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suMMARY The nuclear probe was used for measuring left ventricular function in 11 normal subjects and the results compared with those using a digital gammacamera. The probe was then used to measure left ventricular function in patients with coronary artery disease during dynamic exercise and stress atrial pacing. The ability of the probe to detect changes induced by glyceryl trinitrate was also evaluated in separate parallel studies. In the 11 normal subjects there was a good correlation between the left ventricular ejection fraction measured by the gammacamera and the nuclear probe both at rest and during exercise. Exercise increased this value by at least 5% in all normal subjects during measurements with both the gammacamera and the nuclear probe. The mean (SD) difference was -0 3% (2.60) at rest and 2.3% (5 02) at peak exercise. Both exercise and pacing produced angina in the patient group and the mean (SEM) value fell from 52% (3.5) to 28% (2.6) and from 46% (5-1) to 34% (3.2) respectively. Glyceryl trinitrate prolonged the exercise and pacing times, and the corresponding falls in ejection fraction were significantly reduced.The non-imaging nuclear probe is a cheap and portable instrument capable of assessing left ventricular function in patients with cardiac disease. It is designed for high count rate acquisition over a short period of time and can thus provide both beat to beat and summated left ventricular time activity curves suitable for quantitative analysis. It therefore has important advantages in the clinical setting and during controlled interventions compared with the gammacameras.In patients with stable coronary artery disease angina pectoris is provoked by an imbalance between myocardial oxygen supply and demand. Electrocardiographic ST segment depression, a decrease in left ventricular ejection fraction, and the appearance of segmental wall motion abnormalities may all occur during episodes of myocardial ischaemia. Radionuclide angiography has been used extensively to study these changes in left ventricular function using both equilibrium blood pool and the first pass techniques. '

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The efficacy of nicardipine, a new calcium ion antagonist, was studied in 39 patients aged 42 to 70 years with chronic stable angina in two different placebo-controlled single- and double-blind crossover trials and with long-term follow-up, using serial quantitated exercise testing and ambulatory ST segment monitoring. In the first study the minimal effective dose was determined, and in the repeat study the effects of three different dose levels were evaluated. Treadmill exercise testing was performed at the end of each 2 week treatment period with on-line computer analysis of the electrocardiogram. The mean (+/- standard error of the mean) exercise time was 6.8 +/- 0.7 minutes on placebo and 7.0 +/- 0.8 minutes during treatment with nicardipine, 60 mg/day (p = NS). This increased to 8.7 +/- 0.8 (p less than 0.001) and 9.2 +/- 0.9 minutes (p less than 0.001) with 90 and 120 mg/day, respectively. The mean heart rate at rest during placebo administration was 75 +/- 2 beats/min and increased to 85 +/- 3, 84 +/- 2 and 88 +/- 3 beats/min (p less than 0.02, p less than 0.01, p less than 0.01, respectively) at each dose level. The time taken to develop 1 mm of ST segment depression was prolonged from 4.8 +/- 0.6 minutes during placebo administration to 5.3 +/- 0.7 (p = NS), 6.4 +/- 0.7 (p less than 0.01) and 6.7 +/- 0.8 minutes (p less than 0.001), respectively, at each dose level. The improvement achieved after 2 weeks of nicardipine, 120 mg daily, was maintained over a period of 6 months of follow-up. Three patients were withdrawn, one taking 60 mg of nicardipine, one taking 90 mg of nicardipine and one taking placebo, but the overall incidence of side effects was low. Nicardipine is an effective antianginal agent with an optimal dose of 90 to 120 mg/day.

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