Restenosis and the risk of sub-acute thrombosis still compromise the advantages of coronary stent... more Restenosis and the risk of sub-acute thrombosis still compromise the advantages of coronary stenting. This report aims to present a clinical audit of the first 100 patients to receive the South African-developed 'low injury' S-Flex coronary stent at Groote Schuur Hospital. From September 1999 to March 2001, 102 patients received one or more S-Flex stents. There were no special criteria for the use of the S-Flex and the stents were used routinely with stents from other manufacturers. Procedural and patient demographic information was obtained through a retrospective examination of patient records. All but two patients were followed up through clinical interview or telephone contact six months or more after the procedure. The primary endpoint was clinical restenosis, defined as angiographic restenosis (> 50% diameter narrowing), or recurrence of significant symptoms of ischaemic heart disease or target lesion revascularisation (TLR) after discharge from the hospital, unless shown angiographically that the S-Flex was not implicated. Device success was achieved in all cases. There were five cases of in-hospital major adverse cardiac events (MACE), including the deaths of two patients who had initially presented with cardiogenic shock. The six-month MACE rate was 7.9%, the six-month TLR rate was 3.0% and the total six-month mortality was 4.0%. The clinical restenosis rate after six months was 7.1% and the total event-free survival (i.e. survival without MACE or clinical restenosis) at six months was 86.1%. The S-Flex stent has a low clinical restenosis rate in a non-selective population undergoing stenting for coronary artery disease.
The goal of this study was to evaluate a new drug-eluting stent (DES) comprising a bioabsorbable ... more The goal of this study was to evaluate a new drug-eluting stent (DES) comprising a bioabsorbable polymer eluting a moderate dose of paclitaxel in a clinically relevant animal model. Although DES limit restenosis, adverse vascular pathologies and toxicities continue to be of major concern. Optimization of DES components, especially completely absorbable polymers, may reduce these toxicities. Bare-metal (BM), absorbable polymer coating only (POLY), and polymer-based paclitaxel-eluting (PACL) stents were implanted in porcine coronary arteries using intravascular ultrasound (IVUS) to optimize stent apposition. The dose density of paclitaxel was 0.30-0.35 mcg/mm2, with in vitro elution studies demonstrating a gradual elution over 6-8 weeks. The animals were terminated at 1 week, 1 month and 3 months. Histopathologic and histomorphometric analyses were perform. The arteries with PACL showed extensive smooth muscle cell necrosis at 1 week and poor apposition of stent struts at 1 month (malapposition measured as gap width between strut and internal elastic lamina), with greater gap width compared to the BM and POLY groups (0.22 mm +/- 0.02 vs. 0.03 mm +/- 0.02 and 0.02 mm +/- 0.01, respectively; p < 0.001). At 3 months, the PACL group showed rebound neointimal thickness and histological percent stenosis compared to the BM group (0.48 mm +/- 0.14 vs. 0.07 mm +/- 0.02, respectively; p < 0.001 and 59% +/- 11 vs. 17% +/- 2, respectively; p < 0.001). Despite in vitro data showing slow, sustained release of paclitaxel from a bioabsorbable polymer, the porcine coronary artery model demonstrated a sequence of medial necrosis, stent malapposition and late neointimal thickening. Since the therapeutic window for paclitaxel may be narrower than currently inferred, thorough preclinical testing coupled with the polymer development process for stents eluting paclitaxel is needed.
Aim To report clinical follow-up at 6 months after implanta-tion of the ultra-thin strut cobalt c... more Aim To report clinical follow-up at 6 months after implanta-tion of the ultra-thin strut cobalt chromium SolarFlex stent in a real-world setting. Methods and results Patients (n=240) with single or multiple vessel coronary artery disease undergoing percutaneous coronary intervention (PCI) at four sites in Europe were enrolled in the SOLSTICE (SolarFlex Stent in Routine Clinical Practice) registry. Follow-up at 6 months was 100 %. Diabetes was present in 29 % of the patients, 30 % presented with acute myocardial infarction and 17 % had unstable angina. Of the patients, 27 % had previously undergone PCI or coronary artery bypass surgery. Lesion complexity was high (50 % B2+C type lesions). Device success was achieved in 99.7 % of cases and the major adverse cardiac event (MACE) rate was 5.8 % at 6 months of follow-up. Target lesion revascularisation (TLR) was 5.0 % at 6 months. Conclusions The SOLSTICE registry showed that in a complex real-world setting the SolarFlex bare metal stent, with ultra-thin struts and customised scaffolding, provided low clinical MACE and TLR rates. These results provide support for the use of the latest generation bare metal stent in contemporary European practice.
Background
Transcatheter aortic valve implants (TAVI) have revolutionised the treatment of elderl... more Background Transcatheter aortic valve implants (TAVI) have revolutionised the treatment of elderly patients requiring aortic valve replacement. These patients often do not tolerate balloon valvuloplasty well, and a valvuloplasty balloon that would allow a degree of continued cardiac output during expansion would be beneficial. We tested such a balloon and describe our results in the sheep model.
Methods and Results We developed a non-occlusive balloon (NOB) catheter. An acute experiment was performed where the NOB was inflated in six sheep in the aortic valve position without any attempt to arrest cardiac output. Two inflations were performed per animal: the first for 30 s and the second for 2–3 min. Standard occlusive balloons were inflated in two animals under rapid ventricular pacing to serve as controls. Mean pressure gradient across the NOB was 9.7 ± 5 mmHg during the inflations and all animals remained hemodynamically stable during NOB inflations.
Conclusions The novel non-occlusive balloon catheter, which permitted uninterrupted cardiac output for a prolonged period without the need for pacing-induced temporary cessation of cardiac output, is both feasible and well tolerated in the acute sheep model.
Restenosis and the risk of sub-acute thrombosis still compromise the advantages of coronary stent... more Restenosis and the risk of sub-acute thrombosis still compromise the advantages of coronary stenting. This report aims to present a clinical audit of the first 100 patients to receive the South African-developed 'low injury' S-Flex coronary stent at Groote Schuur Hospital. From September 1999 to March 2001, 102 patients received one or more S-Flex stents. There were no special criteria for the use of the S-Flex and the stents were used routinely with stents from other manufacturers. Procedural and patient demographic information was obtained through a retrospective examination of patient records. All but two patients were followed up through clinical interview or telephone contact six months or more after the procedure. The primary endpoint was clinical restenosis, defined as angiographic restenosis (> 50% diameter narrowing), or recurrence of significant symptoms of ischaemic heart disease or target lesion revascularisation (TLR) after discharge from the hospital, unless shown angiographically that the S-Flex was not implicated. Device success was achieved in all cases. There were five cases of in-hospital major adverse cardiac events (MACE), including the deaths of two patients who had initially presented with cardiogenic shock. The six-month MACE rate was 7.9%, the six-month TLR rate was 3.0% and the total six-month mortality was 4.0%. The clinical restenosis rate after six months was 7.1% and the total event-free survival (i.e. survival without MACE or clinical restenosis) at six months was 86.1%. The S-Flex stent has a low clinical restenosis rate in a non-selective population undergoing stenting for coronary artery disease.
The goal of this study was to evaluate a new drug-eluting stent (DES) comprising a bioabsorbable ... more The goal of this study was to evaluate a new drug-eluting stent (DES) comprising a bioabsorbable polymer eluting a moderate dose of paclitaxel in a clinically relevant animal model. Although DES limit restenosis, adverse vascular pathologies and toxicities continue to be of major concern. Optimization of DES components, especially completely absorbable polymers, may reduce these toxicities. Bare-metal (BM), absorbable polymer coating only (POLY), and polymer-based paclitaxel-eluting (PACL) stents were implanted in porcine coronary arteries using intravascular ultrasound (IVUS) to optimize stent apposition. The dose density of paclitaxel was 0.30-0.35 mcg/mm2, with in vitro elution studies demonstrating a gradual elution over 6-8 weeks. The animals were terminated at 1 week, 1 month and 3 months. Histopathologic and histomorphometric analyses were perform. The arteries with PACL showed extensive smooth muscle cell necrosis at 1 week and poor apposition of stent struts at 1 month (malapposition measured as gap width between strut and internal elastic lamina), with greater gap width compared to the BM and POLY groups (0.22 mm +/- 0.02 vs. 0.03 mm +/- 0.02 and 0.02 mm +/- 0.01, respectively; p < 0.001). At 3 months, the PACL group showed rebound neointimal thickness and histological percent stenosis compared to the BM group (0.48 mm +/- 0.14 vs. 0.07 mm +/- 0.02, respectively; p < 0.001 and 59% +/- 11 vs. 17% +/- 2, respectively; p < 0.001). Despite in vitro data showing slow, sustained release of paclitaxel from a bioabsorbable polymer, the porcine coronary artery model demonstrated a sequence of medial necrosis, stent malapposition and late neointimal thickening. Since the therapeutic window for paclitaxel may be narrower than currently inferred, thorough preclinical testing coupled with the polymer development process for stents eluting paclitaxel is needed.
Aim To report clinical follow-up at 6 months after implanta-tion of the ultra-thin strut cobalt c... more Aim To report clinical follow-up at 6 months after implanta-tion of the ultra-thin strut cobalt chromium SolarFlex stent in a real-world setting. Methods and results Patients (n=240) with single or multiple vessel coronary artery disease undergoing percutaneous coronary intervention (PCI) at four sites in Europe were enrolled in the SOLSTICE (SolarFlex Stent in Routine Clinical Practice) registry. Follow-up at 6 months was 100 %. Diabetes was present in 29 % of the patients, 30 % presented with acute myocardial infarction and 17 % had unstable angina. Of the patients, 27 % had previously undergone PCI or coronary artery bypass surgery. Lesion complexity was high (50 % B2+C type lesions). Device success was achieved in 99.7 % of cases and the major adverse cardiac event (MACE) rate was 5.8 % at 6 months of follow-up. Target lesion revascularisation (TLR) was 5.0 % at 6 months. Conclusions The SOLSTICE registry showed that in a complex real-world setting the SolarFlex bare metal stent, with ultra-thin struts and customised scaffolding, provided low clinical MACE and TLR rates. These results provide support for the use of the latest generation bare metal stent in contemporary European practice.
Background
Transcatheter aortic valve implants (TAVI) have revolutionised the treatment of elderl... more Background Transcatheter aortic valve implants (TAVI) have revolutionised the treatment of elderly patients requiring aortic valve replacement. These patients often do not tolerate balloon valvuloplasty well, and a valvuloplasty balloon that would allow a degree of continued cardiac output during expansion would be beneficial. We tested such a balloon and describe our results in the sheep model.
Methods and Results We developed a non-occlusive balloon (NOB) catheter. An acute experiment was performed where the NOB was inflated in six sheep in the aortic valve position without any attempt to arrest cardiac output. Two inflations were performed per animal: the first for 30 s and the second for 2–3 min. Standard occlusive balloons were inflated in two animals under rapid ventricular pacing to serve as controls. Mean pressure gradient across the NOB was 9.7 ± 5 mmHg during the inflations and all animals remained hemodynamically stable during NOB inflations.
Conclusions The novel non-occlusive balloon catheter, which permitted uninterrupted cardiac output for a prolonged period without the need for pacing-induced temporary cessation of cardiac output, is both feasible and well tolerated in the acute sheep model.
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Papers by Ken Park
Transcatheter aortic valve implants (TAVI) have revolutionised the treatment of elderly patients requiring aortic valve replacement. These patients often do not tolerate balloon valvuloplasty well, and a valvuloplasty balloon that would allow a degree of continued cardiac output during expansion would be beneficial. We tested such a balloon and describe our results in the sheep model.
Methods and Results
We developed a non-occlusive balloon (NOB) catheter. An acute experiment was performed where the NOB was inflated in six sheep in the aortic valve position without any attempt to arrest cardiac output. Two inflations were performed per animal: the first for 30 s and the second for 2–3 min. Standard occlusive balloons were inflated in two animals under rapid ventricular pacing to serve as controls. Mean pressure gradient across the NOB was 9.7 ± 5 mmHg during the inflations and all animals remained hemodynamically stable during NOB inflations.
Conclusions
The novel non-occlusive balloon catheter, which permitted uninterrupted cardiac output for a prolonged period without the need for pacing-induced temporary cessation of cardiac output, is both feasible and well tolerated in the acute sheep model.
Thesis Chapters by Ken Park
Transcatheter aortic valve implants (TAVI) have revolutionised the treatment of elderly patients requiring aortic valve replacement. These patients often do not tolerate balloon valvuloplasty well, and a valvuloplasty balloon that would allow a degree of continued cardiac output during expansion would be beneficial. We tested such a balloon and describe our results in the sheep model.
Methods and Results
We developed a non-occlusive balloon (NOB) catheter. An acute experiment was performed where the NOB was inflated in six sheep in the aortic valve position without any attempt to arrest cardiac output. Two inflations were performed per animal: the first for 30 s and the second for 2–3 min. Standard occlusive balloons were inflated in two animals under rapid ventricular pacing to serve as controls. Mean pressure gradient across the NOB was 9.7 ± 5 mmHg during the inflations and all animals remained hemodynamically stable during NOB inflations.
Conclusions
The novel non-occlusive balloon catheter, which permitted uninterrupted cardiac output for a prolonged period without the need for pacing-induced temporary cessation of cardiac output, is both feasible and well tolerated in the acute sheep model.