Novel, vessel anatomy adjusting drug-coated balloon-Preclinical evaluation in peripheral porcine arteries.

BACKGROUND: The diameter of balloons or stents is selected according to the estimated reference vessel diameter and do not adapt to the vessel anatomy. The aim of the present preclinical studies was to investigate a novel, vessel anatomy adjusting hypercompliant drug-coated balloon catheter (HCDCB). METHODS: Hypercompliant balloon membranes were coated in a constricted state with high drug density. Drug adherence was investigated in vitro, transfer to the porcine peripheral arteries and longitudinal distribution in vivo. In young domestic swine, neointimal proliferation was induced by vessel overstretch and continuous irritation by permanent stents. Uncoated hypercompliant balloons (HCB), and standard uncoated balloons and drug-coated balloons (DCB) served as controls. Efficacy was assessed by angiography, optical coherence tomography (OCT), and histomorphometry. RESULTS: HCDCB lost 18.0 ± 3.9% of dose during in vitro simulated delivery to the lesion. Drug transfer to the vessel wall was 13.9 ± 6.4% and drug concentration was 1,044 ± 529 ng/mg tissue. Four weeks after treatment, the histomorphometric neointimal area was smaller with HCDCB versus uncoated HCB (2.39 ± 0.55 mm2 vs. 3.26 ± 0.72 mm2 , p = .038) and area stenosis (OCT) was less (11.6 ± 6.9% vs. 24.7 ± 9.7%, p = .022). No premature death occurred and no in-life clinical symptoms or treatment-associated thrombi were observed. CONCLUSIONS: HCDCB were found to inhibit excessive neointimal proliferation. Balloon adaption to different vessel diameters and shapes may provide drug-delivery in irregular lumen and facilitate balloon selection.

Paclitaxel-Coated Balloons: Investigation of Drug Transfer in Healthy and Atherosclerotic Arteries - First Experimental Results in Rabbits at Low Inflation Pressure.

PURPOSE: Beyond antiproliferative properties, paclitaxel exhibits anti-inflammatory activity, which might be beneficial in the local treatment of nonocclusive coronary artery disease. Paclitaxel release and tissue concentrations after paclitaxel-coated balloon treatment using different pressures have not been investigated so far. The aim of the study was to investigate in an atherosclerotic rabbit model whether drug transfer from paclitaxel-coated balloons into the vessel wall is affected by the presence of atherosclerotic lesions and to which extent it depends on the inflation pressure used. METHODS: Paclitaxel-coated balloons (3.5 µg/mm(2) paclitaxel) were inflated with pressures of 1, 2, or 6 atm (60s) in healthy (n = 39) and atherosclerotic (n = 22) arteries of New Zealand White Rabbits. Paclitaxel content in arterial walls (10 min after interventions) and paclitaxel remaining on balloons after treatment were analyzed using high-performance liquid chromatography. RESULTS: Median paclitaxel tissue concentrations were 829.3 µg/g (IQR 636.5-1487 µg/g) in healthy and 375.7 µg/g (IQR 169.8-771.6 µg/g) in atherosclerotic arteries (p = 0.0002). The paclitaxel tissue concentration was dependent on inflation pressure (1 atm vs. 2 atm vs. 6 atm) in atherosclerotic arteries (p = 0.0106) but not in healthy arteries (p ≥ 0.05). CONCLUSIONS: Atherosclerotic lesions impede the transfer of paclitaxel into arterial walls. Higher inflation pressures resulted in an increased paclitaxel transfer in atherosclerotic but not in healthy arteries. However, it is assumed that the tissue concentrations achieved with an inflation pressure of 2 atm are potentially effective in this model.

One single drug-coated balloon for all shapes/diameters? Neointimal proliferation inhibition in porcine peripheral arteries.

BACKGROUND: Long diseased vessel segments of peripheral arteries may display irregular shapes with different diameters. The aim of this study was to investigate inhibition of neointimal proliferation in porcine peripheral vessels with different diameters covered by one single hyper-compliant drug-coated balloon (HCDCB), compared to conventional drug-coated balloons (DCB), each selected according to the respective vessel diameter. METHODS AND RESULTS: Neointimal proliferation was stimulated in proximal and distal segments of the peripheral arteries by balloon overstretch and stent implantation. Inhibition of neointimal proliferation by one single HCDCB was compared to two vessel diameter-adjusted DCB per artery and to one single uncoated hyper-compliant balloon (HCB). Sixteen HCB, 16 HCDCB, and 32 DCB were used in 16 arteries each. Quantitative angiography (QA), optical coherence tomography (OCT) and histology showed a similar anti-restenotic effect for one HCDCB compared to two vessel diameter-adjusted DCB in narrow distal and wider proximal segments (QA diameter stenosis: 18.7±12.3% vs. 22.8±15.5%, p = 0.535; OCT area stenosis: 21.4±11.6% vs. 23.6±12.3%, p = 0.850; histomorphometry diameter stenosis: 27.5±7.1% vs. 26.9±8.0%, p = 0.952) and indicated significant inhibition of neointimal proliferation by HCDCB vs. uncoated HCB (QA diameter stenosis: 18.7±12.3% vs. 30.3±16.7%, p = 0.008; OCT area stenosis: 21.4±11.6% vs. 34.7±16.0%, p = 0.004; histomorphometry diameter stenosis: 27.5±7.1% vs. 32.5±8.5%, p = 0.038). CONCLUSIONS: HCDCB were found to be similar effective as DCB in inhibiting neointimal proliferation in vessel segments with different diameters. One single long HCDCB may allow for treatment of segments with variable diameters, and thus, replace the use of several vessel diameter-adjusted DCB.

Drug-Coated Balloons: Drugs Beyond Paclitaxel?

BACKGROUND: Although controversially discussed, paclitaxel is the only clinically proven drug that inhibits restenosis when released from drug-coated balloons (DCBs). Limus drugs are currently being explored as alternatives. The aim of the preclinical studies was to investigate drug candidates beyond paclitaxel considered for balloon coating. METHODS: Drugs were tested with respect to dissolution in organic solvents, coating on balloons, and drug transfer to the vessel wall. Inhibition of neointimal proliferation was tested in the porcine model of coronary in-stent stenosis. Intravascular drug treatment was achieved by DCBs at the time of stent implantation. RESULTS: Coating had to be adjusted for each drug. Doses on the balloons ranged from 1.0 to 8.6 µg/mm2 balloon surface. Satisfactory amounts of drug ranging from 5% to 29% of initial doses were transferred into the vessel wall. Angiographic parameters such as late lumen loss (LLL) at 4 weeks did not show reduction of in-stent neointimal proliferation by treatment with arsenic trioxide (0.87 ± 0.44 mm), betamethasone dipropionate (1.00 ± 0.54 mm), bortezomib (1.74 ± 0.46 mm), green tea extract (1.24 ± 0.51 mm), fantolon, an epothilone (0.86 ± 0.61 mm), methotrexate (1.09 ± 0.72 mm), and thalidomide (1.59 ± 0.55 mm) compared to treatment with uncoated balloons (1.07 ± 0.60 mm), while coatings with paclitaxel reliably reduced in-stent stenosis (LLL = 0.36 ± 0.25 mm). CONCLUSIONS: Despite the proven antiproliferative and/or anti-inflammatory effect of the drugs, none of the coatings significantly reduced LLL compared to uncoated balloons and thus, based on the results presented here, none of the tested coatings may be considered a substitute for the paclitaxel-based coatings currently in clinical use.

A novel constrained, paclitaxel-coated angioplasty balloon catheter.

AIMS: The study aimed to assess drug adherence, transfer to the vessel wall, tolerance and efficacy of a constrained angioplasty balloon coated with an excipient-enhanced paclitaxel coating (Chocolate coated balloon [CCB]) in the porcine model. METHODS AND RESULTS: Drug adherence was investigated in vitro. Drug transfer was evaluated in porcine arteries. A stent overstretch model was chosen to provoke intimal thickening in the efficacy and tolerance study. Conventional uncoated balloons were used as controls. CCB were coated with a nominal (3 µg/mm2) and high dose (two completely overlapping inflations each at 6 µg/mm2) of paclitaxel. Efficacy was assessed by histomorphometry and quantitative coronary angiography (QCA). Tolerance, including potential downstream effects, was assessed by myocardial function and histopathology. The CCB lost 6±12% of dose during in vitro simulated delivery to the lesion; drug transfer to the vessel wall was 14±4%. QCA and histomorphometry revealed no baseline differences between treatment groups. Thirty days after treatment, both doses of the CCB resulted in a 50% reduction in neointimal thickening of arteries relative to the uncoated balloon group. Maximum neointimal thickness was 1.12±0.36 mm for uncoated control specimens and 0.46±0.06 mm and 0.44±0.30 mm for the two CCB doses (3 and 2×6 µg/mm2), respectively. There were no device-related animal deaths or changes in left ventricular ejection fraction or device-specific myocardial histopathologies. There were no statistically significant differences between inflammatory scores among treatment groups. CONCLUSIONS: The results demonstrate efficacy and tolerance of a mechanically unique constrained angioplasty balloon within the tested dose range of the selected paclitaxel coating in the chosen porcine preclinical model.