Biomedical subjects

M Lindstaedt

Publications and source records attributed to M Lindstaedt.

6 recordsLinked to original sources

PubMed2006

[Angiographic assessment of functionally insignificant left main coronary artery stenoses: reliability compared to intracoronary pressure measurement].

BACKGROUND AND OBJECTIVE: Left main coronary artery disease (LMCA) is still a widely accepted indication for coronary artery bypass surgery. Intermediate LMCA disease, however, often cannot be evaluated reliably on the basis of clinical and angiographic information alone. The deferral of surgical revascularization based on fractional flow reserve (FFR) measurements has been shown to be safe and feasible when taking an FFR value of (3) 0.75 as cutoff. This study was performed to compare the accuracy of visual angiographic assessment of intermediate LMCA stenoses by experienced interventional cardiologists with functional assessment by FFR in a patient population with excellent long-term outcome after deferral of surgery on the basis of FFR measurements. PATIENTS AND METHODS: 24 of 51 consecutive patients with intermediate LMCA disease were deferred from surgery based on an FFR value of > or = 0.75. Each angiogram was retrospectively reviewed independently by three experienced interventional cardiologists. Reviewers were blinded to initial FFR results, clinical data, and clinical outcome and asked to classify each lesion as SIGNIFICANT (FFR < 0.75), NOT SIGNIFICANT (FFR > or = 0.75), or UNSURE if the observer was unable to make a decision based on the angiogram. RESULTS: Mean follow-up was 29 +/- 13.6 months. No death or myocardial infarction was observed, event-free survival was 69 %. When taking the "unsure" classifications into consideration the individual reviewers achieved correct lesion classification with respect to FFR results on average in 58 % to 82 % of cases. Interobserver variability resulted in only 46 % of cases in concordant lesion classification (3 agreements or 2 agreements and 1 "unsure" evaluation). The number of concordant agreements between the individual pairs of reviewers did not exceed the rate of coincidental agreements that could be expected to result from simple guessing (mean KAPPA coefficient 0.04). More than 50 % of patients with excellent long-term outcome after deferral of surgery would potentially have undergone operative revascularization if consensual decision making had been solely based on angiographic lesion assessment. CONCLUSION: The functional significance of intermediate or equivocal LMCA lesions should not be based on visual assessment alone, even when performed by experienced interventional cardiologists.

Blood Pressure↗

PubMed2005

Normal angiogram in acute coronary syndrome-preangiographic risk stratification, angiographic findings and follow-up.

BACKGROUND: Coronary angiographies performed during acute coronary syndrome show different coronary morphologies-vessel occlusions, thrombi and various types of stenoses. In a few cases of acute coronary syndrome, angiography reveals normal coronary arteries. It is the purpose of this study to analyze this specific subset of patients who presented with an acute coronary syndrome but had a normal coronary angiogram with respect to the preangiographic diagnostics, risk stratification and clinical follow-up. METHODS AND RESULTS: A total of 897 coronary angiographies were performed as an emergency procedure in our institution. The majority of patients (n = 821) presented with coronary artery disease and the majority was treated by mechanical revascularization (86.3%). In 76 patients (8.5%), no coronary artery stenosis was documented. However, according to the preangiographic risk stratification, coronary artery disease was expected in these patients. Observations documented angiographically included coronary spasms (6.6%) and muscle bridges (5.3%). During a mean follow-up of 11.2 +/- 6.4 months, one patient developed an acute myocardial infarction requiring coronary intervention. All other patients were free of any cardiac event. CONCLUSIONS: In summary, we have to consider that coronary angiography may not always detect the cause of myocardial ischemia in every patient. There is a small group of patients with normal coronary angiograms during acute coronary syndrome. Additional diagnostic procedures like intravascular ultrasound (IVUS) or the assessment of intracoronary physiological parameters may increase the diagnostic value of angiography.

Acute Disease↗

PubMed2005

Access-site complications after rescue percutaneous coronary intervention during thrombolysis for acute myocardial infarction.

Aggressive antithrombotic medical therapy may increase the rate of access-site complications after percutaneous coronary intervention. Frequently, emergency coronary interventions have to be performed in a situation when thrombolysis therapy was administered as the first-line therapeutic approach in acute myocardial infarction but failed to achieve stable conditions. We analyzed the rate of femoral bleeding complications after emergency coronary intervention in 76 consecutive patients with unsuccessful thrombolysis in acute myocardial infarction. All invasive procedures were performed in a time period no longer than eight hours after thrombolysis was administered. Additional antithrombotic therapy with heparin and glycoprotein IIb/IIIa-inhibitors was given during intervention in 100% and 38.2% of patients, respectively. In three patients (3.9%) femoral hematomas without therapeutic consequences were documented; one patient (1.3%) developed a hematoma requiring blood transfusion. A pseudoaneurysm, fistula or surgical vascular intervention did not occur. Coronary interventional procedures in rescue situations can be performed with excellent safety with respect to access-site bleeding complications even under conditions of ongoing thrombolysis therapy and aggressive antithrombotic medical regimens.

Aged↗

PubMed2003

Strain imaging with intravascular ultrasound array scanners: validation with phantom experiments.

Intravascular Ultrasound (IVUS) is routinely used in interventional cardiology for imaging coronary plaque morphology. However, the use of B-mode images for tissue characterization and detection of vulnerable coronary plaques is limited. Strain imaging with ultrasound is a new modality that provides additional information for tissue characterization by imaging differences in tissue stiffness. The aim is to differentiate between vulnerable (soft) plaques and less dangerous calcified (hard) plaques. In this work, the applicability of a time efficient strain imaging algorithm in conjunction with data from IVUS array transducers is evaluated. Unfocused radiofrequency (rf) data from the transducer array is acquired using custom made hardware. Rf line reconstruction is performed offline by synthetic aperture focusing techniques. Vessel mimicking phantoms of different geometries and material stiffness are made from agar and Polyvinyl Alcohol Cryogel (PVA). Experiments are conducted in a water tank and a water column is used for applying intraluminal pressure differences required for strain imaging. The results show that strain images can be calculated with A-lines reconstructed from unfocused rf raw data. Regions of different stiffness can be identified qualitatively by local strain variations. With the used algorithm strains of up to 2% can be imaged without significant decor-relation.

Algorithms↗

PubMed2001

Anti-MPO-ANCA-positive microscopic polyangiitis following subacute bacterial endocarditis.

Although infectious agents such as Staphylococcus aureus have been implicated in the pathogenesis of Wegener's granulomatosis, the role of bacterial infections in the pathogenesis of other types of small-vessel vasculitides associated with antineutrophil cytoplasmic antibodies (ANCA) is less clear. We describe a patient who developed a non-granulomatous necrotising small vessel vasculitis and perinuclear ANCA (p-ANCA) directed against myeloperoxidase (MPO) after recurrent episodes of bacterial endocarditis due to Staph. aureus. Although cytoplasmic ANCA (c-ANCA) directed against proteinase 3 have been reported in single patients with bacterial endocarditis, to our knowledge this patient is the first reported case of an anti-MPO-ANCA positive systemic vasculitis following bacterial endocarditis.

Antibodies, Antineutrophil Cytoplasmic↗

PubMed2001

Efficacy and safety of ticlopidine monotherapy versus ticlopidine and aspirin after coronary artery stenting: follow-up results of a randomized study.

A combined antiplatelet treatment with ticlopidine and aspirin has been accepted as standard pharmacological regimen after coronary artery stenting. No data of a randomized trial are available on ticlopidine monotherapy. This prospective, randomized monocenter trial investigates the role of ticlopidine monotherapy versus combined antiplatelet therapy with ticlopidine and aspirin in unselected patients undergoing coronary artery stenting. After successful placement of 378 coronary artery stents, two hundred and forty-three consecutive patients were randomly assigned to receive antiplatelet therapy with 2 x 250 mg ticlopidine (121 patients) or a combination of 2 x 250 mg ticlopidine plus 100 mg aspirin (122 patients) daily. The primary endpoint included the absence of death, cardiac events and vascular access-site complications during the in-hospital phase. Angiographic and clinical assessment was repeated at the 3-month follow-up exam. Two hundred and thirty-seven patients (97.5%) were free from cardiac and non-cardiac events. Stent thromboses were seen in 2 patients of the combined treatment group, while none were observed in the monotherapy group. No statistically significant differences were found between the 2 groups regarding the primary endpoint. Angiography performed in 210 patients (86.4%) at follow-up revealed a restenosis rate of 29.4% in the combined treatment group and 27.8% in the monotherapy group. Monotherapy with ticlopidine is as safe and effective as a combined regimen of ticlopidine plus aspirin after coronary artery stenting in an unselected patient population. These results need to be confirmed in a larger multicenter trial.

Aged↗