Search PubMed⌕ Search

Biomedical subjects

H J Wessel

Publications and source records attributed to H J Wessel.

11 recordsLinked to original sources
PubMed1984

[Sensitivity of the dipyridamole test. A placebo-controlled double-blind crossover study].

The sensitivity of the dipyridamole test was examined with the double-blind crossover technique in 30 patients with 2 or 3 coronary vessels disease, treatment-refractory stable angina and positive exercise ECG tests. On two successive days, according to a randomized code, patients received either 0.5 mg/kg dipyridamole or a placebo, both given intravenously. The test was judged to be positive if during or immediately after the injection typical angina occurred which regressed after the subsequent intravenous injection of 0.24 g aminophylline within 3 minutes, or if the ECG showed signs of acute ischemia. The test was judged to be questionably positive if the anginal symptoms regressed spontaneously or later than 3 minutes after aminophylline injection. In a total of 13 of 30 patients (43%) the dipyridamole test was positive, while in a further 4 (13%) it was questionably positive. Ischemic repolarization abnormalities occurred in 9 patients; 5 of them also had positive test signs of angina, in 2 each the results were questionably positive or negative. In 13 patients there were neither anginal symptoms nor ECG changes. Thus the dipyridamole test with its low sensitivity is not suitable for the initial routine diagnosis of coronary heart disease.

Adult↗
PubMed1980

Echocardiographic pattern of motion of the aortic root as a correlate of left atrial volume changes.

The movement of the aortic root under resting conditions was analyzed echographically in 82 patients (32 were postoperative examinations of Björk-Shiley aortic and/or mitral valve prostheses). Additionally, ECG, PCG, carotid pulse curve or apexcardiogram were recorded simultaneously in the majority of the cases. In view of the time correlation between these noninvasive parameters, the results clearly show that both ventrally and dorsally directed motions of the aortic root during the cardiac cycle only reflect the change in volume of the left atrium. Thus aortic root motion might, if at all, be an indirect index of left ventricular stroke volume and only so if sinus rhythm is present and no mitral insufficiency or atrial septum defect exist.

Adolescent↗
PubMed1976

[Echocardiography].

Explore the source record for details and available documents.

Echocardiography↗
PubMed1975

Ajamline-induced changes in mechanical and electrical activity of vascular smooth muscle.

The effects of ajmaline on vascular smooth muscle were studied using helical aortic strips and portal veins of male rats. This report is based on the results of 104 mechanical experiments. In 30 additional experiments electrical activity was recorded simultaneously at different points of the preparation using extracellular methods (liquid paraffine or pressure electrodes technique). Ajmaline induces relaxation of aortic helical strips (activated by 2.0 mug/l norepinephrine) to 75 percent of initial tension in a dose of 0.6 mg/l, to 50 percent by 2.0 mg/l, and to 25 percent by 4-5 mg/l. The relaxation slope is shifted to the right by increasing the [Ca++]o from 2.0 to 4.0 mM, by increasing the initial norepinephrine concentration to 4.0-10 mug/l, or by KCl depolarization, [K+]o ranging from 15 to 60 mM. The relaxing effect of ajmaline on aortic strips can partly be attributed to a change in electrical activity with a dose-dependent conduction impairment or block and, at high concentrations, also a decrease in the frequency of pacemaker excitations. Experiments on aortic strips in K+ contracture show relaxation independent of changes in phasic electrical events. Ajmaline ranging from 0.2 to 80-100 mg/l causes on the portal vein a marked increase in amplitude and a small decrease in frequency of rhythmical contractions. Integrated isometric force reaches 300 percent of initial values. The increasing amplitude of contractions is related to a prolongation of excitation trains, while the frequency and amplitude of the individual spike are reduced. Our results suggest that the effects of ajmaline on the mechanical and electrical activity of vascular smooth muscle may be partly related to a reduction in Ca++ and probably Na+ conductance.

Ajmaline↗
PubMed1975

[Plethysmographic and in vitro studies of the vasodilator effect of furosemide (Lasix)].

The beneficial effect of furosemide in treatment of chronic and particularly of acute congestive heart failure has been attributed to its potent diuretic action. In recent studies [16], it has been postulated that the effect of this diuretic agent is primarily vascular in origin. The results of venous occlusion plethysmographic experiments (modificated Whitney-gauge technique) carried out in this study on the forearm of 6 healthy men, show that furosemide (40 mg. i.v.) does not influence arterial blood flow (4-5 ml/100 ml tissue - min). In contrast furosemide induces a prompt significant (p less than 0.001) and sustained (about 45 min) increase in venous capacitance (deltaV/100 ml tissue = 15%) and a corresponding decrease in E'. The direct effect of furosemide on vascular muscle tone was studied in vitro on portal vein and aortic strip preparations from 76 male rats. In 18 experiments mechanical and electrical activity (using three pressure electrodes) were simultaneously recorded. The results of the in vitro experiments show: 1. Only extremely high furosemide concentrations (greater than 500 mg/l) induce slight relaxation of aortic strips. 2. Furosemide causes in contrast a marked dose-dependent per cent decrease of the integrated isometric tension in portal vein preparations: 14 mg/l reduce the initial tension (= 100%) to 80%; 35 mg/l to 65%; 70 mg/l to 50% and 100 mg/l to 35%. 3. The venodilating furosemide effect is significantly (p less than 0.001) increased by reduction in external Na+-concentration [Na+]0 to 120 mM though further reduction in the [Na+]0 to 90 mM does not cause additional changes in the relaxation slope. 4. The simultaneous records of electrical activity demonstrate that the relaxing effect of furosemide is based on decreased spike frequency in shortened bursts as well as on pronounced impairment of conduction velocity without relevant changes in pacemaker frequency. These in vitro results are discussed from the point of view that a furosemide induced decrease in Na+-permeability may determine the changes obtained in electrical and mechanical behaviour of portal veins of the rat.

Adult↗