The purpose of this study was to evaluate the incidence of ventricular ectopy and catheter movement during left ventriculography with a new 5F halo angiographic catheter that has a unique helical-tip design unlike the design of standard 5F and 6F pigtail catheters. The pigtail catheter is presently preferred for left ventriculography, although its use is associated with a high incidence of ventricular ectopy, which often limits precise interpretation of data. In this study, 155 patients (in 145 unpaired and 10 paired studies) underwent left ventriculography during diagnostic cardiac catheterization. In the unpaired group, the 5F Halo catheter was used in 63 studies and standard 5F and 6F pigtail catheters in 40 and 42 studies, respectively. An aditional 10 patients had two consecutive left ventriculograms with 5F Halo and pigtail catheters. Ventriculograms were performed with the same technique in the 30-degree right anterior oblique projection. The left ventricle was divided into a basal zone, midzone, and apical zone. Catheter movement within the ventricle was scored as significant if there was at least one zone change. Ventricular ectopy was quantified by a simultaneous electrocardiographic recording during contrast injection. There were no significant differences in the left ventricular systolic or end-diastolic pressures, left ventricular score, or diagnostic quality of the ventriculograms between the 5F Halo catheter group and the 5F and 6F pigtail catheter groups. Mean ventricular ectopy with the 5F Halo catheter was significantly less (0.9 ± 1.4 ventricular premature beats [VPBs]) than with the 5F pigtail catheter (2.3 ± 2.5 VPBs, p < 0.001) or the 6F pigtail catheter (2.9 ± 2.9 VPBs, p < 0.001). The incidence of ventricular ectopy also was significantly less for the 5F Halo catheter than for the 5F pigtail catheter (35% vs 63%, p < 0.001) or the 6F pigtail catheter (35% vs 62%, p < 0.001). Catheter movement was significantly less with the 5F Halo catheter than with the 5F pigtail catheter (6% vs 35%, p < 0.001) or the 6F pigtail catheter (6% vs 21%, p < 0.05). In the paired group, mean ectopy (0.2 ± 0.6, p < 0.01) and the incidence of ventricular ectopy (10% vs 70%, p < 0.01) were significantly less for the 5F Halo catheter than for the 5F pigtail catheter. It is concluded that the 5F Halo catheter, with its novel helical tip, is an improved catheter design for left ventriculography.