Theoretical analysis and clinical evaluation of single and multi-angled guidewires as an alternative to widely used J-wires suggested that the major determinants of the wire function are the shortest distance between the tip and a long axis of the wire-reaching distance (RD), angulation of the tip, and the length of the angled arm. Their relationship can be characterized by a formula; reaching distance = sin beta X length of the arm. The two clinically most useful multiple angulations--double and triple angles--were evaluated in 54 patients in whom commercial J-wire failed to pass the lesion in 120 s. This value was compared with an average time of 57.90 +/- 3.9 s needed to pass an angled, individually shaped guidewire from the tip of the guiding catheter through the lesion. (P much less than 0.001 or highly significant.) All patients had tortuous vessels, sharply angled branches, and the largest diameter of the stenosed vessel less than 50% of the largest diameter of the left main coronary artery. Thirty-seven lesions were in the obtuse marginal arteries and 17 in the diagonal arteries. The study suggested that angled guidewires shaped according to described guidelines have superior success to commercial, unshaped J-wires in instrumentation of the tortuous vessels with angled branches and markedly varying diameter.