Biomedical subjects

C Ozbek

Publications and source records attributed to C Ozbek.

At least 19 recordsLinked to original sources

PubMed2005

A novel approach: ascending venous arterialization for atherosclerosis obliterans.

OBJECTIVE: Lower limb arterial occlusion with no patent distal artery suitable for revascularisation is a common problem. The aim of this study was to assess the role of revascularisation to distal veins (ascending venous arterialization) in patients not reconstructable by conventional bypass. METHOD: Ascending venous arterialization is a distal arteriovenous fistula. Reversed great saphenous vein grafts, from above the knee, were anastomosed to the common femoral artery, superficial femoral artery or popliteal artery and distally to the saphenous vein at the level of medial malleolus. No intervention was done to destroy the venous valves. The great saphenous vein was ligated below the knee. In this way, oxygenated blood could reach to dorsal venous arch and the tissues below the knee in an ascending fashion through the great saphenous vein, which was not removed. RESULTS: All of the patients recovered immediately after the operation. The lesions on the feet and on the toes of the patients improved in a short time. Intermittent claudication of the patients disappeared. Strong pulses were detected on the dorsal venous arch with manual Doppler in 3 weeks. The below knee tissues were perfused with the applied technique. CONCLUSION: Ascending venous arterialization can be applied for limb salvage to the patients who do not have a suitable arterial bed to revascularize with conventional techniques.

Adult↗

PubMed2001

Long-term follow-up of a randomized study of primary stenting versus angioplasty in acute myocardial infarction.

PURPOSE: Primary stenting leads to better short-term outcomes than does balloon angioplasty among patients with acute myocardial infarction, but there are no data available on long-term follow-up. SUBJECTS AND METHODS: We designed a randomized study with long-term follow-up to compare primary angioplasty with angioplasty accompanied by implantation of a silicon carbide-coated stent in patients within 24 hours after the onset of acute myocardial infarction. All 88 patients had lesions that were suitable for coronary stenting. RESULTS: There were 44 patients in each of the randomization groups. During long-term follow-up (mean +/- SD: 710+/-282 days), primary stenting was associated with a reduction in the combined endpoint of death, reinfarction, or target vessel revascularization (10 [23%] versus 19 [43%], P = 0.03); death (4 [9%] versus 8 [18%], P = 0.18); reinfarction (1 [2%] versus 4 [9%], P = 0.18); and target lesion revascularization (7 [16%] versus 15 [34%], P = 0.04). Rehospitalization due to ischemic events (unstable angina or reinfarction) was also less frequent in the stent group (6 [14%] versus 10 [23%], P = 0.20). CONCLUSION: Primary stenting in acute myocardial infarction is significantly superior to angioplasty alone in both short-term and long-term follow-up.

Aged↗

PubMed2001

Simultaneous surgical revascularization and angiogenic gene therapy in diffuse coronary artery disease.

OBJECTIVE: The cytokine vascular endothelial growth factor (VEGF) is capable of triggering angiogenesis and at higher concentrations vasculogenesis. We report on a pilot study where VEGF-DNA as an additional therapy to coronary artery bypass grafting was injected into the myocardium in 24 patients (pts) with proximal coronary artery stenosis and diffuse peripheral disease. One region of the myocardium with proven ischemia remained unsupplied after surgery because the respective epicardial coronary artery was not graftable. METHODS AND RESULTS: Plasmid DNA encoding for the 165- and 167-amino acid isoform of the human VEGF genes was injected directly into the myocardium, not amenable to surgical revascularization at a dosage of 1000 microg each, using a standardized protocol. A (99m)Tc-sestamibi-SPECT at rest performed 7 days prior to the operation, had shown decreased marker activity in the region of interest. Controls were made 1 week and 80-100 days postoperatively. Transmural scarring was ruled out intraoperatively. Coronary and left ventricular angiographies were performed preoperatively and 3 months postsurgery, respectively. One or more of the following angiographic items were found in 16/24 patients postoperatively. (1) Improvement of regional left ventricular function at the VEGF treated myocardial sector (5/24 pts). (2) Newly visible vessels considered as collaterals (8/24 pts). (3) Earlier filling of parent vessels (6/24 pts). (4) An increase in diameter of preoperatively existing collateral vessels (7/24). An increased perfusion at rest in the region of gene application was detected in 3/24 patients by early postoperative (99m)Tc-sestamibi-SPECT investigation. In six additional cases, local perfusion increased markedly until the late examination. No perioperative myocardial infarctions and no signs of inflammation were observed. Newly developed abnormal vasculature was not detected in any patient. CONCLUSIONS: Direct intramyocardial administration of VEGF(165)-DNA and VEGF(167)-DNA may result occasionally in an enhancement of collateral vascularization in regions with diffuse peripheral coronary artery disease not surgically amenable. During midterm follow-up no adverse effects of VEGF-DNA application are observed so far. The very slight midterm improvements caused us to stop further VEGF-DNA application and, in our opinion, do not justify a prospective, and randomized study with a control group.

Aged↗

PubMed2001

An intraaortic solution trial to prevent spinal cord injury in a rabbit model.

OBJECTIVES: to evaluate the effectiveness of an intraaortic delivered solution on preventing spinal cord injury. DESIGN: forty rabbits were allocated into five equal groups. MATERIALS AND METHODS: one clamp was placed just distal to the left renal artery, and another was placed just above the iliac bifurcation for 40 min. Group 1 was not infused (control group). Through a 24G vascular catheter inserted into the isolated aortic segment, 20 ml of LR solution at room temperature (Group 2) 20 ml of LR solution at 3 degrees C (Group 3), and 20 ml of LR solution at 3 degrees C containing 30 mg/kg of methylprednisolone (Group 4) were infused over 3 min. In Group 5, 10 mg/kg of vitamins E and C were delivered two days before the experiment, and 20 ml of LR solution at 3 degrees C containing 30 mg/kg of methylprednisolone, and 10 mg/kg of vitamins E and C was infused at the operation. Postoperative spinal cord function was assessed using Tarlov's criteria. RESULTS: the neurologic status of Groups 3, 4, and 5 was significantly superior to that of Groups 1 and 2. No paraplegia was observed in Groups 4 and 5. Spastic paraplegia occurred in all rabbits of Groups 1 and 2, and in 20% of Group 3. In the electron microscopic evaluation of spinal cord specimens, normal histologic structure was observed in Groups 4 and 5, whereas, some derangements were observed in all others. CONCLUSIONS: intraaortic infusion of a hypothermic blended solution containing methylprednisolone, vitamins C and E provided best protection against postischaemic spinal cord dysfunction.

Animals↗

PubMed2001

The role of Helicobacter pylori infection in the cause of squamous cell carcinoma of the larynx.

OBJECTIVE: Helicobacter pylori can cause chronic infection that has been linked to the development of both benign and malignant disease of the aerodigestive tract. The purpose of this study was to determine the link between H pylori infection and squamous cell carcinoma of the larynx (SCCL). METHODS: We estimated the presence of IgG antibodies against H pylori antigens by using ELISA technique in the sera of 26 patients with SCCL and 32 matched controls without carcinoma of the larynx. RESULTS: The incidence of seropositivity of patients with SCCL was 73.07% and of controls was 40.62%. These data support an etiologic role for H pylori infection on development of SCCL (chi(2) = 4.85, P< 0.05). CONCLUSION: H pylori infection of the upper aerodigestive tract might result in mucosal disruption, allowing for subsequent transformation by known carcinogens such as tobacco and alcohol.

Aged↗

PubMed2000

A synergistic approach to optimal stenting: directional coronary atherectomy prior to coronary artery stent implantation--the AtheroLink Registry. AtheroLink Study Group.

OBJECTIVES: The AtheroLink registry sought to observe the effect of plaque burden reduction by directional coronary atherectomy (DCA) prior to stenting on acute lesion success rate, on the clinical success rate and on the incidence of in-stent restenosis six months after intervention. BACKGROUND: Although coronary stenting has reduced restenosis, its effect has been less favorable in complex lesions with a high plaque burden that results from suboptimal stent expansion. Therefore, plaque removal by DCA may improve the results of coronary stenting. METHODS: A total of 167 patients with >60% stenosis in a native coronary artery of 2.8 to 4.0 mm in diameter were enrolled in 10 study centers on an intention-to-treat basis. All patients underwent DCA aimed at an optimal result (residual diameter stenosis <20%) followed by stenting. Angiographic follow-up was performed in 120 (71.8%) patients at 5.3+/-2.8 months. RESULTS: Lesion success was achieved in 164/167 (98.2%) patients, and the clinical success rate was 95.2% (159/167 patients). The overall restenosis rate in the 120 patients with angiographic follow-up was 10.8% (13/120). Incidence of restenosis was lower (8.4%) in patients with optimal stent deployment following DCA compared to patients with a persisting caliber reduction >15% (restenosis rate 15.3.%) and restenosis occurred with a significantly higher frequency (p<0.04) in distal lesions (37.5%) compared to proximal stenoses (9.0%). CONCLUSIONS: This observational multicenter registry points to a potential reduction in restenosis by a synergistic approach of DCA and stenting performed under routinely accessible angiographic guidance. Therefore, multicenter-based randomized clinical trials are clearly warranted to finally clarify the validity of this complex approach versus conventional angioplasty plus stenting.

Aged↗

PubMed2000

A randomized comparison of balloon angioplasty versus rotational atherectomy in complex coronary lesions (COBRA study).

AIMS: Rotablation is a widely used technique for the treatment of complex coronary artery lesions but is so far only poorly supported by controlled studies. The Comparison of Balloon-Angioplasty versus Rotational Atherectomy study (COBRA) is a multicentre, prospective, randomized trial to compare short- and long-term effects of percutaneous transluminal coronary angioplasty (PTCA) and rotablation in patients with angiographically pre-defined complex coronary artery lesions. METHODS AND RESULTS: At seven clinical sites 502 patients with pre-defined complex coronary artery lesions were assigned to either PTCA (n=250) or rotablation (n=252). Primary end-points were procedural success, 6-month restenosis rates in the treated segments, and major cardiac events during follow-up. Procedural success was achieved in 78% (PTCA), and 85% (rotablation) (P=0.038) of cases. Crossover from PTCA to rotablation was 4% and 10% vice versa (P=0.019). There was no difference between PTCA and rotablation with respect to procedure-related complications such as Q wave infarctions (2.4% each), emergency bypass surgery (1.2% versus 2.4%), and death (1.6% versus 0.4%). However, more stents were required after PTCA (14.9% versus 6.4%, P<0.002), predominantly for bailout or unsatisfactory results. Including bail-out stents as an end-point, the procedural success rates were 73% for angioplasty and 84% for rotablation (P=0.006). At 6 months, symptomatic outcome, target vessel reinterventions and restenosis rates (PTCA 51% versus rotablation 49%, P=0.33) were not different. CONCLUSION: Complex coronary artery lesions can be treated with a high level of success and low complication rates either by PTCA with adjunctive stenting or rotablation. The long-term clinical and angiographic outcome is comparable.

Adult↗

PubMed1999

Three-year follow-up of patients with silent ischemia in the subacute phase of myocardial infarction after thrombolysis and early coronary intervention.

In order to assess the prognostic value of silent myocardial ischemia in acute myocardial infarction after thrombolysis and early coronary angiography (14-48 h after start of thrombolysis) including percutaneous transluminal coronary angioplasty, if indicated, 126 patients underwent 24 h-Holter-monitoring in the early postinfarction period. The 24 h-Holter-recording was initiated directly after early coronary intervention (40+/-11 h after onset of symptoms). Of the 126 patients initially eligible for the study 29 had to be excluded from further analysis for clinical or methodical reasons. Of the remaining 97 patients, 10 (10%) had silent ischemia (group A) and 87/97 (90%) patients showed no significant ST-segment alterations. Both groups did not significantly differ from each other with regard to baseline clinical characteristics, severity of coronary artery disease and frequency of successful percutaneous transluminal coronary angioplasty. The left ventricular ejection fraction showed a trend towards lower values in patients with than in those without silent ischemia (47+/-15% vs. 55+/-13%, p=0.07). When both silent ischemia and left ventricular ejection fraction <40% were present, a subset of patients at high risk for cardiac death could be identified (specificity: 98%, positive predictive accuracy: 75%). By Kaplan-Meier analysis, significantly more cardiac deaths occurred in group A than in group B (30% vs. 6%, p<0.01) during the three-year follow-up (950+/-392 days) after acute myocardial infarction. Regarding the cardiac events during long-term follow-up (emergency percutaneous transluminal coronary angioplasty, coronary artery bypass grafting, non-fatal reinfarction, and cardiac death) there was no significant difference between both groups (30% vs. 18%, NS). In conclusion, Holter monitor-detected silent ischemia in the subacute phase of myocardial infarction after thrombolysis followed by early delayed coronary intervention occurs in 10% of the patients indicating either a residual ischemia in the infarcted zone despite a combined reperfusion strategy or a remote ischemic potential in case of multivessel disease. In this small selected group of infarct patients too, silent ischemia is to be considered as an important non-invasive parameter to predict cardiac death during long-term follow-up and provides valuable complementary information to left ventricular dysfunction, a well established prognostic marker in the postinfarction period.

Adult↗

PubMed1999

Cerebral microemboli during left heart catheterization.

BACKGROUND: The aim of this study was to describe the rate of microemboli signals (MES) during left heart catheterization (LHC). METHODS: A monitoring of both middle cerebral arteries using transcranial Doppler ultrasonography was performed to investigate cerebral microemboli during LHC. Seventy-two patients undergoing LHC and 29 patients with LHC followed by coronary intervention were studied. RESULTS: During a standardized LHC (n = 52), 95 +/- 45 MES were detected of which 67.5% occurred during injection of contrast media or saline solution, 30% during movements of wire and catheter, and 2% during catheter manipulation. During coronary interventions only, rotablation (n = 2) was followed by a massive increase in MES. The use of injection fluids prepared with minor gas content reduced the MES rate by 67% (P <.05). All MES were clinically silent. CONCLUSIONS: Cerebral microembolism is a current finding during LHC. The dependence of the MES rate during diagnostic LHC on the gas content of the injection fluids provides evidence that most of the MES are caused by microbubbles and not by solid emboli. The high rate of MES during coronary rotablation may be explained by the formation of cavitation bubbles. The clinical results of the MES during LHC appear to be benign.

Adult↗

PubMed1999

Early time course of heart rate variability after thrombolytic and delayed interventional therapy for acute myocardial infarction.

In 89 of 97 consecutive patients with myocardial infarction (MI) undergoing thrombolysis and delayed early coronary angiography with PTCA, if indicated, heart rate variability (HRV) in time domain was evaluable 40 +/- 11 h after the onset of chest pain using 24-hour ECG recordings. Patients with anterior MI (n = 40) had lower values for HRV and left ventricular ejection fraction (p < 0.05). The mean of all 5-min standard deviations of RR intervals (SDNNi) and the root-mean-square difference of successive RR intervals (rMSSD) decreased significantly (p < 0.001 each), whereas the standard deviation of all normal RR intervals and the percentage of absolute differences between successive RR intervals only showed a tendency to lower values 4 weeks after MI (p = 0.20 and 0.08, respectively). The decreases in SDNNi and rMSSD were more evident in inferior than in anterior MI. The time course of HRV following MI was similar in patients with and without PTCA. These results indicate an initial vagal hyperactivity in inferior MI, which is quickly predominated by sympathetic activation and a prolonged recovery of the cardiac autonomic imbalance after MI despite a successful combined reperfusion therapy.

Adult↗

PubMed1998

[Roentgen contrast media in invasive cardiology, side effects and different indications].

For invasive catheter procedures both ionic and nonionic contrast media (CM) with excellent tolerability are available. The governing practical factors for CM are X-ray opacity and biocompatibility. Tolerability of a contrast medium is governed among its physical properties by its viscosity, osmolality, and ionic concentration. In Germany the nonionic CM are currently preferred. Because of its low thrombotic complications, the ionic CM Ioxaglat is an important alternative in high risk interventions. In patients with known CM incompatibility, the prophylactic application of H1-receptor antagonists and corticosteroids allows catheterization safely without complications. In impaired renal function, hydration is the most effective prophylactic measure to be taken.

Angioplasty, Balloon, Coronary↗

PubMed1998

Influence of thermal stress on the incidence of acute myocardial infarction in a temperate climate.

Using a Poisson regression model the relative incidence of acute myocardial infarctions (AMI) prospectively registered in 8 hospitals within a radius of 50 km during a 2-year period was correlated with the outside conditions characterized by a complete thermophysiological model (Klima-Michel Model) defining thermal stress. An increase in the incidence of AMI related to thermal stress could be demonstrated neither by splitting the study period into 12 equally sized 'felt-temperature' classes by months of the year nor by single days. This was confirmed by correlation of the AMI rate with the mean felt-temperature level during the preceding 14 days. Thermal stress caused by the atmospheric conditions in a temperate climate may be too weak to influence significantly the incidence of AMI.

Aged↗

PubMed1998

Lack of evidence for a pathogenic role of Chlamydia pneumoniae and cytomegalovirus infection in coronary atheroma formation.

Atherosclerotic cardiovascular disease is generally accepted to be the result of metabolic disturbances. However, recent studies have suggested an infectious agent, especially Chlamydia pneumoniae or cytomegalovirus, to be involved in the pathogenesis of atherosclerosis. Atherosclerotic plaque specimens obtained from patients with coronary disease either by balloon dilatation catheter (13 cases) or atherectomy (16 patients) were examined for the presence of C. pneumoniae and cytomegalovirus. Using two primer pairs for C. pneumoniae, two primer pairs for the identification of unknown bacteria and primer pairs for the detection of immediate early gene E2 and the late genomic region of cytomegalovirus, we were unable to detect the suspected agents. The absence of C. pneumoniae, other bacteria and CMV in coronary atheromas is against the hypothesis of a pathogenetic role of these agents in coronary atheroma formation in the patients studied.

Adult↗

PubMed1998

Experimental intracoronary stenting: comprehensive experience in a porcine model.

Appropriate animal models for intracoronary stenting are most important for improving understanding of the pathophysiology of acute occlusion and long-term re-stenosis, which currently limits the safety and efficacy of percutaneous transluminal coronary angioplasty in humans. Since the anatomy and physiology of swine coronary arteries closely resemble those of humans, the procine model should be ideal for testing of stents. This is a comprehensive report on an experimental set-up in pigs, communicating in detail the necessary techniques as well as some modifications facilitating safe intracoronary stent placement and successful follow-up studies for weeks or months. Stent procedure is performed in mechanically ventilated and haemodynamically monitored animals under balanced anaesthesia. Intracoronary application of flow wires allows the assessment of local flow conditions, flow properties and coronary flow reserve. Real-time intravascular ultrasonography (IVUS) provides detailed information on coronary morphology and enables the appropriate sizing of the coronary lumen. From our own experience, we like to propose that the use of the porcine model has the potential to gain new insights into the pathophysiology of intracoronary stent placement-associated complications and allows for the study of modifications in techniques and materials, and the development of novel pharmacological therapeutic strategies.

Angioplasty, Balloon, Coronary↗

PubMed1998

Silicon carbide-coated stents: clinical experience in coronary lesions with increased thrombotic risk.

PURPOSE: To report the results of a prospective, nonrandomized, multicenter study of a semiconductor-coated stent in coronary lesions at high risk for stent thrombosis. METHODS: A balloon-expandable tantalum stent was coated with silicon carbide to enhance thromboresistance (Tensum). Patients were enrolled in an observational study that compared coronary stenting with the Tensum stent in patients at low risk for stent thrombosis against those with factors predisposing to local thrombosis (acute myocardial infarction, small vessel diameter, recanalized chronic total occlusion, saphenous vein bypass grafts, and coronary allograft vascular disease). RESULTS: In 294 patients with 364 coronary lesions, 111 patients with 142 lesions were assigned to the high-risk group. Overall, 406 Tensum stents were implanted (94% procedural success) using antiplatelet medication only after the procedure. The stent thrombosis rate (2.7% overall) in the high-risk group (3.6%) was not significantly different from that of the low-risk patients (2.1%). CONCLUSIONS: Silicon carbide coating on coronary stents may inhibit acute/subacute stent thrombosis even in patients at high risk. Randomized trials are underway for further evaluation of this promising coated stent.

Adult↗

PubMed1997

Incidence and clinical significance of short-term recurrent ventricular tachyarrhythmias in patients with implantable cardioverter-defibrillator.

Aims of the present study were (1) to investigate the clinical significance of short-term recurrent tachyarrhythmias (STRTs) in ICD recipient, (2) to identify basic characteristics of the subgroup of patients with STRTs and (3) to compare the frequency and circadian pattern of single arrhythmic events and STRTs. We reviewed data from 119 consecutive patients with late generation ICD. All registered spontaneous ventricular tachyarrhythmias were divided into STRTs (defined as two or more consecutive episodes separated by < or =1 h of sinus rhythm) and single events. During a mean follow up of 36+/-18 months (range 2-67 months) 1849 ventricular arrhythmic events were detected in 57 out of 119 ICD recipients (48%). 202 STRTs consisting of 1128 single detection (6+/-7/STRT, range 2-52) occurred in 34/57 patients (60%; 6+/-6 per patient, range 1-21). Recurrent ventricular tachycardias before device implantation and a high number of single arrhythmic events during follow-up distinguished patients with STRTs. Cardiac mortality was significantly higher in patients with STRTs (26 vs. 4%, P<0.05). The majority of both single episodes and STRTs were registered between 8 a.m. and noon and in the evening. This study reveals a high incidence of STRTs in ICD recipients with spontaneous tachyarrhythmias during follow-up and identifies STRTs as prognostic significant events. Comparable circadian variations suggest that similar triggering factors may be involved in the genesis of STRTs and single tachyarrhythmias.

Adult↗

PubMed1997

Coronary implantation of silicone-carbide-coated Palmaz-Schatz stents in patients with high risk of stent thrombosis without oral anticoagulation.

Coronary stenting in bail-out situations is effective but associated with increased stent thrombosis and bleeding rates. Silicone-carbide coating reduces fibrinogen activation on alloplastic surfaces and thus may also reduce stent thromboses. A total of 44 patients received 58 silicone-carbide-coated stents for threatened (80%) or abrupt (20%) closure. In addition to heparin, patients were treated with aspirin and ticlopidine (75%) or aspirin (25%) only. Two patients (4.5%) died in the hospital. The combined in-hospital complication rate including death, emergency revascularization, stent-related myocardial infarction, and stent thrombosis was 9% (4 of 44 patients). Major bleeding occurred in 4 patients (9%). Six-month follow-up angiography was obtained in all eligible patients (42 of 44), revealing a restenosis rate of 21% (9 of 42). Thus, coronary implantation of silicone-carbide-coated stents is feasible in bail-out situations without oral anticoagulation and with a low complication rate. Further studies are required to optimize the anticoagulation regimen with this type of coating.

Adult↗

PubMed1997

Trouser-like stenting: a new technique for bifurcation lesions.

We report on a new technique of stenting a bifurcation lesion. A manually bent 180 degrees hinged slotted tube stent was implanted using the kissing balloon technique (resembling two trouser legs). In addition, the proximal part of the main vessel was covered with a stent mounted on two balloons corresponding to the trousers' waist. This "trousers-like stent technique" ensures open accesses to both vessels not obstructed by stent struts and could be a promising solution for main bifurcation lesions.

Angioplasty, Balloon, Coronary↗