Perfusion Balloon Research Articles

Perfusion-modulated MR imaging-guided radiofrequency ablation of the kidney in a porcine model.

This study was performed to test the hypothesis that temporary renal ischemia will result in increased thermal lesion size during radiofrequency thermal ablation in the kidney. Twelve kidneys were treated in six pigs that were placed under general anesthesia in the MR suite, using a 0.2-T open C-shaped MR imaging system. A 4-cm-long, 14-mm-diameter balloon catheter was placed into the aorta using a transfemoral approach, and the balloon was positioned proximal to the renal arteries via guidance with MR imaging. A 2-cm exposed-tip MR-compatible 17-gauge radiofrequency electrode was placed into one kidney under MR fluoroscopy using fast imaging with steady-state free precession (FISP) sequences. Thermal ablation was performed with the electrode tip temperature maintained at 90 +/- 2 degrees C for 10 min. This procedure was repeated in the contralateral kidney. The balloon was inflated during one ablation. Postablation images were obtained, the pigs were sacrificed, and both kidneys of each animal were harvested for pathologic correlation. Technical success was achieved in all animals. The lesion measured 14.2 +/- 2.2 mm (mean +/- standard deviation) for the ischemic kidney versus 8.0 +/- 2.6 mm in the normally perfused kidney (p = 0.00002). No significant complications were noted. In all images, thermal lesions displayed low signal intensity with a sharp rim of high signal intensity best visualized using short tau inversion recovery (STIR) sequences with a mean accuracy of 1.3 +/- 1.2 mm when compared with pathologic findings and a mean contrast-to-noise ratio of 4.9 +/- 2.5. We accept the hypothesis that temporary renal ischemia leads to a significantly increased radiofrequency ablation lesion size. We conclude that catheter-based balloon perfusion reduction is feasible, that the procedure does not lead to major complications, and that it can be performed using MR imaging as the sole imaging modality.

Treatment of Palmaz-Schatz In-stent Restenosis: 6?Month Clinical Follow-up

To identify predictors of Palmaz-Schatz in-stent restenosis and determine outcomes of treatment, we assessed 6–month outcomes in 402 patients who had coronary intervention with stent placement; 60 (15%) developed angiographic and clinical evidence of restenosis. Predictors of restenosis included family history of cardiovascular disease, prior bypass surgery, nonelective stenting, stenting of a vein graft, and multiple stents. Of 60 patients with stent restenosis, 47 had repeat percutaneous intervention and 10 had bypass surgery; only 1 of these 10 patients developed symptoms requiring repeat revascularization. Of the 47 with repeat percutaneous intervention, 32 (68%) had conventional balloon angioplasty; the others had perfusion balloon catheters, laser ablation, and repeat coronary stenting. During follow-up, 22 (47%) of these 47 patients suffered recurrent angina, myocardial infarction, or death. A third revascularization procedure was performed in 14 (30%), including 5 referred for bypass. This study shows the limitations of percutaneous modalities for patients with Palmaz-Schatz in-stem restenosis. Such patients are likely to have recurrent symptoms and to undergo repeat target-vessel revascularization.

Effect of transcatheter endovascular radiation with holmium-166 on neointimal formation after balloon injury in porcine coronary artery

Background. Neointimal formation in response to arterial injury is a major contributing element in restenosis after coronary balloon angioplasty and stenting. Endovascular irradiation has been reported to be effective in reducing restenosis. The purpose of this study was to investigate the effect of beta-emitting holmium-166 for the inhibition of neointimal formation in porcine coronary artery. Methods and Results. A total of 34 pigs weighing 25 to 30 kg underwent oversized balloon injury (balloon/artery ratio, 1.3:1.4) at the proximal portion of the left anterior descending and circumflex arteries. One artery was randomly assigned to receive radiation after injury. Ho-166 was left in the balloon within the delivery catheter for a period sufficient to deliver 9 Gy and 18 Gy to a depth of 1 mm from the surface of the balloon. Four weeks later, pigs were sacrificed and hearts were perfusion-fixed, followed by histopathologic analysis and planimetry for measurement of maximal intimal thickness, intimal area, and fracture length. The coronary segment of the pigs in the control group had neointimal area of 1.18 ± 0.55 mm 2; the pigs in the 9-Gy group had neointimal area of 0.68 ± 0.40 mm 2 ( P < .05 vs control); and the pigs in the 18-Gy group had neointimal area of 0.29 ± 0.12 mm 2 ( P < .01 vs control). The maximal intimal thickness in the 18-Gy group (0.14 ± 0.11 mm) was significantly reduced compared with the maximal intimal thickness in the control group (0.48 ± 0.13 mm) ( P < .01). Conclusions. Intracoronary radiation with liquid Ho-166 contained in a perfusion balloon catheter is feasible and effective in reducing neointimal formation after coronary overstretch injury in pigs. Therefore intracoronary irradiation on the injured segment may further reduce restenosis after balloon injury. (J Nucl Cardiol 2000;7:478-83.)

Balloon optimization versus stent study (BOSS): provisional stenting and early recoil after balloon angioplasty

“Optimal” percutaneous transluminal coronary angioplasty (PTCA) may have a late restenosis rate similar to stenting. We sought to assess short- and long-term results of a provisional stenting/optimal PTCA approach compared with elective stenting in a prospective, randomized study. A total of 97 patients with discrete, de novo lesions in native coronary arteries ≥3 mm in diameter were randomized 2:1 in PTCA with prolonged perfusion balloon inflation (n = 66) versus elective stenting (n = 31). Recoil after PTCA was assessed by routine delayed angiograms (5 and 20 minutes). Cross over to stent was allowed for an inadequate result; there was no on-line quantitative angiography. An independent core angiographic laboratory assessed all results and evaluated the adequacy of the subjective interpretation. Within the PTCA arm, there were 24 (36%) crossovers to stenting (5 of 24 [21%] due to recoil), whereas 2 stents could not be delivered to the lesion and crossed over to PTCA. As assessed by quantitative angiography, baseline reference vessel diameters were similar between the PTCA and stent groups. The immediate lumen diameter achieved with PTCA was smaller than that achieved with stenting (2.18 ± 0.49 vs 2.44 ± 0.38 mm, respectively, p = 0.01). There were no differences in angiographic results between elective and crossover stenting and there were no in-hospital complications in any patient. Target lesion revascularization at 8 months was 19% (n = 6) in the elective stent arm versus 21% (n = 14) in the PTCA arm, p = NS; respective rates in PTCA alone and crossed over-to-stent subsets were 23% (n = 10) versus 17% (n = 4), p = NS. Angiographic restenosis was 47% after elective stenting versus 38% after PTCA (intention to treat), p = NS. By received treatment, it was 41% (11 of 27) in the group treated with the PTCA versus 33% (5 of 15) in the crossover-to-stent arm (p = NS). Thus, provisional stenting can be safely performed in the treatment of discrete, native de novo lesions. Early recoil after PTCA cannot be reliably assessed without quantitative angiography.

Role of Autoperfusion Balloon in Endovascular Interventions

The development of the autoperfusion balloon catheter provided the ability to perform prolonged balloon inflations during angioplasty procedures. For a number of years the autoperfusion balloon catheter was successfully used to treat acute complications of percutaneous coronary interventions. However, with the advent of stent implantation procedures and the use of platelet glycoprotein IIb/IIIa receptor inhibitors, the role of autoperfusion balloon angioplasty has decreased. However, the perfusion balloon may have an important role in angioplasty and/or stenting of coronary lesions with unfavorable coronary anatomy and also in carotid angioplasty. The perfusion balloon also may be helpful for the treatment of in‐stent restenosis. In the future the autoperfusion balloon or its principle may hold promise in emerging interventions, such as gene therapy and vascular brachytherapy where prolonged interrupted of coronary circulation is required.

Occurrence of a saccular pseudoaneurysm formation two weeks after perforation of the left anterior descending coronary artery during balloon angioplasty in acute myocardial infarction

We describe the occurrence of a localized saccular pseudoaneurysm in a 69-year-old patient 2 weeks after perforation of the left anterior descending coronary artery during balloon angioplasty in acute myocardial infarction. The therapy of perforations requires prolonged balloon inflations, perfusion balloons, covered stents, or surgery. Coronary peudoaneurysm formations are rare; their therapy requires covered stents or surgery. Cathet. Cardiovasc. Intervent. 47:341–346, 1999. © 1999 Wiley-Liss, Inc.

Radioactive beta-emitting solution-filled balloon treatment prevents porcine coronary restenosis

Purpose. Intracoronary gamma or beta radiation from centrally located sources at the time of overstretch balloon injury inhibits neointimal proliferation. In an effort to deliver homogeneous, centered radiation fields in a technically straightforward fashion, we studied the effects of a beta-emitting solution used as a balloon inflation fluid to deliver radiation at the time of coronary injury. Methods. Twenty-one coronary arteries in 13 juvenile swine underwent irradiation (control and 11 or 25 Gy media dose). Radiation was delivered using a perfusion balloon inflated with an Re-188 solution. Subsequently, overdilatation percutaneous transluminal coronary angioplasty was performed at the pretreated segment. Histopathologic and histomorphometric analysis was performed at 30 days after injury on the entire irradiated artery. Results. Balloon overdilation was associated with significant vascular injury and marked neointimal proliferation in control and low-dose (11 Gy)-treated arteries. High-dose radiation (25 Gy) significantly inhibited neointima formation compared with controls (neointimal area: 0.49 ± 0.29 mm 2 vs. 1.51 ± 0.22 mm 2, respectively; p = 0.02) and low-dose radiation (neointimal area 1.75 ± 0.54 mm 2, p > 0.1 compared with controls). Conclusions. Liquid Re-188 is an effective beta-emitting vehicle to deliver intracoronary radiation and prevent restenosis in this model. Intracoronary radiation treatment using aqueous radioisotope sources is technically straightforward and provides the optimally achievable radiation dose distribution.

Comparison of immediate and in-hospital results of conventional balloon and perfusion balloon angioplasty using intracoronary ultrasound

Angiographic studies have demonstrated that perfusion balloon percutaneous transluminal coronary angioplasty (PTCA) may result in modestly improved luminal gains and fewer major dissections than conventional balloon PTCA. However, intracoronary ultrasound (ICUS), which is more sensitive than angiography in evaluating the incidence, extent, and severity of dissection, was not used. We randomized 48 patients with 54 coronary stenoses to conventional or perfusion balloon PTCA. Four 2-minute inflations were permitted with conventional balloon PTCA. Two 10-minute inflations were allowed with perfusion balloon PTCA. Quantitative coronary angiography and ICUS were performed before and after treatment. In-hospital clinical events were recorded. Conventional and perfusion balloon PTCA achieved similar improvements in lumen diameter (1.25 ± 0.51 vs 1.28 ± 0.51 mm) and reductions in percent stenosis (−45 ± 21% vs −44 ± 15%) by quantitative coronary angiography. Comparable gains in lumen diameter (0.62 ± 0.39 vs 0.50 ± 0.38 mm) and lumen area (2.70 ± 1.96 vs 2.05 ± 1.52 mm 2) were observed on ICUS. Angiography demonstrated similar rates of any dissection (36% vs 21%) and major dissection (12% vs 7%). ICUS identified a similar incidence of any dissection (60% vs 76%) and type II dissection (52% vs 62%). The relative dissection area was also similar (9.2 ± 5.6% vs 7.8 ± 5.8%). One conventional balloon patient experienced postprocedural chest pain. No patient in either group died, or had myocardial infarction, abrupt closure, or urgent revascularization.

Endovascular Repair of Arterial Pseudoaneurysms with Use of a Perfusion Balloon Catheter

Pseudoaneurysms represent contained disruption of the arterial wall. Iatrogenic pseudoaneurysms frequently complicate complex endovascular procedures. With use of an animal model, the authors attempted to determine the safety and efficacy of using a perfusion balloon catheter (PBC) to thrombose surgically created pseudoaneurysms. An in vitro system measured maximum flow volume through a 5-F PBC. Pseudoaneurysms were created in domestic swine with use of a jugular vein patch anastomosed to a femoral arteriotomy. The PBC was inflated across the pseudoaneurysm neck for 30-minute intervals until thrombosis was confirmed by ultrasound. Completion arteriography was performed to evaluate for vascular complications. Maximum flow through the PBC was 62.6 mL/min measured at a constant pressure gradient of 120 mm Hg. Five pseudoaneurysms were created in four animals. The PBC completely thrombosed all five lesions. The mean treatment duration was 129 minutes (+/- 39 minutes SD). No native arterial injury, in situ thrombus, or distal embolization occurred. Partial recanalization of three of the five treated pseudoaneurysms was identified on follow-up arteriography and gross sectioning (n = 2 and n = 1, respectively). The PBC safely and effectively thrombosed surgically created pseudoaneurysms. Partial recanalization of treated pseudoaneurysms was demonstrated. Clinical trials are warranted.

Coronary Artery Bypass Surgery on the Beating Heart by the Aid of a Novel Perfusion Balloon Catheter

Coronary Artery Bypass Surgery on the Beating Heart by the Aid of a Novel Perfusion Balloon Catheter

Coronary artery bypass surgery on the beating heart by the aid of a novel perfusion balloon catheter

Coronary artery bypass surgery on the beating heart by the aid of a novel perfusion balloon catheter

Percutaneous Transluminal Angioplasty for Acute Thrombotic Occlusion of the Cervical Internal Carotid Artery Using a Perfusion Balloon Catheter

We performed emergency percutaneous transluminal angioplasty (PTA) with a perfusion balloon catheter (PBC) for PTCA and, at the same time, thrombolytic therapy was administered by urokinase (UK) perfusion in five cases of severe cervical internal carotid artery stenosis in which sudden cerebral hemisphere ischemia occurred due to acute thrombotic obliteration. In four out of the five cases, effective revascularization was obtained; three resulted in Good recovery, but one showed extensive cerebral infarction after PTA. In the remaining one case, where stenosis of the internal carotid artery of the opposite side occurred subclinically, effective revascularization by PTA was impossible resulting in the death of this patient. While "artery to aetery embolism" was confirmed in all four cases in which revascularization was successful, most emboli were dissolved by combined thrombolysis. As poor prognostic factors, findings of a low density area and closing of cerebral sulci in an initial CT and poor development of the collateral circulation mediating the circle of Willis and leptomeningeal collateral on the cerebral surface were indicated. Since PBC is capable of performing PTA while assuring circulation distant from the balloon, it facilitates gradual and prolonged balloon inflation, which is said to be safer and more effective, and is considered a reasonable method of revascularization at the time of an acute obliteration in the cervical internal carotid artery. In addition, this method can be used as a bridge to carotid endarterectomy. However, "artery to artery embolism" accompanying PTA in the acute stage remains a major problem, and a combination of thrombolysis seems indispensable.

Economic Impact of Angioplasty Salvage Techniques, With an Emphasis on Coronary Stents: A Method Incorporating Costs, Revenues, Clinical Effectiveness and Payer Mix

Objectives. We sought to broaden assessment of the economic impact of percutaneous transluminal coronary angioplasty (PTCA) revascularization salvage strategies by taking into account costs, revenues, the off-setting effects of prevented clinical complications and the effects of payer mix.Background. Previous economic analyses of PTCA have focused on the direct costs of treatment but have not accounted either for associated revenues or for the ability of costly salvage techniques such as coronary stenting to reduce even costlier complications.Methods. Procedural costs, revenues and contribution margins (i.e., “profit”) were measured for 765 consecutive PTCA cases to assess the economic impact of salvage techniques (prolonged heparin administration, thrombolysis, intracoronary stenting or use of perfusion balloon catheters) and clinical complications (myocardial infarction, coronary artery bypass graft surgery [CABG] or acute vessel closure with repeat PTCA). To assess the economic impact of various salvage techniques for failed PTCA, we used actual 1995 financial data as well as models of various mixes of fee-for-service, diagnosis-related group (DRG) and capitated payers.Results. Under fee-for-service arrangements, most salvage techniques were profitable for the hospital. Stents were profitable at almost any level of clinical effectiveness. Under DRG-based systems, most salvage techniques such as stenting produced a financial loss to the hospital because one complication (CABG) remained profitable. Under capitated arrangements, stenting and other salvage modalities were profitable only if they were clinically effective in preventing complications in >50% of cases in which they were used.Conclusions. The economic impact of PTCA salvage techniques depends on their clinical effectiveness, costs and revenues. In reimbursement systems dominated by DRG payers, salvage techniques are not rewarded, whereas complications are. Under capitated systems, the level of clinical effectiveness needed to achieve cost savings is probably not achievable in current practice. Further studies are needed to define equitable reimbursement schedules that will promote clinically effective practice.

Evaluation of an active coronary perfusion balloon device using Doppler flow wire during PTCA.

The aim of this study was to assess whether active coronary perfusion catheters (APC) can provide a sufficient coronary flow in large caliber vessels during balloon inflation. To prevent myocardial ischemia during PTCA, these APC may be employed. However, it is as yet unknown whether the active flow rate of these devices approaches the flow rate prior to PTCA during balloon inflation. Therefore, we measured the efficacy of the APC during balloon inflation in vessels supplying a large amount of myocardium. In 12 patients (1 female, 11 males, 53 +/- 12.6 yr) with stenosed vessels (average diameter 3.4 +/- 0.26 mm), the coronary flow velocity was measured using a 0.014" Doppler guidewire, which was placed distally bypassing the balloon of the APC. The active perfusion balloon catheter was advanced through a 7F guiding catheter along a 0.014" guidewire. After removal of the guidewire, arterial blood being withdrawn from the side port of the femoral angioplasty sheath was pumped through the catheter to the distal coronary vessel. The perfusion volumes of the pump were set to different levels between 30 to 60 ml/min. Intracoronary flow rate was calculated by the angiographically assessed vessel luminal area [symbol: see text] average peak velocity [symbol: see text] 0.5. The mean coronary flow rate prior to PTCA was 43 +/- 17.7 ml/min. Maximum flow during PTCA was 55 +/- 19.6 ml/min. We found a good correlation between the preset external pump rate and the coronary flow in situ (r = 0.92). Pre-PTCA flow rates were achieved in 11 of 12 patients (92%) during balloon inflation. No relevant decrease in the arterial pressure occurred during dilation times of 4.6 +/- 1.63 min. Only two patients showed significant ECG changes during these balloon inflations. After an average follow-up period of 13 +/- 6.3 mo, only one patient (8%) had a significant re-stenosis requiring the implantation of a stent. The combination of intravascular Doppler velocity measurements with quantitative coronary angiography offers the opportunity of exact online flow registration during angioplasty. Using APC, It is possible to maintain a sufficient coronary flow in the distal vessel during balloon inflation even in large vessels. Therefore, as compared with mechanical circulatory assist devices, coronary assist by APC is a little invasive, but according to our measurements it might be a sufficient tool for performing PTCA also in high-risk patients.

Evaluation of an active coronary perfusion balloon device using Doppler flow wire during PTCA

Evaluation of an active coronary perfusion balloon device using Doppler flow wire during PTCA

Prolonged Dilation Improves an Unsatisfactory Primary Result of Femoropopliteal Artery Angioplasty: Usefulness of a Perfusion Balloon Catheter

Prolonged Dilation Improves an Unsatisfactory Primary Result of Femoropopliteal Artery Angioplasty: Usefulness of a Perfusion Balloon Catheter

Mechanical methods of improving blood flow during cardiopulmonary resuscitation

Mechanical measures intended to increase blood flow to vital organs are the mainstay of therapy for patients in cardiac arrest. Several new cardiopulmonary resuscitation techniques and devices have been developed and tested since the first report of manual closed-chested cardiopulmonary resuscitation nearly four decades ago. These include vest cardiopulmonary resuscitation, active compression-decompression cardiopulmonary resuscitation, an intra-aortic perfusion balloon pump, and an inspiratory impedance threshold valve, interposed abdominal counterpulsation cardiopulmonary resuscitation, and phased thoracic-abdominal compression and decompression. Many of these new mechanical advances in the treatment of cardiac arrest are currently undergoing clinical evaluation in patients in cardiac arrest. Although some of those new methods and techniques have shown promise in small human clinical trials, none have yet to be found to be conclusively superior to manual closed-chested cardiopulmonary resuscitation.

Intracoronary stent implantation using a single high-pressure perfusion balloon catheter.

Currently, the recommended strategy for Palmaz-Schatz intracoronary stent implantation is to use two balloons: an undersized balloon for predilation to facilitate a channel for the stent and a high pressure balloon for postdilation to obtain good apposition of the struts into the vessel wall. We reported our experience using the perfusion balloon as the initial balloon to dilate intracoronary lesions and demonstrated a reduction in the total number of balloons used per angioplasty procedure. The objective of this study was to examine whether a single balloon could effectively be used for stent implantation. The study population included 95 patients who underwent elective intracoronary stent placement to 100 lesions using 110 Palmaz-Schatz stents by nine individual operators. Lesions were predilated with an ACS RX LIFESTREAM balloon at a low pressure of 4-6 atm (mean 5.7 +/- 2.6). After stent deployment, the same balloon was used at a high pressure (mean 16.2 +/- 1.2). Mean balloon size, which was chosen as the stent size, was 3.4 +/- 0.4 mm. Comparison of this strategy with the recommended strategy of 68 consecutive elective stent deployments at a single center during the same time was performed. Stent implantation using a single balloon strategy was angiographically successful in 99 of 100 (99.0%) lesions. The single balloon strategy was associated with a balloon burst rate of 9.1%. The number of balloons used per stent deployment was 1.2 vs. 2.4 using the recommended strategy (P < 0.0001). There was no evidence of stent thrombosis, any MI, or target lesion revascularization during the procedure and hospitalization. One in-hospital death as a result of nonhemorrhagic stroke was documented in the treated group. We concluded that using a single high pressure perfusion balloon for pre and postdilation in patients undergoing elective stent placement is safe and reduces the number of balloons used per procedure.

Intracoronary stent implantation using a single high‐pressure perfusion balloon catheter

Currently, the recommended strategy for Palmaz-Schatz intracoronary stent implantation is to use two balloons: an undersized balloon for predilation to facilitate a channel for the stent and a high pressure balloon for postdilation to obtain good apposition of the struts into the vessel wall. We reported our experience using the perfusion balloon as the initial balloon to dilate intracoronary lesions and demonstrated a reduction in the total number of balloons used per angioplasty procedure. The objective of this study was to examine whether a single balloon could effectively be used for stent implantation. The study population included 95 patients who underwent elective intracoronary stent placement to 100 lesions using 110 Palmaz-Schatz stents by nine individual operators. Lesions were predilated with an ACS RX LIFESTREAM balloon at a low pressure of 4–6 atm (mean 5.7 ± 2.6). After stent deployment, the same balloon was used at a high pressure (mean 16.2 ± 1.2). Mean balloon size, which was chosen as the stent size, was 3.4 ± 0.4 mm. Comparison of this strategy with the recommended strategy of 68 consecutive elective stent deployments at a single center during the same time was performed. Stent implantation using a single balloon strategy was angiographically successful in 99 of 100 (99.0%) lesions. The single balloon strategy was associated with a balloon burst rate of 9.1%. The number of balloons used per stent deployment was 1.2 vs. 2.4 using the recommended strategy (P < 0.0001). There was no evidence of stent thrombosis, any MI, or target lesion revascularization during the procedure and hospitalization. One in-hospital death as a result of nonhemorragic stroke was documented in the treated group. We concluded that using a single high pressure perfusion balloon for pre and postdilation in patients undergoing elective stent placement is safe and reduces the number of balloons used per procedure. Cathet. Cardiovasc. Diagn. 40:140–143, 1997. © 1997 Wiley-Liss, Inc.

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

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 humans. Cathet Cardiovasc Diagn 40:109–116, 1997. © 1997 Wiley-Liss, Inc.