Biomedical subjects

Thomas Meinertz

Publications and source records attributed to Thomas Meinertz.

78 records · Page 5Linked to original sources

PubMed2002

Laser coronary angioplasty: history, present and future.

The efficacy of percutaneous transluminal coronary angioplasty (PTCA) is limited by remaining plaque tissue and the development of restenosis. It has been demonstrated that the restenosis rate is low if a large lumen diameter is achieved after coronary intervention. Debulking of coronary stenoses is a concept to increase the luminal diameter after intervention. Laser angioplasty debulks coronary stenoses by ablation of atherosclerotic plaque. Since the first intravascular laser intervention, the technique has been significantly improved by the use of optimized wavelength, the development of flexible optimally spaced multifiber catheters and an additional saline flush technique. These technical advancements allowed a reduction in the incidence of adverse events, such as the number of dissections and perforations, associated with the use of the laser technique. Coronary laser angioplasty is commonly combined with adjunctive balloon angioplasty to optimize the outcome. Laser coronary angioplasty was not followed by a lower restenosis rate compared with plain balloon angioplasty in lesions without stents, however, a randomized comparison of the techniques including the use of the saline flush technique is not available yet. The value of excimer (acronym for excited dimer) laser coronary angioplasty for treatment of in-stent restenosis is still under investigation. So far, nonrandomized single center studies have not suggested a relevant benefit for this technique used for in-stent restenosis. In nonstented lesions there remain niche indications for laser angioplasty such as the treatment of ostial lesions, diffuse lesions or lesions traversable with a guidewire but not with an angioplasty balloon. Laser coronary angioplasty may also be useful after a failed balloon angioplasty and in patients with chronic total occlusions. The potential advantages of combining laser coronary angioplasty with vaporization of thrombus in patients with acute coronary syndromes are currently under evaluation.

Angioplasty, Laser↗

PubMed2001

Implications of troponin testing in clinical medicine.

During the past decade considerable research has been conducted into the use of cardiac troponins, their diagnostic capability and their potential to allow risk stratification in patients with acute chest pain. Determination of risk in patients with suspected myocardial ischaemia is known to be as important as retrospective confirmation of a diagnosis of myocardial infarction (MI). Therefore, creatine kinase (CK)-MB - the former 'gold standard' in detecting myocardial necrosis - has been supplanted by new, more accurate biomarkers.Measurement of cardiac troponin levels constitute a substantial determinant in assessment of ischaemic heart disease, the presentations of which range from silent ischaemia to acute MI. Under these conditions, troponin release is regarded as surrogate marker of thrombus formation and peripheral embolization, and therefore new therapeutic strategies are focusing on potent antithrombotic regimens to improve long-term outcomes. Although elevated troponin levels are highly sensitive and specific indicators of myocardial damage, they are not always reflective of acute ischaemic coronary artery disease; other processes have been identified that cause elevations in these biomarkers. However, because prognosis appears to be related to the presence of troponins regardless of the mechanism of myocardial damage, clinicians increasingly rely on troponin assays when formulating individual therapeutic plans.

Journal Article↗

PubMed2000

Design of a trial evaluating myocardial cell protection with cariporide, an inhibitor of the transmembrane sodium-hydrogen exchanger: the Guard During Ischemia Against Necrosis (GUARDIAN) trial.

Inhibition of the sodium-hydrogen exchanger (NHE) is a powerful experimental tool to inhibit sodium and calcium accumulation within the ischemic myocyte and halt progression of cell ischemia to cell necrosis. This paper describes the protocol and rationale of a first large-scale clinical trial designed to evaluate the safety and efficacy of cariporide, a novel specific and potent inhibitor of the exchanger.

Journal Article↗

PubMed1998

Initial single-center experience with a new intracoronary stent.

We investigated the safety and efficacy of the recently introduced intracoronary beStent(TM). High flexibility, zero shortening after expansion and delineating gold markers at either end of the stent are favorable features of this device. Between July 1996 and February 1997, 117 patients received a total of 126 stents, measuring 15, 25 and 35 mm in length. The majority of lesions were located in the LAD (n = 48; 38%), followed by lesions in the RCA (n = 41; 33%) and the circumflex artery (n = 28; 22%). Nine additional stents were delivered into vein grafts (7%). Successful stent deployment was achieved in 94% (n = 118), even in cases with complex lesion morphology and angulated segments. The markers proved to be helpful in placing the stent close to side-branches and whenever serial stents were used. Complications during hospitalization were as follows: one cardiac death unrelated to stenting, one subacute stent thrombosis after 30 min of effective anticoagulation and one Q-wave myocardial infarction due to peripheral thrombus embolization after stent placement in a vein graft. One patient was sent for elective CABG after an unsatisfactory procedural result. Stent loss occurred in four patients, and all stents could be retrieved successfully; in another four patients stent placement at the target site was impossible. We conclude that the investigated stent demonstrates several favorable stent characteristics which have proved to be useful in treating complex lesions by providing favorable acute results with a low complication rate.

Journal Article↗

PubMedDate not supplied

Emergency stent-graft placement in thoracic aortic dissection and evolving rupture.

BACKGROUND: Even with rapid diagnosis and effective medical treatment mortality in type B aortic dissection with evidence of extraaortic leakage of blood remains high. Considering a mortality rate of 29% to 50% associated with emergency surgical repair, the concept of endovascular stent-graft placement may become a life-saving option in impending or evolving rupture by endovascular sealing of the entry tear and subsequent abortion of leakage. METHODS: The concept was tested by comparing short-term and 1-year outcomes of 11 patients after emergency endovascular stent-graft placement with historic-matched control patients subjected to conventional therapy. All patients had acute type B dissection complicated by loss of blood into periaortic spaces. RESULTS: Emergency stent-graft placement was successful without periprocedural morbidity, aborted leakage, and ensured reconstruction of the dissected aorta; at a mean follow-up of 15 +/- 6 months no death had occurred in the stent-graft group whereas four patients had died with conventional treatment (p < 0.05). CONCLUSION: With appropriate logistics and expertise, type B aortic dissection with leakage and evolving rupture may benefit from nonsurgical reconstruction of the dissected segment by endovascular stent grafts.

Acute Disease↗

PubMedDate not supplied

Value of intravascular ultrasound for endovascular stent-graft placement in aortic dissection and aneurysm.

BACKGROUND: Endovascular stent-graft placement is a new concept for the treatment of aortic dissection and aneurysm. Intravascular ultrasound (IVUS) with established diagnostic features may be instrumental in guiding endovascular procedures. METHODS: We performed IVUS and digital angiography before, during, and after implantation of 47 stent grafts in 40 patients with Stanford type B dissection (26 patients, 28 stent grafts), thoracic aneurysm (9 patients, 11 stent grafts), and abdominal aneurysm (5 patients, 8 stent grafts). RESULTS: IVUS could clearly identify the aortic anatomy and differentiate between true and false lumen in all cases of dissection. In four patients with type B dissection extending from the thoracic to the abdominal aorta the true lumen was exclusively identified by IVUS, and thus, essential for safe execution of the procedure. In another patient stent-graft placement in the aorta was optimized by covering a second entry detected by IVUS, but undetected by angiography. The site of stent implantation, the true and false lumen, as well as entry and reentry were always identified in both thoracic and abdominal aorta. In comparison with angiography, IVUS information led to additional balloon molding due to incomplete stent apposition in seven cases. CONCLUSIONS: As an adjunctive imaging modality IVUS is likely to improve stent-graft placement in aortic type B dissection, especially in patients with abdominal extension.

Adult↗