New concept in coronary angioplasty: dilatation with a helical balloon that allows simultaneous autoperfusion.

Abstract

These preclinical studies investigate a new concept in coronary angioplasty and balloon catheter technology (the P100 catheter). The study sought to evaluate the morphology of experimental coronary arterial plaques dilated with the P100 in comparison to standard balloons, to determine the in vitro flow rates occurring during the inflation of the P100 in comparison to available perfusion catheters, and to assess the in vivo coronary flow velocity and the presence of ischemia during prolonged inflations with the P100. The development of myocardial ischemia is a major limitation of standard balloon angioplasty. To limit ischemia, autoperfusion catheters have been developed, in which blood flows through the balloon in the central catheter shaft. However, as the flow lumen profile is reduced to enhance the performance of these devices, so is the accompanying flow. An angioplasty catheter was designed to evaluate the feasibility of continuous autoperfusion around the dilatation balloon. The balloon surface was engineered to develop a helical trough for blood flow to occur during inflation. Arterial plaque morphology following angioplasty with the P100 (n = 8) and with standard balloons (n = 8) was evaluated in a swine model. In vitro flow rates during inflation of the P100 and available perfusion catheters were determined using 33% glycerol solution. In vivo coronary flow velocity was determined with a Doppler-tipped wire during 60-min continuous inflations with the P100, and 15-sec inflations with a standard balloon in 12 vessel segments in 7 dogs; using 3.0-3.5-mm-diameter balloons. All lesions were successfully dilated (< 50% luminal diameter stenosis) with the P100 and standard balloons. There were no morphologic differences in plaques dilated with P100 compared to standard balloons. In vitro flow rates with conventional 3.0-mm balloon perfusion catheters ranged from 27.1 +/- 2.1 ml/min (RX Flowtrack) to 38.7 +/- 0.9 ml/min (Stack Perfusion), P < .05. Flow with the P100 ranged from 54.8 +/- 4.3 ml/min (2.5-mm balloon) to 103.2 +/- 4.5 ml/min (3.5-mm balloon), P < .05. Distal average peak coronary flow velocity during prolonged P100 inflations varied from 69 +/- 7% of baseline at 5 min to 83 +/- 8% of baseline at 40 min, with an upward trend in velocity the longer the balloon was inflated. Hemodynamics remained stable. Experimental plaques are successfully dilated with a helical balloon by a mechanism that appears similar to the dilatation mechanism of standard balloons. These preclinical studies show that angioplasty and autoperfusion can be accomplished by a balloon that does not have complete surface area contact with the vessel wall. A gap created by the helix can thus provide a conduit for blood flow. Clinical studies will determine whether this innovation, which alters the tubular geometry of current angioplasty balloons, will provide autoperfusion and equivalent dilatation effects in human.