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L H van Kempen

Publications and source records attributed to L H van Kempen.

3 recordsLinked to original sources

Value of the addition of amlodipine to atenolol in patients with angina pectoris despite adequate beta blockade.

Anginal patients who remain symptomatic despite optimally dosed beta blockade may also be given dihydropyridine calcium antagonists. This treatment regimen was examined in a double-blind parallel, randomized, controlled study in 147 patients with angina and positive bicycle exercise tests despite optimal beta blockade with atenolol (heart rate at rest <60 beats/min). Patients were randomized to atenolol and/or placebo (control), and atenolol and/or amlodipine. The main outcome measurement was exercise tolerance after 8 weeks compared with baseline. After 8 weeks, no significant differences in time to 0.1-mV ST-segment depression, time to chest pain, and time to end of exercise were observed. The number of patients with chest pain during exercise decreased significantly in the amlodipine group (p = 0.04 vs controls). The subgroup of patients with an early (<6 minutes) onset of chest pain at baseline showed a significant increase in time to chest pain after amlodipine (p = 0.0001 vs controls). In the amlodipine group, ST depression and rate-pressure product at submaximum comparable workload decreased to 0.4 mm (0.56) (p = 0.03 vs controls) and 1.223 (2.652) beats/ min x mm Hg (p = 0.01 vs controls). The number of patients in each group with adverse events was not different. The addition of amlodipine to the treatment of patients with myocardial ischemia, despite optimal beta blockade, is well tolerated and may lead to improvement in symptomatic anginal patients, who have a rapid onset of exercise-induced ischemia.

Adolescent↗

The CO2 conductivity electrode, a fast-responding CO2 microelectrode.

A fast-responding CO2 microelectrode system is presented; it consists of a double-lumen polyethylene catheter provided with a stainless steel catheter tip covered by a CO2-permeable membrane, and connected with each lumen separately to a conductivity cell. The catheter is flushed with bidistilled water at constant flow rate and conductivity of inflowing and outflowing water is measured. The change of conductivity in the water leaving the catheter after exposure of the electrode to a medium containing CO2 is related to the PCO2 of the medium. High sensitivity and fast response, both depending on the flow rate of the carrier water, are shown to oppose each other. When cells are placed at a distance of 45 cm from the membrane, response time for 90% deflection is about 10 sec (at flow rates of 5 ml/min), but when located inside the electrode tip at a distance of within 10 mm from the membrane response time is reduced to about 4 sec. Hydrodynamical aspects concerning dispersion of CO2 in the carrier water and reaction kinetics of CO2 hydration are discussed.

Carbon Dioxide↗