Percutaneous valve replacement: a novel low-profile polyurethane valved stent.
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Heart Valve Prosthesis↗
Biomedical subjects
Jochen Cremer
Publications and source records attributed to Jochen Cremer.
Alternative technique of the right atrial anastomosis (cavo-atrial) in orthotopic heart transplantation.
An alternative technique of the right atrial anastomosis in heart transplantation, which allows a more anatomical reconstruction of the right atrium and is easier in handling than bi-caval anastomoses is described.
Anastomosis, Surgical↗
Percutaneous pulmonary valve replacement: 3-month evaluation of self-expanding valved stents.
PURPOSE: In a recent study our group established an acute animal model of percutaneous pulmonary valve replacement using self-expanding nitinol stents. The present study was performed to evaluate these valved stents over a 3-month period. DESCRIPTION: Bovine jugular xenografts were sutured into nitinol stents. Transfemoral implantation in the pulmonary position using a modified commercially available application device (with a 22-French outer diameter) was evaluated in 9 sheep. EVALUATION: Two sheep died shortly after successful valved stent implantation due to internal venous hemorrhage. Another 1 sheep died 2.5 months after the procedure due to vegetations on the neovalve leading to subtotal stenosis. All other animals survived the 3-month study time (n = 6). An orthotopic pulmonary valved stent position was achieved in 4 animals and a supravalvular position in 1. During the deployment procedure, rhythm disturbances occurred in all animals, and mean arterial blood pressure dropped from 83.9 +/- 26.0 mm Hg to 68.3 +/- 22.3 mm Hg (p = 0.006) (n = 5). The peak-to-peak transvalvular gradient was 5.1 +/- 4.0 mm Hg initially (n = 5), and 3.6 +/- 1.6 mm Hg at follow-up (n = 5). Three-month angiographic and echocardiographic follow-up confirmed competent neovalves without paravalvular leakages. CONCLUSIONS: After 3 months of implantation, percutaneously implanted memory nitinol valved stents demonstrated good function in the sheep.
Animals↗
Two-stage surgical and endovascular treatment of an aneurysmal aberrant right subclavian (Lusoria) artery.
We report a case of a 75-year-old male patient with an asymptomatic aneurysm of an aberrant right subclavian artery (ARSA). Timely elective therapy of this entity is indicated due to the high risk of rupture. Because of the patient's reduced physical state, we performed an interdisciplinary endovascular aortic stent-grafting for the exclusion of the ARSA aneurysm. However, the proximal landing zone for the thoracic stent had to be chosen proximal to the origin of the left subclavian artery. Thus, 2 days before the endovascular procedure, a left-sided carotido-subclavian bypass was accomplished. The peri- and postoperative course was uneventful. The technical results in our patient were excellent, no leakage was visible so far.
Aged↗
Midterm follow-up after minimally invasive direct coronary artery bypass grafting versus percutaneous coronary intervention techniques.
BACKGROUND: Revascularization of the left anterior descending coronary artery can be performed by minimally invasive direct coronary artery bypass grafting (MIDCAB) or percutaneous coronary intervention techniques (PCI). The study compared the midterm results of both techniques. METHODS: The outcome of 206 consecutive MIDCAB and 256 PCI patients treated from 1998 until 2001 was retrospectively analyzed. Cardiologists determined the primary patient allocation for the distinct revascularization technique. Periprocedural complications and midterm follow-up, including quality-of-life assessment (SF-36), was reported up to 5.2 years (3.4 +/- 0.7 years). RESULTS: Periprocedural and overall mortality (p = 0.206) showed no differences. Four MIDCAB patients required early reoperation but not for repeated target vessel revascularization. In 16 patients secondary PCI (7.8%) of other coronary vessels was performed. Repeated revascularization of the left anterior descending coronary artery was necessary in 24.2% of patients in the PCI group (p < 0.001), with 4.7% finally requiring surgical revascularization. The incidence of major adverse cardiac events, including myocardial infarction (p = 0.581), repeated target vessel revascularization (p < 0.001), or death (p = 0.206) was higher in the PCI group. This difference consisted basically of the need for repeated target vessel revascularization. Patient-based quality-of-life assessment (SF-36) was independent from the primary chosen revascularization method. CONCLUSIONS: At midterm follow up, MIDCAB resulted in significantly superior results regarding the need for repeated target vessel revascularization compared with PCI, with no significant differences regarding other major cardiac events.
Adult↗
Advances in experimental percutaneous pulmonary valve replacement.
BACKGROUND: Percutaneous pulmonary valve implantation is emerging as an alternative and additional option for a successful surgical scheme. To date, these procedures are performed by the balloon-in-balloon technique. The use of self-expanding stents for percutaneous valve replacement is assumed to improve preservation of the valve in its folded condition in the application device and the valve's long-term functioning. Therefore, initial experience with the development of a completely percutaneous transfemoral technique for pulmonary valve implantation using a self-expanding valved stent is described. METHODS: Bovine jugular xenografts were sutured into nitinol stents, and functional in vitro tests of valved stents were carried out. Transfemoral implantation in pulmonary position was acutely evaluated in 6 sheep weighing 22 to 29 kg. Radiologic evaluation was performed by angiography and multislice computed tomography (MSCT) scan. In addition, pathoanatomical studies were performed. RESULTS: Exact implantation in pulmonary valve position was achieved in 5 of 6 sheep, with 1 early stent migration. Another sheep died before stent placement owing to perforation of the right ventricle by the delivery system. Orthotopic pulmonary valved stent position was depicted by MSCT in all other sheep (n = 4). The peak-to-peak transvalvular gradient was 8.2 +/- 3.9 mm Hg (n = 5). Postmortem examination revealed intact stent valves with no adherent clots. No macroscopic damage of the pulmonary artery was noted, whereas minor hematoma of the right atrium and the right ventricular outflow tract were observed in 2 hearts. CONCLUSIONS: This acute study demonstrates that memory nitinol valved stents can be optimally deployed in the pulmonary position through the groin in sheep.
Animals↗
Percutaneous aortic valve replacement: resection before implantation.
OBJECTIVE: After transluminal endovascular implantation of a new valved stent, the aim of this study was to evaluate the feasibility of using a high-pressure water stream to endovascularly resect human calcified aortic valves. METHODS: First, human calcified aortic valves were excised and then resected in vitro to determine optimal water jet parameters. Second, healthy porcine aortic valves were ablated in vitro to evaluate possible destruction to the surrounding anatomy. Third, resection was performed endoluminally by introducing microsystemic tools into the descending aorta, passing them through the arch and ascending aorta to the aortic valve in an in vitro porcine model. Macro- and micropathology of specimens were analyzed. RESULTS: First, resection of human calcified valves took a mean of 6.0+/-2.4min per three leaflets at 150bar (n=17). The maximum size of the cut leaflets was 7.1+/-1.7mm. Second, resection of healthy porcine aortic valves at 60bar took 2.3+/-0.3min per three leaflets (n=10). Only the aortic annulus was moderately affected in six cases. Third, endoluminal resection via the descending aorta took 12.2+/-0.8min per three leaflets at 60bar (n=10). The aortic wall was affected in four cases, the aortic annulus and the coronary ostia only once. Microscopic analysis also revealed superficial lesions with a maximum lesion depth of 1200microm in one case, and an average of 580+/-145microm in subsequent lesions. The mitral valve and the left ventricular outflow tract were not affected. CONCLUSIONS: Percutaneous resection of heart valves is emerging as a promising auxiliary method for the resection of calcified aortic heart valves because they can be cut endoscopically. Nonetheless, before this resection tool can be clinically applied by surgeons to perform a true percutaneous valve replacement, an additional aortic valve resection chamber (already at the prototype stage) designed for capturing all debris, has to be established.
Animals↗
Endovascular repair of ruptured abdominal aortic aneurysm: feasibility and impact on early outcome.
PURPOSE: Open repair of ruptured abdominal aortic aneurysms (AAAs) still has a high associated mortality rate. The impact of the introduction of endovascular treatment on the early outcomes of ruptured AAAs was examined at a single institution. The suitability of acute endovascular aneurysm repair (EVAR) in patients with ruptured AAAs was also assessed. MATERIALS AND METHODS: Retrospective review was conducted in 39 consecutive patients treated for ruptured AAA from 2001 to 2004. The patients were divided into 15 who underwent open repair from 2001 to 2002 (group I) and 24 who were treated with open repair (n=13; 54%) or endovascular repair (n=11; 46%) from 2003 to 2004 (group II). Hospital charts and computed tomographic scans were reviewed to evaluate the feasibility of EVAR. RESULTS: Age, sex, and aneurysm size were similar between the two groups. The 30-day mortality rates were 53% in group I and 8% in group II (P=.003). Median procedure times were shorter in the patients who underwent EVAR. Intensive care unit stay and hospital stay were 22.0 days+/-29.6 and 29.7 days+/-33.8, respectively, in group I, and 5.6 days+/-4.4 and 16.1 days+/-10.9, respectively, in group II (P<<.03). Eleven patients were found ineligible for EVAR as a result of an unsuitable neck (n=5) or iliac arteries (n=3) or both (n=3). No graft failure was detected during follow-up. CONCLUSIONS: After introduction of acute EVAR, a total of 46% of patients with ruptured AAAs were treated with the procedure. Potentially, 54% of patients could have been suitable for EVAR. Endovascular stent-graft implantation has significantly improved outcomes in ruptured AAAs and may therefore be beneficial in the overall treatment strategy in these patients.
Aged↗
Composite valve graft versus separate aortic valve and ascending aortic replacement.
To ascertain if the operative technique has any influence on outcome, the surgical results after aortic root replacement using either a composite valve graft (CVG) or a separate graft and valve (SVG) were analyzed. Eighty-four patients received a CVG, and 36 had SVG replacement. The operative mortality rate was 6% for patients receiving a CVG and 3% for SVG replacement (nonsignificant). Follow-up extended to 21 years (mean 124 +/- 45 months). The type of the procedure (SVG versus CVG) was not a significant predictor of in-hospital mortality, length of hospital stay, subsequent root dilatation (SVG), anastomotic dehiscence and subsequent surgery. The early and long-term results after CVG or SVG were similar, which reflects proper patient selection.
Adult↗
Percutaneous valve replacement: current state and future prospects.
Percutaneous valve implantation is the development of a foldable heart valve that can be mounted on an expandable stent delivered percutaneously through standard catheter-based techniques and implanted within a diseased valve annulus. In cases with severe aortic stenosis, the diseased valve has to be pre-dilated. To perform a true replacement the diseased valve has to be ablated and removed. In this article, we review the development of percutaneous valve replacement technology and discuss future prospects in this field.
Forecasting↗
Stent-graft repair versus open surgery for the descending aorta: a case-control study.
PURPOSE: To compare the clinical outcomes of open surgery versus endovascular repair in patients with pathologies of the descending thoracic aorta (DTA). METHODS: This retrospective study included 44 patients (28 men; mean age 68+/-12 years, range 37-86) treated for DTA pathologies between 1995 and 2003. Twenty-two patients (15 men; mean age 68+/-13 years, range 37-86) undergoing stent-graft implantation were matched for sex, age, emergency operation, and comorbidities (coronary artery disease, chronic obstructive pulmonary disease) with a 22-patient contemporaneous surgical cohort (13 men; mean age 69+/-11 years, range 41-80). RESULTS: Thirty-day mortality was 5% in the stent-graft group and 27% in the open surgery group (p=0.047). The incidences of postoperative stroke and paraplegia were both 5% in the stent-graft group and 9%, respectively, in the open surgery cohort. One patient required a second stent-graft due to an endoleak during the same hospital stay, and 2 reoperations were performed in the standard operation group (p = NS). Lengths of stay in the intensive care unit (ICU) and hospital were 4.3+/-5.4 and 11.9+/-15.0 days, respectively, in the stent-graft group and 10.0+/-7.4 and 21.5+/-17.4 days, respectively, in the open surgery group (p<0.006). CONCLUSIONS: Stent-graft repair was associated with lower 30-day mortality and comparable complication rates in older patients with significant comorbidities and a high percentage of emergency operations compared to open surgery. Stent-graft implantation shortens ICU and hospital stays significantly. In the future, subgroups of patients who may experience the greatest benefit from stent-graft repair in the long term should be defined.
Adult↗
Percutaneous aortic valve replacement: more than palliation?
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Aortic Valve↗
Long term follow-up of left ventricular performance and size of the great arteries before and after one- and two-stage arterial switch operation of simple transposition.
OBJECTIVE: Long-term angiographic evaluation of left ventricular performance and size of the great arteries after one-stage neonatal versus two-stage arterial switch operation (ASO) of simple transposition. METHODS: Analysis of cineangiographic studies obtained during the process of two-stage ASO for 34 patients and after neonatal repair for 52 patients. RESULTS: At early follow-up after two-stage ASO the left ventricular enddiastolic volume (LVEDV) was +1.8 standard deviations (S.D.) larger than LVEDV of control patients, but normalized completely (0.0 S.D.) at late follow-up. In contrast, after neonatal repair the LVEDV was always normal, and the median EF was significantly higher than after two-stage ASO (73 vs. 68%). The diameters of the native pulmonary annulus and sinus increased significantly after pulmonary artery banding to +4.5 and +4.8 S.D., respectively. After ASO, a significant decrease of the respective sizes occurred from early to late follow-up (annulus: +6.0 to +2.1 S.D.; sinus: +7.1 to +4.1 S.D.). After neonatal ASO the neoaortic annulus and sinus were only +1.5 and +2.7 S.D. larger than the comparable normal structures. The differences to the two-stage group were significant. In both groups, the neoaortic anastomosis had no diameters significantly different from normal. After one- and two-stage repair, the size of the neopulmonary annulus and sinus decreased similarly in both groups from early to late follow-up (annulus +0.9 to -2.4 S.D.; +0.3 to -2.8 S.D.; sinus: -0.7 to -1.6 S.D.; -0.7 to -1.8 S.D.). CONCLUSIONS: Neonatal ASO has definite advantages over two-stage repair concerning LV-performance and the degree of dilation of the neoaortic root. The significantly reduced size of the neopulmonary root after both procedures is remarkable, but fortunately mostly without clinical significance.
Aorta↗
Predictors of aneurysmal formation after surgical correction of aortic coarctation.
OBJECTIVES: We sought to identify the predictors of aneurysmal formation after surgical correction of aortic coarctation. BACKGROUND: In 9% of patients, aneurysms develop late after corrective surgery of coarctation of the aorta, with a 36% mortality rate if left untreated. However, the predictors of postsurgical aneurysmal formation are unknown. METHODS: Of 25 aortic aneurysms requiring corrective surgery 152 +/- 78 months after the initial coarctation repair, 8 were located in the ascending aorta (type A) and 17 at the site of previous repair (local type). Seventy-four patients without progression of the aortic diameter within 189 +/- 71 months after coarctation repair were used for categorical data analysis in an attempt to identify the predictors of postsurgical aneurysmal formation. RESULTS: Advanced age at coarctation repair (p = 0.004) and patch graft technique (p < 0.0005) independently predicted local aneurysmal formation. Type A aneurysm was univariately associated with the presence of a bicuspid aortic valve (p = 0.02), advanced age at coarctation repair (p = 0.044) and a high preoperative peak systolic pressure gradient of 74 +/- 21 mm Hg (p = 0.041). Conversely, multivariate analysis confirmed only the presence of a bicuspid aortic valve (p = 0.015) as an independent predictor of type A aneurysm. Receiver operating characteristic curve analysis revealed that 72% of patients with a postsurgical aneurysm had an operation at age 13.5 years or more, whereas 69% with no postsurgical aneurysm had an operation at a younger age. CONCLUSIONS: Use of the patch graft technique and late correction of coarctation can predict aneurysmal formation at the site of coarctation repair, although patients with a bicuspid aortic valve may be at risk for an aneurysm developing in the ascending aorta, particularly after late repair of aortic coarctation with high preoperative pressure gradients.
Adolescent↗
[Minimally invasive coronary surgery].
Regardless the general acceptance of cardiac operations by physicians and patients as routine procedures since the early seventies conventional cardiac surgery is still associated with a significant surgical trauma and exceptional invasiveness in part effected by the extracorporeal circulation. In parallel to the common interest of nearly all surgical fields to minimize the invasiveness of surgery the intentions in cardiac surgery aim at minimizing surgical access on the one hand and avoidance of extracorporeal circulation on the other hand. Subsequently a broad variety in applying minimal surgical access including total endoscopic procedures as well as beating heart surgery without extracorporeal circulation with modified cannulation and clamping technology was investigated. Out of these three different concepts were essentially developed for coronary surgery. 1. The MIDCAB (minimally invasive direct coronary artery bypass) procedure with revascularisation of the LAD through an anterior mini-thoracotomy using the left IMA on the beating heart. 2. The OPCAB (off-pump coronary artery bypass) procedure by use of a median complete or partial sternotomy with multi-vessel revascularisation on the beating heart. 3. The TECAB (totally endoscopic coronary artery bypass) procedure with total endoscopic access usually under conditions of extracorporeal circulation. Concluding from significant experience over several years MIDCAB and OPCAB procedures are adequately accepted and can be offered for suitable patients. Regarding the yearly case-load of around 70,000 procedures in coronary surgery in Germany minimally invasive techniques are applied in just up to 4-5%. The individual coronary anatomy and presence of co-morbidities represent essential selection factors deciding over the potential use of minimally invasive techniques.
Coronary Disease↗
Partial ex situ surgery of the heart.
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Adult↗
Experience on endothelial cell adhesion on vascular stents and stent-grafts: first in vitro results.
RATIONALE AND OBJECTIVES: To evaluate endothelial cell (EC) attachment on different stents and stent-grafts combined with different coating materials. MATERIALS AND METHODS: Three segments (approximately 1cm(2) each) of Cragg-, Memotherm-, Palmaz-, Strecker-, and Wall-stents, uncovered or covered with polytetrafluoroethylene (PTFE), polyurethane (PU) or polyester (Dacron) were precoated with fibronectin and seeded in vitro under steady conditions with 2 x 10(5) human venous EC/cm(2) for 2 days. EC attachment and morphology was assessed by scanning electron microscopy. RESULTS: Superior EC attachment on uncovered stents was seen on Memotherm-, Palmaz-, and Wall-stent. On uncovered Cragg- and Strecker-stent only a few single and rounded EC could be detected. PTFE-covering lead to an equal or decreased EC coverage in comparison with the uncovered prostheses. An increase in EC coverage on PU-covered stents was seen and on polyester covered stents as compared with uncovered stents. CONCLUSION: In vitro, EC attachment is clearly different on vascular stents and stent-grafts, probably depending on the material of the stents stent and unknown manufacturing related components. When EC adhesion is desired and stent covering is used, the choice of covering material may influence EC adhesion.
Cell Adhesion↗
Mid-term results after endovascular stent-grafting of descending aortic aneurysms in high-risk patients.
PURPOSE: To analyze our experience with endovascular stent-grafting of descending aortic aneurysms in high-risk patients. METHODS: Nineteen patients underwent endovascular stent-graft repair of descending aortic aneurysms using the Talent Stent Graft System (Medtronic). All patients were considered high-risk for open surgical repair due to their age, requirement for emergency surgery, and comorbidities. Computed tomography and/or MR tomography were performed at 3, 6 and 12 months postoperatively and thereafter every 12 months. RESULTS: Secondary technical success was 100%. Thirty-day mortality was 5%. Incidence of postoperative stroke and paraplegia were 5% each. One patient required a second stent-graft due to a type I endoleak during the same hospital stay (primary technical success 95%). All patients have been followed for a median of 20 months. No migration, wire fractures or endoleak appeared during follow-up. CONCLUSION: Endovascular stent-grafting had a low 30-day mortality and morbidity in high-risk patients. One patient developed an aortoesophageal fistula 40 days after stent implantation. Stent-graft repair is a valuable supplement to surgical therapy in high-risk patients.
Adult↗