Slow-release oxprenolol compared with oxprenolol in hypertensive patients: a multicenter clinical trial.

Oxprenolol (OX) is a nonselective, beta-adrenergic blocking agent with intrinsic sympathomimetic activity. We studied 178 patients in five centers to determine whether a polymer-matrix-based, slow-release preparation of oxprenolol (SR-OX) given once daily was as effective as the standard preparation given twice daily for the treatment of patients with mild to moderate hypertension. After a placebo washout phase, patients were treated with OX until blood pressure was controlled. They were then randomized in a double-blind fashion to continue the same dose, given as either OX bid or SR-OX qd with a placebo as the second dose. All patients took hydrochlorothiazide 50-100 mg/d throughout the study. Blood pressure was reduced 23/15 mm Hg (p less than 0.001) and pulse 8 beats/min in the SR-OX group (n = 67) and 24/17 mm Hg (p less than 0.001) and 8 beats/min in the OX group (n = 72) by titrating standard OX. After randomization to SR-OX or OX, there were no further changes over six weeks. Home-determined blood pressures showed no loss of control in the evening. There were no unexpected adverse effects. We conclude that SR-OX given once daily is as effective as OX given twice daily for the treatment of hypertension.

Computer enhanced digital angiography.

A new computer image enhancement technique was employed on cardiac images of 10 dogs and 7 patients to demonstrate the feasibility of an on-line automatic delineation of the left ventricular endocardial silhouette with a peripheral venous injection of contrast material while simultaneously reducing the x-ray dosage. This technique employs a very fast analog-to-digital conversion system capable of digitizing on-line video frames. By storing and continuously updating the first 30 video frames and then subtracting each incoming frame from this memory, most of the background is eliminated leaving only the contrast filled ventricle. Using calibrated densitometric measurements, we found that iodine concentrations in the human left ventricle following venous injection of 40 ml Renografin-76 (25 ml/s), peaked at 4.3 +/- 0.3 mg/ml (mean +/- SD) compared to 14.8 +/- 0.8 mg/ml following direct injection of 40 ml at 13 ml/s (p less than 0.001). The computer enhanced venous-injected images had an optical contrast 14 times greater than that of the unenhanced direct left ventriculogram. This increase in optical contrast provided unambiguous subjective definition of the endocardial borders. This technique is applicable to both central and peripheral contrast injection whereby high quality images can be obtained at approximately 98% reduction in radiation (5 mA, 65-85 kV), allowing performance of serial studies.