Clinical value of ambulatory blood pressure monitoring in the assessment of antihypertensive therapy.

Non-invasive ambulatory blood pressure monitoring (ABPM) is particularly useful for assessing the efficacy of antihypertensive drugs. It provides a large number of blood pressure readings during daytime as well as night-time, which results in a more precise assessment of prevailing blood pressure than can be obtained from sporadic measurements taken by a doctor. Because of this greater precision ABPM reduces the number of patients required in clinical trials to demonstrate differences. It also allows one to define precisely the profile of the blood-pressure-lowering effect of a given drug. Placebo has little effect on ABPM. Thus, a placebo phase is not absolutely necessary. ABPM makes it possible to evaluate the efficacy of an antihypertensive medication by analysing data for patients with a placebo effect separately from data for true responders to the medication. In everyday practice ABPM helps one to detect among patients with hypertension refractory to treatment those who exhibit controlled blood pressures outside the medical environment, thus permitting one to avoid an unnecessary step-up of treatment. In addition ABPM can also help one to identify symptoms occurring during antihypertensive treatment that are related to excessive drug-induced changes in blood pressure.

Assessment of angiotensin II receptor blockade in humans using a standardized angiotensin II receptor-binding assay.

An in vitro angiotensin II (AngII) receptor-binding assay was developed to monitor the degree of receptor blockade in standardized conditions. This in vitro method was validated by comparing its results with those obtained in vivo with the injection of exogenous AngII and the measurement of the AngII-induced changes in systolic blood pressure. For this purpose, 12 normotensive subjects were enrolled in a double-blind, four-way cross-over study comparing the AngII receptor blockade induced by a single oral dose of losartan (50 mg), valsartan (80 mg), irbesartan (150 mg), and placebo. A significant linear relationship between the two methods was found (r = 0.723, n = 191, P<.001). However, there exists a wide scatter of the in vivo data in the absence of active AngII receptor blockade. Thus, the relationship between the two methods is markedly improved (r = 0.87, n = 47, P<.001) when only measurements done 4 h after administration of the drugs are considered (maximal antagonist activity observed in vivo) suggesting that the two methods are equally effective in assessing the degree of AT-1 receptor blockade, but with a greatly reduced variability in the in vitro assay. In addition, the pharmacokinetic/pharmacodynamic analysis performed with the three antagonists suggest that the AT-1 receptor-binding assay works as a bioassay that integrates the antagonistic property of all active drug components of the plasma. This standardized in vitro-binding assay represents a simple, reproducible, and precise tool to characterize the pharmacodynamic profile of AngII receptor antagonists in humans.

[Ambulatory blood pressure monitoring in the assessment of the hypertensive patient]. / L'enregistrement tensionnel en ambulatoire dans l'évaluation du malade hypertendu.

Non-invasive ambulatory blood pressure monitoring allows to record numerous blood pressures during everyday activities. The relationship between blood pressure and target organ damage is closer with ambulatory than conventional office blood pressures. Monitoring blood pressure outside the doctor's office appears more and more useful in diagnosing and treating hypertension. This approach makes it possible to recognize high-risk hypertensive patients, i.e. patients exhibiting abnormally increased blood pressures in the presence as well as in the absence of the doctor.

[Noninvasive assessment of morphology and function of the great vessels]. / Evaluation non-invasive de la morphologie et de la fonction des grands vaisseaux.

Hypertension is well recognized as a risk factor that is associated with an increased incidence of stroke and myocardial infarction. The early detection of atherosclerosis is a real challenge and should be carried on at a cost and with a degree of risk and invasiveness that does not preclude its use in subjects with cardiovascular risk factors. For this purpose we have developed a non-invasive approach using a high resolution echotracking device making it possible to measure internal diameter and wall thickness of conduit arteries as well as their biomechanical properties. We present here a methodological overview of the system with a brief clinical study addressing the biomechanical properties of a medium size artery in hypertension as compared with normotension.

Interactions between NPY and its receptor: assessment using ant-NPY antibodies.

The present data show that monoclonal antibodies (NPY02, NPY03, NPY04, NPY05) directed against 4 distinct epitopes on NPY may have different actions on NPY binding and NPY-induced cellular responses. NPY02 and NPY05 recognize the 11-24 and 32-36 amidated form of NPY, respectively. These 2 antibodies block the binding of NPY to its receptor as well as the NPY-induced inhibition of cAMP accumulation caused in SK-N-MC cells by forskolin. NPY02 and NPY05 have also an inhibitory action on NPY-induced contraction of rabbit femoral arteries. NPY03 and NPY04 are directed against the 27-34 and 1-12 part of NPY, respectively. NPY03 and NPY04 inhibit the binding of NPY only at very high concentrations and have a weak effect on cAMP response to NPY. NPY02 and NPY05 might provide useful tools to study the effect of NPY in cellular systems and organ preparations.

Non-invasive method for the assessment of non-linear elastic properties and stress of forearm arteries in vivo.

AIM: To propose a method for obtaining non-invasive highly accurate measurements of arterial diameter, thickness and pressure at a single location on a peripheral arm artery, and use this data to estimate the status of the arterial wall. METHODS: Diameter and thickness were measured with an A-mode ultrasonic echo-tracking device, with a precision of close to 1 micron. Pressure was measured with a photoplethysmograph at the finger level. A simple hemodynamic model was used to estimate, from the measured pressure pulse, the pressure waveform at the diameter-measuring site. RESULTS: The collected data made it possible to assess (1) the elastic response of the artery, through the compliance and distensibility, (2) the loading conditions, through the average stress-diameter curve and (3) the elastic properties of the wall material, through the incremental modulus of elasticity. CONCLUSION: This information can be used to assess the overall status of the arterial wall.

Blood pressure monitoring for quality assessment of antihypertensive therapy.

Despite many new therapeutic approaches to the treatment of hypertension and new diagnostic methods, the measurement of the most basic parameter, the blood pressure itself, has not changed over many years. The most commonly used method records the blood pressure on a single occasion and it is then assumed that this single reading is representative of the blood pressure of that patient at all times. This paper presents evidence, based on published studies, showing that the single "office" blood pressure reading gives little information about the blood pressure during daily activities. A study in 101 volunteers and a study in 38 patients with hypertension both showed that, not only is the "office" reading not the same as the average of many blood pressure readings made over 24 h using a Remler device, but also that the difference cannot be predicted. In some cases, the "office" pressure is higher and in some cases lower than the Remler blood pressure. This difference may explain the apparent blood pressure lowering effect of placebo. This has been frequently reported when the blood pressure is measured by the physician but ambulatory blood pressure readings have failed to show this effect. Finally, the inaccuracy of the "office" blood pressure may obscure smaller differences between two treatment groups in a clinical trial which could have been clearly demonstrated if the blood pressure had been recorded using an ambulatory method.

Regionalized self-care hemodialysis. A solution to the increasing cost.

To cope with an ever-increasing number of patients with end-stage renal disease, a regionalized self-care hemodialysis program was set up and combined with the existing home and center hemodialysis, peritoneal dialysis, and renal transplantation. Five years later, of a total of 105 patients treated by hemodialysis, 66 were dialyzing themselves--31 at home and 35 in seven local self-care facilities. This proportion of patients engaging in autonomous treatment (69%) was obtained without restrictive selection criteria, since we treat 210 patients per million population with hemodialysis. The annual intake of new patients could be managed without increasing the number of center dialysis beds and by only slightly increasing the specialized staff. The cost reduction obtained with this program when compared with all center dialysis treatment represents 37%, or approximately 1,200,000 US dollars per year. These results were obtained without compromising the quality of treatment.