Search PubMed⌕ Search

Biomedical subjects

P Wicker

Publications and source records attributed to P Wicker.

At least 91 records · Page 5Linked to original sources
PubMed1986

Study of the electrophysiologic properties of clonidine administered intravenously.

A few cases of sinus node dysfunction (SND) and AV block (AVB) were described with clonidine therapy. The aim of this study is to evaluate the electrophysiologic properties of clonidine in volunteers with normal electrophysiologic data. Twenty-eight subjects were investigated by endocavitary techniques. The following parameters were measured before and 20 min after intravenous administration of clonidine: systolic and diastolic blood pressure (BP); sinus cycle (SC); PA, AH, and HV intervals; effective (ERP) and functional (FRP) refractory period of right atria (RA); AV node (AVN); His Purkinje system (HP); right ventricle (RV); corrected sinus node recovery time (SNRT); and sinoatrial conduction time (SACT). Blood pressure was reduced from 149/89 to 115/74 mm Hg. Sinus cycle was prolonged by 71 ms (p less than 0.01), corrected SNRT by 81 ms (p less than 0.05), and FRP of AVN by 16 ms (p less than 0.05). SND was more marked when initial SC was longer. Atrioventricular node depression was more marked when the PR interval was longer and when subject was older. Electrophysiologic effects of clonidine are similar to those of beta-blockers. The tensional effects are more marked than electrophysiologic effects. Clonidine in the high risk subject (age, bradycardia, long PR) may be cautiously dosed. Drug association with digitalis antiarrhythmic drugs, beta-blockers, and calcium antagonists may be avoided.

Adult↗
PubMed1986

[Effects of exercise on coronary circulation in left ventricular hypertrophy caused by hypertension].

Exercise is known to promote myocardial vascularity. We therefore studied whether it could prevent coronary abnormalities of hypertensive left ventricular (LV) hypertrophy. Female Sprague-Dawley 1 clip-2 kidneys Goldblatt hypertensive rats (RHR) and their appropriate controls (Sham-SH), were either made to swim (RHR-SW, SH-SW) or kept sedentary (RHR-SED, SH-SED) for 9 weeks. Maximal coronary blood flow (LV CBF, ml/min/gm) and minimal coronary resistance after carbochrome (total LVCR/LV mmHg/ml/min), an index of the functional cross sectional area (CSA) of coronary resistance vessels, were determined in conscious rats by microspheres. Results (m +/- SD) (n = 12 in all groups): (Table: see text). Exercise increased functional coronary CSA in normotensive rats only. This beneficial effect did not occur in hypertension, probably because of functional changes in the coronary vessels of RHR.

Animals↗
PubMed1985

[From labile or borderline arterial hypertension to mild hypertension. Current data and practical management].

The concept of labile hypertension (also called borderline hypertension) has been proposed to define those patients in whom blood pressure is sometimes below, sometimes above the frontier which separates normal and high blood pressure. Current evidence does not support the individualization of this concept, since numerous studies have demonstrated a similar or even higher blood pressure variability in hypertensive patients than that found in normotensive patients. The main objective, when measuring blood pressure, is to assess the risk of a cardiovascular event. It has been shown that the average value of several blood pressure determinations provides a better estimate of cardiovascular risk, and correlates better with hypertensive target organ disease, than a single blood pressure measurement. Therefore, we propose to define these so-called labile hypertensive patients on the basis of the average and to classify them into the category of mild hypertension, the later being defined as a diastolic blood pressure between 90 and 105 mmHg on several occasions according to the WHO. The increase in cardiovascular risk carried by a mild elevation in blood pressure, either untreated or treated with general health measures, is small, approximately 3% per year. Moreover, whereas the beneficial effects of pharmacological antihypertensive therapy have been demonstrated on a whole population basis, these effects remain controversial on an individual basis. Thus, it appears justified to give these hypertensive patients general health measures advice without any pharmacological therapy during the first months of follow-up. During this time, blood pressure measurements are repeated so that blood pressure status, and thus the need for pharmacological therapy, can be assessed more precisely.

Antihypertensive Agents↗
PubMed1985

Right ventricular coronary flow in arterial hypertension.

Right ventricular (RV) coronary circulation in systemic hypertension offers an opportunity to assess the effects of marked increases in coronary perfusion pressure in vivo without appreciable increases in workload or marked hypertrophy of the cardiac chamber. This study investigates RV coronary circulation in renal hypertensive rats (RHR). Mean arterial pressure rose by 50% to 60% in RHR as compared to control groups and RV mass increased by 15% (7.15 vs 6.19 mg/gm body weight, p less than 0.01). Coronary blood flow, which was measured by left atrial injection of microspheres in conscious rats, was not significantly different between study groups both at rest and after maximal coronary vasodilation with carbochrome (6 mg/kg). However, minimal RV coronary resistance level per gram were significantly elevated (p less than 0.05) in RHR. A second study was designed to further dissociate the effects of arterial hypertension from the effects of changes in RV mass in RHR. In one group, blood pressure was acutely reduced by 1 week of captopril therapy, while RV mass remained high. In the second group, captopril was discontinued after 14 weeks of treatment, allowing arterial pressure to rise, while RV mass, which had regressed with treatment, remained normal. After treatment, RV minimal coronary resistance levels remained high in the short-term-treated hypertensive rats, but returned to normal levels in the long-term-treated RHR. These results suggest the following possibilities: the RV is not immune to the effects of systemic hypertension, coronary structural changes are probably the main factor that accounts for the increase in RV coronary resistance levels, and coronary alterations are amenable to long-term antihypertensive therapy.

Animals↗
PubMed1985

[Evaluation of left ventricular mass by M-mode and bidimensional echocardiography].

The aim of this study was to validate an echocardiographic method of evaluating LV mass by assessing the reproducibility and comparing the results with those of angiography. 20 patients without abnormal regional wall motions or asymmetric septal hypertrophy underwent left ventriculography in the RAO plane and three successive M mode and 2D echocardiograms. Three 2D echo methods of measuring volumes and mass were used: the monoplane ellipsoid model obtained from apical views, the biplane ellipsoid model from an apical and a short axis parasternal view and the hemi-ellipsoid-cylinder model (HEC). The M mode evaluations showed good reproducibility with respect to volume (variation coefficient (VC): inter observer 9.8 p. 100 and intra patient 15.6 p. 100). The reproducibility of 2D echo measurements was much poorer (intra patient volume: VC = 34 to 45 p. 100; mass 29 to 46 p. 100). A close correlation was observed between the results of M mode echo and angiography; volume r = 0.85, SD = 60 g. With respect to the 2D method, the best results were obtained with the HEC model; volume r = 0.90, SD = 31 ml; mass r = 0.82, SD = 41 g. We suggest a method combining the M mode and 2D techniques, using a HEC model in which the long axis is obtained by 2D echocardiography and the short axis and wall thickness by M mode recordings. The following correlations with the angiographic method were obtained: volume r = 0.91, SD = 36 ml; mass r = 0.89, SD = 27 g.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Treatment of hypertension by a new transdermal form of clonidine.

We studied one or two adhesive systems per week of clonidine TTS (2.54 or 5.08 mg/week). The results showed a more marked antihypertensive action with these adhesive systems than with 0.15 or 0.30 mg/day of the oral form. The transdermal system was better tolerated systemically and local cutaneous reactions prevented its use in only one case in our series. Overall, the patients were satisfied with the treatment. In our opinion, the simplicity of administration of clonidine TTS should improve the long term patient compliance with antihypertensive treatment.

Adhesiveness↗
PubMed1985

[Thrombophlebitis and pulmonary embolism in congenital factor XII deficiency].

The case of a young man hospitalised for bilateral lower limb deep vein thrombosis is reported. None of the usual causes were found after systematic wide-ranging investigation. The only abnormality on admission was a spontaneous increase in the cephalin-kaolin time to 65 seconds compared to a control time of 40 seconds. Measurements of the clotting factors showed a moderate and isolated deficiency in factor XII (30 p. 100), also present in a brother (50 p. 100) and a sister (42.5 p. 100). Fibrinolytic therapy was administered : an initial course of Streptokinase was followed by extension of a left femoral vein thrombosis and pulmonary embolism. Two courses of Urokinase were given with an eight day interval without significantly improving the venous circulation. This case is an example of thrombogenic disease due to a deficiency of a clotting factor resulting in non-activation of physiological fibrinolysis.

Adult↗
PubMed1984

The prolonged antihypertensive effect of once daily atenolol: a study of continuous non-invasive arterial blood pressure monitoring.

This study was carried out on 12 hospitalized hypertensive patients to assess the antihypertensive efficiency and the duration of action of a once daily dose of atenolol. 100 mg of atenolol was given at 8 am every day for 5 days. Before and during the therapeutic period. 24-h blood pressure recordings were obtained with a continuous, automatic, non-invasive method working on the principle of oscillometry (Dinamap 845.950). Atenolol induced a significant reduction in mean blood pressure from 119 +/- 3.6 to 102.3 +/- 4.7 (P less than 0.001). This effect was significant from the very first day of treatment and was maintained over the duration of the study in ten patients. The decrease in blood pressure induced by atenolol lasted 24 h. Clinical tolerance of atenolol was excellent. In particular no case of excessive bradycardia was noted.

Adult↗
PubMed1983

Coronary blood flow during the development and regression of left ventricular hypertrophy in renovascular hypertensive rats.

Left ventricular (LV) coronary flow (CF) was determined by left atrial injection of microspheres in conscious rats during the development and after the reversal of LV hypertrophy in 2-kidney, 1-clip Goldblatt hypertension. Two groups of untreated renal hypertensive rats (RHR) were studied, the first (RHR1, n = 17) at 10 weeks and the second (RHR2, n = 9) at 24 weeks after clipping. Beginning 9 weeks after clipping, 2 other groups were treated either with captopril (40 to 60 mg/kg/day) in drinking water (RHR-C, n = 8) or left nephrectomy (RHR-N, n = 9) and followed for 15 weeks. Sham-operated animals followed for similar periods of time served as controls (Sham-1, n = 12, as a control for RHR1, and Sham-2, n = 11, as a control for RHR2). In all groups, LV mass increased or decreased in close correlation with changes in arterial blood pressure, and minimal total LV coronary resistance remained unchanged. The development of hypertrophy was associated with a tendency toward reduction in CF reserve (defined as maximal CF/unit mass); this flow reserve was restored with reversal of hypertrophy. The importance of the relation between pressure and LV mass as a determinant of CF reserve was investigated in a second study in which this relation was changed by altering the periods of captopril therapy; in these cases, CF reserve correlated significantly with the ratio of arterial pressure to LV mass (r = 0.76, n = 12, p less than 0.01). The results suggest that maintenance of CF reserve in LV hypertrophy depends on an appropriate balance between arterial pressure and LV mass, and might be disturbed by antihypertensive therapy that leaves LV hypertrophy unchanged.

Animals↗
PubMed1983

Prevalence and significance of asymmetric septal hypertrophy in hypertension: an echocardiographic and clinical study.

To assess the prevalence of asymmetric septal hypertrophy (ASH) in hypertensive patients, 613 echocardiographic examinations performed over a period of one year were reviewed. Asymmetric septal hypertrophy (defined by an echocardiographic interventricular septum to left ventricular free wall thickness ratio of greater than or equal to 1.3 and by the presence of suggestive two-dimensional echocardiographic abnormalities) was found in 28 patients (5%). Clinical characteristics of asymmetric septal hypertrophy were assessed in 101 patients who underwent a complete evaluation. Patients with asymmetric septal hypertrophy (n = 9) were compared with patients with echocardiographic symmetrical left ventricle hypertrophy (n = 38) and without left ventricular hypertrophy (n = 54). Our results indicate that neither the severity of hypertension, nor the renin-angiotensin system nor sympathetic nerve activity appear to be the primary determinants in the development of asymmetric septal hypertrophy.

Adult↗
PubMed1982

Coronary blood flow measurements with left atrial injection of microspheres in conscious rats.

Since left atrial (LA) injection of microspheres has been shown to give more precise coronary blood flow (CBF) determinations, and also since studies in a conscious state have obvious advantages, we have developed a technique of chronic LA catheterisation for these purposes in rats. Through a thoracotomy in the third left intercostal space, the LA appendage was cannulated and a catheter (PE-10 tubing) advanced into the left atrium. The catheter itself was passed through the chest and exteriorised at the back of the neck. Following recovery over 24 to 48 h, flow studies with microspheres could be performed for 3 to 8 days. One-hundred and twenty procedures performed over a 4 month period were analysed. Left atrial catheterisation could be performed in approximately 45 min with no bleeding in 79% of cases and only minimal or moderate bleeding in the rest (13% and 4%, respectively); respiratory complications were rare (less than 1%). The rats recovered rapidly, and all catheters remained patent for the duration of the preparation. Infections developed in 5% and the total mortality rate was 7%; a complete haemodynamic study could be obtained in 130/120 rats (86%). Small renal infarcts were found in 25% of the rats, but neither the infarcts nor the intraoperative blood loss had any significant effect on haemodynamic indices and flow measurements performed 3 to 8 days after atrial catheterisation. Coronary blood flow values in 33 normal rats were within the range of values reported in the literature. These results demonstrate that chronic LA catheterisation is possible in rats with no major difficulties and will allow the precise determination of coronary blood flow with microspheres in conscious animals.

Animals↗
PubMed1982

Importance of injection site for coronary blood flow determinations by microspheres in rats.

Because coronary blood flow (CBF) determinations require that blood and microspheres be uniformly mixed in the root of the aorta, we developed a technique of left-atrial (LA) catheterization in rats and compared the variability of results obtained by LA injection and left-ventricular (LV) injection as regards systemic [cardiac output (CO)], proximal (coronary), and distal (renal, cerebral) flows in anesthetized animals. CBF values averaged 410 +/- 224 and 358 +/- 99 (SD) ml.min-1.100 g-1 from LV and LA injection, respectively, or 5.7 +/- 2.9 and 4.9 +/- 1.3 (SD) %CO. The variability with LA injection was significantly lower than with LV injection as shown by the marked differences in standard deviations obtained with the two methods (224 vs. 99 ml.min-1.100 g-1 or 2.9 vs. 1.3 %CO, P greater than 0.01). In contrast, no significant difference in variability was found for either CO or more distal regional flows. These results indicate that LV injections might be adequate for systemic flow and regional flows to relatively distal beds but that accurate measurements of CBF require LA injection of microspheres.

Animals↗
PubMed1982

[Coronary flow in experimental cardiac hypertrophy caused by arterial hypertension].

We studied the effects of left ventricular hypertrophy (LVH) induced by one clip-two kidney Goldblatt hypertension on coronary circulation of conscious rats. Twenty four weeks after clipping, coronary blood flow per unit mass after pharmacological dilation by carbochrome (6 mg/kg) (coronary flow reserve-CFR) was measured using radioactive microspheres. Coronary flow reserve remained normal either during development or LVH in untreated rats or after reversal of LVH in rats treated with captopril or nephrectomy. An appropriate relationship between pressure and mass, which varied in parallel, layed a significant role in maintaining a normal CFR. This, if confirmed in man, our results would suggest that antihypertensive drugs that alter this relationship by decreasing pressure but not LV mass may adversely affect CFR.

Animals↗
PubMed1981

Surgical constriction of the pulmonary artery. A new experimental technique.

The classical "banding" of the pulmonary arterial trunk (PAT) is often difficult to remove at the time of definite repair of the cardiac congenital malformation; often its removal alone requires the use of a cardiopulmonary bypass and an angioplasty of the PAT. These difficulties have led the authors to study experimentally, in 16 dogs, the value of a palliative stenosis of the PAT by lateral compression (LC) of the arterial wall. Three types of compressing materials have been used: Teflon band wrapped in pericardium (5 dogs), cuneiform pieces made of either Teflon (5 dogs), or stainless steel (6 dogs). The experiment has led to the following conclusions: 1. The LC of the PAT is able to create a pressure gradient which tends to decrease when the animal is growing. 2. Cuneiform pieces made of Teflon or stainless steel should be used to realize the LC. 3. After the LC has been removed the PAT recovers its normal shape, as attested by absence of a systolic pressure gradient across the PAT. This technique of LC seems to be an interesting alternative to creating a temporary palliative stenosis of the PAT.

Animals↗