powers tended to be higher in non dippers than in dippers but in a non significative way. BRS was roughly the same in dippers and non dippers (7.5 +/- 2.7 vs 7.0 +/- 3.1 ms/mmHg, NS). The interaction between non dipper/dipper status and sex was non significant whatever the LF spectral power.

CONCLUSIONS

1) The greater the nocturnal BP fall, the higher the sympathetic activity indexes. 2) This relationship was found both in males and females.

Study of arterial blood pressure by a Windkessel-type model: influence of arterial functional properties

OBJECTIVE

To analyse the performance of a Windkessel blood pressure (BP) modeling of arterial compliance adjusted in a dynamic fashion according to a non-linear relationship between the arterial compliance (AC) and BP. Non invasive measurements of the radial BP waveform (MILLAR tonometry) were compared to those constructed by an electric simulator reproducing the model in a symmetrical network subdivided into 121 segments. We introduced at cardiac level the aortic stroke volume (Doppler echocardiography) and the dynamic values of compliance (relation of compliance-to pressure, constant or variable) whether the model was linear or non linear, measured by high resolution Doppler (NIUS 02) for each subject.

RESULTS

At the radial artery segment the modelled BP obtained by the non linear model of AC was not significantly different from the measured BP wave, while in the linear model (AC constant at mean BP level) the systolic BP was significantly underestimated. (*P < 0.05).

CONCLUSION

This work shows the limits inherent in simplification of arterial compliance in the Windkessel model using constant parameters. This demonstrates the influence of the dynamic properties of the arterial wall in a conduction artery on the level of systolic and diastolic BP.

Toward a portable blood pressure recorder device equipped with an accelerometer

The 24-h ambulatory systolic blood pressure (ASBP) recording has become a helpful tool in the diagnosis of hypertension and evaluation of the efficiency of anti-hypertensive drugs. Yet, the very high variability of ASBP makes the analysis of the recording rather difficult. A potential solution to reduce ASBP variability has been studied and is presented in this article. It consists of equipping the portable ASBP recorder device with other sensors, a three axes accelerometer and a heart rate recorder, so as to enable an analysis to be undertaken of the arterial pressure profile in the light of these concomitant data. A database has been collected, and a model linking ASBP variations with body acceleration and heart rate measurements is developed. Its performance is tested in prediction and the results compared with those obtained from one of the solutions currently used by physicians to deal with ASBP variability. The results obtained with 16 young subjects from the database, for whom two 24-h recordings are available, are significantly improved and very encouraging.

Clinical value of ambulatory blood pressure monitoring

Ambulatory blood pressure monitoring (ABPM) has now become an established clinical tool. It is appropriate to take stock and assess the situation of this technique. UPDATE ON EQUIPMENT: Important improvements in equipment have occurred, with reductions in weight, in awkwardness and in noisiness of the machines, better acceptability and tolerance by the patients, and better reliability. Validation programmes have been proposed and should be referred to. Limitations of the technique persist with intermittent recording in current practice. The reproducibility is limited in the short-term while recording over 24 h is acceptable. DIAGNOSIS AND PROGNOSIS: White-coat effect (WCE) is manifested as a transient elevation in blood pressure during the medical visit The frequency of this phenomenon, the size of the effect, age, sex and level of blood pressure (BP) or the situation of occurrence (general practitioner, specialist or nurse) have been interpreted differently. It does not seem that WCE predicts cardiovascular morbidity or mortality. White-coat hypertension (WCH) is diagnosed on the evidence of abnormal clinical measures of BP and normal ABPM. The latest upper limits of normality by ABPM recommended by the JNCVI are < 135/85 mmHg while patients are awake and < 120/75 mmHg while patients are asleep. If we accept these upper limits of normality in ABPM, WCH does not appear to be a real problem as regards risk factors or end-organ effects. In terms of prognosis, data are limited. Cardiovascular morbidity seems low in WCH but identical to that of hypertensive subjects in these studies. However, further studies are needed to confirm these results. WCH does not appear to benefit from anti-hypertensive treatment. It is obvious that the lower the BP regarded as the limit of normality, the less likely the occurrence of secondary effects of metabolism, or end-organ effects or complications in those classified as hypertensive. 24 HOUR CYCLE: One of the most specific characteristics of ABPM is the possibility of being able to discover modification or alteration of the 24 h cycle of BP. Non-dippers are classically defined as those who show a reduction in BP of less than 10/5 mmHg or 10% between the day (06.00-22.00 h) and the night, or an elevation in BP. In contrast, extreme dippers are those in whom the BP reduction is greater than 20%. CARDIOVASCULAR SYSTEM: The data remain inconclusive with regard to the existence of a consistent relationship between the lack of a nocturnal dip in blood pressure and target organ damage. As regards prognosis, it seems that an inversion of the day-night cycle is of pejorative significance. CEREBROVASCULAR SYSTEM: Almost all studies have shown that non-dippers had a significantly higher frequency of stroke than dippers. In contrast, too great a fall in nocturnal BP may be responsible for more marked cerebral ischaemia. RENAL SYSTEM: Non-dippers have a significantly elevated median urinary excretion of albumin. There is a significant correlation between the systolic BP and nocturnal diastolic BP, and urinary excretion of albumin. Various studies have confirmed the increased frequency of change in the 24 h cycle in hypertensive subjects at the stage of renal failure.

DIABETES

BP abnormalities should be considered as markers of an elevated risk in diabetic subjects but cannot be considered at present as predictive of the appearance of micro-albuminuria or other abnormalities. ABPM is thus of interest in type I or type II diabetes both in the initial assessment and in the follow-up and adaptation of treatment. PHARMACO-THERAPEUTIC USES: The introduction of ABPM has truly changed the means and possibilities of approach to the study of the effects of anti-hypertensive medications, with new possibilities of analysis such as trough-peak ratio smoothness index, etc.

[Current aspects of arterial hypertension. Prognostic value of self-monitoring blood pressure measurements in aged hypertensive patients: a SHEAF study protocol]

HOW TO MEASURE BLOOD PRESSURE: Studies conducted in large series have established the prognostic value of blood pressure measured by conventional methods. This measurement technique has however a certain number of limitations and alternative systems have been proposed, including self-monitoring methods. A preliminary study suggested that the prognostic value of self-monitoring blood pressure measurements would be superior to those obtained with conventional methods. These findings require confirmation. A LARGE SCALE STUDY: The primary objective of the SHEAF study is to determine the prognostic value of self-monitoring blood pressure measurements in terms of cardiovascular mortality in a population of hypertensive elderly subjects living in France. The study protocol projects to include 5,000 hypertensive patients, whether treated or not, aged 60 and over. Baseline pressures are to be measured by a physician using a mercury sphygmomanometer (3 successive measurements at 2 visits) and by the participants using a self-monitoring device in their home (3 measurements in the morning and evening for 4 consecutive days). The patients will be followed for 3 years and all cardiovascular events will be recorded, including: death, myocardial infarction, cerebral vascular events, transitory ischemic events, hospitalization for angina, episodes of angina, heart failure, angioplasy or coronary bypass. The results of this large-scale epidemiology study should be available in 2002. METHODOLOGICAL PRECAUTIONS: The SHEAF study will analyze the patient's usual blood pressures, whatever the treatment at study inclusion, rather than blood pressures observed after treatment withdrawal. Efforts will be made to limit the number of drop-outs.

[The measurement of arterial pressure and the diagnosis of hypertension]

Blood pressure measurement remains the determining factor in defining hypertension. In daily practice, measurement in the practitioner's office is the reference used for diagnosis and follow-up. According to the classification established in the VIth Report of the NIH Joint National Committee in 1997, the upper normal value is below 139 mmHg for systolic and 89 mmHg for diastolic pressure. Hypertension cannot be confirmed by a single high measurement or at a single consultation. In addition, it should be remembered that: self-measurement should remain under medical control; its upper normal values (135/85) have the advantage of being obtained outside the medical setting; exercise tolerance tests, often using an ergometric bicycle, demonstrate the possibility of cardiovascular adaptation to physical exercise; ambulatory blood pressure measurement affords repeated measurements over 24 h, also with lower reference values (135/85 mmHg), and detects "white coat" hypertension and anomalies of the nycthemeral cycle.

Cardiac and vascular remodelling: effect of antihypertensive agents

The 1996 World Health Organization (WHO) recommendations for mild hypertension stressed the need to evaluate target-organ lesions as treatment criteria. The effects of both vascular and heart remodelling on hypertension must to be taken into account, as they adversely influence the prognosis of patients with hypertension. It was previously demonstrated that at least three classes of antihypertensive agents were able to decrease morbidity and mortality in patients with hypertension. Meta-analyses have shown that angiotensin-converting enzyme inhibitors seem to have a marked effect on regression of left ventricular hypertrophy (LVH). However, the relationship between drug-induced LVH regression and reduced morbidity and mortality remains to be confirmed. The effect of antihypertensive agents on vascular hypertrophy, as assessed by intima-media thickness, and their involvement in reducing morbid events, also have to be determined at the vascular level. As experimental data have highlighted the involvement of angiotensin II in animal models of LVH and vascular hypertrophy development, the role of angiotensin II AT1 receptor blockers should also be assessed in this indication.

Twenty-four hour antihypertensive efficacy of indapamide, 1.5-mg sustained release: results of two randomized double-blind controlled studies

The antihypertensive efficacy of a 1.5-mg sustained-release formulation (SR 1.5) of indapamide, a diuretic related to thiazide, has been pointed out by using conventional sphygmomanometric measurement 24 h after dosing in clinic, in two large European randomized, double-blind, controlled studies (2 and 3 months). One of these studies was then extended to 12 months, as a complementary open study. Quality-controlled ambulatory blood pressure monitoring (ABPM) data for a total of 216 patients from these studies are presented, including subgroups of hypertensives and responders. Indapamide SR 1.5 achieves an adequate 24-h blood pressure control by significantly reducing the 24-h, diurnal, and nocturnal blood pressures versus baseline, confirming the sphygmomanometric data. The benefit at 2 and 3 months is maintained at 1 year, which confirms the long-term efficacy of SR 1.5 mg. The trough-to-peak ratio--not previously calculated for a diuretic according to international guidelines--meets Food and Drug Administration requirements and confirms the 24-h efficacy of indapamide SR 1.5.

[Influence of some parameters on the blood pressure reduction under treatment: experience from the Hypertension Optimal Treatment Study]

The HOT study is the largest controlled therapeutic trial conducted to date in hypertension. This international, prospective, randomised trial is designed to determine the optimal blood pressure to be obtained during treatment, in order to achieve optimal reduction of complications and cardiovascular mortality. The HOT study is conducted according to the PROBE methodology (Prospective Randomised Open Blinded Endpoints. It has three objectives: 1) to evaluate the relationship between the development of major cardiovascular events and the DBP target level (DBP < or = 90, DBP < or = 85 or DBP < or = 80 mmHg. 2) to evaluate the relationship between the development of major cardiovascular events and real DBP observed, 3) to determine whether low-dose acetylsalicylic acid (75 mg/day) provides an additional benefit in terms of cardiovascular morbidity and mortality in treated hypertensive subjects. Between April 1992 and October 1994, 18,790 patients, between the ages of 50 and 80 years (26 countries), were randomised to these 3 target DBP groups and several parameters likely to influence the blood pressure fall were identified. The reduction of DBP was all the more pronounced the higher the baseline DBP. For a baseline DBP equal to 100 mmHg, the mean fall was 18 mmHg and for a baseline DBP equal to 110 mmHg, the mean fall was 27 mmHg. Advanced age was also found to be a factor promoting reduction of DBP, which increased after the age of 65 years. Analysed in relation to the type of treatment, this more marked reduction in the elderly showed that monotherapy with a calcium channel blocker was very effective on DBP and especially after the age of 75 years. The data of the study also showed that SBP decreased in parallel to DBP, but to an even greater extent. Thus, a 10 mmHg reduction of DBP induces a reduction of SBP by approximately 20 mmHg. This reduction of SBP related to the level of DBP was even more marked the higher the baseline SBP and the higher the target DBP objective. Thus 80% of patients in the DBP < or = 80 mmHg group had an SBP < or = 150 mmHg during treatment. Among the other factors, weight appeared to clearly influence reduction of DBP, as the reduction of DBP was more marked the lower the patient's weight. In contrast, the body mass index was poorly correlated with the reduction in blood pressure. The blood pressure reduction, regardless of weight, was more marked when a stricter blood pressure objective was adopted (DBP < or = 80 mmHg). Finally, in the particular case of elderly subjects, treatment with a calcium channel blocker appeared to be very effective in reducing the blood pressure.

[A quantitative analysis of a predictive model of ambulatory blood pressure monitoring integrating physical activity recording]

OBJECTIVE

To determine how much of the variations of blood pressure during a 24 hour period could be accounted for by a change in activity using an accelerometer to detect the physical activity and establish a predictive model.

MATERIALS AND METHODS

18 healthy subjects (mean age 25 +/- 2 yrs) were studied during daily life (24 hours) twice one week apart. The systolic and diastolic blood pressure, heart rate (HR), and time of measure were recorded by ambulatory monitoring using Spacelabs (4 measures per hour). A portable digital memory device was designed for the 24 hours ambulatory monitoring of HR (ECG) and physical activity. This device consists of an ECG Holter (ELA medical model Cinesis with digital memory) and a three piezoresistive type accelerometer sensors (prototype ELA research) able to record physical activity in the 3 space dimension.

RESULTS

The data of the first recording were compared to the predicated values from the application of a logarithmic model of activity to the second recording. The model then predicted 53 +/- 19% of the systolic BP values of the test day. The mean individual difference for a given time period of one hour between the measured and the predicted systolic BP from the model was 1.45 +/- 3.1 mmHg with a range of [-6.9; 3.4 mmHg]. The mean individual systolic BP difference for the same given time period of one hour but without predictive model was 1.29 +/- 10 mmHg with a range of [-28; 43 mmHg].

CONCLUSION

This study show that 3 D accelerometer is an easy tool to program individual model of ambulatory blood pressure variability. The introduction of this qualitative method seems logical in therapeutic trial.

[Models of arterial pressure using a Windkessel type model: role of the functional arterial properties]

The Windkessel model is a linear model which does not take into account the structural and functional variations of the arteries related to the pulsatility of the blood pressure (BP) and its variations between systole and diastole.

OBJECTIVE

To analyse the performance of a BP modelisation where the parameters of AC are adjusted in a dynamic fashion according to a curvilinear relationship of the arterial properties (compliance) in relationship to the BP between systole and diastole.

DESIGN AND METHODS

9 control subjects (age 25 +/- 3). The non invasive measures of the radial BP waveform (Millar tonometry) was compared to that constructed by an electric simulator reproducing the model in a sysmetrical network subdivised into 121 segments where we introduced for each subject: at cardiac level, the aortic stroke volume (Doppler echocardiography), and at the radial level, the dynamic values of compliance and diameter according to an arc-tangent model (measured by arterial echography NiUS02).

RESULTS

The BP obtained by the adjusted model, where the AC parameter follows the curvilinear, relationship dV/dP measured experimentally, was not significantly different from the experimental, while in the constant model (AC at mean BP level) the systolic BP was different.

CONCLUSION

This work shows in an experimental way the limits inherent in simplification in the Windkessel modelisation of the vascular system with constant parameters. It shows in a conduction artery the influence of the functional properties of the arterial wall on the level of systolic and diastolic BP.

[The Hypertension Optimal Treatment Study: efficacy and tolerability on the 36th month]

The international, prospective, randomized HOT study was aimed at determining the influence of a targeted BP reduction on cardiovascular morbidity and mortality. Patients were randomly allocated to 3 DBP targets (< 80, < 85, < 90 mmHg). In addition, the impact of a coprescription of aspirin was studied. The BP target had to be reached within 3 months, according to a well-defined strategy : felodipine 5 mg o.d. as a 1st intention drug, 1, 2 or 3 additional drugs, if necessary, on the following steps. BP measurements were made, using an oscillometric automatic device (Hestia). From April 1992 to October 1994, 18,790 patients with an age range 50-80 years, coming from 26 countries, entered the study. The data collected on the 36th month were in agreement with those obtained on the 12th and the 24th months. Baseline DBP was reduced by 21, 23 and 25 mmHg in the 90, 85 and 80 mmHg target groups, respectively. The rate of patients whose DBP reached the target, obviously increased from the 3rd to the 12th month: from 43 to 56%, 60 to 70%, 74 to 83% in the 90, 85 and 80 mmHg, target groups, respectively. From the 2nd to the 3rd year, BP control was further improved, with a slightly higher rate of controlled patients in the elderly (age > 60 y), especially in the 80 mmHg target group. From inclusion to the 3rd month, one-drug treated patients decreased, whereas 2- or 3-drug treated patients increased. Felodipine-treated patients decreased on the 36th month, but remained over 80%. From the 6th to the 36th month, additional prescription of a betablocker or an ACE-inhibitor increased from 36 to 39%, and from 23 to 28%, respectively; moreover, the side-effects rate decreased from 10.5 to 3.6%, with a special decline in ankle edema from 4 to 1%. In conclusion, the BP reduction observed on the 36th month was of the same extent as that observed in the first months. It seems obviously possible to reach a targeted DBP and to maintain it over time, along with a good acceptability of the treatment. Targeted DBP could be more easily achieved in elderly patients, possibly due to a better drug compliance.

A population-based survey of drug treatment efficacy by the French National Committee for the Control of Arterial Hypertension

To assess the adequacy of antihypertensive treatment in the French population, a survey was conducted from October 1990 to April 1991 in five French cities during sales exhibitions. A total of 7107 individuals visited the stand of the French National Committee to have their blood pressure (BP) measured. Among them, 1289 were treated hypertensive subjects fully aware of their treatment. The efficacy of antihypertensive treatment was assessed in this population. Among those hypertensive treated subjects 35 to 65 years old, 60% had a BP < 160/95 mm Hg and 27% < 140/90 mm Hg. Among those > 64 years of age, 44% had a BP < 160/90 mm Hg. In 1992, these results were included in a publication by the World Hypertension League. Data obtained with this new and interesting approach were reviewed 4 years later. The approach is inexpensive (the equivalent of US $28,000) and made it possible to directly inform thousands of people, normotensive and hypertensive, about arterial hypertension and antihypertensive drug therapy, as well as risk factors for cardiovascular disease. This kind of approach may be worth a strict evaluation, to assess whether it is really useful in improving high blood pressure control in the population.

Left ventricular hypertrophy and arterial hypertrophy

In the most recent WHO recommendations of 1996 it was reiterated that the classification of HT still remains based on the actual BP figures but also on the importance of target organ lesions. Thus the study of cardiac and vascular function and in particular the presence of hypertrophy or remodeling is of importance. A limited number of studies have examined the prevalence, the association and the correlation between modifications and remodeling in the heart and in the vasculature. It is important to distinguish compliance vessels such as the carotid from resistance vessels such as the radial. For compliance vessels the prevalence of cardiac and vascular hypertrophy are nearly identical being around 5% for normotensive subjects and around 12% for hypertensive subjects. This prevalence of thickening in the intima-media is more evident in subjects with left ventricular hypertrophy (LVH). The left ventricular geometric pattern is also an element to take into account. The presence of concentric remodeling of the left ventricle without LVH has already been associated with an increase in intima-media thickness (IMT). When there is an LVH this IMT is similar in severity to the LVH and in particular concentric. For resistance vessels such as the radial artery the number of studies is limited but a significant correlation between left ventricular mean wall thickness and common carotid artery distensibility and compliance has been found. There is also a significant correlation between the radial median lumen ratio and the relative wall thickness but this correlation disappears when age and systolic BP are taken into account. Thus for this type of vessel it is too early to conclude the elements contributing to structural changes. The determinant factors for these structural changes in the heart and the carotid arteries associated with hypertension are certainly multiple be they haemodynamic, hormonal or genetic. The observation establishing an association between anomalies at cardiac and vascular level may have undoubted diagnostic, prognostic and therapeutic implications which are all intimately related and which require refinement and confirmation.

Compliance, electronic monitoring and antihypertensive drugs

Hypertension, even of mild-to-moderate severity, is undoubtedly a risk factor for cardiovascular morbidity and mortality. It has been well demonstrated, in numerous studies that have been subjected to meta-analysis, that the introduction of antihypertensive treatment leads to reductions in cardiovascular and cerebrovascular events. These results can be obtained with even a moderate reduction in blood pressure, of the order of 4-5 mmHg in diastolic blood pressure. However, many studies have shown that the percentage of treated hypertensive individuals who have a reduction in blood pressure to normal values of systolic blood pressure/ diastolic blood pressure (< 140/90 mmHg) is of the order of 30%. The reduction in blood pressure data are well correlated with the level of compliance. This compliance can be defined as the adherence by the patient to the directions given by the doctor for medication dosage, and this can be considered as 'good' when it is of the order of 80%. Until recently the examination of compliance relied on questioning the patient, pill counts or ultimately blood sampling for drug levels, which could be used only in research. The use of an electronic pill box with a microprocessor in the cover that records the date and hour each time the box is opened is a precise method of recording compliance. The purpose of such a method is to study overall compliance, which deteriorates as time passes and falls by approximately 50% after 1 year. However, this compliance can be modified and improved if instruction and follow-up are given to the patient. Prescription compliance can be improved by once daily dosing and by instructing for this to be taken in the morning. In contrast compliance is considerably reduced when more than two doses are to be taken each day. Using the pill counting box allows us to describe and focus on different types of patients, ranging from rigidly adherent to completely chaotic. It seems that factors such as age and activity can influence these patterns of compliance.

Arterial mechanics predict cardiovascular risk in hypertension

Systolic and diastolic blood pressures are the exclusive mechanical factors considered as predictors of cardiovascular risk for members of populations of normotensive and hypertensive subjects. However, if hypertension is considered as a mechanical factor acting on the arterial wall with deleterious consequences, the totality of the blood pressure curve should be considered in order to investigate the risk. The purpose of this review is to show that in addition to systolic and diastolic blood pressures, other hemodynamic indexes with particular relevance for cardiac complications and that originate from pulsatile pressure should be taken into account, namely brachial pulse pressure, pulse pressure amplification, early wave reflections, and pulse wave velocity.

Effect of low-dose positive inotropic drugs on human internal mammary artery flow

BACKGROUND

Dobutamine (a beta-receptor agonist), enoximone (a type III selective phosphodiesterase inhibitor), and epinephrine (an alpha- and beta-mimetic) frequently are used in the perioperative management of patients undergoing coronary artery bypass grafting.

METHODS

We performed a double-blind clinical study to compare the effects on internal mammary artery free flow of low doses of these three positive inotropic drugs. Thirty patients in whom the left internal mammary artery was used for coronary artery bypass grafting were randomized into three groups. Internal mammary artery free flow and hemodynamic measurements were evaluated before and 10 minutes after the intravenous infusion of dobutamine (3 microg x kg(-1) x min(-1)), enoximone (200 microg/kg), or epinephrine (0.05 microg x kg(-1) x min(-1)).

RESULTS

A significant increase in free flow occurred only in the dobutamine group (33 +/- 7.5 and 42.2 +/- 7.9 mL/min before and after drug infusion, respectively; p = 0.013). Comparison of the increase in flow between the groups, however, showed no difference. These drugs, at doses designed to produce a positive inotropic effect, caused little increase in the free flow of the internal mammary artery.

CONCLUSIONS

The use of dobutamine, enoximone, and epinephrine as low-dose positive inotropic treatments in the perioperative and postoperative periods of coronary artery bypass grafting should depend on their positive inotropic effects rather than their vasodilative effects on the arterial grafts.

Association between high heart rate and high arterial rigidity in normotensive and hypertensive subjects

BACKGROUND

The dynamic elastic modulus of central arteries is very frequency-dependent Although resting heart rate is a potent independent risk factor for morbidity and mortality both from cardiovascular and from noncardiovascular disease, no link between tachycardia and arterial stiffness has ever been established.

OBJECTIVE

To relate arterial stiffness to heart rate in a population with relatively low cardiovascular risk.

METHODS

Pulse-wave velocity measurements and high-resolution echo-tracking techniques were used to determine the degree of arterial distension (of carotid and femoral arteries, and terminal aorta) and the velocity of the pulse wave (aorta and upper and lower limbs) at the same time as heart rate, in members of a large population of normotensive and hypertensive subjects in a multicenter study in Paris, Fleury-Merogis and Grenoble (France).

RESULTS

A high heart rate was strongly associated with reduced distension and elevated pulse-wave velocity, even after adjustment for age and blood pressure. A high aortic pulse-wave velocity was also negatively associated with a low baroreflex sensitivity. The most significant associations between high heart rate and high arterial rigidity were found for the carotid artery, the thoracic aorta, and the lower limbs, but there was no significant result for the terminal aorta and the arm arteries.

CONCLUSION

This study demonstrates that there is a statistically significant positive link between high heart rate and high arterial stiffness measured at the site of central and lower limb arteries. Since an elevated heart rate has been shown to be associated with cardiovascular risk, such findings may be relevant for future cardiovascular studies in epidemiology.

[Myocardial localization of malignant non-Hodgkin lymphoma responsive to chemotherapy]

Cardiac malignant non-hodgkinian lymphoma, which is usually asymptomatic, is observed in 15 to 25% of autopsy cases of this condition. The authors report an unusual case of myocardial lymphoma diagnosed during pulmonary oedema. Echocardiography showed left ventricular hypertrophy with increased echogenicity of the myocardial walls and marked decrease in left ventricular ejection fraction. Myocardial biopsy confirmed the diagnosis of a high grade malignant lymphoma. The disease responded to chemotherapy. Early diagnosis of myocardial involvement of a lymphoma, presenting with non-specific electrocardiographic changes, requires investigation by histological study of a myocardial biopsy. This invasive technique is justified because of its therapeutic implications.